Surface morphology and electrochemical characterization of electrodeposited Ni–Mo nanocomposites as cathodes for hydrogen evolution

In this work, we study the influences of current density on surface morphology and electrochemical characterization of electrodeposited Ni-Mo. The Ni-Mo composite coatings are deposited on pretreated copper substrates by electrolytic deposition. The Ni-Mo solution is taken from nickel sulfate fluid and ammonium heptamolybdate with 10 g/l. The Ni-Mo composite coatings are deposited at a temperature of 303 K with an applied current density of j_dep= 10 A/dm²-30 A/dm². We find that the corrosion resistance is improved by incorporating Mo particles into Ni matrix in 0.6-M NaCl solution. From the potentiodynamic polarization curve of electrodeposited Ni-Mo it is confirmed that the corrosion resistance decreases with increasing applied current density. The x-ray diffraction (XRD) analyses of Ni-Mo coatings indicate three phases of MoNi₄, Mo_1.24Ni_0.76, and Ni₃Mo phases crystallites of nickel and molybdenum. The scanning electronic microscopy (SEM) tests indicate that Ni-Mo coatings present cracks and pores.