将CO₂转化为高附加值的化学品是实现碳循环, 缓解能源危机和环境问题的有效途径之一。金属与半导体复合电极, 利用光电耦合技术为CO₂转化提供了一种新思路。本研究通过电沉积的方法在碱刻蚀处理后的Si片上制备了双金属Bi、Zn共修饰的Si基光电阴极(BiZn_x/Si), 用于CO₂的光电催化还原。研究表明, 引入金属Bi和Zn能够改善光的吸收性能, 降低电化学阻抗, 提高电化学活性比表面积(ECSA)。其中, BiZn₂/Si最优的光电极电化学比表面积可达0.15 mF·cm^-2。除此之外, 研究发现双金属共同作用有助于增强电极对中间体*OCHO的吸附作用, 在-0.8 V(vs. RHE)电势下, 最优的光电阴极BiZn₂/Si生成HCOOH的法拉第效率高达96.1%。更重要的是, 光电阴极BiZn₂/Si的光电流强度在10 h内维持-13 mA·cm^-2, 表现出良好的性能稳定性。

The conversion of CO₂ into high value-added chemicals is an effective way to realize the carbon cycle, alleviate energy crisis and environmental problems. The preparation of metal-semiconductor electrodes provides a new idea for CO₂ conversion by photoelectric coupling technology. In this study, Si was etched in alkali solution, on which a bimetallic Bi, Zn co-modified Si photoelectrocathode (BiZn_x/Si) was prepared via the electrodeposition process, for the photoelectrochemical reduction CO₂. The results show that the introduction of Bi and Zn can improve the light absorption performance, reduce the electrochemical impedance, and increase the electrochemical active surface area (ECSA). Especially, the ECSA of the best photoelectrocathode BiZn₂/Si is 0.15 mF·cm^-2. Besides, the cooperative effect of Bi and Zn can improve the adsorption performance toward the intermediates *OCHO. During the photoelectrochemical reduction of CO₂, the Faradaic efficiency for HCOOH reaches up to 96.1% on the best photoelectrocathode BiZn₂/Si at the potential of -0.8 V (vs. RHE). Moreover, the photocurrent intensity on the photoelectrocathode BiZn₂/Si remained -13 mA·cm^-2 during the 10 h photoelectric stability test, suggesting its high stability.