Controllable fabrication of abundant nickel-nitrogen doped CNT electrocatalyst for robust hydrogen evolution reaction

The graphical abstract shows the good morphology and activity of the nickel-nitrogen doped CNT fabricated through a straightforward route. [Display omitted] •Simplistic fabrication of abundant nickel-nitrogen doped carbon nanotubes (Ni-NCNT).•Variation of carbon and nickel sources to obtain the optimum concentration.•The Ni-NCNT8.0 achieves a robust HER activity and stability in 1 M KOH.•The abundant NCNT of Ni-NCNT8.0 averts aggregation of the nickel nanoparticles.•DFT showed low HOMO-LUMO value, high ionization potential and adsorption energy. Designing highly effective and durable non-noble metal based electrocatalysts for hydrogen evolution reaction (HER) is cardinal for the sustainability of clean energy technologies. This present work explores the fabrication of nickel-nitrogen doped CNT through a simplistic approach. The as-fabricated Ni-NCNT8.0 showcases a robust HER performance amongst the other catalysts (Ni-NCNT7.5, Ni-NCNT8.5, Ni-x, and Glu-x) with a small overpotential of 147 mV and Tafel slope of 57.6 mV dec-1 to approach a current density of 10 mA cm−2 in alkaline medium. It also exhibits an excellent stability for 20 h. The high HER performance originates from the abundant and well-formed N-doped CNT that serves as conductive support and the synergy between the nickel nanoparticles which suffice as the catalyst active sites and the N-doped CNT. Additionally, the optimized electronic structure of the nickel nitrogen-doped CNT provided by density functional theory calculations, revealed a low HOMO-LUMO energy gap and high ionization potential that enhanced the stability of the electrocatalyst and conveys an effective HER.