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Goldene monolayer as a highly effective catalyst for polysulfide anchoring and conversion: A theoretical study

Nicolas F. Martins, José A. dos S. Laranjeira, Bill D. A. Huacarpuma, Kleuton A. L. Lima, Luiz A. Ribeiro, Julio R. Sambrano

Abstract

We use first-principles density functional theory to investigate how lithium sulfide and polysulfide clusters (Li2S, Li2S2, Li2S4, Li2S6, Li2S8, and S8) bind to Goldene, a new two-dimensional gold allotrope. All Li-S species exhibit robust binding to Goldene. The adsorption energies range from -4.29 to -1.90 eV. S8 that is alone interacts much less strongly. Charge density difference and Bader analyses indicate that substantial charge is transferred to the substrate, with a maximum 0.92 e for Li-rich clusters. This transfer induces polarization at the interface and shifts the work function to 5.30-5.52 eV. Projected density-of-states calculations indicate that Au-d and S-p states strongly mix near the Fermi level. This hybridization indicates that the electronic coupling is strong. Based on these results, the reaction free-energy profile for the stepwise conversion of S8 to Li2S on Goldene is thermodynamically favorable. The overall stabilization is -3.64 eV, and the rate-determining barrier for the Li2S2 -> Li2S step is 0.47 eV. This shows that Goldene is an effective surface for anchoring and mediating lithium polysulfide reactions.

Goldene monolayer as a highly effective catalyst for polysulfide anchoring and conversion: A theoretical study

Abstract

We use first-principles density functional theory to investigate how lithium sulfide and polysulfide clusters (Li2S, Li2S2, Li2S4, Li2S6, Li2S8, and S8) bind to Goldene, a new two-dimensional gold allotrope. All Li-S species exhibit robust binding to Goldene. The adsorption energies range from -4.29 to -1.90 eV. S8 that is alone interacts much less strongly. Charge density difference and Bader analyses indicate that substantial charge is transferred to the substrate, with a maximum 0.92 e for Li-rich clusters. This transfer induces polarization at the interface and shifts the work function to 5.30-5.52 eV. Projected density-of-states calculations indicate that Au-d and S-p states strongly mix near the Fermi level. This hybridization indicates that the electronic coupling is strong. Based on these results, the reaction free-energy profile for the stepwise conversion of S8 to Li2S on Goldene is thermodynamically favorable. The overall stabilization is -3.64 eV, and the rate-determining barrier for the Li2S2 -> Li2S step is 0.47 eV. This shows that Goldene is an effective surface for anchoring and mediating lithium polysulfide reactions.
Paper Structure (7 sections, 5 equations, 8 figures)

This paper contains 7 sections, 5 equations, 8 figures.

Table of Contents

  1. Introduction
  2. Computational Methods
  3. Results and Discussion
  4. Structural description
  5. Interaction of S$_8$ and Li$_2$S$_n$ (n = 1, 2, 4, 6, and 8) clusters
  6. Catalytic potential of Goldene during charge-discharge reaction
  7. Conclusion

Figures (8)

  • Figure 1: (a) Top and side views of the optimized Goldene monolayer and (b) its electronic band structure, with the Fermi level set to 0 eV. (c) Fully optimized isolated sulfur-containing species considered in this study, including Li$_2$S, Li$_2$S$_2$, Li$_2$S$_4$, Li$_2$S$_6$, Li$_2$S$_8$, and S$_8$.
  • Figure 2: (a) Young's moduli and (b) Poisson's ratio for Goldene monolayer.
  • Figure 3: Optimized adsorption configurations of Li$_2$S$_n$ and S$_8$ clusters on Goldene, together with their corresponding adsorption energies ($E_{\mathrm{ads}}$). Panels (a)–(f) show the most stable geometries for Li$_2$S, Li$_2$S$_2$, Li$_2$S$_4$, Li$_2$S$_6$, Li$_2$S$_8$, and S$_8$, respectively, viewed from the top and side.
  • Figure 4: (a) Comparison of adsorption energies (E$_{ads}$) of Li$_2$S$_n$ and S$_8$ cluster species on Goldene and in common organic electrolyte solvents (DOL and DME), and the (b) Li-S bond distances before and after each lithium polysulfide adsorption on Goldene.
  • Figure 5: Charge density difference (CDD) plots for Li$_2$S$_n$ and S$_8$ clusters adsorbed on Goldene. Panels (a)–(f) correspond to Li$_2$S, Li$_2$S$_2$, Li$_2$S$_4$, Li$_2$S$_6$, Li$_2$S$_8$, and S$_8$, respectively. Yellow and cyan isosurfaces represent charge accumulation and depletion, respectively, induced by adsorption.
  • ...and 3 more figures