Cobalt Phosphide-Doped Porous Carbon Derived from Co-MOF/zinc Phosphate as a Bifunctional Electrocatalyst for Hydrogen, Oxygen Evolution Reactions

Widespread adoption of electrolytic water splitting for hydrogen production is limited by the high overpotential and slow kinetics of the oxygen evolution reaction. This work presents a bifunctional electrocatalyst of cobalt phosphide-doped porous carbon electrocatalyst (CoP/Co 2 P/C). The catalyst was synthesized via direct pyrolysis of a composite precursor (denoted as Co/Zn-PO@Co-MOF), which consisted of spherical cobalt/zinc phosphate (Co/Zn-PO) coated with Co-based metal-organic framework. The spherical Co/Zn-PO served as a novel and safer phosphorus source, eliminating the need for conventional NaH 2 PO 2 carbonization which releases toxic gases. Although minimally incorporated into the composite precursor, Ni 2+ played two key roles: it primarily functioned to assist the coordination of Co 2+ with 2-methylimidazole on the surface of Co/Zn-PO, and additionally modulated the resulting CoP/Co 2 P ratio. Moreover, the carbonization temperature was a critical variable in converting Co/Zn-PO@Co-MOF into CoP/Co 2 P and affected the final ratio between them. Based on the interfacial synergistic effect between CoP and Co 2 P, along with three catalytic active sites of Co, P and Pyridinic N, the optimized CoP/Co 2 P/C achieved a current density of 10 mA cm − 2 at low overpotentials (η 10 ) of 204 mV for HER and 339 mV for OER. The performance of CoP/Co 2 P/C remains comparable to that of most recently reported cobalt phosphide-based catalysts. Graphical The alternative text for this image may have been generated using AI.