Exploiting renewable energy sources is the only way to achieve carbon neutrality. This perspective first outlined the key strategies for the conversion and utilization of renewable energy, and stated that the theoretical foundation of new energy chemical engineering and technology covered various engineering science including the electrochemical engineering, photochemical engineering, biochemical engineering, molecular chemical engineering, systems engineering, and artificial intelligence, etc. Secondly, taking hydrogen generation from renewable power, fuel cells for chemical and energy cogeneration, solar energy conversion as examples, we elucidated the role of chemical engineering in the process of renewable energy conversion and utilization. Thirdly, we revealed the process engineering characteristics of electrochemical energy storage materials and devices according to the manufacturing process of multi-element transition metal oxide cathodes for lithium- and sodium-ion batteries. Fourthly, we introduced the applications of process system engineering and artificial intelligence in the construction of a battery state of charge/health/power prediction model, integrated energy system management, as well as optimal photovoltaic-energy storage-charge system. Finally, based on detailed case studies, we concluded that the essence of renewable energy chemical engineering is the scaling up of bio-, photo- and electro-chemical reactions involved in renewable energy conversion and storage from laboratory-scale to large-scale devices, and to elucidate the corresponding mass, heat and charge transfer mechanisms and the reaction engineering characteristics. Regarding the future research and development of renewable energy chemical engineering technology, multiple research directions were proposed in respect of the common scientific issues and key technologies.

Power generation driven by intermittent renewable energy such as wind and solar energy, has brought new vitality and opportunity for the rapid development of energy technology. Therefore, developing efficient energy conversion and storage system has become one of the major challenges in the world. The development tendency of electrochemical energy conversion and storage in the future is prospected, which could provide a significant theory and technique guidance for solving the key problems in the industrial applications. Chemical engineering perspectives on the research progress of electrochemical energy conversion and storage in battery, supercapacitor and electrocatalysis are given. Moreover, the status and problems of this field are clarified and analyzed from the aspects of ‘momentum, heat and mass transfer’, system engineering, separation engineering, novel & green and energy-saving strategies.

Clathrate hydrate is the use of the cage structure constructed by water molecules through hydrogen bonding to store and extract methane and other energy gases. Therefore, nature gas storage via clathrate hydrates is the best option for a large-scale storage system because of its non-explosive nature, mild storage conditions, high volumetric capacity and being an environmentally benign process. Natural gas hydrate is a bridge fuel between traditional energy and green energy, which has become a hot spot of research and development by scientists all over the world for research and development. In this paper, it is discussed that as an important research direction of energy and chemical industry, the research of clathrate hydrate mainly focuses on energy and environment, flow safety and engineering application, etc. In all aspects, it covers the fields of energy conversion and energy storage, such as solidified natural gas (SNG), CO₂ capture and gas separation, refrigeration and cold storage, seawater desalination, automobile fuel, hydrogen production and hydrogen storage. Vigorously develop clathrate hydrate derivation technology to achieve the extraction of methane while capturing carbon dioxide, which will help achieve the goal of carbon neutrality. The formation of clathrate hydrate depends on its own thermodynamic phase equilibrium conditions, the dynamic properties of the reaction process and the transfer process. The process from formation to decomposition mainly includes a series of steps, such as dissolution, nucleation, growth, crystal cracking and desorption. The micro mechanism of the process is complex. The use of multi-scale methods to study the microstructure, interface phenomena, macro-applications and mechanism of hydrate formation will help expand the principles and knowledge of chemical engineering. It will also benefit the development of new materials and new processes in the energy and chemical engineering, and promote the development of energy and chemical engineering.

Energy storage and conversion technology in electrochemistry is an important part of human energy system, which involves a variety of physical and chemical processes. Through the theoretical and simulation calculation methods of thermodynamics, most of the problems of energy storage, release and conversion can be solved efficiently. In this paper, the research results of thermodynamics in the field of electrochemistry at home and abroad are summarized, the research of thermodynamics is classified, and its properties, advantages and disadvantages, application scope are introduced in detail. This paper introduces the classical thermodynamics, molecular and statistical thermodynamics, non-equilibrium thermodynamics, high-throughput computing and machine learning in the field of electrochemical energy storage and conversion. Solving electrochemical problems through non-equilibrium thermodynamics is the current development direction and trend. With the development of computer technology, machine learning is a promising research method in this field. It is hoped that this review will play a certain reference role in the further research and technical development of thermodynamics in the field of electrochemistry.

Micro-channel has been successfully applied in gas-liquid two-phase chemical reaction system due to its high specific surface area and strong mass transfer ability. In addition, the research achievement in the field of chemical engineering can also be utilized to improve the fuel cell electrochemical conversion efficiency. However, due to the small scale of micro-channel and the complexity of gas-liquid two-phase flow rules, further study is required to clarify the characteristics of gas-liquid two-phase flow in micro-channel, which can promote it to perform better in practical applications. In this paper, the research progress of the critical characteristics as flow patterns, pressure drop and mass transfer are illustrated. Moreover, the features of different flow patterns and its forming conditions are described, while the corresponding pressure drop and mass transfer capacity are expounded. According to this relationship, readers can get the design parameters and the necessary operated condition to achieve the expected flow patterns which can cost low pressure loss and provide great mass transfer ability. The existing prediction models of pressure drop and mass transfer coefficient and their optimization measures were reviewed. Moreover, the research progress of improving the performance of proton exchange membrane fuel cell (PEMFC) flow field design by using the relevant parameters of these key characteristics were analyzed. Base on that, the optimum proposal toward flow field type, channel size, channel shape, channel surface characteristics can be obtained. However, due to the special structure and working condition of the fine flow channel in PEMFC, it shows great different from the traditional microchannel. Therefore, it was suggested that the two-phase flow patterns, the dynamic change law of pressure drop and mass transfer should be explored aiming at the special characteristics of the fine flow channel of fuel cell, and the specific pressure drop prediction model should be developed. The further study suggested would provide a more accurate reference for the flow field design, and then enhance the performance of PEMFC, accelerate its commercialization process.

