Photocatalytic H2O2 generation assisted photoelectrochemical water oxidation for enhanced BiVO4 photoanode performance

Abstract

A method is devised to integrate a photocatalytic and photoelectrochemical (PEC) systems to achieve enhanced water oxidation performance of a BiVO4 photoanode. The reduced gC3N4 (R-gC3N4) photocatalyst suspended in the anode compartment electrolyte of the PEC cell can serve as an agent to integrate the systems. The performance of BiVO4 photoanode in PEC water splitting is hampered by the surface states back electron-hole recombination. This is overcomed by incorporating R-gC3N4 in the electrolyte to produce hydroxyl radicals and hydrogen peroxide reactive intermediates, thereby reducing the onset potential for oxygen evolution reaction in the BiVO4 photoanode. The enhanced charge-transfer for water oxidation reaction kinetics at the photoanode/electrolyte interface is observed by suspending R-gC3N4 photocatalyst in the electrolyte. Approximately 3-fold increase in photocurrent density (105 μA/cm2 at 1.23 V vs. RHE) and a significant reduction in the onset potential (395 mV vs. RHE) of the BiVO4 photoanode is observed in R-gC3N4 + 2-propanol + 0.1 M PBS electrolyte. The application of R-gC3N4 photocatalyst to promote the reactivity of neutral pH electrolytes introduces a new paradigm for hydrogen generation.