Nanostructured Au Electrode with 100 h Stability for Solar-Driven Electrochemical Reduction of Carbon Dioxide to Carbon Monoxide

[Image: see text] Solar-to-chemical energy conversion is a potential alternative to fossil fuels. A promising approach is the electrochemical (EC) reduction of CO(2) to value-added chemicals, particularly hydrocarbons. Here, we report on the selective EC reduction of CO(2) to CO on a porous Au nanostructure (pAu) cathode in 0.1 M KHCO(3). The pAu cathode anodized at 2.6 V exhibited maximum Faradaic efficiency (FE) for conversion of CO(2) to CO (up to 100% at −0.75 V vs reversible hydrogen electrode (RHE)). Furthermore, commercial Si photovoltaic cells were combined with EC systems (PV-EC) consisting of pAu cathodes and IrO(2) anodes. The triple-junction cell and EC system resulted in a solar-to-CO conversion efficiency (SCE) of 5.3% under 1 sun illumination and was operated for 100 h. This study provides a PV-EC CO(2) reduction system for CO production and indicates the potential of the PV-EC system for the EC reduction of CO(2) to value-added chemicals.