Bi–Sn Co-Catalyst-Modified p-Si Nanowire Array Photocathodes for Photoelectrocatalytic CO<sub>2</sub> Reduction to Formate
Wangqiang Shen, Zepeng Yang, Junjie Wang, Jiewu Cui, Zhiyong Bao, Dongbo Yu, Minna Guo, Guangqing Xu, Jun Lv
Abstract
Co-catalyst modification has been studied as a strategy to enhance silicon nanowires’ (SiNWs’) photoelectrocatalytic performance for CO 2 reduction since their high light absorption efficiency and unique radial structure facilitate electron transport. However, their limited activity and poor selectivity toward CO 2 reduction remain a challenge. Herein, we report the fabrication of core–shell structured, non-noble metal Bi and Sn co-catalyst-loaded SiNW photoelectrodes for CO 2 reduction to formate. Microscopic morphology results revealed that Bi co-catalysts were deposited as nanoparticles and Sn co-catalysts as thin films on Bi and Si surfaces. Notably, Bi–Sn/SiNW photocathodes showed enhanced formate yield and selectivity compared to electrodes modified with only Bi or Sn. Specifically, at −1.02 V vs reversible hydrogen electrodes, the Faraday efficiency of formate reached 88.67% and the product rate was 80.07 μmol h –1 cm –2 . Further experimental analysis and computational results demonstrated that the reasonable band structure formed by Si and the two co-catalysts Bi and Sn improved migration of photogenerated electrons, thus promoting CO 2 reduction reaction toward formate with high efficiency and selectivity. This work lays the foundation for composite photocathodes with multiple co-catalysts for synergistic catalysis, addressing the challenges related to CO 2 reduction and sustainable energy development.