Abstract:

The conversion of CO₂ into the high-value ethanol using renewable electrical energy is an important way to address the fuel storage challenge and reduce carbon emissions. The synthesis of Cu-based dual active site electrocatalysts to achieve catalytic CO₂ reduction to C₂ products is a research hotspot. Au nanoparticles were loaded on sea urchin-like CuO/Cu₂O to prepare Au _x -CuO/Cu₂O catalysts with different Au loads to improve the selectivity of electrocatalytic CO₂ reduction to ethanol. The reduction performance was evaluated in a flow cell with 1mol/L KOH as the electrolyte, and the total Faraday efficiency of the dicarbon products (C₂) reached 73.4% for Au₅-CuO/Cu₂O at a current density of 150mA/cm², with the ethanol Faraday efficiency reaching 40.0%, which was 4.2 times and 2.2 times higher than that of Au₂-CuO/Cu₂O and Au₈-CuO/Cu₂O, respectively, and the Faraday efficiency ratio of ethylene to ethanol was 1.35, which was 1.6 times and 3.46 times higher than that of the other two catalysts. The significant improvements of C₂ and ethanol selectivity by Au₅-CuO/Cu₂O were attributed to the suitable Au loading on the surface of CuO/Cu₂O, which realized an effective tandem catalytic process, i.e. The Au active sites promoted the generation of CO intermediates, and the Cu active sites accelerated the C—C coupling reaction of CO molecules to generate the C₂ product. This work could provide an important reference for the design and preparation of catalysts for electrocatalytic CO₂ reduction reaction with high ethanol selectivity.

Key words: electrocatalytic CO₂ reduction reaction, tandem catalysis, C—C coupling, ethanol, copper-based catalyst

摘要：

利用可再生的电能将CO₂转化为高价值产品乙醇是解决燃料的储存和减少碳排放的一种重要途径。合成Cu基双活性位点电催化剂实现催化CO₂还原制C₂产物是当前的研究热点，在此将Au纳米粒子负载在海胆状CuO/Cu₂O上，合成出不同Au负载量的Au _x -CuO/Cu₂O催化剂，以提高电催化CO₂还原为乙醇的选择性。在以1mol/L KOH为电解液的流动池中进行电催化CO₂还原性能评价，Au₅-CuO/Cu₂O在150mA/cm²的电流密度下，二碳产物（C₂）的总法拉第效率达到了73.4%，其中乙醇法拉第效率达到40.0%，分别是Au₂-CuO/Cu₂O和Au₈-CuO/Cu₂O的4.2倍和2.2倍，并且乙烯和乙醇法拉第效率的比值为1.35，分别是另外两种催化剂的1.6倍和3.46倍。Au₅-CuO/Cu₂O对电催化CO₂还原为C₂和乙醇选择性的显著提高归因于CuO/Cu₂O表面上适宜的Au载量，实现了有效的串联催化过程，即Au活性位点促进CO中间体生成，Cu活性位点加速CO分子的C—C偶联反应生成C₂产物，这为设计和制备具有高乙醇选择性的电催化CO₂还原反应的催化剂提供了重要参考。

关键词: 电催化二氧化碳还原, 串联催化, C—C偶联, 乙醇, 铜基催化剂