Mo-doped Co9S8 nanorod array as a high performance electrochemical water splitting catalyst in alkaline solution

Abstract

Abstract It is very important to exploit robust electrocatalysts for the water splitting in an alkaline medium. Hence, a series of Mo-doped Co9S8 nanorod array on Ni foam (Mo–Co9S8/NF) was successfully synthesized through hydrotherma and sulfuration processes for the first time and used as an efficient and stable difunctional electrocatalyst for the overall water splitting. Such Mo–Co9S8-3//Mo–Co9S8-2 electrodes couple display superior water splitting performance with the requirement of a cell voltage of 1.50\xa0V to drive a catalytic current density of 10\xa0mA\xa0cm−2, which is lower than that of RuO2//Pt/C (1.52\xa0V). The activity of the catalyst is greatly enhanced by the molybdenum ion doping and the instability of the sulfide is resolved. The experiment result shows that the relationship between the current density and pH is different in neutral and alkaline media, which is most be likely assigned to the change of O–O formation by transforming the reactants from water molecule to the hydroxy ion.