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 (Conp) 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 Conp 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 Conp 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.