Se/Te/N掺杂Cu基催化剂及其调控CO2还原产物研究

Achieving high selectivity using facile prepared catalysts is a challenge for CO2 electroreduction catalysts, especially for Cu-based catalysts with complex catalytic products. However, the positive correlations between the binding strengths of *COOH/*H and *CO on the surface of transitional metals in the CO2 reduction reaction would prevent a single metal from simultaneously inhibiting hydrogen evolution and promoting CO2 reduction. In the present project, Se/Te/N, the p-Block elements, will be introduced into Cu-based catalysts to circumvent the traditional scaling relationships of binding strengths between *COOH/*H and *CO. This method can effectively suppress hydrogen evolution and efficiently regulate product selectivity to hydrocarbons. At the same time, the key parameters of the Se/Te/N doped Cu-based catalysts, such as the valence state and electronic structure of Cu et al., can be rationally adjusted by the contents of Se/Te/N, which would basically determine the CO2 electroreduction performances and further reveal the intrinsic relationship of catalyst structure with reduction activity. Focusing on the functional states and structural evolutions of Se/Te/N elements in the reaction process, electrochemical and physical characterizations will be applied to verify the influences of Se/Te/N elements on Cu catalyst and microenvironment. Furthermore, various in-situ characterization techniques (FTIR and Raman Spectroscopies) can be further utilized to detect the important reaction intermediates and explore the phase transformation of the catalyst in the CO2 electroreduction process, and deepen the understandings on fundamental reasons for performance enhancements using non-metal doped catalysts, leading to the rational designs of highly efficient CO2 electroreduction catalysts and profound insights into the formation mechanisms of multi-carbon products.

Cu基催化剂具有优良的CO2还原催化性能，但产物非常复杂，如何提高产物选择性是一个关键问题。过渡金属表面上*COOH、*CO与*H的键能往往呈正比例关系，导致单一金属很难同时促进CO2还原却抑制析氢。本项目拟向Cu基催化剂引入非金属p区元素Se/Te/N掺杂，打破成键比例，使其容易吸附和稳定CO2还原的关键中间体，并抑制析氢，提高多碳产物的选择性。重点考察Se/Te/N掺杂对Cu价态和电子结构的影响，并通过改变掺杂量等调控催化剂性质，研究其对CO2还原的催化性能，分析构效关系。同时利用原位电化学红外与拉曼技术检测CO2还原过程中重要吸附态中间体和催化剂物相结构变化，进而阐明Cu催化剂掺杂Se/Te/N对CO2还原的促进机制。本项目有望为CO2还原电催化剂的设计合成提供指导，并加深对多碳产物生成机理的认识。

耦合间接电源将CO2转化为可用的燃料或化工产品是有效减少碳排放的方式之一，其商业化的主要挑战是需要提高催化剂对所需产品的活性和选择性。尤其对于能够大量生成具有高附加值C2产物的Cu基催化剂，因其涉及多电子、多步骤的复杂反应过程，提高目标产物活性和选择性更具难度和挑战。因此，本项目通过Se掺杂构筑富缺陷的Cu基催化剂，有效提高C2产物活性和选择性。Se掺杂打破了金属表面吸附反应中间物种的传统线性关系，即在增强对*COOH的吸附的同时优化了对*CO吸附模式，因此有效促进生成C2产物。本项目围绕Cu基催化剂的定向构筑，首先研究了缺陷和晶界对增加催化反应活性和降低反应能垒的促进作用，然后通过流动池体系的测试研究提高CO2还原活性密度，最终成功制备出在流动池体系中表现出优异CO2还原性能的富缺陷和多晶界Cu基催化剂，其还原电流超过1 A cm-2，C2产物选择性超过60%，并通过原位ATR-SEIRAS光谱证明催化剂具有较高*CO覆盖度，因此显著提高了其C2产物选择性。本项目针对Cu基催化剂的定向构筑，初步阐明其对生成C2产物的促进机制，为进一步设计构筑CO2还原催化剂提供指导，也加深对CO2还原生成C2产物机理的认识。