The effect of near-surface electron trapping layer on the acetone sensing performance of black TiO2 capped 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 TiO2 and 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-TiO2 layer, 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.