Cu2O基异质结光阴极高效光电催化还原CO2与作用机制研究

Photo-electro catalyze CO2 conversion to fuels and high value-added chemicals under solar irradiation is one of the most promising ways to address energy shortages and excessive CO2 emissions. The competition of hydrogen evolution reaction severely hampers the efficiency of photo-electro catalytic CO2 reduction reaction in water-containing system. The general photo-catalyzed CO2 reduction system with p-type or n-type semiconductor as photocathode is still limited due to the poor selectivity, low visible light utilization and low efficiency. This project will propose to systematically develop a new type of Cu2O-based heterogeneous p-n junction semiconductor as photocathode. Through rational design and controllable preparation of vertically ordered Cu2O-based composites with the high catalytic activity and visible-light performance as photocathode to further build the highly efficient photoelectrocatalytic CO2 reduction system. From the theoretical level, this project will study the synergistic mechanism of photochemical and electrochemical catalytic CO2 reduction; In addition, this project will also from the technical level to develop highly visible light utilization, efficient selective and high catalytic CO2 reduction activity of Cu2O-based heterogeneous p-n junction semiconductor. The purpose of this study is to provide practical support and theoretical insight for the design and construction of high-efficiency photoelectrocatalytic CO2 reduction catalyst.

利用太阳能还原CO2为燃料和高附加值化学品，是有效解决能源危机和温室效应的路径之一。而水相光电催化CO2还原反应中，析氢反应的竞争严重制约了光电催化CO2还原反应效率。本项目主要针对水相催化CO2还原反应体系中的单一半导体光阴极材料弱可见光响应、低催化活性和低选择性这一关键科学问题。拟通过理性设计与可控制备Cu2O基p-n结复合材料，通过调控其带隙和优化特定界面电子结构，以增加催化反应活性位点，并提高电子传递的效率，从而构建高效光电催化CO2还原光阴极。进一步通过理论计算从分子层面上系统研究Cu2O基光阴极材料在光催化、电催化及光电催化还原CO2反应体系中的催化规律，阐明其光电催化CO2还原的协同增效机理；从实验技术层面上，实现构建可见光利用率高的光电催化CO2还原光阴极，以期高效且选择性催化CO2还原，最终为设计制备高效光电催化CO2还原催化剂提供实践支持和理论依据。

本项目主要针对水相催化CO2还原反应体系中的单一半导体光阴极材料弱可见光响应、低催化活性和低选择性这一关键科学问题。开展了高性能且高选择性的过渡金属氧化物异质结材料的设计与制备技术研究：如Cu2O/α-Fe2O3/g-C3N4基异质结复合材料，通过调控其带隙和优化特定界面电子结构，以增加催化反应活性位点，并提高电子传递的效率，从而构建高效光电催化CO2还原光阴极。.其中，制备的Bi和α-Fe2O3共同修饰的ZnO纳米棒阵列Bi@ZFO NTs做光阴极选择性光电催化CO2还原为HCOOH，法拉第效率达到61.2%，起始电位为-0.53 V vs RHE，Tafel斜率 101.2 mV dec-1。我们继续在上一个工作的基础上通过电沉积法构建了Cl离子修饰的Cu2O/ZnO异质结材料，其在-0.3 V vs. RHE的电压下，催化CO2还原为CH4的法拉第效率达到88.6%，在5小时以上的电解实验中保持高稳定性。.项目通过理论计算从分子层面上系统研究光阴极材料在光催化、电催化及光电催化还原CO2反应体系中的催化规律，阐明其光电催化CO2还原的协同增效机理。在高效光电催化CO2还原催化剂设计与应用、阐明催光阴极-CO2分子构效关系、调控还原产物选择性方面取得了系列成果。同时拓展了相关材料多功能应用领域、如：光电/电催化制氢/制氧、光电催化四环素降解。项目实施期间超额完成项目预期目标，以第一作者和通讯作者身份总共发表高水平论文7篇。