Plasmonic Heterostructure TiO 2 ‐MCs/WO 3− x ‐NWs with Continuous Photoelectron Injection Boosting Hot Electron for Methane Generation

Nonmetallic plasmonic heterostructure TiO 2 ‐mesocrystals/WO 3− x ‐nanowires (TiO 2 ‐MCs/WO 3− x ‐NWs) are constructed by coupling mesoporous crystal TiO 2 and plasmonic WO 3− x through a solvothermal procedure. The continuous photoelectron injection from TiO 2 stabilizes the free carrier density and leads to strong surface plasmon resonance (SPR) of WO 3− x , resulting in strong light absorption in the visible and near‐infrared region. Photocatalytic hydrogen generation of TiO 2 ‐MCs/WO 3− x ‐NWs is attributed to plasmonic hot electrons excited on WO 3− x ‐NWs under visible light irradiation. However, utilization of injected photoelectrons on WO 3− x ‐NWs has low efficiency for hydrogen generation and a co‐catalyst (Pt) is necessary. TiO 2 ‐MCs/WO 3− x ‐NWs are used as co‐catalyst free plasmonic photocatalysts for CO 2 reduction, which exhibit much higher activity (16.3 µmol g −1 h −1 ) and selectivity (83%) than TiO 2 ‐MCs (3.5 µmol g −1 h −1 , 42%) and WO 3− x ‐NWs (8.0 µmol g −1 h −1 , 64%) for methane generation under UV–vis light irradiation. A photoluminescence study demonstrates the photoelectron injection from TiO 2 to WO 3− x , and the nonmetallic SPR of WO 3− x plays a great role in the highly selective methane generation during CO 2 photoreduction.