Improving TiO2 gas sensing selectivity to acetone and other gases via a molecular imprinting method

The effect of near-surface electron trapping layer on the acetone sensing performance of black TiO2capped with ZnO

In recent years, high-performance acetone gas sensors have attracted great attention for their potential in noninvasive blood glucose monitoring. In this work, black TiO₂(B-TiO₂) was introduced as an electron trapping layer between TiO₂and ZnO to form TiO₂@B-TiO₂@ZnO core-shell nanoparticles, through a simple and safe method. The acetone sensing performance of TiO₂@B-TiO₂@ZnO varied with the thickness of ZnO. Because of the electron trapping effect of the introduced B-TiO₂layer, the best performing sample exhibited a low optimal operating temperature of 275 °C and a high response of 49.25-50 ppm acetone. In addition, a low detection limit of 170 ppb was obtained. The pretty selectivity of the sample was also been proved. The mechanism of enhanced acetone response was explained by the energy band-based model of TiO₂@B-TiO₂@ZnO core-shell nanoparticle and depletion layer theory.

Preparation and Gas Sensing Properties of PANI/SnO2 Hybrid Material

A sensor operating at room temperature has low power consumption and is beneficial for the detection of environmental pollutants such as ammonia and benzene vapor. In this study, polyaniline (PANI) is made from aniline under acidic conditions by chemical oxidative polymerization and doped with tin dioxide (SnO₂) at a specific percentage. The PANI/SnO₂ hybrid material obtained is then ground at room temperature. The results of scanning electron microscopy show that the prepared powder comprises nanoscale particles and has good dispersibility, which is conducive to gas adsorption. The thermal decomposition temperature of the powder and its stability are measured using a differential thermo gravimetric analyzer. At 20 °C, the ammonia gas and benzene vapor gas sensing of the PANI/SnO₂ hybrid material was tested at concentrations of between 1 and 7 ppm of ammonia and between 0.4 and 90 ppm of benzene vapor. The tests show that the response sensitivities to ammonia and benzene vapor are essentially linear. The sensing mechanisms of the PANI/SnO₂ hybrid material to ammonia and benzene vapors were analyzed. The results demonstrate that doped SnO₂ significantly affects the sensitivity, response time, and recovery time of the PANI material.