Plasma-engineered NiO nanosheets with enriched oxygen vacancies for enhanced electrocatalytic nitrogen fixation

Abstract

Active and durable catalysts toward the N₂ reduction reaction (NRR) play a crucial role in electrocatalytic fixation of N₂ to NH₃. Herein, we designed an efficient NiO-based NRR electrocatalyst by introducing oxygen vacancies (OVs) through a facile plasma technique. Although the pristine NiO nanosheets exhibited poor NRR activity, the plasma-engineered NiO nanosheets with enriched OVs delivered significantly enhanced NRR activity with an NH₃ yield of 29.1 μg h⁻¹ mg⁻¹ and a faradaic efficiency of 10.8% in 0.1 M Na₂SO₄ at −0.5 V (RHE) under ambient conditions, comparable or superior to most reported NRR catalysts. Density functional theory calculations revealed that OV introduction could readily tailor the electronic structures of NiO to result in enhanced conductivity, improved N₂ adsorption, a reduced reaction energy barrier, and a less-promoted hydrogen evolution reaction.