Direct synthesis of bismuth nanosheets on a gas diffusion layer as a high-performance cathode for a coupled electrochemical system capable of electroreduction of CO2 to formate with simultaneous degradation of organic pollutants

Abstract

A coupled electrochemical system (CES) for the electroreduction of CO2 to formate (ERCF) and simultaneous degradation of organic pollutants is a promising approach for CO2 conversion. Cathode material is a critical component of CES. However, the poor performance and complexity of synthesis limit its real application. Here, we report a Bi-based binder-free gas diffusion electrode (EBGDE) as a high-performance cathode for CES. The EBGDE was fabricated via direct electrodeposition of Bi nanosheets on a gas diffusion layer. By optimizing the deposition time of Bi nanosheets, a good Faraday efficiency (91.46 ± 6.58%) and formate production rate (1849.96 ± 127.69 μmol m−2 s−1) were obtained. Simultaneously, the methyl orange decolorization efficiency and chemical oxygen demand removal efficiency reached 100% and 55.25 ± 6.87%, respectively. This performance towards ERCF is better than recently reported ERCF electrodes. It probably results from the excellent performance of associated Bi-nanosheets catalysts, a high electroactive surface area, as well as fast electron transfer in the EBGDE. This work offers design rules to fabricate high-performance cathode materials for CES in industrial applications.