Photoelectrocatalytic Reduction of CO2 to Syngas via SnOx‐Enhanced Cu2O Nanowires Photocathodes

Abstract Photoelectrochemical (PEC) reduction of CO 2 with H 2 O into syngas is an effective way to relieve the greenhouse effect and produce valuable chemicals. In this study, controllable PEC reduction of CO 2 with H 2 O to syngas is achieved by the Cu 2 O‐SnO x hybrid nanowires (NWs) photocathode, which can effectively produce the mixture of syngas (CO and H 2 ) with a total Faradaic efficiency of 90.32% at −0.35 V versus RHE. In addition, the CO/H 2 ratio of syngas can be adjusted in a wide range from 2.2:1 to 4.6:1. The investigations of linear sweep voltammetry, incident photon to current efficiency, electrochemical impedance spectroscopy, and temperature programmed desorption indicate that the charge transfer efficiency and CO 2 adsorption capacity are highly enhanced by the electrodeposition of SnO x on the Cu 2 O NWs electrode. In situ diffuse reflectance Fourier transformed infrared spectroscopy spectra results indicate that visible light irradiation can accelerate the accumulation of CO 2 reduction intermediates and thus facilitate the release of CO. This study provides an available way for the rational development of high‐performance PEC systems for CO 2 reduction to valuable carbon‐based compounds, as well as a new strategy for atmospheric CO 2 treatment.