Visible-light-driven hydrogenation of styrene via plasmon-induced H2 dissociation on Au/ZrO2 catalysts

Abstract

Herein, we report the visible-light-driven hydrogenation of styrene using a supported gold (Au) particle catalyst. Various metal oxides (MO_x: TiO₂, SiO₂, ZrO₂, and CeO₂) were investigated as support materials to elucidate the role of the metal semiconductor interface in plasmon-induced charge separation and catalytic activity. Au/ZrO₂ exhibited the highest activity, producing ethylbenzene with a turnover number of 12. Characterization techniques, including XPS, UV-vis spectroscopy, and TEM, confirmed the presence of metallic Au nanoparticles with an average size of 6.8 nm on the ZrO₂ support. Action spectrum and light intensity dependence studies revealed that the reaction was driven by the surface plasmon resonance of Au nanoparticles rather than thermal activation. In situ DRIFT spectroscopy detected the formation of Au-H species under visible-light irradiation, confirming the dissociative adsorption of H₂ on the Au surface. Kinetic isotope effect analysis using H₂ and D₂ yielded an exceptionally large k_H/k_D value of 22, suggesting that the dissociative adsorption of H₂ is the rate determining step. A catalytic cycle involving hot electron injection into the antibonding orbital of H₂ was proposed. These findings provide mechanistic insights into plasmon-induced hydrogenation on Au nanoparticles and demonstrate the potential of sustainable and selective catalytic systems.