For PEC performance measurements, a three-electrode electrochemical cell with a potentiostat (BioLogic SP-300) was used. The light source consisting of AM 1.5 G filter was provided by a 150 W Xe-lamp to simulate AM 1.5 G sunlight. The light intensity was calibrated using a silicon diode from PV Measurement, Inc. (100 mW cm -2 ). A Pt wire and an Ag/AgCl electrode (KOSLOW, saturated KCl, +0.197 V vs. normal hydrogen electrode) were used as the counter and reference electrodes, respectively. The electrolyte used for the measurements was 1 M H2SO4 (pH = 0) electrolyte. The J-V curves were recorded under intermittent or continuous light illumination with a scan rate of 10 mV s -1 . IPCE measurements were performed using a home-built system equipped with a halogen light source and a double monochromator. Before the IPCE measurements, the light intensity was calibrated with a silicon photodiode. EIS measurement was scanned from 0.4 to -0.2 V with a small potential amplitude of 15 mV under 10% light illumination, applying an AC perturbation frequency ranging from 7 MHz to 0.2 Hz.