| VOCs as an important component of air pollution,not only harm the human body,but also a major disease and even cancer incentives. However, the traditional chemical sensors currently tested for VOCs gas are poor in stability sustainability.The metal oxide semiconductor (TiO2) considered in this paper has been extensively studied because of its environmental friendliness, good selectivity, reliable stability and fast response. However, in practical use, it is affected by its low quantum effect and wide bandgap width, so that it has a high photogenerated hole recombination rate and can not absorb visible light. In order to prolong the life span of the photo-generated electron-hole pairs in TiO2 and narrow the bandgap width and improve the response of the materials and related devices, the synergistic effect of the graphene-based materials and TiO2 and the UV-induced sensing materials were used to make the sensing materials Surface generation of photo-generated electron-hole pairs, increase the concentration of carrier, effectively improve the response of TiO2-based sensors. Our main work is divided into the following sections:(1)The Pt/GQDs-TiO2 sol solution and the Pt/GQDs-TiO2 mesoporous composite film were prepared by sol-gel method.(2)The Pt/GQDs-TiO2 mesoporous composite films were treated and characterized. Mainly from the post-steaming and roasting two aspects of research.Among them, the post-steam treatment study, taking into account the sub-temperature and time changes; research roasting is the main consideration of the temperature change. The characterization of materials mainly includes the use of UV-vis spectrophotometry (UV) analysis, fluorescence spectroscopy (PL) analysis,X-ray diffraction (XRD), transmission electron microscopy (TEM) and atomic force microscopy (AFM) Of the sample structure and morphology of the characterization.The results show that GQDs are successfully doped with mesoporous composites.The mesoporous composites have an average grain size of about 10 nm and mesoporous TiO2 is anatase. At the same time,Good crystallinity and orderly channels.(3)The obtained Pt/GQDs-TiO2 mesoporous composite film was prepared as a sensor and studied at room temperature to enhance the sensing performance of various VOCs gas under ultraviolet light irradiation, including (i) considering the detection of gas invariance, (ii) the use of sensors to detect multiple concentrations of VOCs at different concentrations. The experimental results show that UV detection has a significant improvement in the detection performance of the enhanced mesoporous composite sensor. In particular, in the detection of benzene, if there is no UV light, the sensor has little resistance to the concentration of 25 ppm benzene. UV irradiation,the same thin film sensor showed a good resistance response at 25 ppm benzene, with response and response times of 8s and 23 s, respectively. Based on the analysis of various VOCs gas (ether, benzene and ethanol), we found that UV radiation has a greater effect on the resistance response of the whole sensing system.In addition, Pt/GQDs-TiO2 mesoporous composites are not only converted into n-type semiconductors by p-type semiconductors when ultraviolet light is used to irradiate n-type roasted Pt/GQDs-TiO2 mesoporous composites which have no resistance to VOCs, But also showed good response of resistance to the ether and selectivity. At this time,Pt/GQDs-TiO2 mesoporous composites responded to 25 ppm benzene, with response times and recovery times of 11 s and 9 s, respectively. |
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