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

Abstract

We use first-principles density functional theory to investigate how lithium sulfide and polysulfide clusters (Li$_2$S, Li$_2$S$_2$, Li$_2$S$_4$, Li$_2$S$_6$, Li$_2$S$_8$, and S$_8$) 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. S$_8$ 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 S$_8$ to Li$_2$S on Goldene is thermodynamically favorable. The overall stabilization is -3.64 eV, and the rate-determining barrier for the Li$_2$S$_2$ $\rightarrow$ Li$_2$S step is 0.47 eV. This shows that Goldene is an effective surface for anchoring and mediating lithium polysulfide reactions.