Impregnation of metal carbides in Raney Ni–PTFE hydrogen electrodes

A series of interstitial metal carbides (M = Zr, Ti, V, Mo, W, Nb, Ta) were incorporated in Raney Ni and polytetrafluoroethylene (PTFE) based gas diffusion electrodes. Structural properties of the electrodes were examined by pore distribution analysis, SEM-EDX observation and XRD measurement. The performance of the electrodes was evaluated by the polarization characteristics of hydrogen electrooxidation reaction (HOR) in 25 wt% potassium hydroxide solution. Improved polarization characteristics were realized by impregnation of zirconium carbide (ZrC) and tungsten carbide (WC) to the Raney Ni–PTFE electrode. Among the metal carbides, ZrC revealed highest performance with respect to the electrode stability and polarization characteristics. Temperature dependence of polarization profile suggested that the enhanced material diffusion, i.e., electrolyte in the micropores is one of the major contributions to the improved performance of ZrC-impregnated electrode. Metal like high conductivity of the metal carbides also contributed to the improvement of the polarization characteristics.