High-efficiency electrochemical H2O2 synthesis by heteroatom-doped NiX/Ni nanocomposites with honeycomb-like porous carbon

Abstract

Transition metal Ni anchored in carbon material represents outstanding 2e⁻ oxygen reduction reaction (ORR) catalytic selectivity, but enhancing the adsorption strength of intermediate *OOH to promote its selectivity remains a major challenge. Herein, the NiX/Ni@NCHS composite catalyst with heteroatom doping (O,S) is modulated by controlling partial pyrolysis strategies on honeycomb-like porous carbon to manipulate the electronic structure of the metal Ni. With the synergistic effect of honeycomb structure and O atom, NiO/Ni@NCHS-700 exhibits an exceptional H₂O₂ selectivity of above 89.1% across a wide potential range from 0.1 to 0.6 V in an alkaline electrolyte, and an unexpected H₂O₂ production rate up to 1.47 mol g_cat^‒1 h^‒1@0.2 V, which outperforms most of the state-of-the-art catalyst. Meanwhile, NiS/Ni@NCHS exhibits excellent electrocatalytic performance, with 2e⁻ ORR selectivity of 91.3%, H₂O₂ yield of 1.85 @0.3 V. Density functional theory simulations and experiments results reveal that the heteroatom doping (O,S) method has been employed to regulate the adsorption strength of Ni atoms with *OOH, and combined with the self-sacrificing template-assisted pyrolysis approach to improve the microstructure of catalysts and optimize the active site. The heteroatom doping method in this work provides significant guidance for promoting 2e⁻ ORR electrocatalysis to produce H₂O₂.