Catalytic activity of Pt-based intermetallics for the hydrogen production - Influence of ionic activator

In continuous search for advanced electrocatalytic materials for the hydrogen evolution reaction (HER), based on transition metal series, two types of intermetallic compounds, TiPt and MoPt2, were investigated as cathode materials. Additionally, ionic activator (i.a.), the mixture of Na-molybdate and tris(ethylenediamine)Co(III) chloride, was in situ added into electrolyte, 6 M aqueous potassium hydroxide solution. The objective was to qualitatively compare their electrocatalytic efficiency evaluated by quasi-potentiostatic and galvanostatic technique. Results are presented to show: the Tafel slope, the exchange current density, the overpotential needed for a fixed hydrogen production rate and the apparent energy of activation. Obtained kinetic parameters reveal advanced catalytic ability of the MoPt2 over the TiPt cathode towards HER. Also, important step forward was achieved by using ionic activator. The presence of Mo and Co species attached to the cathode surface was confirmed by XRF analysis. Thus, enhanced catalytic activity was assigned to the formation of Mo-Co-based electrodeposit. Results suggest to significant catalytic performance of the MoPt2 cathode specially if used with ionic activator in alkaline water electrolysis. (c) 2007 Elsevier B.V. All rights reserved.