the Ag/AgCl electrode, and the pH is the pH of the electrolyte solution. The light-chopped linear sweep voltammograms (LSV) were recorded with a scan rate of 5 mV s -1 within the potential range of -0.5 V to 1.0 V vs. Ag/AgCl. The PEC performance of Au/BiVO4/WO3 was also examined under AM 1.5G conditions at 0.5, 1.0, and 1.5 sun, corresponding to 44.2, 87.5, and 129.1 mW cm -2 , respectively. Additionally, the Mott-Schottky (MS) analysis was acquired in the dark, using 20 potential steps at 1.5 kHz.