Self-supported 2D Fe-doped Ni-MOF nanosheets as highly efficient and stable electrocatalysts for benzylamine oxidation

Abstract

Electrocatalytic water splitting is a competitive method to produce clean energy hydrogen, but it is largely limited by the slow anodic oxygen evolution reaction (OER). Replacing OER with low-thermodynamic oxidation process of benzylamine oxidation reaction (BOR) will significantly reduce energy consumption and produce economically beneficial chemicals simultaneously. Here we constructed self-supported 2D Fe-doped Ni-MOF nansheets on nickel foam (NiFe-MOF/NF) with precise control over Ni/Fe atomic ratios via a simple solvothermal method. When used as electrocatalysts for BOR, NiFe-MOF/NF shows an optimal performance with ultralow potential of 1.30 and 1.35 V at current densities of 10 and 100 mA cm⁻² as well as accelerated electron transfer kinetics with an ultrasmall Tafel slope of 24.3 mV dec^-1, which ranks among the top of BOR catalysts reported so far. The benzenitrile yield and Faraday efficiency reaches as high as 0.181 mmol mg⁻¹h⁻¹ and 99% with excellent stability. Such outstanding catalytic performances can be ascribed to the self-supported 2D nanosheets on 3D NF, hierarchical porous structure, abundant surface metallic sites, enhanced electrical conductivity and boosted synergy between metals after Fe doping. Our result suggests that such MOF catalysts are attractive for energy-saving water splitting and benzonitrile production.