Strain-Engineered ψ-Graphene for Enhanced Sensing of Dioxin Molecules: A First-Principles Investigation

The persistence of ultratoxic dioxins such as 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in postcombustion environments demands sensor materials that combine high sensitivity, fast recovery, and structural stability under operational conditions. This study investigates ψ-graphene (ψ-Gr), a predicted two-dimensional carbon allotrope, as a metal-free sensing platform for TCDD using density functional theory (DFT). Instead of conventional doping, mechanical strain engineering is employed as a nonchemical strategy to tune surface reactivity and electronic sensitivity. Adsorption energetics, electronic coupling, work-function modulation, and recovery behavior of pristine and strained ψ-graphene are examined using optimized geometries, density-of-states analyses, and charge-transfer evaluations. Pristine ψ-graphene exhibits metallic conductivity and moderate physisorption dominated by π–π stacking and van der Waals interactions. Biaxial strain (0.5–1.5%) enhances adsorption strength and induces measurable buckling, promoting orbital overlap and electronic polarization. DOS and Bader analyses reveal strengthened hybridization between TCDD O 2p and ψ-graphene C 2p states, increasing electronic activity near the Fermi level. Work-function shifts and rapid recovery (∼10 s at 372 K) confirm good responsiveness and reusability. Comparative benchmarking shows that strain-engineered ψ-graphene achieves sensitivity comparable to Sc-decorated biphenylene but with faster desorption and no dopant-related instability. These results identify ψ-graphene as a promising, metal-free candidate for next-generation dioxin sensing.