CH ₄ , CO, CS ₂ , and Cl ₂ Adsorption on γ‐Graphyne: A First‐Principles Study

Reliable detection of toxic and flammable gases requires materials that distinguish chemically distinct adsorbates. Dispersion‐corrected density functional theory was used to compare CH ₄ , CO, CS ₂ , and Cl ₂ adsorption on pristine γ‐graphyne at four high‐symmetry sites through adsorption energies, optimized geometries, Kohn–Sham band gaps, projected densities of states, and Löwdin populations. CH ₄ physisorbs with adsorption energies of −0.25 to −0.27 eV and leaves the 0.51 eV gap essentially unchanged. The lowest‐energy CO and CS ₂ states (−0.26 and −0.33 eV) also produce negligible gap changes, whereas more perturbing configurations are energetically unfavorable. By contrast, Cl ₂ initialized near an acetylenic‐carbon site forms two 1.78 Å C─Cl bonds, lengthens Cl─Cl from 2.01 to 2.88 Å, has an adsorption energy of −0.42 eV, and reduces the gap to 0.47 eV. Löwdin populations indicate symmetric orbital reorganization without resolved net charge transfer, consistent with predominantly covalent chemisorption. A configuration initialized near an sp ² carbon gives the largest gap reduction (27.18%) and an estimated transfer of 0.16–0.19 electrons from γ‐graphyne, but is energetically unfavorable (adsorption energy = +0.11 eV). These results identify a preferential calculated response to Cl ₂ among the molecules examined while delimiting sensing‐relevant configurations.