Robust 2D/0D/2D MXene@TiO2/ZnIn2S4 ternary integrated heterojunction with efficient multi-interface charge transport and enhanced surface adsorption for gas sensing

MXene-based materials have received increasing attention in gas sensing due to their excellent electrical conductivity and favorable surface properties. However, their practical applications are severely limited by low sensitivity, limited selectivity and poor stability. In this study, a robust sandwich-like 2D/0D/2D MXene@TiO 2 /ZnIn 2 S 4 ternary integrated heterojunction is designed and constructed. The architecture effectively promotes charge transfer across multiple heterointerfaces (metal/semiconductor interface, semiconductor/semiconductor interface), enabling highly sensitive and selective detection of volatile organic compounds, particularly triethylamine. The MXene@TiO 2 /ZnIn 2 S 4 ternary integrated heterojunction exhibits a high response value of ∼48 (R a /R g ) toward 100 ppm triethylamine at 300 °C, along with excellent selectivity, fast response/recovery, low limit of detection (697.2 ppb), remarkable humidity tolerance and long-term stability over 110 days. It is found the efficient multi-interface charge transport channel and enhanced gas adsorption/oxidation characteristics of the MXene@TiO 2 /ZnIn 2 S 4 ternary integrated heterojunction contribute to the excellent gas sensing performance. Moreover, the construction of sandwich-like 2D/0D/2D hierarchical open structure not only greatly promotes the diffusion of gas molecules, but also enhances the stability of pristine MXene. This work not only offers a novel strategy to enhance the performance of MXene-based gas sensing materials, but also provides significant insight into charge transport mechanisms at muti-interfaces in resistive-type gas sensors.