Enabling Reaction Selectivity of Platinum Catalysts by Photoinduced Electronic Effects

Reaction selectivity is crucial to producing target molecules of importance with minimum waste. This work reports an efficient and green strategy to improve reaction selectivity in visible-light-mediated chemical transformations by employing Pt/SiO _x photocatalysts, which is ascribed to light-induced surface electronic modification in the small Pt nanocrystals. This strategy has been successfully applied to synthesize commercially valuable but thermodynamically unfavorable arylhydroxylamines with high selectivity via partial hydrogenation of the respective nitroarenes. Surface modification of the small Pt nanocrystals with triethanolamine (TEA) molecules further optimizes the Pt electronic structure to favor the reaction selectivity. The light-induced surface electronic structure alterations and the TEA chemical modification act synergistically to prevent the readsorption of desorbed electron-rich arylhydroxylamines. This prevents the complete hydrogenation of arylhydroxylamines to respective anilines, leading to high arylhydroxylamine selectivity of 81-91%. In addition, photoillumination of Pt nanocrystals always accelerates the reaction kinetics significantly regardless of their surface modification.