Constructing Surface Plasmon Resonance on Bi2WO6 to Boost High-Selective CO2 Reduction for Methane

Plasmonic Bi2WO6 with strong localized surface plasmon resonance (LSPR) around the 500-1400 region is successfully constructed by electron doping. Oxygen vacancies on W-O-W (V1) and Bi-O-Bi (V2) sites are precisely controlled to obtain Bi2WO6-V1 with LSPR and Bi2WO6-V2 with defect absorption. Density functional theory (DFT) calculation demonstrates that the V1-induced energy state facilitates photoelectron collection for a long lifetime, resulting in LSPR of Bi2WO6. Photoelectron trapping on V1 sites is demonstrated by a single-particle photoluminescence (PL) study, and 93% PL quenching efficiency is observed. With strong LSPR, plasmonic Bi2WO6-V1 exhibits highly selective methane generation with a rate of 9.95 μmol g-1 h-1 during the CO2 reduction reaction (CO2-RR), which is 26-fold higher than 0.37 μmol g-1 h-1 of BiWO3-V2 under UV-visible light irradiation. LSPR-dependent methane generation is confirmed by various photocatalytic results of plasmonic Bi2WO6 with tunable LSPR and different light excitations. Furthermore, the DFT-simulated pathway of CO2-RR and in situ Fourier transform infrared spectra on the surface of Bi2WO6 prove that V1 sites facilitate CH4 generation. Our work provides a strategy to obtain nonmetallic plasmonic materials by electron doping.