Enhanced electroreduction of CO2 and simultaneous degradation of organic pollutants using a Sn-based carbon nanotubes/carbon black hybrid gas diffusion cathode

Coupled electrochemical system (CES) for electroreduction of CO2 and simultaneous degradation of organic pollutants is a promising CO2 conversion method. However, its performance is severely restrained by insufficient reactants and low electroactive surface areas on the cathode material. Here, a series of novel Sn-based carbon nanotubes (CNTs)/carbon black hybrid gas diffusion electrodes (CNTx/ESGDEs) were fabricated and used as cathodes to enhance the performance of the CES with methyl orange (MO) as a target pollutant. The results show that at an appropriate content of CNTs, the CNTx/ESGDEs offered increased total pore area, porosity, electroactive surface area, and decreased charge transfer resistances. The current density, Faraday efficiency, formic acid production rate, MO removal efficiency, and COD removal efficiency were improved by 140%, 92%, 404%, 76%, and 131%, respectively, at 40 wt% CNTs probably due to enhancement in the electroactive surface area as well as reactant transfer. This study benefits the large-scale applications of CES.