Hematite photoanodes for solar water splitting

doi:10.16085/j.issn.1000-6613.2017.02.001

Abstract

Abstract: Photoelectrochemical cell is able to turn sunlight into stored energy conveniently in the form of hydrogen,and the stable and low-cost photoanode catalyst is crucial in this device. Hematite is considered as one of the most promising photoanode catalysts due to its suitable band gap,high theoretical solar to hydrogen efficiency,chemical stability under illumination and rich storage in earth. However,the poor conductivity,short photo-generated charge carrier lifetime and high turn-on voltage have limited the performance improvement of hematite severely. This review introduces the basic mechanism of photoelectrocatalysis and energy band excitation,then it summarizes the synthesis of nanostructure α-Fe₂O₃ and the improvements on the photoelectrocatalysis property of hematite in recent years,including conductivity enhancement by element doping,oxygen evolution overpotential or trap concentration reduction by surface treatment,and photo-induced voltage or specific area increase by coupling with other materials. The future developing perspectives of hematite are also presented,and multi-modified technologies are considered as important ways to improve the photocurrent density.

Key words: hematite, solar energy, photoelectrocatalysis, hydrolysis, hydrogen

摘要： 光电化学池可以将太阳能以氢气的形式储存起来，其中稳定、廉价的催化剂是关键。α-Fe₂O₃具有合适的禁带宽度，较高的理论光-电转化效率，光稳定性好，在地壳中的储量丰富，被认为是最具有发展前景的光电催化材料之一；但是它的导电性差、光生电荷寿命短、氧化反应过电位高，严重阻碍了其发展。本文首先介绍了光电催化理论，然后重点综述了近些年α-Fe₂O₃纳米结构的制备技术，以及针对其不足所采用的改性方法，包括通过元素掺杂来增强α-Fe₂O₃的导电性，表面处理来降低氧化反应过电势或陷阱浓度，与其他材料复合来增加光生电压或催化剂表面积，最后对α-Fe₂O₃作为光阳极催化剂分解水制氢未来的发展前景作出展望，指出多种手段的有效结合是提高其光电流密度的重要途径。

关键词: 赤铁矿, 太阳能, 光电催化, 水解, 氢气

CLC Number:

WANG Kaifang, LIU Guang, GAO Xusheng, HE dongying, LI Jinping. Hematite photoanodes for solar water splitting[J]. Chemical Industry and Engineering Progree, 2017, 36(02): 397-409.

王开放, 刘光, 高旭升, 贺冬莹, 李晋平. α-Fe₂O₃光电催化分解水制备氢气研究进展[J]. 化工进展, 2017, 36(02): 397-409.