Photochemical transformations are considered as an important way to effectively utilize luminous energy for the realization of chemical reactions, and microreactor technology provides a strong platform for improving its process efficiency. In the introduction section, firstly it is pointed out that microreactors have many obvious advantages on various aspects such as distribution of light intensity, process scale-up and utilization efficiency of luminous energy, compared with conventional batch photoreactors, and they can intensify photochemical reaction processes efficiently. Afterwards, the basic characteristics of photochemistry and photochemical microreaction technology are introduced, and the design and construction of photomicroreactors and its applications on the fields of organic synthesis, polymerization, etc., are systematically reviewed. Then photochemical microreaction systems with automation control and its applications are elaborately introduced. In particular, the progress on the photochemical synthesis in microreactors under ultraviolet or visible light irradiation and its process scale-up are highlighted. Finally, the progress in the photochemical microreactor technology is summarized, and its development trend is prospected.

Hydrogen energy is one of the most promising energy carriers to support smart grid and large-scale of power generation by renewable energy. Water electrolysis is one of the most important routes to realize the large-scale of hydrogen production. Among the technologies of water electrolysis, proton exchange membrane electrolyzer (PEMEL) technology has attracted the attention of scientific and industrial communities because of its advantages of high current density, high purity of hydrogen production and fast response speed. This paper firstly introduces the structure of PEMEL and the main functions of each component. The technical differences between the alkaline electrolyzer, solid oxide electrolyzer and proton exchange membrane electrolyzer are compared and analyzed. Through explaining the mechanism of oxygen evolution reaction and hydrogen evolution reaction, this paper introduces common electrocatalysts for electrochemical water splitting. With the advantages of low cost and improved performance, non-noble metal catalysts are becoming more competitive. Then, from the initial laboratory research stage to the current megawatt-level PEMEL, this paper reviews the development process and application of the technology. Further, the current bottlenecks of the technology are discussed from multiple perspective. The major bottlenecks of PEMEL are the cost of hydrogen production, the performance of electrode material and the life of stacks. Finally, it is prospected based on the advantages of PEMEL that the application of such technology has a promising future for the renewable energy demand as well as the joint application with other industries.

The research of photocatalytic water splitting for hydrogen (H₂) generation has been devoted a lot to the efficient utilization of solar energy and the development of hydrogen energy. The design of photocatalysts in photocatalytic hydrogen production is the key step of photocatalytic reaction. The preparation of outstanding and highly efficient photocatalyst is a vital point to improve the photocatalytic performance. In this review, the study of metal sulfides with hollow structures were comprehensively reviewed, including the preparation, application and further progress of the hollow materials. Further, the importance of hollow structure to increase surface area, enhance light absorption, accelerate charge separation and enhance reaction performance was analyzed. Herein, we propose the advantages and future development of hollow-structure in the development of photocatalysis, and provide a reference for the future design of novel photocatalysts, aiming to improve the utilization efficiency of sunlight and accelerate H₂ evolution for the industrial applications of photocatalytic H₂ generation.

Hydrogen energy as a kind of clean energy has the advantages of environmental friendly, zero pollution and zero carbon emission. The steam reforming of aromatics with vast raw materials has a high hydrogen production per unit volume and shows great application value in tar removal and upgrading, portable hydrogen production, etc. The core of aromatics steam reforming is the development of high performance catalysts. Firstly, the progresses of aromatics reforming kinetics and mechanism were summarized mainly from the aspects of reaction characteristics, reaction network, kinetic model construction, adsorption and dissociation. It was considered that the key to deepening the understanding of kinetic process and mechanism was the integration of thermodynamic theoretical calculations, advanced in-situ characterization technologies and rigorous logical demonstration experiments. Then, various active components, supports and promoters of catalysts for aromatics steam reforming were reviewed according to the classification of supported catalysts components. Based on the nickel-based bimetallic synergy, strong oxygen storage-release capacity of perovskite supporters and acidity regulation of alkaline additives, the development of nickel-based bimetallic supported perovskite catalysts promoted by the alkaline additives was proposed.

Photocatalytic hydrogen production with pollutants as electron donors has become a new water treatment technology. While pollutants are degraded in the process, solar energy can be converted into clean hydrogen energy, which effectively alleviates the problems of environmental pollution and energy shortage. This article summarizes the main research achievements in this direction at home and abroad in recent years following the synergistic mechanism of photocatalytic hydrogen production and pollutant degradation, and then lists several commonly used catalysts. The effects of different operating parameters, such as pollutant species, catalyst types and composition, microstructure of catalyst, catalyst dosage, pH, pollutant concentration, different ions and other coexisting substances in the solution, reaction temperature and light intensity, on the photocatalytic degradation rate and hydrogen evolution activity are also discussed. Finally, it is pointed out that the photocatalytic water treatment with pollutants as electronic donors still faces the challenges of few options and low hydrogen production efficiency in the selection of photocatalytic materials, and the exploration of reaction influencing factors is still insufficient. It is also suggested that the multi-unit water treatment system integrating multiple processes should be a mainstream water treatment mode in the future.

As an efficient hydrogen storage method, liquid hydrogen will be widely used in the future, while relatively backward of the storage and transportation technology and the lack of related standards restrict the rapid development of the liquid hydrogen industry. This paper introduced the characteristics and development status of liquid hydrogen, compared different liquid hydrogen storage containers and transportation methods, investigated the current status of international and domestic standards of liquid hydrogen, discussed the urgent need for the establishment of liquid hydrogen standard system, analyzed the difficulties and future development of liquid hydrogen storage and transportation technology, and looked forward to the standard system of liquid hydrogen storage and transportation technology. The analysis showed that, for the storage and transportation technology of liquid hydrogen, reducing the evaporation rate of storage tanks and the cost of equipment would be an important development trend. Furthermore, a sound standard system was imperative for the development of liquid hydrogen storage and transportation technology. The LNG standard system had important reference significance for the standardization of liquid hydrogen storage and transportation.

