基于三元铁基光阴极构建高选择性CO2还原催化剂的研究

Due to the severely environmental pressure and tremendous applicable prospect, it is urgent to develop the full utilization of carbon dioxide (CO2) resource. However, plain photochemical or electrochemical carbon dioxide reduction remains a number of problems. Therefore, combining the photochemical and electrochemical reduction and using novel nanomaterials to catalyze the CO2 into storable liquid energy resources is a substantially promising method for the gas conversion and storage. Photoelectrochemical CO2 reduction would benefit from the synergistic effect of photocatalysis and electrocatalysis, and enhance the efficiency and selectivity in CO2 reduction reactions. The ternary iron-based p-type semiconductor materials have great potential in catalyzing the multi-step reaction of CO2 reduction, and forming liquid compounds with very high selectivity due to the matched band structure and unique bi-metal atom structure in the crystal. This project is planning to construct their nanoarray structures, improve charge carrier density and regulate the electron density of specific atoms to facilitate the photoelectric conversion and tune the absorbing/desorbing force of the transition groups during the reactions. The engineering strategies would boost the efficiency and selectivity of photoelectrochemical CO2 reduction reactions. Meanwhile, we would use the in-situ Raman technique and simulation calculations to reveal the reaction mechanism and process, which including the energy transfer and deliver modes of photons and electrons in the reactions. This project can provide the guidance for synthesizing nanostructure photocathode with high efficiency and selectivity for the CO2 reduction reactions, and essential foundation for investigating carbon resource cycling in large-scale industry.

由于巨大的应用前景以及环境压力，二氧化碳能源化利用刻不容缓。而单纯的光或电还原二氧化碳技术仍存在部分缺陷，因而，在光、电协同作用下利用新型纳米电极，将气态二氧化碳催化转化为液态（醇类）可储存能源，有望为二氧化碳的资源化利用提供新思路和方法。三元铁基p型半导体材料因匹配的能带结构以及独特的双金属原子结构，在光电催化二氧化碳发生多步反应、选择性生成液态能源等方面具有巨大的潜力。本项目拟通过纳米阵列结构的构筑、半导体载流子浓度的提升、双金属原子电子密度的特异性调节，提升光阴极的光电转化效率以及表界面吸/脱附过渡基团的能力，从而提高光电催化二氧化碳的效率与选择性。同时通过原位拉曼测试技术以及模拟计算等方法揭示反应机理过程，阐明光、电协同作用下光子和电子的能量转移和传递方式，为合成高效、高选择性光电催化剂提供指导依据，也为大规模发展碳循环工业提供重要的研究基础。

对于传统的材料制备和表征手段，其多集中于毫克级又或微克级宏观尺度的催化性能测试，材料本身的物质结构、纳米结构等细节信息已经被整体性能效果掩盖，从而使电极材料间的比较失去了应有的意义与价值，也使材料设计本身充满不确定性和随机性。在以研究铁基过渡金属化合物与CO2光电还原效果关系的问题核心下，搭建、改进了国际先进的表征技术（扫描电化学池显微镜；Scanning Electrochemical Cell Microscopy），在其他（原位）表征技术的辅助下，精确全面地研究了电极材料晶面取向与催化学性能的直接关系，消除了以往宏观测量技术中与生俱来的宏观尺度误差，为高效三元铁基光阴极的构建研究提供了重要保证，取得了一定研究成果。