Boosting photocatalytic water oxidation by surface plasmon resonance of AgxAu1−x alloy nanoparticles

Abstract

Abstract Surface plasmon resonance (SPR) induced photocatalysis with multi-metallic nanoparticles stays indistinct, especially in photo-induced water oxidation reaction. Herein, we report a strategy of engineering band structure by noble metal alloying (AgxAu1−x). The modulated composition of AgAu alloy nanoparticles loaded on rutile TiO2 to selectively tune SPR wavelengths and d-band position. We found that SPR-induced water oxidation activity varies as a function of the ratio of Au and Ag in AgxAu1−x/TiO2 photocatalysts, exhibiting“volcano-like” relationship between the oxygen evolution production rate and the metal-composition. The Ag0.6Au0.4/TiO2 photocatalyst shows superior water oxidation performance about 3-folds of individual Ag and Au. Photoemission spectra (PES) of alloy are in correlation with density of states, revealing the sensitivity of d-band onset energies and SPR excitation wavelengths. Furthermore, surface-photovoltage (SPV) response of alloy signifies the superiority of alloy in interfacial charge separation of hot carriers. Density functional theory (DFT) calculations validate the experimental results by revealing complex AgAu alloy-semiconductor (Ti-O-Au-Ag) for oxygen evolution along with electrodynamic simulations to trace distribution of electric-field components. This work demonstrates critical role of d-band tuning across alloy composition for boosting catalytic fraction through the integrated effects of light absorption, Schottky barrier height and d-band position of the plasmonic photocatalysts.