Synergistic catalytic and interfacial effects of Ag-loaded SrTiO3/MXene for selective detection of m-Xylene vapour

Abstract

Detecting aromatic volatile organic compounds (VOCs) like xylene isomers, especially m-xylene, amidst benzene and toluene remains challenging due to their similar structures, boiling points, and overlapping properties. M-Xylene is particularly challenging to identify due to its low reactivity and polarity, often requiring high temperatures that increase power consumption and reduce sensor lifespan, thereby limiting portable and real-time applications. Thus, herein, Ag-decorated SrTiO 3 /MXene heterostructures were synthesized and systematically evaluated to elucidate the influence of Ag incorporation on their structural, optical, and gas-sensing properties. Ag-loading preserved the sheet-like architecture of SrTiO 3 /MXene while inducing notable improvements in microstructure. Structural findings confirmed Ag nanoparticle sizes of ~5–25 nm for 1 wt% and ~15–45 nm for 2 wt% samples. A significant reduction in defect-related electronic states upon Ag addition was observed. Gas-sensing investigations demonstrated that the 1 wt% Ag-loaded sample exhibited a better response toward m-xylene at 100 °C, with a response value of 1.002, a detection limit of 3.1 ppm, and rapid response/recovery times of 15 s/ 25 s, respectively. This enhancement is associated with the increased surface area, stronger catalytic activity, and effective oxygen spillover, which collectively promote the formation of reactive oxygen species and facilitate charge-transfer interactions with m-xylene. Selectivity toward m-xylene was further supported by its electron-rich structure, minimal steric hindrance, and favourable π–π interactions compared to other BTX gases. These findings confirmed that the Ag-modified SrTiO 3 /MXene heterostructure is a capable sensor for low-temperature aromatic VOC detection in complex environments. • Ag-decorated SrTiO 3 /MXene heterostructures were synthesized and evaluated for gas sensing • A significant reduction in defect-related electronic states upon Ag addition was observed. • 1 wt% Ag-loaded sample exhibited a better response toward m-xylene at 100 °C. • A low detection limit and rapid response/recovery times were observed.