References

[1] PRVOT M S,SIVULA K. Photoelectrochemical tandem cells for solar water splitting[J]. J. Phys. Chem. C,2013,117(35):17879-17893.
[2] IORDANOVA N,DUPUIS M,ROSSO K M. Charge transport in metal oxides:a theoretical study of hematite α-Fe₂O₃[J]. The Journal of Chemical Physics,2005,122(14):144305.
[3] HARDEE K L,BARD A J. Semiconductor electrodes:Ⅴ. The application of chemically vapor deposited iron oxide films to photosensitized electrolysis[J]. J. Electrochem. Soc.,1976,123(7):1024-1026.
[4] CARVALHO V,LUZ R A D S,LIMA B H,et al. Highly oriented hematite nanorods arrays for photoelectrochemical water splitting[J]. J. Power Sources,2012,205:525-529.
[5] YEH L S R,HACKERMAN N. Iron oxide semiconductor electrodes in photoassisted electrolysis of water[J]. J. Electrochem. Soc.,1977,124(6):833-836.
[6] FORMAL F L,T TREAULT N,CORNUZ M,et al. Passivating surface states on water splitting hematite photoanodes with alumina overlayers[J]. Chem. Sci.,2011,2(4):737-743.
[7] IANDOLO B,WICKMAN B,ZORIĆ I,et al. The rise of hematite:origin and strategies to reduce the high onset potential for the oxygen evolution reaction[J]. J. Mater. Chem. A,2015,3(33):16896-16912.
[8] MA Y,JOHNSON P D,WASSDAHL N,et al. Electronic structures of α-Fe₂O₃ and Fe₃O₄ from ok-edge absorption and emission spectroscopy[J]. Phys. Rev. B,1993,48(4):2109-2111.
[9] BOSMAN A J,VAN DAAL H J. Small-polaron versus band conduction in some transition-metal oxides[J]. Adv. Phys.,2006,19(77):11-17.
[10] KUDO A,MISEKI Y. Heterogeneous photocatalyst materials for water splitting[J]. Chem. Soc. Rev.,2009,38(1):253-278.
[11] BEERMANN N,VAYSSIERES L,LINDQUIST S-E,et al. Photoelectrochemical studies of oriented nanorod thin films of hematite[J]. J. Electrochem. Soc.,2000,147(7):2456-2461.
[12] PHUAN Y W,CHONG M N,ZHU T,et al. Effects of annealing temperature on the physicochemical,optical and photoelectrochemical properties of nanostructured hematite thin films prepared via electrodeposition method[J]. Mater. Res. Bull.,2015,69:71-77.
[13] AHMED M G,KRETSCHMER I E,KANDIEL T A,et al. A facile surface passivation of hematite photoanodes with TiO₂ overlayers for efficient solar water splitting[J]. ACS Appl. Mater. Interfaces,2015,7(43):24053-24062.
[14] CARVALHO-JR W M,SOUZA F L. Thermal enhancement of water affinity on the surface of undoped hematite photoelectrodes[J]. Sol. Energ. Mat. Sol. C.,2016,144:395-404.
[15] KAY A,CESAR I,GR TZEL M. New benchmark for water photooxidation by nanostructured α-Fe₂O₃ films[J]. J. Am. Chem. Soc.,2006,128(49):15714-15721.
[16] WARREN S C,VO TCHOVSKY K,DOTAN H,et al. Identifying champion nanostructures for solar water-splitting[J]. Nat. Mater.,2013,12(9):842-849.
[17] KLAHR B M,MARTINSON A B,HAMANN T W. Photoelectrochemical investigation of ultrathin film iron oxide solar cells prepared by atomic layer deposition[J]. Langmuir,2011,27(1):461-468.
[18] LIN Y,ZHOU S,SHEEHAN S W,et al. Nanonet-based hematite heteronanostructures for efficient solar water splitting[J]. J. Am. Chem. Soc.,2011,133(8):2398-401.
[19] WANG T,LUO Z,LI C,et al. Controllable fabrication of nanostructured materials for photoelectrochemical water splitting via atomic layer deposition[J]. Chem. Soc. Rev.,2014,43(22):7469-7484.
