Enhanced Photocatalytic Activity of NH ₃ ‐SCR on Sulfur‐Doped TiO ₂ (101) Surface

Abstract Photo‐assisted NH 3 selective catalytic reduction (photo‐NH 3 ‐SCR) has gained significant attention for its potential to reduce NOx emissions at room temperature, offering an energy‐efficient alternative to traditional high‐temperature NH 3 ‐SCR. In this work, we investigated the effects of sulfur‐doping on the anatase TiO 2 (101) regarding photo‐NH 3 ‐SCR and its photocatalytic performance using density functional theory calculations. The results revealed that sulfur‐doping lowers the direct photo‐oxidation barrier, making it more favorable than the stepwise dissociation process. It also enhances the formation and decomposition of the NH 2 NO species which is the rate‐determining step by reducing energy barrier in each step, in particular its decomposition into N 2 and H 2 O. The projected density of states (PDOS) and calculated absorption spectra show that sulfur‐doping reduces the band gap of TiO 2 , thereby enhancing visible light absorption and improving photocatalytic efficiency. Despite sulfur incorporation, the catalytic activity remains centered on Ti sites, implying that sulfur enhances reactivity via electronic modulation rather than direct site participation. Consequently, S‐doped TiO 2 exhibits superior photocatalytic performance in NH 3 ‐SCR compared to pristine TiO 2 . This study demonstrates that sulfur doping is an effective strategy to enhance TiO 2 photocatalysts, particularly for environmental catalysis applications.