Synthesis, Characterization, and Ethanol Gas Sensing Applications of Graded Structured ZnO/g-C۳N۴ Micrometer Spheres

A gas sensor is a detection device that can transform the information of gas concentration into an electrical signal. Its core is gas-sensitive material. Among the gas-sensitive materials, semiconductor materials have been paid more attention. In this work, starting from the metal oxide semiconductor material ZnO, to further improve its performance, graded structured ZnO/g-C۳N۴ microspheres were prepared by a combination method of hydrothermal reaction and high-temperature calcination, and the optimal g-C۳N۴ doped ratio was adjusted in ZnO/g-C۳N۴. The structure and morphology of the synthesized samples were characterized via X-Ray powder Diffraction (XRD), Scanning Electron Microscopy (SEM), and N۲ adsorption-desorption. The gas-sensitive properties of the ZnO/g-C۳N۴ composite and pure ZnO to ethanol are compared and investigated. It was found that the response of the ZnO/g-C۳N۴ composite to ۱۰۰ ppm ethanol at ۲۶۰ °C was ۲۶.۳۶, which was ۲.۱۹ times higher than that of pure ZnO. This experiment's response and recovery time are ۲۶ s and ۳۱ s. The results show that ZnO/g-C۳N۴ composites have better gas-sensitive properties than pure ZnO and g-C۳N۴. Among them, the sample (the g-C۳N۴ doping content was ۵ wt%,) has the best gas sensitivity. The gas-sensitive property of the ZnO/g-C۳N۴ graded structure microspheres to ethanol was attributed to the unique graded structure of the material and the n-n heterojunction. The heterogeneous structure of ZnO/g-C۳N۴ composite inhibits the recombination of electrons and holes and electrons are faster transferred to the material’s surface, resulting in improved gas sensitivity. Furthermore, the gas sensor exhibited excellent selectivity, good repeatability, and long-term stability to ethanol, indicating that ZnO/g-C۳N۴ nanocomposites will be a promising application prospect for ethanol sensors.

کلیدواژه ها:

hierarchical structure ، ZnO/g-C۳N۴ ، Micrometer spheres ، Gas sensing property