[20] SARTORETTI C J,ALEXANDER B D,SOLARSKA R,et al. Photoelectrochemical oxidation of water at transparent ferric oxide film electrodes[J]. Physical Chemistry B,2005,109(28):13685-13692.
[21] SCHREBLER R,LLEWELYN C,VERA F,et al. An electrochemical deposition route for obtaining α-Fe₂O₃ thin films[J]. Electrochemical and Solid-State Letters,2007,10(10):D95.
[22] SPRAY R L,CHOI K S. Photoactivity of transparent nanocrystalline Fe₂O₃ electrodes prepared via anodic electrodeposition[J]. Chem. Mater.,2009,21(15):3701-3709.
[23] SHINDE P S,GO G H,LEE W J. Facile growth of hierarchical hematite (α-Fe₂O₃) nanopetals on FTO by pulse reverse electrodeposition for photoelectrochemical water splitting[J]. J. Mater. Chem.,2012,22(21):10469.
[24] MAO A,SHIN K,KIM J K,et al. Controlled synthesis of vertically aligned hematite on conducting substrate for photoelectrochemical cells:nanorods versus nanotubes[J]. ACS Applied Materials & Interfaces,2011,3(6):1852-1858.
[25] PRAKASAM H E,VARGHESE O,PAULOSE M,et al. Synthesis and photoelectrochemical properties of nanoporous iron (Ⅲ) oxide by potentiostatic anodization[J]. Nanotechnology,2006,17(17):4285.
[26] FAN Z,WEN X,YANG S,et al. Controlled p- and n-type doping of Fe₂O₃ nanobelt field effect transistors[J]. Appl. Phys. Lett.,2005,87(1):13113.
[27] SIVULA K,ZBORIL R,FORMAL F L,et al. Photoelectrochemical water splitting with mesoporous hematite prepared by a solution-based colloidal approach[J]. J. Am. Chem. Soc.,2010,132(21):7436-7444.
[28] JIA C J,SUN L D,YAN Z G,et al. Single-crystalline iron oxide nanotubes[J]. Angewandte Chemie,2005,117(28):4402-4407.
[29] WU Z,YU K,ZHANG S,et al. Hematite hollow spheres with a mesoporous shell:controlled synthesis and applications in gas sensor and lithium ion batteries[J]. J. Phys. Chem. C,2008,112(30):11307-11313.
[30] ZENG S,TANG K,LI T,et al. Facile route for the fabrication of porous hematite nanoflowers:its synthesis,growth mechanism,application in the lithium ion battery,and magnetic and photocatalytic properties[J]. J. Phys. Chem. C,2008,112(13):4836-4843.
[31] PENDLEBURY S R,BARROSO M,COWAN A J,et al. Dynamics of photogenerated holes in nanocrystalline α-Fe₂O₃ electrodes for water oxidation probed by transient absorption spectroscopy[J]. Chem. Commun.,2011,47(2):716-718.
[32] SEGEV G,DOTAN H,MALVIYA K D,et al. High solar flux concentration water splitting with hematite (α-Fe₂O₃) photoanodes[J]. Advanced Energy Materials,2016,6(1):DOI:10.1002/aenm. 201500817.
[33] LIN Y,XU Y,MAYER M T,et al. Growth of p-type hematite by atomic layer deposition and its utilization for improved solar water splitting[J]. J. Am. Chem. Soc.,2012,134(12):5508-5511.
[34] GLASSCOCK J A,BARNES P R F,PLUMB I C,et al. Structural,optical and electrical properties of undoped polycrystalline hematite thin films produced using filtered arc deposition[J]. Thin Solid Films,2008,516(8):1716-1724.
[35] CESAR I,SIVULA K,KAY A,et al. Influence of feature size,film thickness,and silicon doping on the performance of nanostructured hematite photoanodes for solar water splitting[J]. J. Phys. Chem. C,2009,113(2):772-782.
[36] KUMARA P,SHARMAA P,SHRIVASTAV R,et al. Electrodeposited zirconium-doped α-Fe₂O₃ thin film for photoelectrochemical water splitting[J]. Int. J. Hydrogen. Energ.,2011,36(4):2777-2784.
