Plasma-engraved Co3O4 nanorods with enriched oxygen vacancies for efficient electrocatalytic ammonia synthesis

Abstract

Ammonia electrosynthesis, emerging as a promising alternative to the conventional Haber–Bosch process, has garnered increased attention. In this study, a one-step plasma-engraving strategy is employed to modify the surface microenvironment of Co₃O₄ nanorods for the electrochemical nitrate reduction reaction (NO₃RR), leading to a remarkable increase in oxygen vacancies. The resulting V-Co₃O₄ exhibits an exceptional Faraday efficiency of 98.9% and a noteworthy ammonia yield of 27.5 mg cm⁻² h⁻¹, representing an improvement of up to 67.9% at −0.48 V vs. reversible hydrogen electrode (RHE) compared to untreated Co₃O₄. Theoretical calculations highlight the formation of the *N intermediate as a pivotal step, limiting the reaction rate during ammonia synthesis. The special electron state induced by oxygen vacancies plays a pivotal role in enhancing the adsorption of *N, thereby significantly reducing the energy barrier for this step. Our findings underscore the effectiveness of plasma engraving in tailoring catalyst surfaces for enhanced electrocatalytic performance in ammonia electrosynthesis.