Magnetron sputtered Au-decorated vanadium oxides composite thin films for methane-sensing properties at room temperature

Room temperature methane (CH4) gas sensing properties of Au-decorated vanadium oxide (VOx) nanostructured films have been prepared by dc-magnetron sputtering of V metal, followed by rapid thermal annealing (RTA) in O2 atmosphere from 470 °C to 500 °C on the sapphire substrate. The structural properties of the Au/VOx films were measured by X-ray diffraction (XRD) and vanadium oxide phases were found and identified as VOx. The films showed a cracking and porous morphology structure, measured by field emission scanning electron microscope (FESEM). The CH4-sensing properties of the sensor based on Au/VOx composite films were carried out in the temperatures span ranging from room temperature (∼25 °C) to 100 °C. The films sensors achieved their maximum response values toward CH4 at room temperature (RT) and the optimal concentration at the concentration of 1500 ppm. At RT, the sensor exhibited higher gas response, good repeatability and excellent selectivity characteristics toward CH4 gas due to its high specific surface area, special structure, and large amounts of oxygen vacancies. Obtained results revealed that the Au/VOx films sensors showed a broad commercial applications prospect to detect CH4 in the field of RT.