Photohydrolysis of Ammonia Borane for Effective H2 Evolution via Hot Electron-Assisted Energy Cascade of Au-WO2.72/TiO2

Abstract

Catalytic hydrolysis of ammonia borane has drawn much attention for on-board hydrogen generation because of its high hydrogen capacity. Herein, a ternary Au-WO2.72/TiO2 hybrid is synthesized for efficient photohydrolysis of ammonia borane. The Au nanoparticles (NPs) deposited were in situ-reduced by defective WO2.72 nanowires, and 2 wt % Au-WO2.72 is optimal to realize high photoactivity because of the high light absorption and low charge-transfer resistance, which is then combined with TiO2 nanosheets to form a 2%Au-WO2.72/TiO2 hybrid. This hybrid possesses compact interfaces among Au, WO2.72, and TiO2, and the electron pump effect of Au surface plasmon resonances and the electron capture property of TiO2 accelerate the electron transfer from WO2.72 to Au and then to TiO2, leading to the effective separation and long lifetime of photoinduced charges. Therefore, the 2%Au-WO2.72/TiO2 hybrid shows very high catalytic activity under visible light with H2 evolution rates 2.67- and 31-times higher than those for 2%Au-WO2.72 and WO2.72, respectively.