Correlation of electronic structure and catalytic activity of Zr-Ni amorphous alloys for the hydrogen evolution reaction

The electrocatalytic activity of amorphous Zr-Ni alloys with respect to the hydrogen evolution reaction (h.e.r.) was studied in relation to both composition and active surface area. Kinetic parameters of the h.e.r. were evaluated by electrochemical and impedance spectroscopy techniques in 1-M NaOH solution at room temperature. Intrinsic activity of the investigated metallic glasses was related to the real exchange current density, j(0) and the reciprocal value of charge transfer resistance, R-ct(-1). The surface roughness factor was deduced from impedance measurements. Electrocatalytic activity of two investigated Zr100-yNiy alloys, with y = 33; and y = 60 was directly related to the split-band electronic structure of Zr-Ni alloys. An enhanced electrocatalytic activity observed for the h.e.r. with increasing y in the Zr-Ni alloy was associated with a rapid increase of electronic density of states at Fermi energy level, D (E-F) of the 3d Ni band with increasing Ni concentration. The formation of Ni-hydrides during hydrogen evolution was prevented and the high activity of the 3d Ni band for the h.e.r. was preserved. It was shown that alloying of Zr-Ni metallic glasses with varying individual component contents could be explored to optimize the electrocatalytic properties of Zr-Ni glasses and their use in water electrolysis, as electrode materials of long term stability. The highest catalytic activity could be expected for y = 65, when a maximum hybridization of 3d-4d orbitals and a rapid decrease i.e. minimum density of 4d Zr states at the Fermi level were observed. (C) 2000 Elsevier Science Ltd. All rights reserved.