The durability of proton exchange membrane fuel cells (PEMFCs) for vehicles is one of the key factors restricting the commercial application of hydrogen energy in the transportation field. The presence of trace amounts of CO, H₂S and NH₃ contained in the fuel gas is regarded as one of the most important factors affecting the durability of PEMFCs. This article reviewed the effects of CO, H₂S, and NH₃ in hydrogen on the anode performance of PEMFCs, including the poisoning mechanism, kinetics, the effect of operating conditions and the mitigation strategies, and also discussed the theoretical and experimental foundation for the determination of hydrogen impurity limits. Finally, it pointed out the technical problems and future development directions in the research on the effect of hydrogen impurities on vehicle fuel cells, and emphasized the necessity of determining the tolerance limits of hydrogen impurities that met the durability of vehicle fuel cells, according to the technical development level of PEMFCs technology in our country. It is valuable for the optimization and regulation of the China’s hydrogen quality standards for vehicle fuel cells by providing basic data, and thus prolonging vehicle fuel cell lifetime.

The characteristics of rice husk hydrothermal biochar (HB) and pyrolytic biochar (PB) assisted water electrolysis for hydrogen production were studied at low temperature using H-type electrochemical cell. LSV, EIS and hydrogen production of the biochar slurry were tested by electrochemical workstation, and the electrochemical reaction characteristics of the two kinds of biochar were analyzed through XPS, FTIR, BET, XRD and SEM. The influence of physicochemical properties of biochar on its oxidation process was discussed. Results indicated that the onset potential of HB was very low due to the abundance of—OH groups, while PB showed a strong reactivity at a higher anode potential (>1.2V vs. MSE) due to its rich pore structure and high specific surface area. The solution resistance and charge transfer resistance of the biochar slurries decreased with the increase of reaction temperature. The activation energy of biochar oxidation decreased with the increase of anode potential. The silicate in biochar had inhibition effect on its electrochemical reaction. The current density increased due to the exposure of the surface functional groups of PB after pickling, while the current density decreased due to the removal of the easily oxidized radicals in HB by pickling. Under the same conditions, the hydrogen production rate of PB was higher than that of HB.

A new type of Co-Bi-B ternary alloy catalyst was prepared by a liquid phase co-reduction method, which was then characterized by X-ray diffractometer (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS), etc. The effects of doping molar ratio and temperature on the catalytic performance of hydrogen generation from the hydrolysis of sodium borohydride were systematically investigated. The experimental results showed that the ternary alloy catalyst obtained by doping Bi had a well-defined crystal structure and the doping of Bi reduced the particle size of the catalyst and alleviated the agglomeration. When the molar ratio of Bi∶Co was 1∶9 and the reduction temperature was 0℃, the as-prepared Co-Bi-B ternary catalysts exhibited the best catalytic performance, and the activation energy of the catalyst calculated by Arrhenius equation was 38.97kJ/mol.

The materials and technologies of electrochemical energy storage are essential for the utilization of new energy and the achievements of carbon peaking and carbon neutralization. Based on the research work of Shanghai Key Laboratory of Materials Protection and Advanced Materials in Shanghai University of Electric Power, various electrochemical energy storage technologies are comprehensively reviewed in this paper, including lithium-ion batteries, sodium-ion batteries, lithium-sulphur batteries, and supercapacitors. The current problems of electrochemical energy storage technologies are also analyzed. From the perspective of electrochemical energy storage mechanism, the modification methods of cathode, anode, separator, and current collector materials are introduced. These methods provide new ideas for the development of electrochemical energy storage devices with large capacity, long life, high safety and low cost. At last, future development trends of electrochemical energy storage technologies are proposed, including exploring new generation energy storage devices such as all-solid-state batteries and metal-air batteries and expanding the application of electrochemical energy storage devices under wide temperature and flexible conditions.

Flow field structure design and optimization is one of the effective ways to improve the uniformity of electrolyte flow, raise the power density of stack, and accordingly improve the reliability of flow battery. Conventionally, flow field structure design and optimization mainly focuses on designing parallel, interdigitated or serpentine channels on the graphite bipolar plate, which is limited by the channel types and the high cost and poor mechanical property of graphite plate. Thereby, a series of strategies, including designing new types of channels like corrugated parallel, detached serpentine and spiral channels, constructing channels on the electrode, introducing independent flow channel component, and designing novel configurations like circular and trapezoid, have been proposed. This paper systematically reviews the current progress of flow field structure design and optimization for flow batteries from three aspects of bipolar plate, electrode and special shapes. Subsequently, the influence mechanism of flow field structure and key parameters on the battery performance, and their coordination with battery operation and assembly parameters are expounded. The flow field structures that are expected to provide superior battery performance and suitable for scaling up, are finally proposed.

Lithium-ion batteries are energy-storage and conversion devices that play an important role in human society. From the chemical engineering perspective, lithium-ion battery could be considered as a special chemical reactor because it shares similar characteristics in transport and reaction phenomena, such as lithium-ion transport, electron transport, heat transport, and electrochemical reactions. These processes take place in the battery electrode with significant heterogeneities in transport and reactions across different length and time scales. Such heterogeneities lead to difference in the performance and deactivation of electrode materials. Here we first discuss the importance of studying electrode reaction heterogeneity and then review the research progress on both theoretical and experimental studies, with a focus on the results obtained from the pseudo two-dimensional modellings and multiscale characterization techniques. This review may guide the design and development of high-performance, long cycle-life, and fast-charging batteries.

Membrane electrode (MEA) provides an important place for the multiphase transfer and electrochemical reaction of electron, proton, reaction gas and product water in proton exchange membrane fuel cell (PEMFC). Reasonable design and preparation of MEA are highly important to improve the performance of PEMFC, to reduce the manufacturing cost and to accelerate its commercialization. The reaction mechanism of PEMFC was firstly analyzed, and then the role of each component in MEA was elaborated from three aspects of gas diffusion layer (GDL), catalytic layer (CL) and proton exchange membrane structure (PEM). The preparation method, heat and mass transfer mode, numerical model, structure-activity relationship, advantages and disadvantages of each component were also summarized. Finally, various factors affecting MEA were summarized, and the development of PEMFC were prospected combined considering many emerging technologies. We believe that this review would provide a guidance for the future development of MEA with high performance, long life and low cost.

