(Invited) Low-Dimensional High Entropy Ceramic Nanomaterials for the Oer Oxygen Generation Reaction

Abstract

Although high-entropy alloys have been intensively studied in the past decade, there are still many requirements for manufacturing processes and new application directions to be proposed and developed, but most techniques are focused on high-entropy bulk materials and surface coatings. We fabricated high-entropy ceramic (HEC) nanomaterials using simple pulsed-laser-irradiation scanning on mixed-salt solutions (PLMS method) in a low-vacuum condition; this method, allowing simple operation, rapid manufacturing and low cost, is capable of using various metal salts as precursors and is also suitable for both flat and complicated 3D substrates. In this work, we have engineered this PLMS to fabricate high-entropy ceramic oxides containing from four to seven elements. To address the unique catalytic performance of these HEC nanomaterials, we focused on CoCrFeNiAl high-entropy oxides applied to the oxygen-evolution reaction (OER), which is considered a sluggish process in water. We performed systematic material characterization to solve the complicated structure of the CoCrFeNiAl HEC as a spinel structure, AB2O4（A, B = Co, Cr, Fe, Ni or Al). Atoms in A and B sites in the spinel structure can be replaced with other elements; either divalent or trivalent metals can occupy the spinel lattice using this PLMS process. We applied this PLMS method to manufacture electrocatalytic CoCrFeNiAl HEC electrodes for the OER reaction, which displayed activity and stability at the state of the art.