Qingzhi Luo

Characterization and photocatalytic activity of poly(3-hexylthiophene)-modified TiO2 for degradation of methyl orange under visible light

Poly(3-hexylthiophene) (P3HT) was synthesized via chemical oxidative polymerization with anhydrous FeCl(3) as oxidant, 3-hexylthiophene as monomer, chloroform as solvent. TiO(2) nanoparticles modified by a small amount of P3HT (TiO(2)/P3HT) were prepared by blending TiO(2) nanoparticles and P3HT in chloroform solution. The resulting photocatalysts were characterized by the methods of TEM, XRD, FT-IR, XPS and UV-vis diffuse reflectance spectroscope. The photocatalytic activity of TiO(2)/P3HT was investigated by degrading methyl orange under visible light. The degradation rate of methyl orange was 88.5 and 13.5% when it was degradated by TiO(2)/P3HT and neat TiO(2)(P-25) for 10h, respectively. In addition, TiO(2)/P3HT nanocomposites showed excellent photocatalytic stability after 10 cycles under visible light irradiation. A possible mechanism for the photocatalytic oxidative degradation was also discussed.

Highly efficient visible light TiO2 photocatalyst prepared by sol―gel method at temperatures lower than 300 °C

Highly efficient visible light TiO(2) photocatalyst was prepared by the sol-gel method at lower temperature (≤ 300°C), and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and differential scanning calorimetry-thermogravimetric analysis (DSC-TGA). The effects of the heat treatment temperature and time of the as-prepared TiO(2) on its visible light photocatalytic activity were investigated by monitoring the degradation of methyl orange solution under visible light irradiation (wavelength ≥ 400 nm). Results show that the as-prepared TiO(2) nanoparticles possess an anatase phase and mesoporous structure with carbon self-doping and visible photosensitive organic groups. The visible light photocatalytic activity of the as-prepared TiO(2) is greatly higher than those of the commercial TiO(2) (P-25) and other visible photocatalysts reported in literature (such as PPy/TiO(2), P3HT/TiO(2), PANI/TiO(2), N-TiO(2) and Fe(3+)-TiO(2)) and its photocatalytic stability is excellent. The reasons for improving the visible light photocatalytic activity of the as-prepared TiO(2) can be explained by carbon self-doping and a large amount of visible photosensitive groups existing in the as-prepared TiO(2). The apparent optical thickness (τ(app)), local volumetric rate of photo absorption (LVRPA) and kinetic constant (k(T)) of the photodegradation system were calculated.

Novel preparation method for a new visible light photocatalyst: mesoporous TiO2 supported Ag/AgBr

A new method for the preparation of mesoporous TiO2 with a surface deposited with nanoparticles of Ag and AgBr was developed. Cetyltrimethylammonium bromide (CTAB) was used as both a template agent and bromine source in the preparation process of the mesoporous TiO2. Mesoporous TiO2 containing CTAB was synthesized by a sol–gel method, and was dipped into AgNO3 solution to form a mesoporous AgBr/TiO2 nanocomposite. The AgBr/TiO2 nanocomposite was irradiated by visible light to accelerate photolysis of AgBr, forming mesoporous Ag/AgBr/TiO2 photocatalyst. The Ag/AgBr/TiO2 photocatalyst was characterized by small angle X-ray diffraction (SAXRD), wide angle X-ray diffraction (WAXRD), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (UV-Vis DRS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and N2 isothermal adsorption–desorption. Ag/AgBr/TiO2 exhibits high photocatalytic activity for the degradation of methyl orange under visible light irradiation. The photocatalytic reaction follows the first-order kinetics and the rate constant (k) for the degradation of methyl orange photocatalyzed by Ag/AgBr/TiO2 is 63.6, 36.1 and 2.7 times that of mesoporous TiO2 (M-TiO2), commercial TiO2 (P-25), and Ag/AgBr/SiO2, respectively. The recycling runs experiment shows that the photocatalytic stability of the Ag/AgBr/TiO2 photocatalyst is excellent. The visible light photocatalytic mechanism of Ag/AgBr/TiO2 is also discussed.

An efficient visible light photocatalyst prepared from TiO2 and polyvinyl chloride

An efficient visible light photocatalyst has been prepared from TiO2 nanoparticles and a partly conjugated polymer derived from polyvinyl chloride (PVC). It was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV–Vis DRS), Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). The visible light photocatalytic activity of the as-prepared photocatalyst was evaluated by the photocatalytic degradation of Rhodamine B (RhB) under visible light irradiation. The XPS, FT-IR, and Raman spectra show that the partly conjugated polymer derived from PVC exists on the surface of the TiO2 nanoparticles. The UV–Vis DRS, XRD, and TEM results reveal that the modification of the partly conjugated polymer can obviously improve the absorbance of the TiO2 nanoparticles in the range of visible light and hardly affect their size and crystallinity. The visible light photocatalytic activity of the as-prepared TiO2 nanocomposites is higher than that of commercial TiO2 (Degussa P25) and comparable with those of visible light photocatalysts reported in the literature. Their visible light photocatalytic stability is also good. The reasons for their excellent visible light photocatalytic activity and the major factors affecting their photocatalytic activity are discussed.

