ELECTROCHEMICAL BEHAVIOR OF NICKEL COMPOUNDS. I. THE HYDROGEN EVOLUTION REACTION OF NiSi, NiAs, NiSb, NiSi, NiTe2 AND THEIR CONSTITUENT ELEMENTS
TYCO LABS INC WALTHAM MA
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The cathodic polarization behavior of NiSi, NiAs, NiSb, NiTe2, and NiS at room temperature was de termined in 1 M perchlorate solutions at pH 0.04 and pH 10.8 up to -1.0 volts vs. R.H.E. Measure ments were also made on Ni, Si, Sb, Te, and on Ni electrodes exposed to As2O3 and H2S. Sb, Te, Si and NiAs2O3 exhibit kinetic peculiarities which are probably attributable to hydride formation, but these features are not generally shown by the corresponding nickel compounds. With the excep tion of Si in acid solution, all of the electrodes show an extended Tafel line indicating the hydro gen evolution reaction. For NiAs, NiTe2, and NiSi, there exist regions where the current den sities at a given overpotential exceed those on either of the individual elements. The results are discussed with a view to distinguishing th role of atomic and crystal factors in the elec trocatalytic activity of the electrode materials. The intrinsic chemical properties of the surface atoms appear to dominate the mechanism of the h.e.r., while the crystalline properties strongly influence the rates.
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