Porous anode of hot pressed nickel powder - for water electrolysis in alkaline soln. has thin protective coating of nickel mon:oxide

摘要

Porous, catalyst-free electrode of hot pressed Ni powder is used as anode in the electrolysis of water in alkaline soln. It has a 0.0025-0.1 mu m (10-100 layers of mols.) thick protective coating of NiO on its inner and outer surfaces to produce a min. overvoltage and max. operating life at operating temps. up to 80 degrees C. NiO layer is pref. produced in hot pressing or sintering at 300-500 degrees C by the use of Ni powder contg. sufficient oxygen to form the NiO layer. Alternatively, the Ni surface is first oxidised (electro)chemically to nickel hydroxide and then converted to NiO by thermal decompsn. above 150 degrees C. The electrode can be tempered in an O2 atmos. Anode has good catalytic properties for the liberation of O2, even with long operating time and elevated temps., since the formation of voluminous (hydr)oxides is suppressed.