电催化还原CO2至C3高效催化剂的设计、合成及机理研究

Electrochemical reduction of carbon dioxide (CO2RR) to C3 products has the potential to address the urgent need to store otherwise-intermittent renewable electricity, and to reduce net greenhouse gas emissions. However, the catalytic mechanism remains unclear, resulting in the poor selectivity and low efficiency. To synthesize the highly efficient and selective CO2RR electrocatalysts, this project aims to investigate the catalytic mechanism and rate-limiting step of CO2RR to C3 on the low index facets of Cu and PdAu alloy by doping and introducing defects based on the first principles calculations. Eventually, design principles will be provided for synthesis of highly active, selective, and table electrocatalytic reduction of CO2 to C3 catalyst by this project. Under the guidance of the theoretical model, CO2RR electrocatalysts will be synthesized through a variety of methods such as microwave hydrothermal method, molten salt method, electrospinning method and reverse microemulsion. The effects of surface morphology, electronic structure, activity sites and solvent etc. on the reaction rate and selectivity of rate-limiting step will be clarified by adjusting the adsorption state of intermediates on the catalyst surface. Combined with the analysis of active sites and reaction mechanism verified by synchrotron spectroscopies, In-situ Raman, FT-IR etc. will be carried out to determine the intermediates of CO2RR on the surface to further supplement and improve the reaction mechanism proposed by DFT simulations. The final target of this project is to achieve the synthesis of effective catalyst for CO2RR to C3 with the guidance of theory, and eventually to have a deep understanding of the reduction mechanism of CO2 on the catalytic surface and to provide both experimental and theoretical guidance for highly efficient electrocatalysts of CO2RR.

电催化CO2还原生成C3产物对于缓解温室效应、高效存储间歇性可再生电能具有重要意义，但催化机理不清晰导致目前其电催化剂效率低、选择性差。针对以上不足之处，本项目拟在第一性原理计算框架下，以Cu及PdAu合金低指标表面为催化剂模型，通过掺杂原子、引入缺陷等手段重点研究CO2在电极表面还原生成C3产物的反应机理及决速步骤，建立材料微观结构与反应机理和催化剂性能关联模型，提供催化剂设计原则。在理论模型指导下，采用微波水热法、熔盐法、静电纺丝法、反相微乳液法等手段合成电极催化剂，探索催化剂表面形貌、电子结构、活性位点、溶剂效应对决速步骤反应速率和选择性的影响。利用原位Raman、FT-IR等技术检测CO2还原过程中间产物，结合原位同步辐射分析催化剂活性位点及作用机理，与理论提出的反应机理相互修正补充。本项目可望为深入理解CO2在催化剂表面的还原机理及合成高效CO2电催化剂提供理论和实验依据。

电催化CO2还原生成高附加值的C3产物对于缓解温室效应、高效存储间歇性可再生电能具有重要意义，同时为实现国家的“碳中和”战略提供了有潜力的途径。但催化机理不清晰导致目前其电催化剂效率低、选择性差。为克服以上不足之处，本项目在第一性原理计算框架下，以PdAu合金低指数表面为催化剂模型，通过暴露不同的表面模拟台阶、阶梯和缺陷等形貌对电催化CO2还原生成不同产物的选择性的影响。研究发现催化剂的表面粗糙度和电子结构共同决定了催化活性。采用显式和隐式溶剂模型考虑溶剂化效应，揭示显式溶剂水分子在反应过程中稳定中间体和传递质子的重要作用。明确催化剂表面形貌、电子结构、活性位点、溶剂效应对决速步骤反应速率和选择性的影响。建立材料结构与反应机理和催化剂性能关联模型，并运用其他体系中。深入理解CO2在催化剂表面的还原机理，为设计高效、稳定的CO2电催化剂提供理论基础