High temperature proton exchange membrane fuel cell (HT-PEMFC) has the advantages of fast reaction rate and high CO tolerance. However, the phosphoric acid doped high temperature proton exchange membranes (HT-PEM) often suffer from phosphoric acid leakage and polymer degradation. This article reviews the effects of main chain structure, functional group structure and composite fillers on the critical membrane properties. The HT-PEM based on polybenzimidazole and its derivatives, on polybenzimidazole composites and on other aromatic-based polymers have been discussed. In addition, modification methods in recent reports such as increasing free volume, crosslinking, block copolymerization, composition (ILs, MOFs, PIMs, MO_x), and cationic modification are discussed. Further understanding of specific proton transport channel structure, polymer chemical degradation mechanism and physical degradation mechanism is necessitated to address the long-term stability issue of HT-PEM. The development of alternative polymer materials is expected to become the research focus of HT-PEM.

Reversible solid oxide fuel cell (RSOC) is all-solid-state electrochemical energy conversion device integrating functions of solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC), in which chemical energy stored in fuel gases and electric energy can be efficiently reverted reversibly into each other. Based on the operating processes and electrocatalytic mechanism appeared in RSOC, various critical issues (e.g., delamination between oxygen electrode and electrolyte) are outlined and discussed for oxygen electrode materials. In terms of simple perovskites (Mn-based, Co-based and Fe-based), double perovskites and non-perovskites respectively, research status on preparation methods are highlighted and evaluated for these materials, as well as the effects on the electrochemical performance and charge-discharge characteristics of the unit cell employing different materials for the electrolytes and fuel electrodes. Onto avoid the delamination issues appeared between the oxygen electrode and electrolyte layers, some suggestions are proposed, e.g., preparing the intermediate transition layers, developing new types of the oxygen electrode materials with the super oxygen stoichiometry, high oxygen ion conductivity and diffusion coefficient, as well as integrated structures for RSOC functional layers. It is also suggested that the double perovskites materials can be used as one of the promising candidates for the RSOC oxygen electrodes. This work will serve as an important foundation for designing, preparing and optimizing RSOC oxygen electrodes.

Direct methanol fuel cells(DMFC) have become ideal new energy device to replace fossil energy supply due to their high efficiency and cleanliness. As an important part of the DMFC, the catalyst can reduce the reaction activation energy to solve the problem of high over-potential required for methanol electrooxidation. However, the current DMFC anode catalyst has problems such as low catalytic activity, poor anti-CO toxicity, and high cost, which limit the commercialization of DMFC. This article introduces the principle of catalytic electro-oxidation of methanol. The research progress of DMFC anode catalysts at home and abroad is reviewed from three aspects: Pt-based catalysts, non-Pt-based catalysts, and catalyst supports. Besides, four methods to improve the performance and reduce the cost of the catalyst are introduced, namely selecting appropriate crystal face, adding co-catalyst, preparation of catalyst with special morphology, and selecting the appropriate support. The principle that the catalyst improves catalytic activity and anti-CO toxicity through these three aspects is described. The catalytic activity of methanol on the Pt(100) crystal surface is good, but the anti-CO toxicity is weak. The Pt-M alloy catalyst prepared based on the dual function theory and electronic modulation theory, has high resistance to CO toxicity and methanol catalytic activity. The preparation of non-Pt-based catalysts provides research direction for cost reduction. Choosing a suitable catalyst support has also become an important solution to the problems of easy poisoning, low activity and high cost by taking advantages of the interaction between the support and the catalyst.

Fuel cells (FCs) have attracted increasing attention owing to their high energy conversion efficiency and low pollution. However, the bottleneck problems of high cost, low activity and poor stability that are related to the cathodic reduction reaction and anodic oxidation reaction of small molecule substances, have seriously hindered the industrialization of FCs. Therefore, designing efficient and stable catalysts for FCs is very important to further realize their industrial application. Interestingly, advanced platinum (Pt)-based electrocatalysts could be the most effective and important solution. Different from the monometallic Pt nanocrystals, the Pt-based disordered alloy and the ordered intermetallic nanocrystal have some unique and intriguing physicochemical properties, and thus are regarded as the ideal models for exploring the structure-property relationship of metal electrocatalysts. This review summarizes the recent advances in Pt-based electrocatalysts with high activity and stability. First, we introduce the catalytic activity and stability enhancement mechanism for transition metal (M) and Pt. Further, we highlight the regulatory factors and controlled synthesis of Pt-based alloys, and describe the synthetic strategies of intermetallic compounds in detail. Finally, the current challenges and future development directions of the Pt-based electrocatalysts are discussed and outlined to provide new ideas for the development of electrocatalysts.

Currently, the carbon supported Pt and Pt alloy nanoparticles (NPs) are still the primary electrocatalysts for hydrogen fuel cells. However, the large-scale commercialization of hydrogen fuel cells is impeded due to the poor durability, high cost and low reserves of Pt. Hence, the development of low-cost, high-performance non-Pt or low-Pt electrocatalysts is a key for the commercialization of hydrogen fuel cells. With the focus on the cost, durability and poisoning of electrocatalysts, this paper reviews the latest research progress in improving the activity of anode catalysts and reducing the cost of cathode catalysts. Moreover, this paper also summarizes the influence of the composition, structure and size of nanoparticles on the activity and durability of the catalysts. Finally, we provide guidance for the development of fuel cell catalysts, that is, the application of in-situ characterization techniques to unravel the hydroxide (HOR) mechanism in alkaline medium, and the development of facile and efficient strategies to fabricate the small size and highly order intermetallic Pt alloys catalysts.

