Enhancement of electrocatalytic hydrogen evolution on tantalum by submonolayer electrodeposition of silver

Often it is possible to enhance the catalytic properties of a metal by electrochemically decorating its surface with submonolayer amounts of a foreign metal. The earlier studies of this phenomenon have focused primarily on substrate metals that exhibit some intrinsic catalytic properties of their own. In the present work, we demonstrate that it is possible to extend this catalytic effect of foreign metal deposition to the case of a chemically inert substrate metal. We study a catalytically inefficient polycrystalline Ta electrode in aqueous solutions of NaNO3 (pH 3–5) at room temperature, using the hydrogen evolution reaction (HER) as a probe of electrode reactivity. We show that the catalytic efficiency of the Ta electrode (expressed in terms of the charge transfer resistance for HER) is increased by more than an order of magnitude as a result of covering a small fraction of the Ta surface with an electrodeposited foreign metal, Ag.