Crystal-Plane-Engineered TiO₂-Anchored Vanadium Single Atoms and Clusters for Boosting Ultradeep Aerobic Oxidative...

The crystal plane effect has gained extensive attention in heterogeneous catalysis reactions; however, it is far from being systematically probed in titanium dioxide (TiO₂)-supported vanadium catalysts. Herein, a series of vanadium (V) single atoms and clusters anchored on TiO₂ with different crystal planes was fabricated by an improved "top-down" protocol. The dispersion state, electronic structure, and redox properties of the V single-atom and VO cluster-supported catalysts were systematically analyzed by a series of characterization methods, including X-ray absorption near edge structure (XANES) and density functional theory (DFT) calculations, and their catalytic performances were examined for aerobic oxidative desulfurization (AODS) of 4,6-dimethyl-dibenzothiophen (4,6-DMDBT) with O₂ as the oxidant. The results unveiled that the synergistic effect between the V single atom and the VO cluster perceptibly promoted the catalytic performances of VO/TiO₂ samples. Therein, VO/TiO₂-(001) shows the lowest apparent activation energy (E_a) value of 46.3 kJ/mol and the optimal AODS performance with complete 4,6-DMDBT conversion to 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO₂) within 60 min at 120 °C as compared with VO/TiO₂-(101) (81.9 kJ/mol and 180 min) and VO/TiO₂-(100) (68.0 kJ/mol and 240 min), which should be attributed to its higher V⁵⁺/V⁴⁺ ratio, the optimal redox behavior of the V species, the moderate adsorption energy between 4,6-DMDBT and VO active centers, and the synthetic effect of V single atoms and VO clusters. Moreover, VO/TiO₂-(001) exhibits robust durability in seven cycles of reuse, showcasing the potential for practical applications in the future.