The conversion of CO2 into fuels using photocatalysts and solar energy is believed to be one of the best methods to address the energy and environmental crisis. However, the reduction of CO2 with low-cost H2O suffers from fiercely competition with H2 evolution reaction (HER). Here we present a simple strategy using Cu2O as a dark cathode and TiO2 as a model photoanode to construct a stable system for PEC CO2 reduction with high efficiency and selectivity for carbonaceous products (Fig. 1). In order to utilize the active reaction sites on Cu2O for the preferential conversion of CO2 and suppressing HER (Fig. 2a), the surface of Cu2O was directly exposed into the electrolytes. Then, Cu2O film was shadowed by the photoanode from illumination to obtain a high stability and selectivity simultaneously (Fig. 2b). In addition, it was found that the photogenerated holes, instead of electrons, are the major reason for Cu2O corrosion . Therefore, Cu2O film was used as dark cathode to minimize the adverse effects of holes, exhibiting an improved stability compared with that directly used as photocathode under illumination. As a result, a high Faradaic efficiency of 87.45% and a selectivity of 92.65% for all carbonaceous products were achieved, which is among the highest selectivity ever reported for CO2 photoreduction in aqueous solutions without hole scavengers and organic solvents.

Stable aqueous photoelectrochemical CO2 reduction by a Cu2O dark cathode with improved selectivity for carbonaceous products

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.