Fabrication of Co and Ni Phosphide Nanomaterials by DLI-CVD Using Single-Source Precursors for Electrocatalytic Applications

Abstract

Transition-metal phosphides (TMPs) are emerging as versatile materials for diverse applications, yet their scalable fabrication remains a critical challenge, limiting industrial adoption. Here, we report the direct liquid injection chemical vapor deposition (DLI-CVD) of cobalt and nickel phosphide nanomaterials, both as thin films and nanowires, using a novel class of single-source precursors. These precursors, based on a dialkyldithiophosphinate (SPS) scaffold, were synthesized in high yields and large scales, enabling reproducible and scalable production. The cobalt and nickel complexes were isolated post sublimation and fully characterized via mass spectrometry, NMR spectroscopy (1H, 13C, and 31P for the diamagnetic [Ni(SPS)2]), X-ray crystallography, and thermogravimetry analysis (TGA), confirming their structural integrity and thermal stability. When deployed as precursors in DLI-CVD, they produce phase-pure phosphide nanomaterials with precise control over composition and morphology. By modulating the deposition temperature, we demonstrate the tunable growth of CoP and Ni2P as thin films or nanowires, as validated by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). This morphological versatility unlocks opportunities for surface-sensitive applications, notably catalysis. Finally, we showcase their efficacy as electrocatalysts for the hydrogen evolution reaction (HER) by depositing the nanomaterials onto carbon substrates, which underscores their potential for energy-related technologies.