Ultrafine bimetallic phosphide nanoparticles embedded in carbon nanosheets: two-dimensional metal–organic framework-derived non-noble electrocatalysts for the highly efficient oxygen evolution reaction

The development of noble-metal-free highly efficient oxygen evolution reaction (OER) catalysts is crucial for electrochemical energy technology but still challenging. Herein, ultrafine cobalt–iron bimetallic phosphide nanoparticles embedded in carbon nanosheets are synthesized using two-dimensional (2D) metal–organic frameworks (MOFs) as the precursor. The 2D morphology of the carbon matrix and the ultrafine character of Co1−xFexP nanoparticles make contributions to OER catalysis. By optimizing the molar ratio of Co/Fe atoms in MOFs, a series of Co1−xFexP/C catalysts are prepared. Among them, Co0.7Fe0.3P/C shows the best OER performance with an overpotential of 270 mV at a current density of 10 mA cm−2 and an ultralow Tafel slope of 27 mV dec−1 in an alkaline electrolyte. Moderate iron doping preserves the catalytically active sites and improves the ability to be oxidized of the surface of Co1−xFexP nanoparticles, and thus enhances the OER activity. Our finding paves the way to the rational design of the morphology and chemical composition of OER catalysts.