Plasmonic Heterostructure TiO2-MCs/WO3-x-NWs with Continuous Photoelectron Injection Boosting Hot Electron for Methane Generation

Nonmetallic plasmonic heterostructure TiO2-mesocrystals/WO3-x-nanowires (TiO2-MCs/WO3-x-NWs) are constructed by coupling mesoporous crystal TiO2 and plasmonic WO3-x through a solvothermal procedure. The continuous photoelectron injection from TiO2 stabilizes the free carrier density and leads to strong surface plasmon resonance (SPR) of WO3-x, resulting in strong light absorption in the visible and near-infrared region. Photocatalytic hydrogen generation of TiO2-MCs/WO3-x-NWs is attributed to plasmonic hot electrons excited on WO3-x-NWs under visible light irradiation. However, utilization of injected photoelectrons on WO3-x-NWs has low efficiency for hydrogen generation and a co-catalyst (Pt) is necessary. TiO2-MCs/WO3-x-NWs are used as co-catalyst free plasmonic photocatalysts for CO2 reduction, which exhibit much higher activity (16.3 mu mol g(-1) h(-1)) and selectivity (83%) than TiO2-MCs (3.5 mu mol g(-1) h(-1), 42%) and WO3-x-NWs (8.0 mu mol g(-1) h(-1), 64%) for methane generation under UV-vis light irradiation. A photoluminescence study demonstrates the photoelectron injection from TiO2 to WO3-x, and the nonmetallic SPR of WO3-x plays a great role in the highly selective methane generation during CO2 photoreduction.