Insight into Oxidative Desulfurization Mechanism from the Interaction between Different Facets of TiO₂ and V Single Atom or V₂O₅ Cluster

This research was devoted to investigating the oxidative desulfurization (ODS) reaction of thiophene over V₁-TiO₂ and V₂O₅-TiO₂ surfaces through density functional theory calculations. The calculation results showed that V single atoms and V₂O₅ clusters exhibited significantly different binding energies and charge transfer characteristics over the different TiO₂ facets. The density of states and orbital interaction analyses further revealed that V single atoms exhibited a more pronounced advantage in adsorbing and activating the O₂ molecules compared to the V₂O₅ clusters, which was primarily attributed to their unique electronic structure and coordination environment. Based on the calculation results, the V single atoms exhibited the highest catalytic activity in the formation of sulfoxide over the TiO₂ (101) facet. Additionally, this work found that the extra oxygen (O_ext) species also played a key role in reducing the reaction barriers and promoting the formation of sulfoxides, with O_ext species directly contributing to the V₂O₅-catalyzed thiophene ODS reaction. The O_ext species also promoted the continuous conversion of sulfoxides to sulfones. Comprehensive analysis indicated that there was a significant synergistic effect between V single atoms and V₂O₅ clusters, which collectively promoted the effective ODS process of thiophene.