Metal-modified C3N1 monolayer sensors for battery instability monitoring

Abstract

The pressing need for affordable gas sensors with enhanced sensitivity and selectivity in identifying hazardous gases released after the battery becomes unstable cannot be overstated. In this study, a C₃N₁ monolayer modified with Cu and Ag atoms (Cu/Ag–C₂N₁) was selected to achieve selective adsorption of NO₂ under the coexistence of multiple gases (PF₅, NH₃, H₂O, C₂H₄, and C₂H₆) based on density functional theory. The results demonstrate that securely anchoring metal atoms to the monolayer, as indicated by cohesion energy and ab initio molecular dynamics simulations, concurrently enhances the material's conductivity. Analyses of electrostatic potential and work function identified high activity sites and electron-releasing capabilities. Furthermore, the gas–solid interface structures of multiple gases on the Cu/Ag–C₂N₁ monolayers are revealed by the adsorption energy and distance. Importantly, NO₂ exhibits stronger adsorption energy on Cu/Ag–C₂N₁, reaching −3.54 and −3.27 eV, respectively. Crystal Orbital Hamilton Population and d-band center theory unveiled differences in adsorption energy resulting from the modification involving the two metals. Fascinatingly, density of states calculation demonstrates, for the first time, that the two doped metal monolayers generate a distinct response solely to NO₂ in a multi-gas coexistence setting, effectively excluding interference from water. In practice, based on Gibbs free energy and Einstein diffusion law calculations, Cu–C₂N₁ exhibits superior hydrophobicity, a broader temperature range and a lower diffusion activation energy barrier (2.5 kJ mol⁻¹). Our theoretical calculations demonstrate Cu's efficacy in substituting expensive Ag, yielding cost-effectiveness without compromising selectivity, response, stability, and versatility.