Kinetics of hydrogen evolution reaction from aqueous HClO₄ solutions on some codeposited from a binary noble metal surfaces over Pt-substrates by cyclic voltammetry

Abstract

Relative electrocatalytic activities of some codepo-sited bina noble metal surfaces over Pt-substrates [(Pt)M₁-M₂] with different compositions of M₁ = Pt and M₂ = Pd, Ir and Au and M₁ = Pd and M₂ = Pd, Ir and Au have b n studied for hydrogen evolution reaction (HER) from aqueous HC1O₄ solutions by determining the rate constant <em>k</em>_s of the reaction by cyclic voltammetry. The <em>k</em>_s values have been determined by Shain and Nicholson's formulations from the observed quasi-reversible cyclic voltammograms (CVG's) obtained at different scan rates ranging from 0.002 to 0.3 V s^-1 the potential range 0 to - 1.0 V. The observed <em>k</em>_s-M₂ composition profiles of [(Pt)M₁-M₂] surfaces in both the cases with M₁ = Pt or Pd are found to pass through a minimum presumably because of the enhanced overage of the surfaces by nascent hydrogen, <em>ɵ</em>_H, and the consequent decrease of the fraction of free surface, which seemingly dictates the rate of HER in the present cases.