Bimetallic Phthalocyanine Monolayers as Promising Materials for Toxic H₂S, SO₂, and SOF₂ Gas Detection: Insights from DFT Calculations

The development of a high-performance gas sensor for the rapid and efficient detection of harmful SF₆ decomposition gases (H₂S, SO₂, and SOF₂) is crucial for equipment environmental monitoring and safeguarding human health. In this work, first-principles calculations were conducted to assess the adsorption performance and sensing characteristics of these decomposition gases on two-dimensional metal-dimer-modified phthalocyanine (Mn₂Pc, Tc₂Pc, and MnTcPc) surfaces. The results demonstrate that the Mn₂Pc, Tc₂Pc, and MnTcPc monolayers possess enhanced structural stability. The Mn₂Pc, Tc₂Pc, and MnTcPc monolayer materials show strong adsorption capabilities (|<i>E</i>_ads| > 0.90 eV) and significant electron transfer (|<i>Q</i>_t| > 0.017 e) and interact favorably with the aforementioned toxic gases, indicating their superior adsorption capacities for SOF₂, SO₂, and H₂S. The microscopic interaction mechanisms between SF₆-decomposed gas molecules and the Mn₂Pc, Tc₂Pc, and MnTcPc nanosheets are elucidated through analyses of electron density distribution, differential charge distribution, and density of states. Furthermore, upon absorption of H₂S, SO₂, and SOF₂, the work function and band gap energy of the Mn₂Pc, Tc₂Pc, and MnTcPc monolayers undergo significant changes, and the magnetic moments of the Mn₂Pc, Tc₂Pc, and MnTcPc monolayers also exhibit substantial alterations, suggesting high sensitivity to H₂S, SO₂, and SOF₂. Considering the balance of adsorption strength, sensitivity, and recovery time, the single-layer films of Mn₂Pc, Tc₂Pc, and MnTcPc are deemed to be gas-sensing materials with significant potential, suitable for the development of sustainable gas sensors targeting H₂S, SO₂, and SOF₂ with effective recovery capabilities.