Mn-doped RuO2 nanocrystals with abundant oxygen vacancies for enhanced oxygen evolution in acidic media

The substantial demand for renewable hydrogen energy, known for its low pollution, has accelerated in-depth research into green hydrogen production technology and proton exchange membrane water electrolyzer (PEMWE). The crux of advancing PEMWE technology lies in developing a catalyst that maintains high activity at elevated current densities, resists corrosion, and operates stably under acidic conditions. In our work, the synthesis of an Mn-RuO2-120(NaNO3) catalyst is reported, enriched with oxygen vacancy defects through the molten salt method, using an Mn-hexamethylenetetramine metal-organic framework as the precursor. Physical characterization methods, such as synchrotron radiation, indicate that the presence of oxygen vacancies reduces the Ru/O coordination ratio, thereby enhancing the charge transfer efficiency of the catalyst. Theoretical calculations show that the synergistic effects from Mn doping and oxygen vacancies can regulate the binding energy of *OOH at Ru CUS, effectively lowering the energy barrier of OER intermediates, thus boosting electrochemical OER processes. The optimized catalyst demonstrates an overpotential of 189 mV at a current density of 10 mA cm(-2). Meanwhile, the Mn-RuO2-120(NaNO3) catalyst is capable of operating for 200 hours on Ti felt and can maintain steady performance for 90 hours in a PEM electrolyzer. The activity performance evaluation of Mn-RuO2-120(NaNO3) in a PEM electrolyzer revealed that its potential reached 1.69 V at a current density of 1 A cm(-2).