Synthesis of prussian blue analogue derived porous Mo2C/Co9S8/N-doped carbon composite for electrochemical hydrogen storage application

Abstract

The Prussian blue analogue Co3[Co(CN)6]2 (Co-CoPBA) nanoparticles with three-dimensional cubic structure and uniform size were prepared via precipitation method. Using Co-CoPBA as the precursor, the porous Co9S8/N-doped carbon (Co9S8–CN) nanostructure was formed after heat treatment and sulfidation processes. To further improve the electrocatalytic activity of the composite, Mo2C was introduced within the porous Co9S8–CN. The Mo2C/Co9S8–CN materials containing different contents of Mo2C were prepared via high-temperature calcination and subsequent sulfidation. Ultimately, for electrochemical hydrogen storage, the porous Co9S8–CN exhibited higher discharge capacity than conventional Co9S8 prepared by hydrothermal method. The special porous structure and large specific surface area derived from Co-CoPBA provided more electrochemical active sites. The conductivity of Co9S8 was enhanced due to the existence of N-doped carbon. Additionally, the electrochemical performance further enhanced owing to the excellent electrocatalytic activity of the embedded Mo2C species. The Mo2C/Co9S8–CN2 electrode showed an optimum discharge capacity of 647.4 mAh/g. Moreover, the high-rate dischargeability (HRD), corrosion resistance and kinetic properties were also improved after Mo2C loading. Consequently, Mo2C/Co9S8–CN can be used as a potential electrochemical hydrogen storage material.