Cobalt nanoparticles confined nitrogen–doped carbon integrated bimetallic Co₂P–VP heterostructured composite: A MOF integrated 3D arrays for catalytic water splitting

A robust electrode material with outstanding stability at high current density is crucial for the practical application of water splitting. We present an intertwined heterostructure composed of in-situ confined cobalt nanoparticles (Co_np) in nitrogen-doped carbon (N–C), derived from functionalized zeolitic imidazolate framework–67 (ZIF−67), and composited with the hetero phase bimetallic cobalt vanadium phosphide (Co₂P−VP) through a hydrothermal reaction, room temperature aging, and chemical vapor deposition (CVD) for simultaneous phosphidation, graphitization, and reduction. The synergistic effect generated across the multiple heterointerfaces of Co₂P, VP, and Co_np in the N−doped carbon on nickel foam, as the Co₂P–VP@N–C/Co heterostructure, exhibits outstanding electrocatalytic performance for the hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and electrochemical water splitting. The Co₂P–VP@N–C/Co (+,−) alkaline electrolyzer demonstrates a low potential of 1.49 and 1.71 V to achieve current densities of 10 and 100 mA cm⁻², respectively. It exhibits outstanding stability during continuous operation for 100 h at 100 mA cm⁻², with 98.02 % retention. The outstanding performance is credited to the synergistic interaction and d-electronic modulation of the metallic hetero phasic Co₂P–VP moiety and confined Co_np in a functionalized N−doped porous carbonaceous heterostructure. Density Functional Theory (DFT) validates the regulation of electronic structure for efficient redistribution of local charges and electron transfer.