N-doped M/CoO (M1/4Ni, Co, and Mn) hybrid grown on nickel foam as efficient electrocatalyst for the chemical-assisted water electrolysis

In this work, N-Ni1Co3Mn0.4O/NF is synthesized as multifunctional electrocatalyst for hydrogen evolution (HER), urea oxidation reaction (UOR) and hydrazine oxidation reaction (HzOR). The optimal Ni/Co (molar ratio) and the amount of doping Mn are investigated, the sample with Ni/Co = 1:3 and the addition of 0.4 mmol Mn exhibits the best catalytic activity with the largest specific surface area. Then the two-electrode electrolyzers composed of NNi1Co3Mn0.4O/NF are constructed, and the results from experiments show that the voltage required for overall hydrazine splitting (OHzS) at 100 mA cm-2 is 0.272 V, 1.614 V lower than that of overall water splitting (OWS, 1.886 V), while the overall urea splitting (OUS) needs 1.669 V, 0.187 V lower than that of OWS, revealing the outstanding thermodynamic and kinetic advantages of OUS and OHzS. The superior performance may be attributed to the heterostructure between metal and metal oxide and N-doping, which can promote electron transfer and optimizes the decomposition of urea and hydrazine hydrate and hydrogen production, and the research on mechanism will be carried out in the future. (c) 2021 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

N-Ni1Co3Mn0.4O/NF was synthesized as a multifunctional electrocatalyst for hydrogen evolution, urea oxidation reaction, and hydrazine oxidation reaction. The experiments showed that the voltage required for complete hydrazine splitting was 1.614V lower than that for complete water splitting, and the voltage required for complete urea splitting was 0.187V lower than that for complete water splitting.