Endohedral metallofullerenes, M@C60 (M = Ca, Na, Sr): selective adsorption and sensing of open-shell NOx gases

Abstract

Based on density-functional theory and non-equilibrium Green's function calculations, we demonstrate that endohedral metallofullerenes (EMFs) are reactive to open-shell gases, and therefore have the potential application as selective open-shell gas sensors. The adsorption of eight gas species (CO, H₂O, H₂S, NO₂, NO, SO₂, O₂ and NH₃) on three EMFs (M@C₆₀, M = Ca, Na and Sr) shows that the adsorption energies of the EMFs towards NO₂ and NO are significantly higher than the closed-shell species. Moreover, the high selectivity appears relatively insensitive to the inserted metal atoms. The calculated current–voltage characteristics of gold-M@C₆₀-gold structures (M = Ca, Na) show that the adsorption of NO₂ leads to significant change in conductivity, suggesting a potential application as an EMF gas resistive sensing device.