Electron-Trap Induced "Hot" Microenvironment Boosting Photocatalytic Nitrogen Fixation

Plasmonic photocatalysis aims to develop a highly reactive surface enriched with hot carriers to enable challenging chemical processes, including high-energy-barrier nitrogen reduction reactions. In traditional plasmonic photocatalysis, hot carriers often undergo rapid thermalization, leading to suboptimal catalytic efficiency. Moreover, the role of hot carriers in surface reactions is often complex and frequently overlooked. Here, we designed a photocatalyst through loading Au nanoparticles on Mo-doped W₁₈O₄₉ nanorods (Au-MWO-S) to achieve efficient nitrogen reduction to produce ammonia, with a formation rate reaching 571.0 µmol h^-1 g^-1 and solar-to-ammonia (STA) conversion efficiency up to 0.28%. It was revealed through in situ experiments and theoretical simulations that the shallow energy-level defects in MWO-S act as electron traps to rapidly capture, store, and release hot electrons, which greatly reduces the thermalization of hot electrons. At the same time, the local electromagnetic field of MWO-S was enhanced, creating a high-activity "hot" microenvironment on the surface of the photocatalyst. This, in turn, increased the occupancy of electrons in the anti-bonding orbitals of N₂, significantly promoting photocatalytic nitrogen reduction reaction (pNRR). This work unveils the mechanism of hot carrier participation in surface reactions, inspiring the development of catalytic systems with hot-electron-active surfaces.