Hierarchical CoSeS nanostructures assisted by Nb doping for enhanced hydrogen evolution reaction

Abstract Metal doping for active sites exhibits remarkable potential for improving the hydrogen evolution reaction (HER). Multi-doping and the use of a conductive substrate can further modulate catalytic performance. Herein, Nb-CoSe well dispersed in N-doped carbon nanospheres (NCs, Nb-CoSe@NC) was synthesized to serve as a conductive substrate and facilitated good dispersion of active sites for the HER. Nb doping can also change the electronic structure of CoSe, which facilitates the activity for the HER. In order to further improve the conductivity and intrinsic activity of Nb-CoSe@NC, dual, nonmetal doping was realized through gas sulfurization to prepare hierarchical Nb-CoSeS@NC. The prepared Nb-CoSeS@NC, with a core-shell structure, exhibited a low overpotential of 115 mV at 10 mA cm–2, which is smaller than that of the most doped catalysts. In addition, NCs not only improved the dispersion and conductivity of the catalyst but also prevented metal corrosion in an electrolyte, thus facilitating the long-term stability of Nb-CoSeS@NC. Moreover, the synergistic effect of the multi-doping of Nb, S, and Se was explained. This work provides a promising, multi-doping strategy for the large-scale application of transition-metal-based electrocatalysts for the HER.