[37] SHEN S,KRONAWITTER C X,WHEELER D A,et al. Physical and photoelectrochemical characterization of Ti-doped hematite photoanodes prepared by solution growth[J]. J. Mater. Chem. A,2013,1(46):14498-14506.
[38] GURUDAYA L,CHIAM S Y,KUMAR M H,et al. Improving the efficiency of hematite nanorods for photoelectrochemical water splitting by doping with manganese[J]. ACS Appl. Mater. Interfaces,2014,6(8):5852-5859.
[39] LIU J,CAI Y Y,TIAN Z F,et al. Highly oriented Ge-doped hematite nanosheet arrays for photoelectrochemical water oxidation[J]. Nano Energy,2014,9:282-290.
[40] HAHN N T,YE H,FLAHERTY D W,et al. Reactive ballistic deposition of α-Fe₂O₃ thin films for photoelectrochemical water oxidation[J]. ACS Nano,2010,4(4):1977-1986.
[41] REICHMAN J. The current-voltage characteristics of semiconductor-electrolyte junction photovoltaic cells[J]. Appl. Phys. Lett.,1980,36(7):574-577.
[42] KLAHR B,GIMENEZ S,FABREGAT-SANTIAGO F,et al. Water oxidation at hematite photoelectrodes:the role of surface states[J]. J. Am. Chem. Soc.,2012,134(9):4294-302.
[43] GURLO A,BÂRSAN N,OPREA A,et al. An n- to p-type conductivity transition induced by oxygen adsorption on alpha-Fe₂O₃[J]. Applied Physics Letters,2004,85(12):DOI:org/10.1063/1.1794853.
[44] LING Y,WANG G,WHEELER D A,et al. Sn-doped hematite nanostructures for photoelectrochemical water splitting[J]. Nano Letters,2011,11(5):2119-2125.
[45] WANG L,LEE C Y,MAZARE A,et al. Enhancing the water splitting efficiency of Sn-doped hematite nanoflakes by flame annealing[J]. Chemistry-A:European Journal,2013,20(1):72-82.
[46] WANG J J,HU Y,TOTH R,et al. A facile nonpolar organic solution process of a nanostructured hematite photoanode with high efficiency and stability for water splitting[J]. J. Mater. Chem. A,2016,
[47] KLEIMAN-SHWARSCTEIN A,HU Y-S,FORMAN A J,et al. Electrodeposition of α-Fe₂O₃ doped with Mo Cr as photoanodes for photocatalytic water splitting[J]. The Journal of Physical Chemistry C,2008,112(40):15900-15907.
[48] BAKA A,CHOIB W,PARK H. Enhancing the photoelectrochemical performance of hematite (α-Fe₂O₃) electrodes by cadmium incorporation[J]. Applied Catalysis B:Environmental,2011,110:207-215.
[49] LIU Y,YU Y X,ZHANG W D. Photoelectrochemical properties of Ni-doped Fe₂O₃ thin films prepared by electrodeposition[J]. Electrochim. Acta,2012,59:121-127.
[50] ZHANG P,KLEIMAN-SHWARSCTEIN A,HU Y S,et al. Oriented Ti doped hematite thin film as active photoanodes synthesized by facile APCVD[J]. Energy Environ. Sci.,2011,4(3):1020.
[51] FRANKING R,LI L,LUKOWSKI M A,et al. Facile post-growth doping of nanostructured hematite photoanodes for enhanced photoelectrochemical water oxidation[J]. Energy Environ. Sci.,2013,6(2):500-512.
[52] MAO A,PARK N G,HAN G Y,et al. Controlled growth of vertically oriented hematite/Pt composite nanorod arrays:use for photoelectrochemical water splitting[J]. Nanotechnology,2011,22(17):175703.
[53] 洪孝挺,王正鹏,陆峰,等. 可见光响应型非金属掺杂TiO₂的研究进展[J]. 化工进展,2004,23(10):1077-108. HONG X T,WANG Z P,LU F,et al. Study on visble light-activated non-metal doped titanium dioxide[J]. Chemical Industry and Engineering Progress,2004,23(10):1077-1080.
