1D Co6Mo6C‐Based Heterojunctional Nanowires from Pyrolytically “Squeezing” PMo12/ZIF‐67 Cubes for Efficient Overall Water Electrolysis

Abstract

The bi‐transition‐metal interstitial compounds (BTMICs) are promising for water electrolysis. The previous BTMICs are usually composed of irregular particles. Here, this work shows the synthesis of novel 1D Co6Mo6C‐based heterojunction nanowires (1D Co/Co6Mo6C) with diameters about 50 nm and a length‐to‐diameter ratio about 20 for efficient water electrolysis. An interesting growth process based on pyrolytically “squeezing” PMo12 (Phosphomolybdic acid)/ZIF‐67 (Zeolitic Imidazolate Framework‐67) cube precursor is demonstrated. The “squeezing” growth is related to the role of Mo species for isolating Co species. A series of tests and theoretical calculation show the mutual regulation of Co and Mo to optimize the electronic structure, accelerating H2O dissociation and the reduction kinetics of H+. Additionally, the nanowires provide pathways for electron transfer and the transmission of reactants. Consequently, the 1D Co/Co6Mo6C exhibits high activity for hydrogen evolution reaction (η10 of 31 mV) and oxygen evolution reaction (η10 of 210 mV) in 1 m KOH. The electrolytic cell based on 1D Co/Co6Mo6C requires a low voltage of 1.43 V to drive 10 mA cm−2. The catalyst also exhibits good HER performance in 1 m phosphate‐buffered saline solution, exceeding Pt/C at a current density >42 mA cm−2.