Electrodeposited CrMnFeCoNi Oxy-carbide film and effect of selective dissolution of Cr on oxygen evolution reaction

Abstract

High entropy compounds were proven to exhibit excellent catalytic activity. Here, a series of amorphous CrMnFeCoNi Oxy-carbide films were successfully synthesized by one-step electrodeposition. As demonstrated, the film presented superior electrocatalytic activity for oxygen evolution reaction (OER) with an overpotential of 295 mV at a current density of 10 mA/cm2. Uniquely, selective dissolution of Chromium (Cr) was observed, which increased the catalytic activity and showed high stability under a large current density of up to 400 mA/cm2. Cr dissolution not only increased the surface area but also improved the conductivity due to newly formed metal-metal bonding, promoting electron transfer and improving OER performance. As revealed by density functional theory (DFT) calculations, Cr-dissolution mediates the bonding of OER intermediates over surface active sites and ultimately reduces OER overpotential. The one-step electrodeposition method and the micro-dissolution mechanism provided a potential way to design and prepare high entropy compound electrodes, aiming to achieve efficient water electrolysis.