From Capture to Sensing: First-Principles Insights into Sb/Ga/In-Modified Janus ZrSSe for Environmental Monitoring of Hazardous Chlorine-Containing Gases

Abstract

Accidental release of hazardous chlorine-containing gases poses serious risks to ecological integrity and physical well-being, highlighting the need for efficient materials for gas capture and rapid monitoring. In this work, first-principles density functional theory calculations were performed to investigate the adsorption and sensing properties of four representative chlorine-containing gases (COCl2, ClCN, SOCl2, and NOCl) on Sb-, Ga-, and In-modified Janus ZrSSe monolayers. The stability of the modified substrates and the gas-surface interactions were systematically evaluated through formation energy, adsorption energy, charge transfer, density of states, frontier molecular orbitals, and recovery time analyses. The results show that all three metal modifications can be stably introduced onto Janus ZrSSe and effectively reduce its band gap. Among the studied systems, Sb-ZrSSe exhibits the strongest adsorption toward SOCl2 and NOCl (−2.323 and −2.019 eV), indicating strong gas-capture capability. However, the excessively long recovery times make Sb-ZrSSe unsuitable for sensing applications. In contrast, Ga-ZrSSe and In-ZrSSe feature relatively weak substrate–gas coupling intensity and favorable recovery behavior toward SOCl2 and NOCl, with recovery times within 1 s at appropriate temperatures, indicating good potential for rapid monitoring. Compared with SOCl2 and NOCl, COCl2 and ClCN exhibit relatively weaker interactions with the modified substrates, reflecting the selective response of Sb/Ga/In-modified Janus ZrSSe toward different chlorine-containing gases. Overall, these findings reveal the distinct roles of Sb-, Ga-, and In-modified Janus ZrSSe in hazardous gas capture and sensing, and furnish theoretical bases to engineer Janus 2D sensors for contaminant surveillance and leakage prewarning.