The hydrogen evolution reaction in basic medium on iron electrodeposited with heteropolyacids

Abstract

Iron was electrodeposited from dilute aqueous solutions of iron sulphate, containing PW₁₂O ³⁻₄₀ , PMo₁₂O ³⁻₄₀ or MoO ²⁻₄ ions. It was shown that improvement in the overpotential and in the exchange current density of the hydrogen evolution reaction (h.e.r.) on the electrodes depends on the nature of the heteropolyacid of the deposition bath. The h.e.r. electrocatalytic activity of the electrodeposits was then analysed and related to their chemical composition. The results show that some active electrocatalysts are produced when combinations of Fe(SiW₁₂) or Fe(PMo₁₂) are formed. The influence of the type of the heteropolyacid in the electrolyte on the electrocatalytic properties of these deposits for the h.e.r. was investigated. The best electrocatalytic properties for the h.e.r. are obtained with electrodes electrodeposited with 2 g dm⁻³ of PMo₁₂O ³⁻₄₀ . The effect of [PMoO ³⁻₄₀ ] in the deposition bath on the electrocatalytic properties of the h.e.r. of the electrodes was determined.