CuO/g-C3N4/rGO multifunctional photocathode with simultaneous enhancement of electron transfer and substrate mass transfer facilitates microbial electrosynthesis of acetate

Microbial electrosynthesis (MES) is a potential CO2 fixation technique in which biocatalysts obtain electrons from electrodes as a driving force to reduce CO2 to more valuable multi -carbon products. In this study, a novel CuO/g-C3N4/rGO multifunctional photocatalyst was developed, and an MES system was constructed using mixed culture as a biocatalyst. Compared with CuO/g-C3N4, the introduction of rGO into CuO/g-C3N4 can enhance light absorption capacity and improve photogenerated electron-hole separation migration ef-ficiency. Under the action of increasing reducing power, CuO/g-C3N4/rGO can accelerate electron transport rate to microbes in three ways (indirect via formate, indirect via hydrogen, and direct electron transfer). Furthermore, CuO/g-C3N4/rGO was beneficial for enriching electroautotrophic microorganisms and increasing the abundance of Aceto-bacterium and Arcobacter. In addition, the CO2 adsorption capacity of the photocatalyst can be improved. At a potential of-0.9 V (versus Ag/AgCl), the acetate production of MES with the CuO/g-C3N4/rGO photocathode was 0.27 g/L/d, which was 4.2 times higher than that of the control. This study provides an idea for the design of a multifunctional photocathode for reducing energy consumption and improving MES efficiency by simultaneously enhancing electron transfer and substrate mass transfer. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

A novel CuO/g-C3N4/rGO multifunctional photocatalyst was developed and applied in a microbial electrosynthesis (MES) system using mixed culture as a biocatalyst. The introduction of rGO enhanced light absorption capacity and improved electron-hole separation migration efficiency. CuO/g-C3N4/rGO was beneficial for enriching electroautotrophic microorganisms and increasing the abundance of specific bacteria. The study provides insights for the design of multifunctional photocathodes to reduce energy consumption and improve MES efficiency.