Resistive room temperature DMA gas sensor based on the forest-like unusual n-type PANI/TiO2 nanocomposites

TiO2 gas sensors have been limited to apply in some gas detection processes due to their high working temperature. Compositing conductive polymer is a workable strategy to decrease the working temperature. Here we present a resistive gas sensor based on PANI/TiO2 nanocomposite to detect dimethylamine (DMA) at room temperature. The TiO2 nanorod arrays were assembled on the surface of the sensor device by a hydrothermal method first, and then polyaniline was grown on the surface of the TiO2 nanorod arrays by a low-temperature gas phase diffusion method. By changing the diffusion time of polyaniline, the conductivity type of PANI/TiO2 nanocomposites can change from n-type to p-type. When deposited for a short time, the PANI/TiO2 nanocomposite reflects the characteristics of n-type semiconductor TiO2. The sensing test results show that the PANI/TiO2 sensor exhibits high response (6.36-30 ppm), high selectivity and good linearity to DMA at room temperature (25 degrees C), and the lowest concentration for DMA detection reaches 0.050 ppm. When deposited for a long time, the PANI/TiO2 nanocomposite exhibits the characteristic of the p-type semiconductor PANI, and the response to 30 ppm DMA at room temperature is 1.47. This provides a new strategy for the detection of DMA at room temperature, which will also promote the application of low temperature detection of semiconductor sensors.