Adsorption and sensing characteristics of insulating gas C4F7N on 3d late transition metal-phthalocyanine: Theoretical and experimental study

Abstract

Heptafluoroisobutyronitrile (C₄F₇N) is being considered as a promising alternative to the greenhouse gas SF₆ in the electrical industry. However, its biotoxicity necessitates the development of gas sensing technology to detect leaked C₄F₇N. A combination of density functional theory and experiments was employed to evaluate the adsorption and sensing performance of different metal-phthalocyanines as potential sensing materials for C₄F₇N detection. The study included exploring adsorption configurations with adsorption energies, electron transfer, and adsorption distance, as well as comparisons of electronic properties, electron distribution, and density of states (DOS) among the MPcs. Furthermore, gas sensing experiments were conducted using different MPcs to detect 25–100 ppm C₄F₇N. The results revealed that Mn-Pc, Fe-Pc, Co-Pc, and Zn-Pc exhibited considerable chemical interactions, while Ni-Pc and Cu-Pc showed weaker adsorption strength. These findings were further elucidated based on the electron density and DOS of atomic orbitals. Moreover, gas sensing experiments indicated that Co-Pc demonstrated a higher response compared to Fe-Pc at the same concentration of C₄F₇N. Overall, the theoretical and experimental insights offer valuable guidance for C₄F₇N detection and provide a systematic approach to screen and explore organometallic polymer-based gas sensors applicable in various fields.