Cu基化合物表面缺陷结构的可控构建及其对CO2电还原C-C偶联反应的调控机制

The electrocatalytic reduction of CO2 to value-added multi-carbon (C2+) products provides a promising way for carbon recycling . To date, copper (Cu) is one of the most promising candidates for electroreducing CO2 to C2+ hydrocarbons. Unfortunately, the kinetics of C-C dimerization is sluggish, which results in wide products distribution, low C2+ selectivity and low catalytic activity. It is of paramount importance to subtly modify Cu based materials to narrow the distribution of products towards a single class of target hydrocarbons with high Faradaic efficiencies and reaction rates. The subsurface nonmetallic negative elements of Cu based compounds can positively modulate and stabilize the electronic structures of surface Cu sites. Therefore, this project will precisely modify the local surface structures of Cu based compounds via defect chemistry strategy, aiming to boost dynamic process of CO* intermediates coupling. Herein, some novel Cu based compounds with abundant defects on different facets will be controllably synthesized in virtue of theoretical and experimental studies, and the relationship between formation-evolution mechanism of surface defects and reaction environment will be revealed. In addition, some new methods for rational design and precise control of surface defects will also be highlighted. Moreover, this project will conclude the design principles of modulating variety, concentration and distribution of surface defects that affect the coverage of CO* intermediates and the electrostatic difference of adjacent CO*. Furthermore, the structure-performance relationship between surface defects and C-C coupling reaction performance will also be established. Through the implementation of this project, a series of surface defect-rich Cu based compound materials will be developed, further to realize high-efficiency and real-world electroreduction process of CO2 conversion to value-added C2+ products.

电催化还原CO2制备高附加值多碳产物为实现高效碳循环提供了一种理想的转化途径。迄今，Cu基催化剂是最有希望实现CO2至多碳产物高效转化的候选材料，但材料表面C-C偶联反应十分困难，导致其产物分布宽、多碳产物选择性差且催化活性低。若能提升多碳产物的法拉第效率和反应速率，将为Cu基电催化剂的现实应用带来契机。因此，本项目拟围绕Cu基化合物展开研究，基于材料亚表面负电荷中心原子对表面Cu电子结构的调控和稳定作用，通过精确调节表面缺陷结构来促进CO*耦合反应。应用理论与实验相结合的手段，揭示Cu基化合物不同晶面缺陷形成演化与反应环境的内在关联，建立材料表面缺陷结构理性设计和精确控制的新方法；阐明材料表面缺陷的种类、浓度及空间分布对吸附CO*覆盖度、相邻CO*电荷差异的影响规律，及其对C-C偶联反应的作用机制；最终开发出表面富缺陷结构的Cu基化合物材料，实现其电还原CO2制备多碳产物的高效转换过程。

电催化CO2转化技术是助力“碳达峰、碳中和”目标实现的理想途径。在众多催化材料中，Cu基催化剂是最有潜力实现CO2电解制多碳（C2+）化学品的材料。本项目采用理论与实验相结合的研究方法，可控制备出Bi2CuO4、S-HKUST等多种高效CO2还原电催化剂材料，其中多碳产物性能最优的催化剂材料在电流密度达到400 mA cm-2时，乙烯法拉第效率高达57.2%，多碳产物（乙烯、乙醇和乙酸）法拉第效率为88.4%；通过十八硫醇分子修饰，提升了Cu基气体扩散电极在CO2电还原过程中多碳产物的选择性与电极稳定性，在200 mA cm-2下稳定工作超过100 h而未出现明显的击穿现象；同时，借助原位谱学及同步辐射技术，阐明了催化剂在工况环境下结构的演化规律，揭示了C-C偶联反应位点的电子结构和几何构型对多碳产物选择性的影响机制，为高C2+产物性能的电催化还原CO2材料的设计与开发提供理论指导。.上述研究工作在Angew. Chem. Int. Ed.、Adv. Mater.等学术期刊上发表标注项目资助的论文24篇，申请相关发明专利5项（2项授权）。项目负责人获批上海市自然科学基金面上项目。