Study On Synthesis And Properties Of Carbon-doped Tungsten Trioxide

Tungsten trioxide (WO3) as an important functional material, it has a wide rangeof applications in terms of gas detection and photocatalysis, the excellent propertiesdependent on its special microstructure and morphology. In this paper, thequasi-one-dimensional carbon doped WO3nanofibers (C-doped WO3) weresysthsised by using cotton fibers as templates, which were designed to improve theirgas-sensing and photocatalytic properties by the means of doping carbon andconstructing quasi-one-dimensional nanostructures. The C-doped WO3werecharacterized by X-ray powder diffraction, transmission electron micros copy,scanning electron microscopy, high-resolution transmission electron microscopy,X-ray photoelectron spectroscopy, Raman spectra. Its gas-sensing properties foracetone and stability were systematically studied. Its photocatalytic activity wasinvestigated by degradation of methylene blue. The results are as follows:(1) C-doped WO3nanofiber was monoclinic, the SEM、TEM、HRTEM imagesshowed that WO3-500had a unique hollow structure with many microporous, whichwas about5-10μm in diameter and consisted a series of ultrafine nanocrystals (20-40nm in diameter). The size of grain increased with the increasing of calcinationtemperature. The carbon doped into WO3lattice could be proved by the XPS andRaman spectra. The W C bond in282.2eV (XPS C1s) and the G bond (Ramanspectra) of ordered carbon could be found respectively.(2) We tested the sensor’s gas sensing properties toward acetone, methanol,ethanol, ammonia gas under different operating conditions. It was found that C-dopedWO3exhibit a high selectivity and sensitivity toward acetone. The optimal calcinationtemperature and operating temperature was500℃and300℃.The lowest detectionlimit of sensor could reach0.1ppm. The sensitivity of WO3-500sample to5ppmacetone reached7.9; it also showed a long-term stability by repeating the gas sensingtest. The sensitivity of the sensor to5ppm could also reach5.72even at a relativehumidity of95%. H2S wouldn’t cause the deactivation of sensor, which showed a long-term stability in repeating tests.(3) Compared to pure WO3, the WO3-500sample can improve the degradationof methylene blue significantly. The degradation rate of methylene blue can reached97.1%under visible light irradiation conditions in120min with the Quasi-Fentonsystem (WO3-500and H2O2) as catalyst. The synergistic effect of WO3-500and H2O2was the main reason for the degradation enhancement of methylene blue. Thecatalysts could be easily separated from the degradation system with a good stability;the reused catalyst could also exhibit high catalytic activity.