Abstract:
Objective Transition metals have been widely studied due to their excellent electrocatalytic properties. However, the poor hydrogen evolution activity and instability of transition metal phosphides in acid hinder their further application. Carbon nanoparticles (CNPs) have several advantages of low cost, simple preparation process, high stability and high electrical conductivity. The structure of transition metal phosphide can be effectively regulated by adding carbon material to improve the hydrogen evolution activity and stability.
Methods Carbon nanoparticles rich in hydroxyl and carboxyl functional groups (P-CNPs) were prepared using glucose as carbon source. P-CNPs-doped NiCo precursor was prepared by hydrothermal method using nickel foam with high specific surface area as substrate. After phosphating reaction, P-CNPs-doped NiCoP-PC/NF was obtained.
Results The cathodic polarization curves in 0.5 mol/L H2SO4 and 1 mol/L KOH showed that the overpotential of NiCoP-50PC/NF was as low as 59 mV and 90 mV at 10 mA/cm2 of current density and 50 mg/L of carbon nanoparticles concentration, respectively, which were much lower than that of commercial Pt/C. Moreover, the cathodic polarization curves of NiCoP-50PC/NC in 0.5 mol/L H2SO4 and 1 mol/L KOH almost coincide, indicating that there is no obvious attenuation of hydrogen evolution activity, and the NiCoP-50PC/NC has good electrochemical stability.
Conclusion The method of doping carbon nanoparticles provides a new way to improve the hydrogen evolution performance of transition metal materials.