ABSTRACT
We present the in situ synthesis of silver nanoparticles (AgNPs) through ionotropic gelation utilizing the biodegradable saccharides lactose (Lac) and alginate (Alg). The lactose reduced silver ions to form AgNPs. The crystallite structure of the nanocomposite AgNPs@Lac/Alg, with a mean size of 4-6 nm, was confirmed by analytical techniques. The nanocomposite exhibited high catalytic performance in degrading the pollutants methyl orange and rhodamine B. The antibacterial activity of the nanocomposite is pH-dependent, related to the alterations in surface properties of the nanocomposite at different pH values. At pH 6, the nanocomposite demonstrated the highest antibacterial activity. These findings suggest that this nanocomposite has the potential to be tailored for specific applications in environmental and medicinal treatments, making it a highly promising material.
ABSTRACT
Recently, there have been publications on preparing hybrid materials between noble metal and semiconductor for applications in surface-enhanced Raman scattering (SERS) substrates to detect some toxic organic dyes. However, the use of cuprous oxide/silver (Cu2O/Ag) to measure the trace amounts of methyl orange (MO) has not been reported. Therefore, in this study, the trace level of MO in water solvent was determined using a SERS substrate based on Cu2O microcubes combined with silver nanoparticles (Ag NPs). Herein, a series of Cu2O/Agx (x= 1-5) hybrids with various Ag amounts was synthesized via a solvothermal method followed by a reduction process, and their SERS performance was studied in detail. X-ray diffraction (XRD) and scanning electron microscopy results confirmed that 10 nm Ag NPs were well dispersed on 200-500 nm Cu2O microcubes to form Cu2O/Ag heterojunctions. Using the as-prepared Cu2O and Cu2O/Agx as MO probe, the Cu2O/Ag5 nanocomposite showed the highest SERS activity of all samples with the limit of detection as low to 1 nM and the enhancement factor as high as 4 × 108. The logarithm of the SERS peak intensity at 1389 cm-1 increased linearly with the logarithm of the concentration of MO in the range from 1 nM to 0.1 mM.
ABSTRACT
We successfully synthesized ZnSe nanoparticles (NPs) by using a hydrothermal method. Careful analyses of X-ray diffraction pattern and high-resolution transmission electron microscopy images showed that the synthesized ZnSe NPs with the size of Ë100 nm and sphere-like morphology crystallized in the zincblende/cubic structure (the F-43m space group). This was also confirmed based upon characteristic vibration modes recorded by using Raman scattering spectroscopy. The study on room-temperature absorption and photoluminescence (PL) spectra proved ZnSe NPs having high crystal quality with the band gap energy Eg≈2.63 eV at 300 K and excitonic emission peaked at Ë2.64 eV (469 nm). Particularly, as studying temperature-dependent PL spectra, we found the shift of the emission peak towards lower energies while the PL intensity decreased when temperature increased from 15 to 300 K. The PL spectral parameters were analyzed by using the Arrhenius and Varshni laws.
ABSTRACT
Rutile TiO2 with highly active facets has attracted much attention owing to its enhanced activity during the photocatalytic degradation of pollutants such as pharmaceuticals in wastewater. However, it is difficult to obtain by controlling the synthetic conditions. This paper reports a simple hydrothermal synthesis of rutile TiO2 nanorods with highly exposed {110} facets. The obtained rutile was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), and Raman spectroscopy. The main contribution to the photocatalytic activity comes from rutile nanorods with highly dominant active {110} facets, which were studied in the photodegradation of reactive cinnamic acid and more recalcitrant ibuprofen. The contribution of active species was also investigated. The present work further confirmed the hydrothermal synthesis route for controlling the preparation of highly crystalline and active rutile nanocrystals.
