Oxygen-Bridged Cu and V Dual Metal Sites for Enhanced Photo-oxidative Coupling of Benzylamine

The surficial active centers of photocatalysts play a critical role in photocatalytic reactions and require rational design to optimize their adsorption and activation properties for substrates. Single atoms anchored to metal oxide semiconductors, forming asymmetric oxygen-bridged dual-metal sites (M₁-O-M₂), exhibit tunable electronic properties for adsorption and activation. However, the catalytic mechanisms of each site remain unclear, and their full performance potential has yet to be explored. Herein, we report oxygen-bridged reductive V⁴⁺ and oxidative Cu^δ+ sites (Cu-O-V) for the photo-oxidative coupling of benzylamine (BA), enabled by the synthesis of single-atom Cu-anchored Na⁺ intercalated V₂O₅ (Cu-SA/NVO) nanoribbons. As characterized by electron paramagnetic resonance (EPR), X-ray absorption spectroscopy (XAS), and Raman spectroscopy, the introduction of Cu^δ+ sites increases the density of nearby V⁴⁺ sites, thereby facilitating the directional migration of photoelectrons to V sites and photoholes to Cu sites. The synergistic effect of the promoted charge transfer and oxygen-bridged dual sites achieved a yield of 2.73 mmol g^-1 h^-1 for photo-oxidative BA to NBI, which was nearly 3 times that of NVO and 91 times that of Cu-SA/V₂O₅ with a selectivity of up to 99%. In situ infrared spectroscopy detected a stronger stretching vibration of *Ph-CH═NH intermediate on Cu-SA/NVO, indicating the Cu-O-V structure facilitated the nucleophilic reaction of the BA intermediate. Density functional theory (DFT) results revealed that the Cu-O-V bridge significantly enhanced the adsorption of O₂ and BA, and lowered the reaction barrier for the conversion of *Ph-CH₂NH₂^•+ to *Ph-CH═NH, thereby substantially improving the yield of NBI. Our work provides new insights into the design and optimization of photocatalysts.