An oxygen-vacancy-rich polyoxometalate-aided Ag-based heterojunction electrocatalyst for nitrogen fixation

Polyoxometalates (POMs) with well-defined molecular structures are sustainable and promising catalysts for reducing nitrogen to ammonia under ambient conditions. In this study, oxygen-vacancy-rich AgPW₁₁/Ag nanocube catalysts were synthesized via a one-pot method using POMs, reductants, and inducers. The oxygen-vacancy-rich AgPW₁₁/Ag heterojunction catalyst exhibited a significant ammonia yield as high as 46.02 ± 1.03 μg h^–1 mg^–1_cat. and faradaic efficiency of 34.07 ± 0.16% at a potential of –0.2 V (vs. RHE), maintaining stable catalysis for 32 h without decay and greatly outperforming the Ag catalyst. The excellent catalytic performance and mechanism were established using density functional theory calculations. The robust interaction between the d orbitals of the Ag atom in AgPW₁₁^12e and π* orbitals of N₂ activates the adsorbed N₂ and promotes the conversion of the first protonation process *N₂ to *N–NH (the potential determination step). This study provides a new avenue for designing stable Ag-based catalysts for nitrogen fixation.