Optimization of Electron Transfer Kinetics Between Photoanode and Biocathode for Enhanced Carbon-Neutral Pollutant Removal in Photocatalytic Fuel Cells

Photocatalytic fuel cells (PFCs) can harness energy from organic waste for electricity generation. However, incorporating CO2 reduction into PFC to achieve carbon neutrality remains significant challenges due to substantial thermodynamic and kinetic barriers. Herein, a PFC is constructed using formate dehydrogenase (FDH)-based biocathode and S-scheme heterojunction TiO2/CdS engineered photoanode. The resulting PFC integrates photoanodic pollutant degradation with bio-cathodic CO2 reduction to achieve formate production rate of 7.13 mol·h-1 with high selectivity and CO2 recovery efficiency of 76.1%, which is the best value in the reported PFC. Furthermore, PFC demonstrates a peak power and current density of 186.3 W cm-2 and 1361.6 A cm-2, respectively. The best performance of PFC is achieved due to the ultrafast electron transfer on the biocathode and the efficient carrier separation of the photoanode. The collaborative dynamics between the photoanode and biocathode lower the CO2 reduction potential, enhancing the reaction kinetics of CO2 reduction to formate.