Self-supported Co-Ni-P ternary nanowire electrodes for highly efficient and stable electrocatalytic hydrogen evolution in acidic solution

Abstract

Self-supported electrodes comprising densely-packed, vertically-aligned Co-Ni-P ternary nanowire arrays supported on a nickel foam current collector (Co-Ni-P/NF) have been fabricated through hydrothermal growth of Co-Ni precursor nanowires on nickel foam, followed by a facile phosphorization treatment using low-cost red phosphorous. The morphology, crystal structure, microstructure and chemical composition of the as-fabricated Co-Ni-P nanowires are comprehensively investigated using scanning electron microscopy, X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. The as-obtained Co-Ni-P nanowires are porous and composed of polycrystalline solid solution, and Co, Ni and P are uniformly distributed over nanowires. Moreover, these nanowires are firmly adhered to the nickel foam with excellent structural robustness, forming an integrated electrode. The self-supported integrated electrode exhibits outstanding catalytic activity towards the hydrogen evolution reaction (HER), which can deliver current densities of −10, −20 and −100mAcm−2 at small overpotentials of 68, 94 and 134mV, respectively. Furthermore, it is able to sustain continuous galvanostatic electrolysis at −10mAcm−2 for 40h without obvious degradation, showing good long-term stability. The excellent electrocatalytic performance can be attributed, on the one hand, to the intrinsically high catalytic activity of Co-Ni-P ternary nanowires; on the other hand, to the unique porous nanowire morphology and monolithic electrode structure that not only offer appreciable electrocatalytically active sites, but also provide efficient conductive paths and facilitate mass transport of electrolyte and release of the generated gas bubbles.