Synergistic effect of Fe/Co-doping and electric field in Niobium Diboride for boosting hydrogen production

Abstract

A primary concern towards achieving a robust and sustainable water-splitting strategy consists in the development and designing of non-precious hydrogen evolution electrocatalysts capable of operating at relatively high current densities. In the present density functional theory (DFT) based study, we explored and identified α-NbB₂-based catalysts consisting of Borophene as graphene-like noble metal-free networks in Niobium-metal based networks, as promising catalysts for the hydrogen-evolution reaction (HER). Our results unveiled that Fe/Co covalent doping in α-NbB₂ {001} surface provides high-efficiency HER activity sites, namely, T_Nb-sites in Nb-terminated Fe/Co-NbB₂ {001} surface with the lowest ΔG_H^∗ Gibbs free energy value of about 0.264/0.278 eV, which further drops to a very optimal value in the range of ΔG_H^∗ ≤ ± 0.10 eV upon the implementation of an external electric field. Furthermore, it was also revealed that in contrast to the extensively used Pt-based surface catalysts, both α-NbB₂ and Fe/Co-NbB₂ catalysts can sustain consistently high catalytic activity for HER over a very large hydrogen coverage and thus ensure a large density of effective catalytic free sites.