Photoelectrocatalytic Reduction of CO 2 to Syngas via SnO x ‐Enhanced Cu 2 O Nanowires Photocathodes

Photoelectrochemical (PEC) reduction of CO2 with H2O into syngas is an effective way to relieve the greenhouse effect and produce valuable chemicals. In this study, controllable PEC reduction of CO2 with H2O to syngas is achieved by the Cu2O-SnOx hybrid nanowires (NWs) photocathode, which can effectively produce the mixture of syngas (CO and H2) with a total Faradaic efficiency of 90.32% at −0.35 V versus RHE. In addition, the CO/H2 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 CO2 adsorption capacity are highly enhanced by the electrodeposition of SnOx on the Cu2O NWs electrode. In situ diffuse reflectance Fourier transformed infrared spectroscopy spectra results indicate that visible light irradiation can accelerate the accumulation of CO2 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 CO2 reduction to valuable carbon-based compounds, as well as a new strategy for atmospheric CO2 treatment.