Synthesis and characterization of Bi-BiPO₄ nanocomposites as plasmonic photocatalysts for oxidative NO removal

Bi metal–BiPO₄ (Bi-BPO) nanocomposites formed by in situ solvothermal reduction were employed as plasmonic photocatalysts for oxidative NO removal, achieving a removal efficiency of 32.8% in a continuous NO flow (400 ppb) under illumination with visible light. This high performance was ascribed to the generation of energetic hot electrons (and their subsequent surface chemical reactions) due to the surface plasmon resonance (SPR) of Bi metal, as validated by numerical simulations. The combined results of density functional theory (DFT) calculations and electrochemical analysis revealed that hot electrons are transferred from Bi metal to BPO via the Bi-BPO interface. DFT calculations further showed that enhanced O₂ activation on the Bi-BPO interface facilitates the generation of both superoxide (^[rad]O₂ ⁻) and hydroxyl (^[rad]OH) radicals, as confirmed by electron spin resonance, while in situ DRIFTS analysis demonstrated that NO is activated on the Bi-BPO interface and then oxidized to nitrates. Thus, this work highlights the SPR effects of Bi metal and promoted O₂ and NO activation in plasmonic photocatalysis, showing that the adopted approach can be generalized to design efficient and cost-effective photocatalytic systems for the removal of other gaseous pollutants.