MOF-Derived Cobalt@Mesoporous Carbon as Electrocatalysts\nfor Oxygen Evolution Reaction: Impact of Organic Linker

Abstract

Water\nelectrolysis has attracted scientists’ attention as\na green route for energy generation. However, the sluggish kinetics\nof oxygen evolution reaction (OER) remarkably increases the reaction\noverpotential. In this work, we developed Co-based nanomaterials as\ncost-effective, highly efficient catalysts for OER. In this regard,\ndifferent Co-based metal–organic frameworks (MOFs) were synthesized\nusing different organic linkers. After annealing under inert atmosphere,\nthe corresponding Co-embedded mesoporous carbon (Co/MC) materials\nwere produced. Among them, Co/MC synthesized using 2-methyl imidazole\n(Co/NMC-2MeIM) expressed the highest surface area (412 m²/g) compared to its counterparts. Furthermore, it expressed a higher\ndegree of defects as depicted by Raman spectra. Co/NMC-2MeIM exhibited\nthe best catalytic performance toward OER in alkaline medium. It afforded\nan overpotential of 292 mV at a current density of 10 mA cm^–2 and a Tafel slope of 99.2 mV dec^–1. The superior\nelectrocatalytic performance of Co/NMC-2MeIM is attributed to its\nhigh content of Co³⁺ on the surface, high surface area,\nand enhanced electrical conductivity induced by nitrogen doping. Furthermore,\nits high content of pyridinic-N and high degree of defects remarkably\nenhance the charge transfer between the adsorbed oxygen species and\nthe active sites. These results may pave the avenue toward further\ninvestigation of metal/carbon materials in a wide range of electrocatalytic\napplications.