What is the predominant electron transfer process for Au NRs/TiO2 nanodumbbell heterostructure under sunlight irradiation?

•Au nanorods/TiO2 nano-dumbbells photocatalysts were prepared by mediating the concentration of surfactant molecules.•Au nanorods/TiO2 nano-dumbbells photocatalysts show good properties in water splitting even without sacrificial agent.•Femtosecond transient absorption spectroscopy demonstrated the electrons were transferred from Au nanorods to TiO2 nanopaticles under visible light irradiation.•We speculated that the directed spatial charge separation lead to the enhanced photocatalytic efficiency rather than the localized surface plasmon resonance effect of Au NRs.

Au nanorods/TiO2 nano-dumbbells photocatalysts exhibited significantly enhanced visible light photocatalytic H2-production activity due to injection of hot electrons of photo-excited Au nanorods to TiO2 nanopaticles, which was confirmed by femtosecond transient absorption spectroscopy. However, it is well known that the electrons were transferred from TiO2 nanopaticles to Au nanorods under UV light irradiation. Considering the practical application, we investigated the photo-catalytic activity of Au nanorods/TiO2 nano-dumbbells photocatalysts under sunlight irradiation. Based on the data analysis, we confirmed the dominant electron transfer direction was from TiO2 nanoparticles to Au nanorods under sunlight irradiation and Au nanorods/TiO2 nano-dumbbells photocatalysts could act as an effective photocatalyst for H2-generation from water even without electron donor due to the efficient charge separation and the spatial separation of reduction and oxidation reaction sites.

Graphical abstractDownload high-res image (154KB)Download full-size imageThe directed spatial partition of charge carriers could be formed no matter under UV, visible and sunlight irradiation on the Au/TiO2 nano-dumbbells structures. More importantly, efficient H2-production rate can be achieved under sunlight irradiation even in absence of any electron donors