Preparation and characterization of uniform-sized chitosan/silver microspheres with antibacterial activities

The chitosan/silver microspheres (CAgMs), which possess effective inhibitory on microorganisms, were prepared by an inverse-emulsification cross-linking method using CS/Ag sol as dispersed phase, whiteruss as continuous phase, and glutaraldehyde as crosslinking agent. The size and shape of CAgMs, greatly affecting their antibacterial activities, were controlled by varying the concentrations of cross-linking agent, emulsifier and CS/Ag colloid. The preparation conditions for obtaining uniform-sized microspheres were optimized. The morphology of CAgMs was characterized by scanning electron microscopy (SEM) and laser particle size analysis. The spherical CAgMs with smooth surface in the mean size of ca. 5 μm exhibited a narrow particle size distribution. Energy Dispersive X-ray spectroscopy (EDX) revealed the elemental composition of the microspheres. Transmission electron micrographs (TEM) and Fourier transform infrared spectroscopy (FTIR) of the microspheres confirmed the formation of silver nanoparticles (AgNPs). The X-ray diffraction (XRD) patterns and UV-Visible diffuse reflectance spectroscopy (UV-vis DRS) of the sample showed that AgNPs with the diameter no more than 20 nm were face-centered cubic crystallites. X-ray photoelectron spectroscopy (XPS) proved that AgO bond existed in the microspheres. Thermogravimetric analysis (TGA) showed that the starting decomposition temperature of CAgMs (ca. 260°C) was much higher than that of CS (ca. 160°C), suggesting that the as-prepared CAgMs possessed better thermal stability than original CS did. Antimicrobial assays were performed using typical Gram bacteria and fungi. The inhibitory effect indicated that the as-prepared microspheres exerted a stronger antibacterial activity as the concentration of the AgNPs is increasing, and the microspheres in smaller size had much better antibacterial activity than those in the larger size. The antimicrobial mechanism of CAgMs was discussed.

Preparation and visible-light photocatalytic performances of g-C3N4 surface hybridized with a small amount of CdS nanoparticles

An efficient visible-light photocatalyst was successfully synthesized by surface-hybridizing graphitic carbon nitride (g-C3N4) using a small amount of cadmium sulfide (CdS) nanoparticles. The CdS/g-C3N4 nanocomposites were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, UV–Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy, electrochemical impedance spectroscopy, and photocurrent–time measurement. The photocatalytic activity of the CdS/g-C3N4 nanocomposites was investigated by evaluating the degradation of Rhodamine B (RhB) under visible-light irradiation. The effects of the CdS content on the nanocomposites, initial RhB concentration, pH value of the investigated system, and dosage of CdS/g-C3N4 nanocomposites on the visible-light photocatalytic activity were systematically investigated. The results revealed that the visible-light photocatalytic activity of g-C3N4-based photocatalysts was significantly improved by surface-hybridization of a small amount of CdS nanoparticles, increased as both CdS content on the nanocomposites and dosage of CdS/g-C3N4 nanocomposites increased, while increased at first and then decreased as both initial RhB concentration and pH value of the investigated system increased. The visible-light photocatalytic mechanism of the CdS/g-C3N4 nanocomposites was discussed.

Synthesis, Characterization and Application of Silver-Based Antimicrobial Nanocomposites

The different types of nanomaterials like copper, zinc, titanium, magnesium, gold, alginate and silver possess the antimicrobial activity [1–3]. Among the various antimicrobials, silver is most promising because of its inherent properties of high thermal stability, little toxicity to mammalian cells and tissues [4, 5], versatile activity (such as good antimicrobial efficacy against bacteria, viruses and other eukaryotic microorganisms) and long-term activity [6]. Therefore, the silver-containing materials having excellent antimicrobial activity against a broad spectrum of microbes have attracted much interest of the scientists [7].

Preparation and characterization of silver/g-carbon nitride/chitosan nanocomposite with photocatalytic activity

ABSTRACT In this work, a visible-light-driven catalyst of Ag/g-C3N4/Chitosan (Ag/g-C3N4/CS) was developed by a facile soniation-assisted method at room temperature. The surface morphology, crystal structure and chemical composition of the as-prepared catalyst was systematically characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and electrochemical impedance spectra (EIS). The photocatalytic activity of Ag/g-C3N4/CS nanocomposite was evaluated on the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride (NaBH4) without separating AgNPs/RGO nanocomposite from the synthesis systems. The result shows that the as-prepared nanocomposite exhibits enhanced photocatalytic activity.