Density Functional Theory Study of Phosphorus Silicide Monolayers as Anodes for Lithium-Ion Batteries and Electrocatalysts for CO2 Reduction.

Using particle swarm optimization methodology for crystal structure prediction and first-principles density functional theory, we predicted a phosphorus silicide (PSi) monolayer that meets the thermodynamical, dynamical, and mechanical stability requirements. The PSi monolayer possesses a graphene-like honeycombed structure with a small puckering corresponding to a distance, d, of 0.939 Å and is metallic under the PBE or HSE06 functional. Based on the metallic property, we first found that the PSi monolayer can be used as the anode of a lithium-ion battery with a barrier energy of 0.65 eV and a theoretical capacity of 306.3 mA g h^–1, for which the puckering structure influences the diffusion of Li ions on the surface of the PSi monolayer. We further studied the adsorption behavior of CO₂, and the Si site in the PSi monolayer has unexpected activity toward adsorption and activation of CO₂, showing that the PSi monolayer exhibits superior catalytic performance for the CO₂ reduction reaction (CO₂RR) to CH₄ with the optimal path of CO₂RR as CO₂ → *COOH → *CO → *COH → *CHOH → *CH → *CH₂ → *CH₃ → *CH₄. This work demonstrates great potential applications of the PSi monolayer on the energy storage battery and low-cost electrocatalytic materials for the efficient separation and conversion of CO₂, respectively. [ABSTRACT FROM AUTHOR]