Surface activation towards manganese dioxide nanosheet arrays via plasma engineering as cathode and anode for efficient water splitting

Developing high-efficiency, low-cost electrocatalysts for water splitting is important but challenging. Two-dimensional nanosheet manganese dioxide (MnO2) arrays are promising candidates for the design and development of advanced catalysts because of their large surface area. Here, a feasible solution to improve the catalytic activity of MnO2 materials via decorating the active sites on the surface is proposed. With the help of plasma engineering, we successfully enabled surface activity of the MnO2 nanosheets by decorating P or Fe species together with rich vacancies on the surface. The decorated P (P-MnO2) or Fe (Fe-MnO2) species were highly beneficial for the absorption of protons and OH− respectively, and rich oxygen vacancies induced the formation of stable Mn3+, which contributed to electron and charge transfer. Thus, increased electrochemically active specific areas, accelerated charge transfer, and a proper surface electronic structure could be achieved. On the basis of this activation strategy, the fabricated P-MnO2 and Fe-MnO2 showed excellent catalytic performance for the hydrogen evolution and oxygen evolution reactions. To our knowledge, the performance of P-MnO2 and Fe-MnO2 outperformed most MnO2-based electrocatalysts in the field of electrocatalytic water splitting. Surface activation of two-dimensional MnO2 materials by decorating active species via plasma treatment can provide a feasible route for modulating the performance of earth-abundant electrocatalysts for practical applications.