The electrocatalytic oxidation of methanol is the core reaction of the direct methanol fuel cell, and the development of efficient and long-life anode catalysts is an important research direction of direct methanol fuel cell. This article summarizes the recent research progress of anode catalysts for direct methanol fuel cells in acidic environments, including methanol electrocatalytic reaction mechanism, catalyst design, synthesis and application. The focus is on the strategies for enhancing the activity and stability of platinum-based nanomaterials, such as composition tuning, shape control, non-metallic doping, taking advantage of the synergistic effects of oxides and the careful selection of supporting materials. In addition, this paper outlines the current problems of anode catalysts including high production cost, insufficient durability and incomplete characterization techniques, and then proposes some research areas for the development of advanced anode catalysts.

This work investigates the influence of the arrangements of a large-scale (100mm×200mm, 200cm²) multiple-serpentine flow field on the output performance of high-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) by numerical simulation and experimental study. Compared with the vertical arrangement manner, the horizontal one allowed the fuel cell to produce a higher average current density of 222.78mA/cm² and a more uniform current density distribution (uniformity index of 75.3%) when the air intake was 1.527L/min and the cell voltage was 0.6V. Furthermore, the number of the gas channels in the flow field was optimized. The results showed that the increase of inlet gas channels significantly reduce the pressure drop, but the average output current density and uniformity index of the fuel cell were decreased accordingly. The multiple-serpentine flow field with 9 channels horizontally arranged showed higher output performance and better current density distribution uniformity than that with 14 channels and lower pressure drop than that with 6 channels. This work provides a good guide for improving the performance and stability of HT-PEMFCs and their commercial applications.

Developing next-generation batteries with high safety and energy density are crucial for electric vehicles, portable electronics and renewable energy utilization. This paper firstly summarizes the solid-state electrolytes and interfacial properties, including the ion transportation mechanisms and classification of solid-state electrolytes. The limited solid-solid interfacial contacts between Li metal anodes and solid-state electrolytes are major obstacles for the application of solid-state Li metal batteries. The interface evolution properties dominate the performances of solid-state batteries, which are mechanical-chemical-electrochemical coupled processes. Afterwards, this paper reviews the battery interface failure mechanisms and construction strategies, indicating that interface failures include battery short circuits induced by dendritic Li deposition and contact loss caused by voids accumulation and interfacial side reactions. Strategies towards solving the interfacial issues include the use of wetting agents, the introduction of a buffer layer and the construction of porous scaffolds for a structured electrode. The paper concludes that, advanced computation techniques and characteristic methods afford an emerging opportunity to understand the solid-solid interfaces and develop solid-state Li metal batteries with great prospects. The synergism from interface chemistry, materials science and systems engineering will jointly promote the development of next-generation energy storage devices with enhanced safety and energy density.

Increasing the driving range of EVs depends on the energy density of lithium-ion batteries, of which the cathode material plays a key role. High-capacity cathode materials such as lithium-rich layered oxides and high nickel materials(Ni≥80%) have become research hotspots, and their precursors have a great influence on the electrochemical performance of cathode materials. This review introduced the reaction process and influencing factors of the co-precipitation method for preparing lithium-rich and high-nickel cathode precursors. The structure and performance of cathode materials such as spherical aggregates, single crystals and concentration gradients were introduced in detail. The principles, advantages and disadvantages of modification strategies such as crystal orientation adjustment, doping and surface/interface treatment in cathode materials were described. In a comprehensive, single crystals can improve cycle life and thermal stability, but the rate performance needed to be further improved. The concentration gradient cathode material not only delivered the high capacity but also kept structural stability and thermal stability, which was expected to break through the bottleneck of the further development of high-capacity cathode materials. Finally, based on the detailed research of our group on high-capacity cathode materials, some suggestions were given for the research directions of cathode materials.

Energy is an important factor limiting human being's development. In recent years, people have higher and higher requirements for energy storage equipment with the development of new energies. Among them, lithium-ion battery (LIB) is considered to be one of the most promising energy storage devices. At present, graphite is the main anode material for commercial LIBs. Although graphite has good electrical conductivity, its theoretical capacity is low. Thus, graphite has gradually been unable to meet the demands for large capacities of high-energy equipment. Transition metal manganese oxides are considered as one of the ideal anode materials for LIBs due to their sufficient reserve, diverse oxidation states, diversified structures, high theoretical specific capacities and environmentally friendly. In this paper, the design and synthesis of four kinds of manganese oxides (MnO, Mn₂O₃, Mn₃O₄ and MnO₂) through nano-crystallization and constructing composite structures were introduced. Moreover, the performance of four kinds of manganese oxides used as anode materials for LIBs was summarized and compared. The development prospects and future trends of manganese oxide in the anode material fields in LIBs were also prospected.

The ionic conductivity of most solid polymer electrolytes at room temperature is low (about 10^–8 —10^-6 S /cm), and has great dependence on temperature. So, the polymer electrolytes cannot meet the practical application requirement for room-temperature solid-state lithium-ion batteries (LIBs). In this regard, we first summarize the main research progress and the advantage/disadvantage of room-temperature polymer electrolytes for LIBs. Then, from physical/chemical aspects, the recent developments of the preparation process, optimization and modification methods, and working mechanism of polymer electrolytes (including all-solid-state polymer electrolytes and quasi-solid-state polymer electrolytes) at room-temperature are reviewed. Finally, future research trends of solid polymer electrolytes for advanced LIBs are proposed.

All-solid-state lithium ion batteries have the advantages of high safety and excellent electrochemical performance, but they have many problems as well such as poor compatibility of the electrode/electrolyte interface and low ionic conductivity at room temperature. This paper reviews the causes and solutions of the above problems. For improving the cathode/electrolyte interfaces, the cathode materials can be combined with solid electrolyte, and solid electrolyte with three-dimensional porous structures can be constructed, or a buffer layer can be introduced at the interface. For improving the anode/electrolyte interfaces, the interface layer can be designed, or the solid electrolyte can be generated by in-situ polymerization. Besides, the solid electrolyte skeleton can be constructed, and the self-healing or elastic solid electrolyte can be used. For the solid electrolytes, taking polyethylene oxide (PEO) solid polymer electrolyte as an example, plasticizers, inorganic ceramic fillers, blend polymers, and block copolymers can be added. Finally, some suggestions on the future research directions are proposed. In future, more attention should be paid to optimize the electrode/electrolyte interfaces, explore the transporting mechanism of lithium ions, and construct solid electrolytes with high ionic conductivity.

