Water oxidation on CrMnFeCoNi high entropy alloy: Improvement through rejuvenation and spin polarization

Developing highly efficient and non-noble electrocatalysts for oxygen evolution reaction (OER) is crucial for the large-scale water splitting. Herein, the CrMnFeCoNi high entropy alloy (HEA) film was deposited on carbon cloth (CC) and Ni foam (NF) by pulsed laser deposition. Meanwhile, it was demonstrated that electrochemical cyclic voltammetry can induce the surface reconstruction of HEA film to form highly active (oxy)hydroxide. After the activation, both HEA/CC and HEA/NF exhibited enhanced electrocatalytic activity with low overpotentials. The stability of HEA films has also been significantly improved. Through the periodic rejuvenation, the surface reconstructed HEA/CC and HEA/NF electrodes exhibited superb stability up to 300 h (at 10 mA cm-2) and 360 h (300 h at 10 mA cm-2 and 60 h at 100 mA cm-2), respectively. On the other hand, the magnetic properties of HEA films were used to facilitate spin polarization by introducing magnetic fields, aiming to improve the activity of HEA/CC. The behavior of outer electrons in the OER process and spin selection were used to explain this phenomenon. In addition, the developed strategies can significantly improve the catalytic activity of ferromagnetic HEAs, which opens up opportunities for their practical application of OER.(c) 2022 Elsevier B.V. All rights reserved.