Abstract
Developing novel reaction mechanisms to simplify the nitrogen reduction reaction (NRR) pathways and break scaling relationships of catalysts remain challenges in improving catalytic efficiency. Here, we propose a novel hydroxide-activated hydrogen spillover (HAHS) mechanism to enhance NRR efficiency, enabled by lattice-distortion engineering of Co(OH)2. Precise tuning of lattice strain weakens the adjacent O–H bonds and promotes interfacial hydrogen desorption, leading to the dynamic formation of surface hydrogen vacancies. The released hydrogen species actively participate in the NRR, substantially lowering the N≡N cleavage energy barrier. Concurrently, the hydrogen vacancies are replenished by hydrogen species from the electrolyte, completing a self-sustained catalytic mediation cycle. This HAHS pathway simplifies the conventional protonation step, accelerates intermediate turnover, and enables the Co(OH)2 to achieve a high NH3 yield of 40.67 ± 0.43 μg h−1 cm−2 with a Faradaic efficiency of 24.9 ± 0.61% at −0.90 V (vs. RHE), representing an optimal balance between NH3 production rate and electrochemical efficiency.