Single-atom metal tuned sulfur vacancy for efficient H2 activation and hydrogen evolution reaction on MoS2 basal plane

• Published in: Applied surface science 2022-09, Vol.597, p.153614, Article 153614
• Main Authors: Su, Hai-Yan, Ma, Xiufang, Sun, Keju
• Format: Article
• Language: English
• Subjects: DFT calculations; H2 activation; Hydrogen evolution; MoS2; S vacancy; Single-atom doping
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2022.153614

[Display omitted] •Doping single-atom M (M = 3d-5d metal) promotes S vacancy (Sv) formation on MoS2(001).•Identifying M modified Sv as active site in H2 scission/recombination and evolution.•M modified Sv presents superior activity in H2 scission/recombination and evolution.•H2 scission/recombination follows homolytic mechanism at M modified Sv on MoS2(001).•BEP relation + energy relation (Sv formation, COHP vs H binding) to design catalyst. MoS2(001) basal plane, modified by doping transition metals (M) or creating S vacancies (Sv), has presented superior catalytic performance in hydrogen evolution, hydrogenation and hydrodeoxygenation reactions. However, the optimal active sites for H2 dissociation/ recombination, a crucial step in the aforementioned reactions, on the modified MoS2(001) are yet to be unequivocally elucidated. Using density functional theory calculations, we find that H2 dissociation activity generally follows the order: M modified Sv > unmodified Sv > M modified S > M modified Sv - M and Sv modified S > M and Sv modified S > Sv modified S > unmodified S. Compared to Mo, the increasing number of outer electrons in M causes less unpaired electrons to bind with S. This facilitates the removal of S, which leaves electrons to fill to the antibonding H2 states, thereby enhancing H2 dissociation through homolytic mechanism. M modified Sv also exhibits superior activity in H2 recombination and hydrogen evolution, indicating it to be the active site for these reactions. Among the dopants, Cu or Pd modified Sv show excellent activity for all the reactions. The energetic proportionality between Sv formation energy, integrated crystal orbital overlap/Hamilton populations and H adsorption energy together with BEP relations open the possibilities to design metal compound catalysts for important reactions involving hydrogen.