Reduced graphene oxide/ bismuth tungstate-based photocatalysts for enhanced dye photodegradation and photoelectrochemical water splitting.

Semiconductor-based heterogeneous photocatalysis generates highly reactive charge carriers under solar illumination, making it a successful approach for wastewater purification and energy production applications. Herein, a simple solvothermal approach was used to generate a promising nanocomposite photocatalyst, reduced graphene oxide/bismuth tungstate (rGO/BiWO). Various analytical tools were utilized to characterize the as-prepared catalysts. The oxidation of methylene blue (MB) and rhodamine B (RhB) dyes in the presence of solar light was performed to assess the photocatalytic activity of the rGO/BiWO combination. Also, photoelectrochemical (PEC) water splitting as an efficient and cost-effective way of producing hydrogen from water using solar energy is tested. The effect of the calcination temperature of BiWO and the amounts of graphene oxide on the catalytic activity was studied. After 30 minutes of exposure, the synthesised 10rGBW calcined at 700 °C (10rGBW-IV) showed good photodegradation percentages of 100.0% and 87.6% for MB and RhB dyes, respectively. Also, the larger photocurrent response intensity and lower arc radius of the electrochemical impedance of rGO/BiWO compared to BiWO revealed the synergistic effect on BiWO visible light responsiveness. According to the Mott-Schottky curve, 10rGBW-IV demonstrates a larger negative shift of the Fermi level (FB = -0.08 V RHE), indicating a stronger oxidation potential for water splitting.