Comprehensive understanding of sulfide oxidation on α-Ag2WO4 (110) surface: A DFT study on ROS storm-driven catalytic mechanism

Understanding how metal oxide surfaces generate and manage reactive oxygen species (ROS) is fundamental to catalytic oxidation; however, the precise nature of active sites and reaction mechanisms remains poorly understood at the molecular level. Herein, using density functional theory calculations, we identify a novel reaction mechanism for the complete activation pathways of O 2 , H 2 O, and H 2 O 2 to generate ROS— 1 O 2 , ·O 2 – , ·OH, and ·OOH—on the α -Ag 2 WO 4 (110) surface. We demonstrate that undercoordinated surface silver cations act as active sites, significantly enhancing adsorption energetics and reducing activation energy barriers. Subsequently, dimethyl sulfide oxidation to sulfoxide and sulfone serves as a benchmark reaction to characterize the free energy profiles of the underlying molecular mechanism, advancing fundamental concepts in the chemistry of the α -Ag 2 WO 4 (110) surface. Notably, this surface exhibits exceptional catalytic performance for H 2 O 2 activation, achieving the formation of reactive intermediates 1 O 2 and ·OOH via low activation energy barriers. These consecutive stages define the most favorable pathways, where mid-gap states induce the necessary structural and electronic characteristics to stabilize paired- and unpaired-electron intermediates in the first and second steps, respectively. Collectively, these insights provide a theoretical foundation for the adsorption and activation processes governing the ROS regulation mechanism at highly reactive multifunctional surface sites, representing a significant advancement in the field of catalysis.