Due to the increasing focus on lithium battery industry with renewable energy developing for many researchers, the related methods with highly effective and environment-friend in lithium extraction have become the spot of light. Among numerous approaches of lithium extraction, as the virtues of its flexible operation, easy control and low energy consumption in continuous operation, membrane separation technology possesses promising application in lithium extraction. In the view of current membrane separation technology which applied to lithium separation, the effects of membrane characteristics including inner membrane pores and membrane surface were summarized and discussed. It was extraction basis that ion transport in the membrane pore, ion size and ion transport form in membrane pores affected their transport rate. The size and morphology of the membrane pores were key factors in separation process. Various sizes, morphologies and the charges of inner membrane pores contributed different effects in lithium extraction process. According to the surface characteristics of the separation membrane, the capability differences of membrane with positive or negative charge and the effect of surface hydrophobicity in lithium separation were generalized. Finally, the challenges and opportunities of membrane separation technology were forecasted via the effect of membrane pore characteristics and surface characteristics in lithium extraction process to accelerate the theoretical research and practical application of membrane separation technology in lithium extraction.

Due to its high energy density, environmental friendly, and low cost, lithium-sulfur battery (LiSB) has attracted more and more attentions as a promising next-generation energy storage device. However, the insulation property, polysulfide shuttle effect, and the slow redox kinetics of the active Li₂S_x material could lead to serious capacity attenuation, and further affect the cycle stability of the batteries. Therefore, the use of catalytic materials to accelerate the redox kinetics and hence to increase the performance and stability of LiSB has extensively developed. In this review, the catalytic transformation of sulfur-related compounds were discussed from the aspects of polysulfides generation, sulfur species transformation, and of lithium sulfides deposition. The state-of-the-art researches of catalytic materials for LiSB was reviewed, including the design strategies, the catalytic mechanisms, and the corresponding evaluation methods, so as to provide new ideas for high activity LiSB catalyst materials.

Supercapacitors have widely been applied in electric vehicle, rail traffic, new energy, electromagnetic launch and laser weapons owing to their high power density, long cycling life, safety and reliability. However, the active carbon, as key electrodes for supercapacitor, is still imported from Japan and South Korea due to the lack of domestic industrialization, which greatly restricts the development of supercapacitors and their downstream industry. This paper summarized the effect of physical and chemical property of active carbons on its electrochemical performances and the industry status of active carbons for supercapacitors. The heat and mass transfer issues during the productive process that limited the quality of active carbons were also discussed. To better guide the domestic industrialization, it was highly desired to establish the comprehensive index system of active carbon for supercapacitor based on the current technology. Meanwhile, simulation study focused on manufacturing technique and equipment was needed to solve the problems of poor stability and consistency of domestic active carbon, ensuring the independence controllable production of critical materials for supercapacitor industry.

Ni-rich (Ni≥0.8) oxide cathode materials can satisfy the demands of high energy density and low cobalt for next-generation power batteries due to their large reversible capacity, high compaction density and low cost. The electrochemical performance of Ni-rich cathode materials is directly affected by the size, sphericity, size distribution and sub-nanoplate stacking of the hydroxide precursor, which is commonly produced by the means of co-precipitation method in commercialization. During the synthesis process, the pH, ammonia concentration and feeding rate affect the precipitation rate and the final product quality. The optimization design of the reactor could improve the mixing of the reactants and enhance the heat and mass transfer. Combining with the theoretical calculation of the co-precipitation reaction process parameters, this review summarized the structure design principle of the continuous stirred tank reactor(CSTR) and the influence rule of key synthesis parameters on nucleation growth and microstructure of precursors. Finally, the improvement trend of precursor in the future was prospected by analyzing the current market situations of Ni-rich (Ni≥0.8) oxide cathodes.

The development and utilization of unconventional natural gas can effectively alleviate the energy problems caused by the shortage of conventional natural gas and reduce the greenhouse effect caused by the wanton emissions of it. Whether the enrichment of low-concentration coalbed methane or the upgrading of low-quality natural gas, the separation of CH₄ and N₂ needs to be resolved. The adsorption and separation of methane and nitrogen is extremely challenging because of very similar kinetic diameters of them. As the new type porous materials, metal-organic frameworks (MOFs) aroused widespread concern due to their diversified structures and functions. This paper mainly reviewed the research progress of MOFs materials in the adsorption and separation of CH₄ and N₂ from the CH₄ and N₂ selective MOFs adsorption materials in recent years. The factors affecting the separation of methane and nitrogen were discussed. The relationship between the adsorption and separation mechanism and the structure and performance of MOFs was summarized and analyzed in detail. A method to improve the selectivity of CH₄ and N₂ was proposed, which required the synergy of appropriate pore size and weak polar surface properties or favorable framework structure. Finally, the application prospects and development trends of MOFs in the field of methane enrichment and purification were prospected.

Graphene has always been regarded as a potential application material in the field of new energy conversion and storage industry because of its unique two-dimensional structure, large theoretical specific surface area, good carrier mobility, high Young's modulus and excellent thermal conductivity. These advantages make it possible to combine with one or more highly active inorganic/organic materials through covalent bond/non-covalent bond, and improve the defects of the materials themselves and optimize the performance of the materials through synergistic effects, thus expanding its application range. Therefore, how to design and synthesize graphene composite materials with certain functions and how to construct novel graphene structures to meet the requirements of energy and related fields for material-related properties have become one of the hotspots in the field of graphene materials. This article reviewed the design ideas of graphene-based composite materials in the fields of new energy conversion and storage industry. Then, it summarized the key issues of graphene-based composites in these various fields. Finally, the future trends and perspectives for the graphene in various fields were discussed.

