A porous high entropy alloy via converse selective phase dissolution for oxygen evolution reaction

The slow kinetics of oxygen evolution reactions (OER) have impeded the advancement of water splitting technology. Therefore, developing active, stable, and cost-effective electrocatalysts for the OER is crucial. In this study, we present the preparation of a porous Ni-Al rich phase high entropy alloy via the converse selective phase dissolution (CSPD) method. The research findings demonstrate that Fe-Cr rich phase can be removed in aqua regia etching solutions, leaving the non noble Ni-Al rich phase unaffected. Compared to bulk high entropy alloys, the porous structure provides a larger specific surface area and mass transfer channel for the OER. Additionally, the synergetic chemical effects of the high entropy alloy enhance the intrinsic reactivity of the electrode towards the OER. The porous Ni-Al rich phase HEA electrocatalysts exhibit a low OER overpotential of only 240 mV at 10 mA cm-2 and a Tafel slope of 47.1 mV dec- 1 in 1.0 M KOH. Density functional theory (DFT) results indicate that the Ni-Al rich phase facilitates the transformation of *O to *OOH, resulting in superior OER performance compared to the Fe-Cr rich phase. This study introduces a novel strategy for preparing efficient, stable, and noble metal-free electrocatalysts for OER.