Co2P nanoparticle/multi-doped porous carbon nanosheets for the oxygen evolution reaction

Abstract

Transition metal phosphides (TMPs) are known as efficient catalysts for water splitting. In this study, a convenient synthetic pathway is proposed to fabricate di-cobalt phosphide (Co₂P) nanoparticles anchored on a multi-element doped carbon nanosheet. Initially, a ligand exchange combined with an ionic-bonding-assisted assembly strategy was developed to synthesize a new type of metal–organic framework (MOF)/polymer composite. Surface ligands of the leaf-like zeolitic imidazolate framework (ZIF-L) are exchanged with multi-nitrogen-containing ligands of polyethylenimine (PEI). Renewable phosphorus-containing ligands of phytic acid (PA) are then incorporated via electrostatic interactions, generating ZIF-L/PEI/PA nanocomposites. Continuously, via a facile one-step carbonization of ZIF-L/PEI/PA, Co₂P nanoparticles hybridized with Co, N and P co-doped carbon nanoleaves (Co₂P@CoNPC) can be obtained. The well-defined Co₂P@CoNPC hybrids exhibited good electro-catalytic performance in oxygen evolution reactions (OERs), which afford low overpotential in 1.0 M KOH on a glass carbon electrode (η@10 mA cm⁻² = 311 mV) with a Tafel slope of 78 mV dec⁻¹, attributing to the synergistic effects of stabilized Co₂P and heteroatom-doped two-dimensional carbon nanosheets.