A systematic investigation on the advantage of confinement effect by nitrogen doped carbon nanotubes for hydrogen evolution reaction

Robust hydrogen evolution reaction (HER) electrocatalyst is of significance important for the realization of water splitting technology. In this work, we report the nitrogen doped carbon nanotubes confined CoRu alloy nanoparticles (CoRu@NCNT) as superior HER electrocatalyst. The d band center of Ru atom is downshifted resulting in loosening the hydrogen binding strength; therefore, a robust HER activity is achieved for CoRu@NCNT with mass activity enhanced by 6-time than commercial Pt/C and CoRu/NCNT in both acidic and alkaline mediums. Moreover, compared to CoRu/NCNT electrocatalyst, CoRu@NCNT exhibits a better HER performance attributed to the prevention of avoidable surface oxidation of Ru. Moreover, a more moderate Gibbs free energy for hydrogen is achieved for CoRu@NCNT. Similarly, the stability of CoRu@NCNT outperforms CoRu/NCNT stemming from the NCNT confinement effect suppressing the movement and coalescence of CoRu nanoparticles.