Surface Phosphate Functionalization for Boosting Plasmon-Induced Water Oxidation on Au/TiO2

Plasmonic photocatalysts suffer from inefficient charge separation and slow reaction kinetics, which result in poor plasmonic photocatalytic performance, especially for the hot hole involved water oxidation. Constructing a hot hole transfer chain and reaction center on plasmonic photocatalysts enables exciting opportunities for efficient plasmon-induced water oxidation. However, it is still challenging to modulate the behavior of the hot holes owing to the fast relaxation dynamics and low mobility. Herein, by introducing a surface phosphate group to functionalize the surface of the plasmonic photocatalyst Au-TiO2, the activity of hot hole involved water oxidation increases to similar to 3 times as compared to the pristine photocatalyst. The optimized apparent quantum efficiency for plasmon-induced water oxidation was measured to be 1.2% at 520 nm. It is found that the plasmon-induced hot holes can be trapped by the phosphate anchored on the TiO2 surface for efficient steady charge separation, and the surface phosphate functionalization also results in a different multi-hole reaction pathway as compared to the Au/TiO2. This study provides an alternative way to modulate the hot hole's separation and catalytic reactions in plasmonic photocatalysis.