Catalytic activity of electrodeposited ternary Co–Ni–Rh thin films for water splitting process

Abstract The influence of the deposition parameters on the composition and structure of Co–Ni–Rh ternary alloys was studied. The catalytic activity of the coatings for the hydrogen evolution process was investigated in 6 M KOH electrolyte. The thin films were deposited from baths containing a mixture of Co2+, Ni2+, and Rh3+ chloride complexes. A wide range of alloy compositions were achieved by applying different deposition potentials from −0.5 to – 0.9 V vs SCE. The obtained coatings were examined by energy dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD) techniques. The surface morphology and chemical composition were also characterized with scanning electron microscopy (SEM) combined with EDX. The hydrogen evolution activity of some selected electrodes were examined in 6 M KOH using current-potential curve and electrochemical impedance spectroscopy (EIS) techniques. The SEM results showed that the surface morphology of the electrodes can be tailored by modification of the deposition potential. The higher exchange current densities were observed in catalytic measurements for the ternary alloys, which confirms their better catalytic activity in the water-splitting process.