Boosting photocatalytic ammonia synthesis performance over OVs-Rich Ru/W18O49: Insights into the roles of oxygen vacancies in enhanced hydrogen spillover effect

Synergistic water activation and nitrogen reduction process is significant to the photocatalytic ammonia synthesis reaction, in which the obtainment of active hydrogen (H*) from H 2 O dissociation and then transfer to N 2 activation site is essential. Herein, the oxygen vacancies (OVs) enhanced hydrogen spillover is used to increase the H* transfer between the H 2 O activation site (Ru) and the N 2 activation site (OVs-rich W 18 O 49 ). Results shown that the OVs-rich Ru/W 18 O 49 achieves high activity for NH 3 production with a yield of 222.75 µmol‧g −1 ‧h −1 , which is 5.60 folds of the OVs-deficient Ru/W 18 O 49 . Control experiments, characterization, and theoretical calculation made it clear that OVs played crucial roles in enhancing the hydrogen spillover by modifying the support's Gibbs free energy for hydrogen adsorption and lowering the barrier of H* migration. Finally, the detail mechanism was explained from a new perspective. This strategy may provide new insights for other hydrogenation reactions under mild conditions.