Synergetic electrocatalytic effect of d metals for the hydrogen evolution reaction on gold substrates

An electrocatalytic method developed previously for the depolarization of the hydrogen evolution reaction (HER) on graphite, iron, steel, nickel and titanium substrate surfaces was employed to improve the polarization characteristics of gold. The combination of two d metals from two branches of Balandin's “volcano” curve for the HER creates a marked electrocatalytic effect, particularly for molybdenum and cobalt which are added in situ as their anionic or complex species during the electrolytic process. The alloy activity appears to be shifted to potential values that are representative of precious metals and even exceeds these values at higher current densities; the shift is more than 700 mV over the current density range important for similar industrial applications. The synergetic electrocatalytic effects and the improvements in the polarization are illustrated by linear potential sweep voltammograms and steady state Tafel lines. The duration (the lifetime) of the electrocatalytic coating was about 4 months with simple reactivation by means of the in situ addition of negligible amounts of cheap and available cobalt and molybdenum species.