质子导体固体氧化物电解池共电解H2O–CO2原位生成CH4的反应机理及法拉第效率调控研究

基于质子导体固体氧化物电解池（H-SOEC）的高温共电解技术能够利用可再生能源电力将H2O和CO2直接转化为CH4，对我国实现CO2减排与利用具有重要意义。本项目针对阴极催化剂活性不足和法拉第效率较低这两个H-SOEC技术的瓶颈问题进行研究，通过构筑不同成分的金属陶瓷阴极材料，结合材料本征性质表征和H2O–CO2共电解原位谱学测试、电化学表征和尾气定量分析，探究共电解时CO2还原加氢的反应路径和机理，阐明电化学增强催化作用机制，指导高活性阴极催化剂开发；通过对质子导体电解质进行阳离子掺杂，研究对其质子迁移数的影响规律，阐明掺杂阳离子的性质和运行参数对法拉第效率的调控机理，筛选高性能电解质；最后构筑H-SOEC单体研究其电化学性能和CH4产率，在恒电流模式下探究其性能演变规律，通过材料表征阐明衰减机理。研究结果将为制备高CH4产率、高法拉第效率和高稳定性的H-SOEC单体提供理论依据。

Proton-conducting solid oxide electrolysis cell (H-SOEC) is a promising technique which is capable of co-electrolyzing H2O and CO2 to directly produce CH4, using the excess renewable electricity. This technique will play a key role in reducing CO2 emission and enabling CO2 utilization. However, the development of H-SOEC is hindered by two aspects, that the catalytic activity of cathode catalysts is insufficient and that the Faradaic efficiency is low for H-SOEC during operation. First of all, the cathode catalysts will be prepared with different compositions and investigated by material characterization. Then in-situ spectroscopy study and electrochemical characterization will be performed on the three-electrode half-cells during H2O–CO2 co-electrolysis, with the exhaust gas analyzed to obtain the gas composition. The electrochemical CO2 reduction and hydrogenation paths can thus be investigated during co-electrolysis, and the underlying physics of electrochemical promotion of catalysis effect during electrochemical CO2 reduction can be elucidated. This is beneficial for future development of cathode catalyst with high catalytic activity. Secondly, the electrolyte materials will be doped with different cations and the effect of cation doping on the proton transport number will be studied. The underlying mechanism accounting for the effect of the properties of doping cations and the operating parameters on the Faradaic efficiency will be clarified, supporting future study on electrolyte materials. Lastly, an H-SOEC button cell will be constructed and tested to study its electrochemical performance, CH4 production performance and the stability. Degradation mechanism will also be investigated by performing material characterization. This study will provide the theoretical basis for the future development of H-SOEC with high CH4 yield ratio, high Faradaic efficiency and high stability.