CoMo carbide/nitride from bimetallic MOF precursors for enhanced OER performance

Abstract

The rational design and facile synthesis of transition metal-based catalysts supported by carbon nanomaterials with high activity, selectivity and stability remain a great challenge. Recently, the low-cost, stable and high-performance electrocatalysts for efficient oxygen evolution reaction (OER) derived from porous metal-organic framework (MOF) precursors have attracted numerous attention. Herein, a new type of CoMo carbide/nitride embedded in the flower-like carbon materials (CoMo-MI-T, MI = 2-Methylimidazole, T = 400, 500, 600, 700 °C) has been synthesized by a simple pyrolysis, in which bimetallic CoMo-MI precursors can be conveniently converted from crystalline cobalt-based MOFs of Co-MI by solvothermal reaction. The pyrolyzed CoMo-MI-T series exhibits a hierarchically porous nanostructure, high Co3Mo3C/N content, suitable N-doping, graphitic carbon layers as well as well-preserved flower-shaped morphology, which shows an excellent OER performance. Among them, the most optimal CoMo-MI-600 owns the small overpotential of 316 mV at 10 mA cm−2 and Tafel slope of 89.9 mV dec−1 in 1.0 M KOH solution. Meanwhile, the rotating ring-disk electrode technique is examined to verify near 4-electron transfer process for CoMo-MI-600 together with a high Faradaic efficiency of 98.7%. The well-performed CoMo-MI-600 electrocatalyst may be stemmed from the best balance of the synergistic effect of abundant multi-component, suitable electrical conductivity and large porosity. The current work will provide a new route to prepare MOF-derived bimetallic active sites in porous carbon nanomaterials with satisfactory activity and robust stability in the relevant energy applications.