Enhanced photoelectrocatalytic activity of FTO/WO3/BiVO4 electrode modified with gold nanoparticles for water oxidation under visible light irradiation

Gold nanoparticles were successfully deposited on FTO/WO₃/BiVO₄ electrode surface by means of electrolysis of AuCl₄⁻ ions. The composite films were characterized by SEM, XPS and XRD techniques. An increase in photocurrent and a negative shift of onset potential for water oxidation were observed upon modification of the electrode surface with the Au particles. The electrochemical impedance spectroscopy was used to confirm the acceleration of charge transfer process by Au deposition at the electrode surface. The photocurrent action spectrum did not correlate with the plasmonic absorbance of Au nanoparticles at 560 nm, suggesting that the Au nanoparticles increased charge separation without undergoing a plasmon resonance effect under visible light irradiation.