Nickel Single-atom Catalysts Anchored on Heteroatom (X=B, N, P, S) Doped Graphdiyne for Highly Efficient Hydrogen Evolution Reaction

Abstract

Identifying efficient and low-cost electrocatalysts for hydrogen evolution reaction (HER) is essential for the renewable energy applications. In recent years, single-atom catalysts (SACs) anchored on graphdiyne (GDY) have attracted great interest as promising HER electrocatalysts. However, the introduction of heteroatom on catalyst is associated with its catalytic performance. Herein, we rationally designed the nickel SACs (Ni/nX-GDY, n=1-2) anchored on four types of heteroatoms (X=B, N, P, S) doped graphdiyne, and explored their HER catalytic activity using density-functional theory calculations. As for the doping of every heteroatom, there are twelve different catalyst configurations with nickel anchored on nX-GDY substrate, and B/N doping possesses superiorly thermodynamic stability compared to P/S doping. By evaluating hydrogen adsorption free energy (ΔG_H*), four optimal HER models (2B55, 1N3, 1P4, 1S4) are identified, especially for N-doped 1N3 model at acetylenic carbon site with the best ΔG_H* value close to zero (-0.004 eV), making Ni/1N3-GDY the most efficient HER catalyst. Furthermore, it is concluded that at zero overpotential, as for Ni/1N3-GDY, the Volmer-Tafel mechanism with electrochemical desorption as rate-limiting step surpasses Volmer-Heyrovsky mechanism. This study not only offers valuable insights into the rational design and discovery of highly efficient GDY-based HER electrocatalysts, but also promotes the development of hydrogen energy technologies.