High entropy spinel metal oxide (CoCrFeMnNi)3O4 nanoparticles as novel efficient electrocatalyst for methanol oxidation and oxygen evolution reactions

In this work, (CoCrFeMnNi)3O4 high entropy spinel oxide-based electrocatalyst is prepared using a facile soft chemical process. The synthesized catalyst has a spherical morphology. The formation of the pure phase material is confirmed using spectroscopic and microscopic studies. The prepared material is used as an electrocatalyst for the methanol oxidation and oxygen evolution reactions. The slurry of the as-synthesized material is coated on nickel foam and used as a working electrode. For methanol oxidation, the catalyst showed a specific current density of ~335 mA cm−2. The observed mass-activity of the catalyst is ~110 mA mg−1 with an observed onset potential of ~0.45 V. For the oxygen evolution reaction, the onset potential of (1.45 V vs. RHE) is observed with a low overpotential of 220 mV at 10 mA cm−2. The corresponding Tafel slope is ~100 mV dec−1. These results showed that the prepared high entropy oxide showed efficient electrocatalytic activity, and they are promising for methanol oxidation and oxygen evolution reactions. This is the first report demonstrating the spinel-type high entropy oxide nanoparticles in electrocatalysis to the best of our knowledge.