Electrocatalytic carbon dioxide reduction (CO₂RR) enables CO₂ transformation to valuable chemicals by applying electrical field under mild conditions. Coupling CO₂RR with suitable anode reactions with lower thermodynamic potential can reduce cell voltage, produce valuable chemicals simultaneously at anode and cathode, and thus reach a higher energy efficiency. This article introduced the strategy for CO₂RR coupled oxidation synthesis system, investigated the effect of electrolysis device such as electrolytic cell and ion exchange membrane on the CO₂RR coupling electrocatalytic performance, summarized the types of electrocatalysts commonly used in CO₂RR coupled oxidation synthesis system and overviewed the latest progress in CO₂RR coupled with typical anodic oxidation reactions such as chlor-alkali reaction, and alcohols and nitrogenous organic compound oxidation. Finally, in view of the existing problems, such as high cost of anode catalyst, difficulty in separation and detection of anode products and low reactants conversion rate, it was proposed that developing more efficient, stable and cheaper anode catalyst, upgrading electrode structure and electrolysis device and expanding new CO₂RR coupling systems were the future research directions.

Carbon dioxide (CO₂) emission reduction and marine antifouling are the two major issues to be solved in coast-area thermal power plants. In recent years, the rapid development of CO₂ solid sorption materials and new-energy-related catalytic reaction technologies has promoted the practical application of CO₂ capture and utilization (CCU) technology. Applying CCU technology to the coal-fired power plants could transform them into CO₂-captured and CO₂-resourced power plants to achieve CO₂ emission reduction, which sets a good future development tendency for thermal power enterprises. Besides, the catalytic reaction technology driven by clean-energy development has been extended to the field of marine antifouling and achieved substantial progress in recent years. In this paper, the new progress in the research and development of solid CO₂ sorption materials is reviewed, particularly emphasizing the structural and functional modification of MOF materials for improving the selective CO₂ sorption performance. Based on the operation situation and rich energy resource of the coastal thermal power plants, we have analyzed and summarized the achievements of thermal catalysis and photoelectron-catalysis in CO₂ resource utilization and marine antifouling. Furthermore, an antifouling strategy using photocatalytic coatings to prevent and/or inhibit the adhesion and growth of marine organisms is proposed, and the feasibility of its application in some specific fields is demonstrated. Finally, we prospect the development trend of CO₂ emission reduction and antifouling technology in coastal power plants.

Directly utilizing sunlight to drive catalytic carbon dioxide (CO₂) reduction into synthetic chemical fuels is one of the most promising approaches to alleviate the energy crisis and reduce the greenhouse effect. However, the inherent chemical stability of CO₂ results in low photocatalytic conversion efficiency, forming a great challenge. Thermal energy is considered to be an important driving force to improve the catalytic conversion rate during the reaction process. Taking advantages of the high selectivity by photocatalysis and the high reaction activity by thermal catalysis, the thermal-enhanced photocatalysis CO₂ reduction exhibits high conversion efficiency. This article summarized the different forms of thermal-enhanced photocatalysis CO₂ reduction, including external heating sources, photothermal effect and plasmonic effect. The external heating source was mainly realized by direct heating device or focused solar energy, which could remarkably increase the production efficiency. The photothermal effect was exerting to increase the local reaction temperature of catalyst, which greatly enhanced the energy utilization efficiency in CO₂ reduction. In addition to the same effect as the photothermal effect, plasmonic effect also played a role in enhancing light absorption, promoting carrier separation and accelerating surface reaction kinetics. In-depth research on the reaction mechanism and rational control of the reaction conditions would greatly promote the development of thermal-enhanced photocatalytic CO₂ reduction technology and provide effective means for CO₂ utilization.

Phase change material heat storage technology has the advantages of high heat storage density, stable phase change temperature, and easy process control. It has broad application prospects in the fields of solar thermal utilization, industrial waste heat recovery, building energy conservation, and electronic device thermal management. Under normal circumstances, the phase change material needs to complete the heat storage and release process in the application. The heat transfer enhancement of heat storage technology transfer characteristics directly determine the time of heat storage and release and the application mainly includes three aspects, one is the heat conduction enhancement of the phase change material, the second is the convection heat transfer enhancement of the latent heat functional thermal fluid,and the third is the heat transfer enhancement of the energy storage heat exchanger. Inorganic and organic phase change materials have low thermal conductivity, which can be combined with high thermal conductivity materials to improve their thermal conductivity. The phase change material is used to increase the specific heat capacity of the latent heat thermal fluid, thereby the heat capacity can be improved, and the heat transfer can be enhanced. High-efficiency heat storage devices such as plate type and spiral coil type are used to realize heat transfer enhancement in the process of heat storage and release. This article reviews the research progress of heat transfer enhancement in phase change heat storage technology at home and abroad, mainly introduces the heat conduction enhancement of phase change materials, such as expanded graphite and metal foam. The heat transfer enhancement of microencapsulation phase change material, latent heat emulsion, and the heat transfer enhancement of thermal storage heat exchanger such as shell and tube, plate and spiral coil heat exchanger. On the whole, the expanded graphite-based composite phase change material has high thermal conductivity, large heat storage density and good shaping characteristics, which has great application prospects. Latent functional thermal fluid has the advantages of large apparent specific heat capacity and small flow resistance, but it has disadvantages such as poor stability and large degree of subcooling. The plate heat storage has a large heat transfer area and high heat transfer power, and is suitable for use in a phase change material heat transfer system. However, due to different application backgrounds, the selection and guidance of different heat storage devices for different scenarios is worthy of further research.

