Enhanced Oxygen Evolution Reaction of Zr-Cu-Ni-Al Metallic Glass with an Oxide Layer in Alkaline Media

Abstract

This study elaborates on the tunability of Zr and O amounts in the ZrO2 layer of a melt-spun Zr65Cu17.5Ni10Al7.5 ribbon under cyclic polarization. The formation of an amorphous Zr-rich oxide layer facilitates the oxygen evolution reaction (OER) as confirmed by the decrease in the Tafel slope from 109 to 80 mV dec–1 as well as conservation of its stability over 250 cycles and at long-term open circuit potential measurement, outperforming many of the precious and transition metal-based oxides and their composites. The evolution of additional binding energy at ∼183.5 eV (Zr3d5 Zr–OH peak) indicates hydroxide ion insertion into the Zr-based metallic glass. The magnitude of impedance (cf. 625 Ω cm2 for as-spun vs 140 Ω cm2 for after-OER at 0.6 V and 100 Hz) and characteristic frequency (c.f. 80° at 0.6 V for as-spun and 30° at 0.9 V for after-OER) vs Ag/AgCl are relatively small for the post-OER electrode compared to the as-spun counterpart, corroborating enhanced kinetics of the post-OER electrode. Modifications in the oxide layer upon the OER yield an enormous increase in ion accumulation and electron transfer with a maximum true capacitance reaching ∼0.0271 F cm–2. Thus, a homogeneous combination of inexpensive Earth-abundant metals and an amorphous structure forms a highly active and stable oxide layer to be used for future renewable energy production materials.