Plasma construction of nitrogen-doped defective NiFe-LDH and its high-efficiency oxygen evolution performance

To achieve the green and controllable preparation of high-efficiency oxygen evolution reaction (OER) catalysts, this study proposes a modification of microwave-synthesized nickel–iron layered double hydroxide (NiFe LDH) using N2 plasma treatment. The effects of plasma treatment power and duration on the material’s structure and catalytic performance were systematically investigated. The results indicate that under optimized conditions (100 W, 90 min), the prepared nitrogen-doped NiFe LDH exhibits an overpotential of only 258 mV at a current density of 10 mA cm−2 and a Tafel slope of 57.4 mV dec−1, significantly outperforming the untreated sample. Characterization results confirm that the plasma treatment successfully introduces nitrogen doping and constructs oxygen vacancy defects while maintaining the layered structure of the material, increasing the oxygen vacancy density by 86.8%, effectively increasing the number of active sites and optimizing the electronic structure. Electrochemical tests reveal a 55.8% reduction in charge transfer resistance and a 10.5% increase in the electrochemical active surface area after modification. Furthermore, after a 200 h stability test, the performance degradation was less than 5%. This study provides a new method for developing efficient and stable non-noble metal OER catalysts and elucidates the mechanism by which nitrogen doping and oxygen vacancies synergistically enhance catalytic performance.