Phosphonate-Based Metal–Organic Framework Derived\nCo–P–C Hybrid as an Efficient Electrocatalyst for Oxygen\nEvolution Reaction

Abstract

Cobalt\nphosphate is considered to be one of the most active catalysts\nfor the oxygen evolution reaction (OER) in neutral or near-neutral\npH media, but only a few transition-metal phosphates are investigated\nin alkaline media, probably due to their poor intrinsic electrical\nconductivity and/or tendency to aggregate. Herein, in situ-formed\ncobalt phosphate decorated with N-doped graphitic carbon was prepared\nusing phosphonate-based metal–organic frameworks (MOFs) as\nthe precursor. It can serve as a highly active OER catalyst in alkaline\nmedia, affording a current density of 10 mA cm^–2 at a small overpotential of 215 mV on the Ni foam. A combination\nof X-ray absorption spectroscopy and high-resolution XPS elucidates\nthe origin of the high activity. Our observations unveil that cobalt\ndiphosphate having the distorted metal coordination geometry with\nlong Co–O and Co–Co distances is mainly responsible\nfor the high OER activity. These results not only demonstrate the\npotential of a low-cost OER catalyst derived from phosphonate-based\nMOF but also open a promising avenue into the exploration of highly\nactive and stable catalysts toward replacing noble metals as oxygen\nevolution electrocatalysts.