GQDs-TiO2 heterojunction based thin films for volatile organic compounds sensor with excellent performance at room temperature

Abstract Crystalline nanoporous GQDs-TiO2 thin films are synthesized under a 120 °C water vapor hydrothermal treatment, and water soluble GQDs are successfully loaded in the thin film in optimum density to form novel GQDs-TiO2 heterojunctions. The optimum sensing performance is achieved at GQDs content of 1.6 wt%, with the isopropanol response value up to 13.8 at 50 ppm and a short response time of ~18 s at room temperature. In general the synthesis procedure described in this work has the advantage of being easy, cost efficient, and highly suitable for the fabrication of gas sensor with the application for monitoring specific harmful and toxic volatile organic compounds (VOCs) in early diagnosis of cancer.