陶瓷电极催化活性结构的原位构筑与调制及电解CO2机理研究

Solid oxide electrolyzers can directly electrolyze CO2 to produce fuel, which has attracted a lot of research interests and also demonstrated important practical application potential in the field of clean energy conversion and utilization. Traditional nickel cathode with poor redox and thermal cycling performances is easy to be oxidized when performing direct high temperature electrolysis. In contrast, redox-stable (La,Sr)TiO3+δ ceramic can perform direct high temperature electrolysis; however, the insufficient electrocatalytic activity still restricts kinetic process. This proposal aims to develop high-performance metal/ceramic composite electrode for direct carbon dioxide electrolysis by combining in situ formation of oxygen vacancy with active metal dopant and in situ growth of Ni1-xCux alloy catalyst. By coupling surface oxygen vacancy and metal catalyst, catalytic active structure will be constructed to enhance catalysis performances. Firstly, the chemical adsorption and activation of carbon dioxide molecules will be studied. Secondly, the composition of Ni1-xCux alloys will be tailored to tune the kinetic process of high temperature car bon dioxide electrolysis. Thirdly, the catalysis mechanism of active structure and the influence of active strcuture size and density will be investigated. The energy conversion, cathode stability and redox cycling performance of high temperature carbon dioxide electrolysis are then studied. Composite metal/ceramic electrode will be developed through control of point defects and reversible phase changes. The creation of new interface and surface in composite electrode will be determined and the CO2 catalysis mechamism is also to be made clear, which will provide valuable references for electrocatalytic carbon dioxide conversion.

固体氧化物电解池可直接电解CO2制备燃料，在能源转换和利用方面具有重要的研究价值和应用前景。传统Ni基阴极直接高温电解易氧化且热循环性能弱，氧化还原稳定的(La,Sr)TiO3+δ陶瓷阴极虽可直接电解CO2但是催化活性较弱。本项目对(La,Sr)TiO3+δ掺杂活性元素M (M=Mn,Cr)构造氧空位，原位可逆生长Ni1-xCux合金催化剂与氧空位耦合构筑催化活性结构，可控构筑纳米金属/陶瓷复合电极表界面新体系。研究电极氧空位吸附与活化CO2的机理和Ni1-xCux组分调控催化动力学的规律，研究催化活性结构催化裂解CO2的机理及其尺寸与密度调变纳米金属/陶瓷复合体系催化裂解CO2动力学的规律，研究新型金属/陶瓷界面对复合体系高温稳定性及热循环性能的增强机制。本项目拟阐明构筑陶瓷电极催化活性结构的一般规律，确定复合电极表界面新体系催化裂解CO2的机理，为催化还原CO2提供有价值的参考。

固体氧化物电解池可高效电解CO2/H2O将电能转化为燃料能源，法拉第电流效率可高达100%，在可再生能源利用方面具有重要的学术研究价值和应用前景。氧化还原稳定且具有n型导电机制的陶瓷SrTiO3电极材料可匹配固体氧化物电解池阴极的强还原条件，但是催化活性不足仍然制约复合电极性能。负载纳米催化剂可有效增加表界面如三相界面提高复合电极催化性能，但是纳米催化剂的烧结与团聚仍然是当前面临的巨大挑战。. 本项目先通过调控钙钛矿型(La,Sr)(Ti,M)O3+δ (M=Mn,Cr)成分筛选电子导电性和氧离子导电性优良的材料体系，确定Mn/Cr掺杂构筑氧空位增强CO2高温化学吸附性能的机制。随后构筑纳米Ni1-yCuy/(La,Sr)(Ti,M)O3+δ复合阴极体系，其中金属-氧化物界面体系对于CO2活化性能增强显著。结合原位热重技术和透射电镜研究，明确了催化活性元素从钙钛矿晶格脱溶生长铆合型纳米金属催化剂的过程与机制，实现了陶瓷电极非化学计量比调控与掺杂协同调控构筑氧空位和纳米金属耦合的催化活性结构。结合原位红外谱学与DFT计算，明确了新型活性界面对CO2裂解的增强机制。. 本项目构筑了全陶瓷固体氧化物电解池实现直接CO2电解，并获得了接近100%的法拉第电流效率和100小时稳定运行和10次氧化还原循环。随后进一步开展了阴极电解CO2耦合阳极电氧化CH4制合成气的工作，通过协同调控外场环境如温度/电场和界面催化，实现了CH4向合成气的高效转化，并获得了100小时的稳定运行和10次热循环。本项目阐明了陶瓷复合电极原位构筑催化活性结构的一般规律，为发展陶瓷基复合电极表界面新体系提供有价值的参考。