Goldene monolayer as a highly effective catalyst for polysulfide anchoring and conversion

Abstract

First-principles density functional theory (DFT-D3) calculations were performed using the GGA-PBE approach 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 0.92e 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.