Xiangyang Wu

One-step hydrothermal synthesis of Fe3O4/g-C3N4 nanocomposites with improved photocatalytic activities

AbstractnThe nanocomposites of g-C3N4 supported by Fe3O4 nanoparticles (Fe3O4/g-C3N4) have been fabricated through a simple hydrothermal route in a water–ethanol system. The nanocomposites were characterized by X-ray diffraction, and transmission electron microscopy, Fourier transform infrared, and thermogravimetric analysis, respectively. The results showed that g-C3N4 nanosheets were decorated randomly by Fe3O4 nanoparticles with average diameters of 7xa0nm. The photocatalytic activities were evaluated in terms of the efficiencies of photodecomposition of Rhodamine B in aqueous solution under visible light illumination. The as-synthesized Fe3O4/g-C3N4 nanocomposites showed unprecedented photodecomposition efficiency compared with pure g-C3N4 under visible-light. The Fe3O4/g-C3N4 nanocomposites with improved photocatalytic activities would have a great potential in removing organic dyes from polluted water.

Highly sensitive formaldehyde chemical sensor based on in situ precipitation synthesis of ZnSnO3 microspheres

Highly sensitive formaldehyde chemical sensor was fabricated using uniform and mono-disperse ZnSnO3 microspheres, which were successfully prepared by a template-free, economical in situ precipitation method combined with subsequent calcination. The orientation and morphology of the precursor, ZnSn(OH)6 microspheres, were carefully controlled by adjusting the added amount of NaOH. This facile process may provide an approach to synthesis of functional nanomaterials with unique structures and excellent physicochemical properties. Moreover, the as-fabricated sensors based on the ZnSnO3 microspheres showed high response and short response-recovery time toward formaldehyde. To 50xa0ppm formaldehyde, the sensor response (S) was 17 at a working temperature of 260xa0°C, and the response and recovery time were 6 and 18xa0s, respectively. The gas response of sensors based on the ZnSnO3 microspheres was linear with the concentration of formaldehyde in the range of 5–100xa0ppm with a correlation coefficient of 0.997. These results showed that the as-prepared ZnSnO3 microspheres have a potential application in gas sensor.

Facile synthesis of α-Fe2O3@graphene oxide nanocomposites for enhanced gas-sensing performance to ethanol

A simple and eco-friendly approach was used to prepare α-Fe2O3@graphene oxide (α-Fe2O3@GO) nanocomposites with different iron oxide content in lower temperature. The nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and nitrogen adsorption–desorption techniques. The results show that α-Fe2O3 nanoparticles with particle sizes of 60–100xa0nm are uniformly anchored on the surface of GO nanosheets at lower hydrothermal reaction. The specific surface area of α-Fe2O3@GO (114.57xa0m2/g) was about threefold larger than that of pure iron oxide (33.37xa0m2/g). Moreover, α-Fe2O3@GO nanocomposites with optimal mass ratio (8:1) between iron oxide and GO, which exhibited enhanced response to 100xa0ppm ethanol (14.82) in comparison with pure α-Fe2O3 (3.48) at 260u2009°C. The improved sensitive performance is in contact with larger surface area and incremental active sites in interface owing to introducing GO. The results reveal that GO is crucial to improve gas sensing performance.

Synthesis and enhanced acetone gas-sensing performance of ZnSnO 3 /SnO 2 hollow urchin nanostructures

A kind of novel ZnSnO3/SnO2 hollow urchin nanostructure was synthesized by a facile, eco-friendly two-step liquid-phase process. The structure, morphology, and composition of samples were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and nitrogen adsorption–desorption techniques. The results revealed that many tiny needle-like SnO2 nanowires with the average diameter of 5xa0nm uniformly grew on the surface of the ZnSnO3 hollow microspheres and the ZnSnO3/SnO2 hollow urchin nanostructures with different SnO2 content also were successfully prepared. In order to comprehend the evolution process of the ZnSnO3/SnO2 hollow urchin nanostructures, the possible growth mechanism of samples was illustrated via several experiments in different reaction conditions. Moreover, the gas-sensing performance of as-prepared samples was investigated. The results showed that ZnSnO3/SnO2 hollow urchin nanostructures with high response to various concentration levels of acetone enhanced selectivity, satisfying repeatability, and good long-term stability for acetone detection. Specially, the 10xa0wt% ZnSnO3/SnO2 hollow urchin nanostructure exhibited the best gas sensitivity (17.03 for 50xa0ppm acetone) may be a reliable biomarker for the diabetes patients, which could be ascribed to its large specific surface area, complete pore permeability, and increase of chemisorbed oxygen due to the doping of SnO2.