[54] 谢先法,吴平霄,党志,等. 过渡金属离子掺杂改性TiO₂研究进展[J]. 化工进展,2005,24(12):1358-1362. XIE X F,WU P X,DANG Z,et al. Research progress of photocatalytic performance of TiO₂ modified by doped transition metal ions[J]. Chemical Industry and Engineering Progress,2005,24(12):1358-1362.
[55] KLEIMAN-SHWARSCTEIN A,HUDA M N,WALSH A,et al. Electrodeposited aluminum-doped α-Fe₂O₃ photoelectrodes:Experiment and theory[J]. Chem. Mater.,2010,22(2):510-517.
[56] LIAO P,KEITH J A,CARTER E A. Water oxidation on pure and doped hematite(0001)surfaces:prediction of Co and Ni as effective dopants for electrocatalysis[J]. J. Am. Chem. Soc.,2012,134(32):13296-309.
[57] PETER L M. Energetics and kinetics of light-driven oxygen evolution at semiconductor electrodes:the example of hematite[J]. J. Solid State Electr.,2012,17(2):315-326.
[58] ZHONG D K,GAMELIN D R. Photoelectrochemical water oxidation by cobalt catalyst ("Co-Pi")/α-Fe₂O₃ composite photoanodes:oxygen evolution and resolution of a kinetic bottleneck[J]. J. Am. Chem. Soc.,2010,132(12):4202-4207.
[59] KLAHR B,GIMENEZ S,FABREGAT-SANTIAGO F,et al. Photoelectrochemical and impedance spectroscopic investigation of water oxidation with "Co-Pi"-coated hematite electrodes[J]. J. Am. Chem. Soc.,2012,134(40):16693-16700.
[60] TILLEY S D,CORNUZ M,SIVULA K,et al. Light-induced water splitting with hematite:improved nanostructure and iridium oxide catalysis[J]. Angew. Chem. Int. Edit.,2010,49(36):6405-6408.
[61] BADIA-BOU L,MAS-MARZA E,RODENAS P,et al. Water oxidation at hematite photoelectrodes with an iridium-based catalyst[J]. J. Phys. Chem. C,2013,117(8):3826-3833.
[62] DU C,YANG X,MAYER M T,et al. Hematite-based water splitting with low turn-on voltages[J]. Angew. Chem. Int. Edit.,2013,52(48):12692-12695.
[63] XU D,RUI Y,LI Y,et al. Zn-Co layered double hydroxide modified hematite photoanode for enhanced photoelectrochemical water splitting[J]. Appl. Surf. Sci.,2015,358:436-442.
[64] RIHA S C,KLAHR B M,TYO E C,et al. Atomic layer deposition of a submonolayer catalyst for the enhanced photoelectrochemical performance of water oxidation with hematite[J]. ACS Nano,2013,7(3):2396-2405.
[65] XI L,TRAN P D,CHIAM S Y,et al. Co3O4-decorated hematite nanorods as an effective photoanode for solar water oxidation[J]. J. Phys. Chem. C,2012,116(26):13884-13889.
[66] WENDER H,GON ALVES R V,DIAS C S B,et al. Photocatalytic hydrogen production of Co(OH)₂ nanoparticle-coated α-Fe₂O₃ nanorings[J]. Nanoscale,2013,5(19):9310-9316.
[67] YANG T Y,KANG H Y,JIN K,et al. Iron oxide photoanode with hierarchical nanostructure for efficient water oxidation[J]. J. Mater. Chem. A,2013,2(7):2297-2305.
[68] YU Q,MENG X,WANG T,et al. Hematite films decorated with nanostructured ferric oxyhydroxide as photoanodes for efficient and stable photoelectrochemical water splitting[J]. Adv. Funct. Mater.,2015,25(18):2686-2692.
[69] CAO D,LUO W,FENG J,et al. Cathodic shift of onset potential for water oxidation on a Ti⁴⁺ doped Fe₂O₃ photoanode by suppressing the back reaction[J]. Energy Environ. Sci.,2014,7(2):752-759.
[70] HISATOMI T,FORMAL F L,CORNUZ M,et al. Cathodic shift in onset potential of solar oxygen evolution on hematite by 13-group oxide overlayers[J]. Energy Environ. Sci.,2011,4(7):2512.
[71] DIAB M,MOKARI T. Thermal decomposition approach for the formation of alpha-Fe₂O₃ mesoporous photoanodes and an α-Fe₂O₃/CoO hybrid structure for enhanced water oxidation[J]. Inorg. Chem.,2014,53(4):2304-2309.
