Nanostructured amorphous Fe29Co27Ni23Si9B12 high-entropy-alloy: an efficient electrocatalyst for oxygen evolution reaction

Proximal configuration of dissimilar metal atoms in amorphous high-entropy-alloys (HEAs) always result in interatomic d-band ligand effect, dense defect distribution, coordinatively unsaturated sites, high potential energy, and loose atom bonding. Herein, nanostructured amorphous Fe29Co27Ni23Si9B12 HEA ribbon is fabricated via a melt spinning method combined with electrochemical corrosion etching process, which is applied as the potential oxygen evolution reaction electrocatalyst. It is found that there are micro/nano pits on the surface of etched amorphous Fe29Co27Ni23Si9B12 ribbons. Various elements of HEAs bond with each other to form a highly disordered configuration, which could result in an optimized bonding energy and enhanced intrinsic catalytic activity. The electrocatalysis activity measurements indicate that the amorphous HEA endows a much higher activity than the crystalline one, which is further improved by the electrochemical etching treatment. Especially, the HEA ribbon etched for 3 h requires a low overpotential of 230 mV to afford 10 mA cm-2 current density. In addition, density functional theory calculations demonstrate that the amorphous structure can weaken the interaction between the surface of Fe29Co27Ni23Si9B12 alloy and the intermediates, leading to an optimized adsorption Gibbs free energy.