CoP-Fe2O3/g-C3N4 photocathode enhances the microbial electrosynthesis of polyhydroxybutyrate production via CO2 reduction

Abstract

The hydrogen energy and CO 2 reduction in-situ recombination has drawn increasing attention. Microbial electrosynthesis (MES) integrated with photocatalytic materials is a novel technology for CO 2 utilization. Here, MES with the photocathode CoP-Fe 2 O 3 /g-C 3 N 4 was constructed using Ralstonia eutropha as biocatalyst to generate polyhydroxybutyrate (PHB). The integration of CoP and Fe 2 O 3 /g-C 3 N 4 facilitated electron–hole pair separation and electron transfer, which enhanced hydrogen evolution reaction and provided additional reducing power for CO 2 conversion. Simultaneously, the concentration of reactive oxygen species was also considerably reduced, increasing the production of PHB. In particular, 87.54 mg/L of PHB was obtained in CoP-Fe 2 O 3 /g-C 3 N 4 at − 1.05 V, which is about three times higher than that in carbon felt. At − 0.9 V, PHB concentration further increased to 142.20 mg/L. This study provides a new approach for converting CO 2 into multicarbon compounds in situ electrolysis of water under visible light.