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