Ni-MoO2 composite cathodes for hydrogen evolution in alkaline solution. Effect of aging of the electrolyte for their electrodeposition

In this work, the effect of aging of the electrolyte in the electrodeposition of Ni MoO2 composite coatings on their morphology (scanning electron microscopy), chemical composition (energy-dispersive X-ray spectroscopy), polarization characteristics and "service life", tested for the hydrogen evolution reaction (HER) in 32 mass % NaOH at 90 degrees C, was investigated. Polarization characteristics and results of the "service life" test of Ni MoO2 composite coatings obtained after different aging periods of the electrolyte for deposition (suspension of MoO2 powder particles in a solution containing 2 M NH4Cl + + 0.2 M NiCl2) were compared with that recorded for the commercial De Nora's Ni+RuO2 cathode coating (DN). It was shown that aging of the electrolyte did not influence the morphology and chemical composition of Ni MoO2 composite coatings electrodeposited under conditions simulating their industrial production, while the polarization characteristics for the HER were influenced. The best coating, obtained after 180 days of electrolyte aging, showed a completely different (layered) structure of the deposit and significantly better performance than the commercial DN electrode during the "service life" test.