Nanostructure polyoxometalates containing Co, Ni, and Cu as powerful and stable catalysts for hydrogen evolution reaction in acidic and alkaline solutions

Abstract A new form of [PW11MO39]5−@Ru-reduced graphene oxide (rGO) (M: Co, Ni, and Cu) was prepared by depositing [PW11MO39]5− on the surface of Ru-rGO. The behaviour of the polyoxometalates (POMs) toward hydrogen evolution reaction (HER) was studied in acidic and alkaline media. Different techniques were used for the characterization of the nanocomposites. These included voltammetry and electrochemical impedance spectroscopy to determine the electrocatalytic properties of the nanocomposites toward HER, and Tafel plots to calculate the kinetic parameters and to identify the possible mechanisms involved in the HER process. Results showed that HER on [PW11MO39]5−@Ru-rGO electrodes obeyed the Volmer–Heyrovsky mechanism. The enhanced HER rates on the modified electrodes were attributed not only to the presence of POM nanoparticles on the electrode surface but also to the resulting enhanced surface areas. These results demonstrate the effective performance of the nanocomposites used as HER catalysts in acidic and alkaline media in conformance with green chemistry objectives. The catalysts are especially advantageous for their desirable capacity, durability, favourable kinetics, and low price.