Mesoporous IrNiTa metal glass ribbon as a superior self-standing bifunctional catalyst for water electrolysis

Abstract

Metallic glasses (MGs) only show single activity for water electrolysis and rarely show superior bifunctional activity for both hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this work, IrNiTa (INT) MG ribbon with mesoporous surface is prepared by using a new synthesis procedure. It shows an overpotential of 48 mV for HER and 266 mV for OER to deliver a current density of 10 mA cm−2 under alkaline conditions. By combining experimental characterizations and density functional theory (DFT) calculations, the outstanding catalytic performance is attributed to: i) the large surface area of the mesoporous structure, ii) the good charge transfer at the electrode/electrolyte interface, iii) the super hydrophilicity/aerophobicity of the MG ribbon and iv) the promotion of Ni and Ta atoms towards the intrinsic activity of Ir atoms in the INT (HER) and of surface IrO2 layer (OER). By using these self-standing INT MG ribbons as both the cathode and anode for overall water splitting, a stable cell voltage of 1.58 V is required to achieve a current density of 10 mA cm−2, which is 60 mV smaller than the value for Pt/C

IrO2 couple. This work demonstrates the potential use of MGs as integrated bifunctional electrodes for scalable water electrolysis. © 2021 Elsevier B.V.