One dimensional AWO4 and A2O3 structured high entropy oxide nanowires and their superior oxygen evolution reaction

Transition metal oxides have shown great potential to replace the noble metal-based catalysts in electrochemical oxygen evolution reaction (OER) process. High entropy oxides (HEOs) containing five or more equimolar cations in a single phase are promising electrocatalysts for enhancing OER efficiency due to their tunable electrochemical properties. Moreover, one dimensional (1D) structure materials with larger surface area can decrease the diffusion length for reactants and products, which is beneficial to the kinetics and mass transport of OER process. In this paper, a series of 1D AWO₄ and A₂O₃ structured HEO nanowires (NWs) which are composed of six or five different transition metal elements are synthesized via a simple electrospinning strategy followed by heat treatment in air. Benefitting from the 1D structure and the synergetic effects between multiple metal cations, the as-synthesized AWO₄ and A₂O₃ structured HEO NWs are proved to exhibit the superior OER performance than that of HEO nanoparticles (NPs), medium entropy oxides (MEOs) NWs and single component metal oxide NWs. The AWO₄ (A₂O₃) structured HEO NWs show excellent catalytic activity with the overpotential of 296–451 mV (348–487 mV) at the current density of 10 mA/cm² and the Tafel slope of 58–75 mV/dec (61–72 mV/dec). Our work enriches the choice of advanced materials for OER catalysts and provides a new idea to design and prepare the nanostructured HEOs in the field of new energy resources.