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 compo sition and active surface area. Kinetic parameters of the h.e.r. were evalu ated by electrochemical and impedance spectroscopy techniques in 1-M NaOH s olution at room temperature. Intrinsic activity of the investigated metalli c glasses was related to the real exchange current density, j(0) and the re ciprocal value of charge transfer resistance, R-ct(-1). The surface roughne ss factor was deduced from impedance measurements. Electrocatalytic activit y of two investigated Zr100-yNiy alloys, with y = 33; and y = 60 was direct ly related to the split-band electronic structure of Zr-Ni alloys. An enhan ced 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 wa s prevented and the high activity of the 3d Ni band for the h.e.r. was pres erved. It was shown that alloying of Zr-Ni metallic glasses with varying in dividual component contents could be explored to optimize the electrocataly tic properties of Zr-Ni glasses and their use in water electrolysis, as ele ctrode materials of long term stability. The highest catalytic activity cou ld be expected for y = 65, when a maximum hybridization of 3d-4d orbitals a nd 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.