Enhanced photocatalytic performance of MoS₂ modified by AgVO₃ from improved generation of reactive oxygen species

In this work, an efficient AgVO₃/MoS₂ composite photocatalyst was successfully synthesized via a hydrothermal method. The photocatalytic activity of the as-prepared photocatalyst was evaluated by using it for assessing the degradation of different organic pollutants under visible-light irradiation. The composite 3%-AgVO₃/MoS₂ catalyst demonstrated a significantly enhanced photocatalytic activity compared to the pure compounds (AgVO₃ and MoS₂). The reason behind the excellent photocatalytic performance was the modification of MoS₂ by AgVO₃ to facilitate O₂ adsorption/activation. In addition, the composite catalyst facilitates the two-electron oxygen reduction reaction whereby H₂O₂ is generated on the surface of MoS₂ to produce additional reactive oxygen species (ROSs). ESR coupled with the POPHA fluorescence detection method and a free radical capture experiment were used to elucidate the mechanism of formation of the ROSs, including •OH, •O₂^- and H₂O₂. Furthermore, the generation of additional ROSs could accelerate electron consumption, leaving behind more holes for the oxidation of organic pollutants. A possible photocatalytic mechanism of the composite is also discussed.