Lignin-derived carbon-supported MoC–FeNi heterostructure as efficient electrocatalysts for oxygen evolution reaction

Abstract

Developing noble-metal-free electrocatalysts for efficient oxygen evolution reactions (OER) is urgently desired to obtain green hydrogen by water electrolysis. Coupling FeNi catalysts with other transition metals is an effective strategy to improve the OER performance, but the electronic structure regulation of the catalytic center is challenging. Herein, heterostructures catalyst composed of MoC and FeNi alloy embedded in N-doped biochar (denoted as MoC–FeNi@NLC) was in situ synthesized by pyrolysis of lignin-metals coordination complex. MoC–FeNi@NLC displayed an overpotential of 198 mV and a long steady running time of 200 h at 10 mA·cm−2 in alkaline media. Furthermore, MoC-FeNi@NLC has demonstrated excellent Faradaic efficiency (FE) of over 90 %. A voltage of 1.50 V was required based on the MoC–FeNi@NLC and Pt/C coupling system, which was superior to that of commercial noble metal catalysts (Pt/C || Ir/C, 1.57 V). The density functional theory demonstrated that FeNi alloy balanced the adsorption energy of OER intermediates and regulated the orbital overlap of Mo above Fermi level. While the lignin-derived carbon layer prevented the deactivation and dissolution of catalytic center. The construction strategy of transition metal alloys and carbides heterojunction by the assistance of sustainable lignin derivatives and its structure–activity relationship toward OER electrocatalytic process provides a promising and cost-efficient pathway for the design of high-performance and stable OER catalysts.