Electrocatalysis of Hydrogen Evolution by Transition Metal Complexes

Abstract

Voltammetric reduction of monothiocyanate complexes of the iron group metals is accompanied by catalytic evolution of hydrogen in two potential regions. Around -1.3 V vs SCE, hydrogen is evolved at the surface of the electrodeposited metal, around -1.6 V at the surface of mercury. The catalyst is the protonated reduced, zero-valent form of the complex which has limited stability. Minor differences in behaviour of the complexes of the three metals are due to different values of their complexation constant.