Phosphorus-Modified Amorphous High-Entropy CoFeNiCrMn Compound as High-Performance Electrocatalyst for Hydrazine-Assisted Water Electrolysis

Exploiting highly active and bifunctional catalysts for both hydrogen evolution reaction (HER) and hydrazine oxidation reaction (HzOR) is a prerequisite for the hydrogen acquisition. High-entropy materials have received widespread attention in catalysis, but the high-performance bifunctional electrodes are still lacking. Herein, a novel P-modified amorphous high-entropy CoFeNiCrMn compound is developed on nickel foam (NF) by one-step electrodeposition strategy. The achieved CoFeNiCrMnP/NF delivers remarkable HER and HzOR performance, where the overpotentials as low as 51 and 268 mV are realized at 100 mA cm(-2). The improved cell voltage of 91 mV is further demonstrated at 100 mA cm(-2) by assessing CoFeNiCrMnP/NF in the constructed hydrazine-assisted water electrolyser, which is almost 1.54 V lower than the HER||OER system. Experimental results confirm the important role of each element in regulating the bifuncational performance of high-entropy catalysts. The main influencing elements seem to be Fe and Ni for HER, while the P-modification and Cr metal may contribute a lot for HzOR. These synergistic advantages help to lower the energy barriers and improve the reaction kinetics, resulting in the excellent bifunctional activity of the CoFeNiCrMnP/NF. The work offers a feasible strategy to develop self-supporting electrode with high-entropy materials for overall water splitting.

Automated summary

Researchers have developed a novel phosphorus-modified amorphous high-entropy CoFeNiCrMn compound on nickel foam through one-step electrodeposition strategy. This compound exhibits remarkable performance in both hydrogen evolution reaction and hydrazine oxidation reaction. The experimental results indicate that Fe and Ni elements play important roles in the hydrogen evolution reaction, while phosphorus modification and Cr metal contribute significantly to the hydrazine oxidation reaction. These synergistic advantages result in excellent bifunctional activity of the CoFeNiCrMnP/NF.