Ni+Ti composite layers as cathode materials for electrolytic hydrogen evolution

Abstract

Ni+Ti composite layers were obtained by electrolytic codeposition of nickel and titanium powder from an electrolyte containing Ti powder suspension. Their chemical composition depends on the amount of titanium powder dispersed in galvanic bath as well as on the size of titanium grains. From the analysis of the Auger spectra line profile of Ti (LMV) the presence of nonstoichiometric Ti oxides and NiTi intermetallic compounds on the layers’ surface was observed. The obtained layers were used as electrode materials for hydrogen evolution in an alkaline environment. Based on recorded j– E curve, the Tafel equation parameters for this process were determined. Electrochemical impedance spectroscopy was used to study the interfacial properties at electrode overpotential η=−0.2 V . It was found, that investigated Ni+Ti composite layers are characterized by increased electrochemical activity for hydrogen evolution compared to nickel coatings. Their greater activity in this process may be attributed to the developed electrode surface arising from the incorporation of Ti powder into the nickel matrix as well as to the presence of nonstoichiometric titanium oxides and intermetallic Ni−Ti compounds. The values of surface roughness factors R f were also determined.