Metal-enhanced carbon-nitrogen material for selective detection of hazardous gases: Insights from interface electronic states

In this study, utilizing density functional theory, the C₃N₁ monolayer modified by Ir, Pd, Pt, and Rh atoms (Ir/Pd/Pt/Rh-C₂N₁) was chosen for selective adsorption of C₂H₂ amidst multiple gases (H₂O, C₂H₂, and C₄H₁₀O₂). According to the results of cohesive energy and ab initio molecular dynamics simulations, it is indicated that precious metal atoms can be stably anchored on the monolayer while enhancing the conductivity of the material The analysis of the electrostatic potential and work function determined the highly active sites and electron release capacity. In addition, the adsorption energy and distance disclosed the gas-solid interface structure of multiple gases on the Ir/Pd/Pt/Rh-C₂N₁ monolayer. Importantly, C₂H₂ exhibits strong responses to p-type semiconductor Pt-C₂N₁ and n-type semiconductor Ir-C₂N₁, respectively. Crystal Orbital Hamilton Population reveals the difference in adsorption energy due to modifications involving four precious metals. Interestingly, for the first time, the density of states calculation reveals that under the coexistence of multiple gases, the Pt/Ir-C₂N₁ monolayer effectively eliminates the interference of other gases and has a unique response only to C₂H₂. In real situations, with the basis of Gibbs free energy and Einstein's law of diffusion, it was determined that Pt-C₂N₁ and Ir-C₂N₁ showed excellent hydrophobicity, a wider temperature range, and a low diffusion activation energy barrier. In summary, Pt-C₂N₁ and Ir-C₂N₁ detect C₂H₂ without interference, maintaining fundamental principles, responsiveness, stability, and versatility unaffected by external factors.