Reverse Sensing Kinetics investigation with STM of Deep-UV triggered TiO2/WO3 NCs for Isoprene detection

Abstract

Abstract Traditional diagnostic technologies in the health sector are either bulky or expensive and invasive; hence, the breath analyzer era emerged, wherein it can be a single sensor for a single illness diagnosis or a multi-sensor array to diagnose a single disease with numerous biomarkers. Isoprene, commonly known as a biomarker for various diseases, mainly for oxidative stress/cholesterol abnormalities, is targeted in this study. A drop-casted layer of microwave-treated Titanium dioxide/Tungsten oxide (TiO 2/WO 3) nanocomposites (NCs) optically activated in the deep UV (λ-300nm) range is employed for the detection of Isoprene. An optimised moderately doped TiO 2/WO 3 NCs calibrated under 20 to 80 ppb of isoprene is considered from our previous work and thoroughly investigated for its sensing pattern discrepancy under optical activation. Our study aims to comprehend the reverse sensing pattern observed during optical activation of the sensing layer utilizing a precision scanning tunnelling microscope (STM) integrated with a deep-UV LED of λ-300nm. STM experiments confirm that the observed reverse sensing pattern, which contradicts the normal mode, is driven by an excess photogenerated surface n-type carrier concentration of 8.785 × 1015 cm −3.