A strategy for supportless sensors: Fluorine doped TiO2 nanosheets directly grown onto Ti foam enabling highly sensitive detection toward acetone

Abstract Herein, a facile approach was adopted to synthesize TiO2 nanosheets directly onto Ti foam via hydrothermal method. On this basis, controlled fluorine doping in TiO2 nanosheets was achieved via impregnation. The obtained TiO2/Ti foam and F-TiO2/Ti foam were structurally characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and X-ray diffraction analysis. Furthermore, they were developed as self-supported sensors for detecting acetone at room temperature (25 °C). It was found that the sensors had excellent acetone sensing properties, including high response, good selectivity, decent repeatability and long-term stability. The sensitivities of TiO2/Ti foam and F-TiO2/Ti foam toward 100 ppm acetone were 4.58 and 5.95, respectively, and the detection linear range was 25–800 ppm. The F-TiO2/Ti foam exhibited higher sensitivity, faster response/recovery toward acetone as compared to the undoped counterpart. The results suggested that fluorine doping could be therefore considered as a favorable method for improving the sensitivity of prepared gas sensor. Furthermore, the in-situ growth of gas-sensing nanosheets onto the support can be a promising strategy for fabricating various supportless sensors.