Oxygen vacancies and band gap engineering of vertically aligned MnO2 porous nanosheets for efficient oxygen evolution reaction

In this work, MnO2 nanosheets arrays vertically grown on nickel foam have been fabricated, and the concentration of oxygen vacancies has increased through electrooxidation treatment. The abundant oxygen vacancies facilitated electron transfer which helps to enhance the conductivity of active material. Besides, the novel porous structure with large surface area and rich Mn3+ catalytic active sites benefit the efficient OER activity. The binder-free VO-MnO2-NF electrode was directly applied for oxygen evolution reaction, which exhibited a compatible overpotential of 0.27 V at 10 mA cm−2 and excellent electrochemistry stability with neglectable potential change for 12 h.