Fabrication of g-C3N4 decorated BiVO4 composites and their application in photoelectrocatalytic and electrocatalytic oxidative desulfurization of dibenzothiophene under visible light irradiation

A novel photoelectrocatalytic oxidative desulfurization (PEODS) process by using BiVO4@C3N4 composites deposited on fluorine tin oxide glass as a catalyst is designed. Accordingly, g-C3N4 and BiVO4@C3N4 composite with different amounts of BiVO4 (72%, 56%, and 39%) were prepared and used in a biphasic system. Also, photocatalytic oxidative desulfurization (PODS) and electrocatalytic oxidative desulfurization (EODS) systems are studied and compared to PEODS. The BiVO4@C3N472 (72% BiVO4) sample showed the best results compared to other composites in PODS. The visible-light sensitivity of the photocatalysts was investigated. This system was studied under different reaction conditions such as reaction times, temperatures, amounts of the oxidizing agent, extractants, catalyst amounts, and solvents. By optimizing the reaction parameters, DBT removal reached 91%, 54%, and 75% for PEODS, EODS, and PEODS, respectively. The stability of the catalyst was investigated by recycling the catalyst at four successive reactions with the same efficiency. By the addition of radical scavengers, the mechanism of the reaction was studied and the desulfurization decreased to 67%, 72%, and 64% for BQ, EDTA, and isopropanol, respectively.