Preparation and electrochemical characterization of Ni + RuO2 composite cathodes of large effective area

RuO2 particles were co-deposited with Ni matrices, under experimental conditions known to produce porous Ni deposits, to yield Ni + RuO2 composites of large effective area, to be used as cathodes for the hydrogen evolution reaction. These conditions involved the use of NiCl2, NH4Cl solutions (pH 4.5) and large deposition current densities. The morphology and composition of these composites were studied by SEM–EDX and compared to those of either Ni + Co3O4 composites or Ni + RuO2 composites obtained from Watt's baths. EIS was used to obtain information on the porosity of the deposited materials, and to measure the capacity of the composites and its dependence on deposition charge. The hydrogen evolution reaction was studied in both acid and basic media. Porous Ni + RuO2 cathodes performed better than analogous materials prepared from Watt's baths.