Anion Engineering of Surface Frustrated Lewis Pairs for Light-Assisted CO2 Hydrogenation to Methanol.

Surface frustrated Lewis pairs (SFLPs) have been widely studied as active sites for light-assisted CO2 hydrogenation, while most efforts have focused on cation engineering to tune the Lewis acidity of metal centers, leaving the Lewis-basic component less directly controlled. Here, we report an anion engineering strategy based on nitridation to prepare nitrogen-doped, non-stoichiometric spinel zinc gallium oxide catalysts for CO2 hydrogenation to methanol. Nitrogen incorporation modifies the local anion coordination environment, promotes oxygen vacancy formation, and reconstructs the coordination structure around Ga sites, thereby generating defect-associated Ga-O/N Lewis acid-base pairs that favor heterolytic H2 splitting. Nitridation also narrows the band gap and introduces localized electronic states, leading to improved light absorption. As a result, the optimized catalyst achieves a methanol production rate of 1203.7 µmol h-1 g-1 with enhanced methanol selectivity and apparent quantum efficiency (AQE) under illumination. This work demonstrates that anion engineering provides an effective route to regulate oxide SFLPs and promote light-assisted CO2 hydrogenation to methanol.