Microencapsulated phase change material (MEPCM) is a kind of phase change materials with good performance and strong stability, and its thermal conductivity is low. However, modification of phase change microcapsule and optimization of heat transfer conditions can improve the thermal conductivity. In this paper, the preparation methods of MEPCM and modified MEPCM were systematically introduced. In addition, the differences between them were also illustrated. Through comparative analysis, it can be concluded that in-situ polymerization was the most commonly used method to prepare modified MEPCM, and modification of wall materials was the most commonly used modification method. Moreover, among many modified materials, graphene oxide was a modified material with high thermal conductivity, excellent mechanical properties and strong stability. Besides, this paper summarized the application of MEPCM and modified MEPCM in microchannel heat exchanger. And it pointed out the problems that the combination of MEPCM with microchannel heat exchanger enhanced heat transfer effect but still increased the flow resistance and pressure drop. Therefore, in practical application, the critical flow velocity of a suspension needed to be determined in order to give full play to the advantages of MEPCM and microchannel heat exchanger.

At present, catalytic pyrolysis has gradually become the main research direction of biomass conversion and utilization technology. Compared with conventional pyrolysis, catalytic pyrolysis could effectively improve the quality of bio-oil and produce high-value products. This paper reviews the new catalyst in recent years, including molecular sieve catalyst (ZSM-5, HZSM-5, USY, etc.), carbon-based catalysts, metal oxides, dolomite, monolithic catalysts, etc., and understands the latest research progress in the field of catalystfor biomass pyrolysis. The good catalyst is the key to ensure the smooth progress of the reaction, and the high-value products produced by different catalyst are also different, so the correct selection of catalyst plays an important role in the quality improvement of bio-oil. According to the current research content in the field, this paper also makes a detailed comparison of the advantages and disadvantages and product characteristics of all kinds of catalyst, and puts forward some suggestions and prospects for the existing problems of this technology. It provides an important theoretical basis for the future research of catalyst in the field of biomass pyrolysis.

Biomass resources are abundant and cheap, which has attracted the attention of researchers due to its advantages such as clean, renewable and carbon neutral. However, its shortcomings such as low energy density, high moisture and oxygen content also limit its large-scale application; in addition, when biomass is directly gasified, the synthesis gas has a low calorific value and a large amount of tar is produced. This article describes the effect of torrefaction on the improvement of biomass fuel quality and the positive regulation of the gasification process. After the biomass is torrefied, the oxygen content, H/C and O/C decrease while the fixed carbon content and high heating value increase. The grindability and hydrophobicity are also improved to a certain extent, which makes up for the torrefaction to a certain extent in terms of energy consumption. The improvement of biomass fuel quality is explained microscopically, and the characteristics and advantages of microwave torrefaction are briefly described. Using torrefied biomass for gasification, the synthesis gas has high combustible components, and the tar output decreases. The follow-up work can be considered from the following three aspects: the whole life cycle assessment of the "torrefaction-utilization" process, the use of microwave technology to more accurately explore the influence mechanism of temperature on the torrefaction effect, and the combination of torrefying and tar catalytic reforming technology to further reduce tar production.

Nicotinamide adenine dinucleotide (NAD) is an essential redox cofactor in life. Albeit there are two anomers, namely β- and α-NAD, of which the anomeric carbon atom linked to the nicotinamide moiety holds an R- and S-configuration, respectively, most NAD-dependent enzymes strongly prefer β-NAD. Recently, simplified NAD analogs have been synthesized and explored as redox cofactors for biocatalysis. The fact that many synthetic NAD analogs are achiral promotes us to wonder whether enzymes discriminate between NAD analog enantiomers. Herein, two pairs of NAD analog enantiomers were prepared through Zincke reaction by using readily available amino-3-phenylpropanates as chiral sources, and tested as cofactors for mutants of cytochrome P450 monooxygenase from Bacillus megaterium (P450 BM3 R966D/W1046S) and glucose dehydrogenase from Sulfolobus solfataricus (SsGDH I192T/V306I). Results showed that P450 BM3 R966D/W1046S had much higher catalytic efficiencies when coupled with the reduced forms of the S-configuration analogs. This preliminary study suggested that amino acids may be used as chiral sources to prepare NAD analogs with defined stereochemistry and that more chiral NAD analogs should be explored to match redox enzymes and their engineered variants.

The effects of different diethanolamine concentrations on growth, CO₂ biofixation, and lipid accumulation of eminent microalga Coccomyxa subellipsoidea C-169 was explored. The results showed that the appropriate concentration of DEA could significantly improve CO₂ biofixation and lipid accumulation efficiency. The highest levels of biomass, CO₂ biofixation rate, lipid content and lipid productivity were achieved to 0.97g/L, 225.98mg/(L·d), 64.33%, and 59.9mg/(L·d) under 40mg/L DEA, respectively, which were separately 1.64-, 1.64-, 1.15- and 1.27-fold more than that without DEA group. Exogenous DEA improved gas-liquid mass transfer coefficient and CO₂ mass transfer efficiency, and consequently enhanced the proportion of available inorganic carbon sources for C. subellipsoidea. Synchronously, exogenous DEA up-regulated 1,5-bisphosphate carboxylase Rubisco and carbonic anhydrase CA in carbon fixation pathway, and consequently improved CO₂ bio-fixation of C. subellipsoidea. DEA also up-regulated acetyl-coa carboxylase ACCase in lipid pathway and down-regulated pyruvate carboxylase PEPC in ACCase competition pathway to strengthen lipid accumulation in C. subellipsoidea. These results provided a basis for industrial CO₂ emission reduction and renewable energy development of C. subellipsoidea.

High-purity monosilane is the most important silicon-containing gas in semiconductor industry, and is widely used in areas such as integrated circuit, photovoltaics, display panel, and battery cells for electric vehicle. However, it has previously been a monopoly of the US, Japan, South Korea, et al. This article reviewed the localization journey of monosilane technology, and introduced the new mass production technology of high-purity monosilane innovated by the authors' group based on the chlorosilane route and the reactive distillation technology, the product of which had been delivered to fields including photovoltaic, display panel, integrated circuit and so on. Prospects of the electronic-grade monosilane industry was presented, holding that represented by the authors' approach, the chlorosilane route would be in the mainstream in future, while the magnesium silicide route would be a convenient way for co-production of monosilane and disilane. It was also pointed out that developing platform enterprises via integration and innovation of associated technologies for multiple products or co-products would be the development direction of monosilane industry.