碳酸根基双位点型催化剂的构筑及其电还原CO2的机制

The development of highly active catalysts and the study on the reaction mechanism of CO2 electroreduction are important issues to be solved in the researches on CO2 reduction. It has been found that carbonate (CO32−) -based nanocatalysts can reduce CO2 to formic acid or methanol at low overpotential, whereas the reaction mechanism is not clear. In this project, a series of CO32−-based nanocatalysts will be prepared for studying the CO2 electroreduction. By regulating the catalyst’s crystal faces and the content of CO32− on the catalyst’s surface, we can study the structure-activity relationship of the catalysts. According to the structure characterization on the catalysts before/after the reaction, and the results obtained by Tafel slope, in-situ spectroscopy and theoretical calculation, the reaction mechanism of high-efficient CO2 reduction using such catalysts can be investigated. Based on the above theoretical basis that the catalyst can reduce the overpotential of CO2 reduction reaction through stabilizing the intermediates of the reaction, CO32−, one of the intermediates of CO2 reduction reaction will be introduced into the catalyst’s structure in this project for achieving the stabilization of intermediates by the catalyst. Through investigating the effect of dual-site adsorption between CO32− and catalyst in the CO2 reduction, the mechanism of the CO2 reduction using carbonate (CO32−) -based catalyst at low overpotential can be revealed. The project will provide new ideas for the design and the construction of the catalyst that can accomplish the CO2 reduction at low overpotential.

开发高活性电还原CO2的催化剂及研究其反应机理是CO2电还原研究中亟待解决的重要课题。碳酸根（CO32−）基纳米催化剂被发现可以在低过电位下将CO2还原为甲酸或甲醇，但反应机理尚不明确。本项目拟制备一系列CO32−基纳米催化剂用于CO2电还原研究。通过调控催化剂的晶面和催化剂表面的CO32−含量来研究其构效关系，并且根据催化剂在反应前后的结构以及Tafel斜率、原位光谱和理论计算等结果研究催化剂高效还原CO2的反应机理。依据催化剂将CO2还原反应的中间体稳定化可以降低反应过电位的理论基础，在催化剂结构中引入CO2还原反应的中间体之一CO32−来实现催化剂对中间体的稳定化。研究CO32−和催化剂之间的双位点吸附形式在CO2还原反应过程中所发挥的作用，揭示CO32−基催化剂低过电位催化还原CO2的机制。本项目的开展将为设计和构筑低过电位还原CO2的催化剂提供新的思路。

碳中和碳达峰大背景下，CO2减排势在必行，传统催化剂电化学转化CO2的能量转化效率较低，需要耗费大量的电能，只有获得高效催化剂才能降低这一过程的电能成本从而使其满足产业化需求。本项目对如何提高电还原CO2的能量效率进行了系统地研究。我们对如何提高电还原CO2能量效率的几个方面进行了研究，发现CO2还原反应的催化剂需要改进以外，阳极析氧反应催化剂同样亟待改进。只有同时采用高活性的阳极和阴极催化剂才能有效提升反应的能量转化效率。本项目中制备了高活性的Bi基催化剂，同时也研究了高活性的过渡金属硫化物阳极催化剂，这将对提升电还原CO2的能量效率起到重要作用。特别是本项目中制备的Fe单原子掺杂Ni3S2催化剂表现出优异的析氧活性和稳定性，在10 mA cm−2电流密度下的过电位仅180 mV。本项目的开展将为实现高效率电还原CO2的应用奠定坚实的基础。