Li-doped C20 nanocage and its derivatives for gas sensing application: A density functional theory study

Abstract

We studied the gas-sensing properties of Li-decorated C₂₀ nanocage and its derivatives, presenting these materials as novel candidates for sensing applications. The derivatives of C₂₀ considered are either B-substituted, N-substituted or B and N co-substituted C₂₀ Nanocages. Toxic gases H₂S and NH₃, were selected for evaluation. Out of 15 derivatives analysed, 10 were confirmed to be stable for Li-doping and gas sensing application. The C₁₂N₈ nanocage demonstrating the strongest Li-anchoring, characterized by a high Li-binding energy of 3.81 eV. The Li-decoration introduced spin polarization near the Fermi level, reflected in asymmetric spin-up and spin-down states, which indicated the magnetic nature of the resulting complexes. Substantial changes in the electronic structure of the nanocages upon interaction with H₂S and NH₃ molecules are observed, both of which were found to adsorb favourably over a broad temperature and pressure range. H₂S molecule was observed to undergo physisorption, while NH₃ exhibited strong chemisorption across all the nanocages. Recovery time analysis highlighted that all nanocages displayed practical recovery times for H₂S, with the C₁₀B₁₀ nanocage showing the shortest recovery time, emphasizing its potential as a highly efficient sensor for H₂S detection. The designed nanocages show better gas sensing performance for H₂S gas molecule than NH₃.