[72] LUO Z B,LI C C,ZHANG D,et al. Highly-oriented Fe₂O₃/ZnFe₂O₄ nanocolumnar heterojunction with improved charge separation for photoelectrochemical water oxidation[J]. Chem. Commun.,2016,52(58):9013-9015.
[73] LI C C,WANG T,LUO Z B,et al. Enhanced charge separation through ALD-modified Fe₂O₃/Fe₂TiO₅ nanorod heterojunction for photoelectrochemical water oxidation[J]. Small,2016,12(25):3415-3422.
[74] HU Y S,KLEIMAN-SHWARSCTEIN A,STUCKY G D,et al. Improved photoelectrochemical performance of Ti-doped α-Fe₂O₃ thin films by surface modification with fluoride[J]. Chem. Commun.,2009(19):2652-2654.
[75] KIM J Y,JANG J W,YOUN D H,et al. A stable and efficient hematite photoanode in a neutral electrolyte for solar water splitting:towards stability engineering[J]. Advanced Energy Materials,2014,4(13):DOI:10.1002/aenm.201400476.
[76] NEUFELD O,YATOM N,CASPARY TOROKER M. A first-principles study on the role of an Al₂O₃ overlayer on Fe₂O₃ for water splitting[J]. ACS Catalysis,2015,5(12):7237-7243.
[77] FORMAL B F L,GR TZEL M,SIVULA K. Controlling photoactivity in ultrathin hematite films for solar water-splitting[J]. Adv. Funct. Mater.,2010,20(7):1099-1107.
[78] HISATOMI T,DOTAN H,STEFIK M,et al. Enhancement in the performance of ultrathin hematite photoanode for water splitting by an oxide underlayer[J]. Adv. Mater.,2012,24(20):2699-2702.
[79] LI J T,CUSHING S K,ZHENG P,et al. Plasmon-induced photonic and energy-transfer enhancement of solar water splitting by a hematite nanorod array[J]. Nat. Commun.,2013,4:DOI:10.1038/ncomms3651.
[80] JUE WANG,PAN S,CHEN M,et al. Gold nanorod-enhanced light absorption and photoelectrochemical performance of α-Fe₂O₃ thin-film electrode for solar water splitting[J]. J. Phys. Chem. C,2013,117(42):22060-22068.
[81] 刘东,于海童,杨震,等. 超薄膜吸收器在太阳能光解水制氢中的应用[J]. 化工学报,2015,66(s1):297-301. LIU D,YU H T,YANG Z,et al. Ultrathin film absorber for solar water splitting[J]. CIESC Journal,2015,66(s1):297-301.
[82] ZHANG K,SHI X,KIM J K,et al. Inverse opal structured α-Fe₂O₃ on graphene thin films:enhanced photo-assisted water splitting[J]. Nanoscale,2013,5(5):1939-1944.
[83] YANG J,BAO C,YU T,et al. Enhanced performance of photoelectrochemical water splitting with ITO@α-Fe₂O₃ core-shell nanowire array as photoanode[J]. ACS Appl. Mater. Interfaces,2015,48(7):26482-26490.
[84] QIU Y,LEUNG S F,ZHANG Q,et al. Efficient photoelectrochemical water splitting with ultrathin films of hematite on three-dimensional nanophotonic structures[J]. Nano Letters,2014,14(4):2123-2129.
[85] LIN Z,LIU P,YAN J,et al. Matching energy levels between TiO₂ and α-Fe₂O₃ in a core-shell nanoparticle for visible-light photocatalysis[J]. J. Mater. Chem. A,2015,28(3):14853-14863.
[86] ZHAO P,KRONAWITTER C X,YANG X,et al. WO₃-α-Fe₂O₃ composite photoelectrodes with low onset potential for solar water oxidation[J]. Phys. Chem. Chem. Phys.,2014,16(4):1327-1332.
[87] QI X,SHE G,HUANG X,et al. High-performance n-Si/α-Fe₂O₃ core/shell nanowire array photoanode towards photoelectrochemical water splitting[J]. Nanoscale,2013,6(6):3182-3189.
[88] KIM J Y,LEE J S,MAGESH G,et al. Single-crystalline,wormlike hematite photoanodes for efficient solar water splitting[J]. Scientific Reports,2013,3:DOI:10.1038/srepo2681.