Desenvolvimento e caracterização de recobrimentos de Ni-Co e de seus óxidos mistos para a produção de oxigênio por eletrólise alcalina da água Development and characterisation of coatings of Ni-Co and their mixed oxides for oxygen production by alkaline water electrolysis

Abstract

This paper describes the development and characterisation of Ni-Co coatings to be used as anodes in water electrolysis. Chemical oxidation of the surface was performed through thermal treatment at 400ºC for 10 h. The resulting surfaces were analysed by X-ray diffraction, EDX, SEM, cyclic voltammetry and constant current electrolysis. The electrochemical oxidation occurring on bare surfaces during electrolysis promotes the formation of thick oxide layers resulting in loss of activity. In oxidised surfaces the chemical Ni-Co oxide grown during the thermal treatment prevents further oxidation thus retaining their activity towards oxygen evolution. An optimum condition for the growth of mixed oxide with high activity was found for the bath containing 50 g L-1 CoSO4.

Keywords

• Ni-Co oxides
• spinel
• water electrolysis
• activated anodes