Efficient cathode for the hydrogen evolution reaction in alkaline membrane water electrolysis based on NiCoP embedded in carbon fibres

Porous carbon nano/microfibres (PCFs) modified by NiCoP nanoparticles (NiCoP/CF) were tested as gas diffusion cathodes in a zero-gap alkaline water electrolyser. Two types of precursors were used for the preparation of carbon fibres by needle-less spinning: polyacrylonitrile (PAN) and a combination of PAN and polyvinylpyrrolidone (PVP). The influence of the selected precursors on the morphology, porosity, and surface area of the carbon fibres was examined. Both samples NiCoP/CF_PAN and NiCoP/CF_PAN-PVP were characterised by means of (i) structural and phase composition, (ii) catalytic activity for the hydrogen evolution reaction (HER), and (iii) performance and stability under membrane alkaline water electrolysis (MAWE) conditions. The more porous, yet stable fibres of the NiCoP/CF_PAN outperformed the NiCoP/CF_PAN-PVP cathode. Nevertheless, both cathodes achieved high activity comparable to the Ni electrode modified by Pt/C catalyst,as well as exceptional stability for long-term intermittent electrolysis under MAWE conditions.