Orbital Hybridation-Driven Selective Adsorption in Cr-Doped C3N2 Monolayers: A DFT Exploration for High-Performance Insulating Gas Sensing

This study uses first-principles DFT to investigate the regulatory mechanism of Cr doping on C3N2 monolayer adsorption of CH4, CO2, and C2N2. Results show Cr atoms stably incorporate into C3N2 pore sites (binding energy: -4.26 eV), altering electronic properties via Cr-3d/N-2p hybridization. Adsorption analyses reveal selective capture: C2N2 shows strong chemisorption via Cr-N covalent bonding (Eads: -2.148 eV, ΔQ: -0.034 e), CO2 moderate adsorption via Cr-O polar interactions (-0.866 eV, -0.082 e), and CH4 physical adsorption (-0.305 eV, 0.004 e). Density of states analysis clarifies hybridization mechanisms, while work function calculations show a 9.2% increase upon C2N2 adsorption, confirming its potential as a gas sensor. This work provides a novel 2D nitride design for insulation fault gas detection and advances understanding of gas-sensitive interfacial interactions.