Mono- and Bimetallic Nanoparticles for Catalytic Degradation of Hazardous Organic Dyes and Antibacterial Applications.

In the present work, gold (Au), silver (Ag), and copper (Cu) based mono- and bimetallic NPs are prepared using a cost-effective facile wet chemical route. The pH for the synthesis is optimized in accordance with the optical spectra and supported by the finite difference time domain simulation studies. FESEM and TEM micrographs are used to analyze the morphology of the prepared nanoparticles. TEM images of bimetallic nanoparticles (BMPs) verified their bimetallic nature. XRD studies confirmed the formation of fcc-structured mono- and bimetallic NPs. Photoluminescence studies of the as-synthesized NPs are in good agreement with the previous publications. These synthesized NPs showed enhanced catalytic activity for the reduction/degradation of 4-nitrophenol, rhodamine B, and indigo carmine dyes in the presence of sodium borohydride (NaBH4) compared to NaBH4 alone. For the reduction of 4-nitrophenol, Au, Cu, and CuAg nanoparticles exhibited good catalytic efficiency compared to others, whereas for the degradation of rhodamine B and indigo carmine dyes the catalytic efficiency is comparatively high for CuAg BMPs. Furthermore, the antibacterial assay is carried out, and Ag NPs display effective antibacterial activity against Klebsiella pneumoniae, Salmonella ser. Typhimurium, Acinetobacter baumannii, Shigella flexneri, and Pseudomonas aeruginosa.

Low-Temperature Operating Black SnO2-Based VOC Sensor Setup.

Volatile organic compounds (VOCs) are harmful to human beings and animals. VOCs include a carbon compound and its derivatives. VOCs irritate the eyes, ears, and throat, ahigh concentration of VOCs may cause cancer; also, it affects the central nervous system. A concentration below 0.3 mg/m3 is harmless, above which it is harmful to human beings. The present work discusses the detection of harmful VOCs using a lab-made portable device setup. Hydrothermally synthesized tin oxide (SnO2) nanocubes are used as an active material for VOC detection. The SnO2 pellet is prepared using a hydraulic press method and is used in the portable setup. Temperature-dependent VOC detection is carried out using a microheater. An external potential is applied to the microheater, which stimulates the active material to sense ethanol at 40 °C. SnO2 and EA deposited on graphite interdigitated electrodes projected on cellulose are used to detect isopropanol, ethanol, and acetone at room temperature. Temperature-dependent studies on acetone are carried out. A significant change in the current levels is observed for different VOCs. A positive shift in the Dirac point is noticed upon VOC exposure. The developed portable device plays a vital role in analyzing sensors based on various active materials for VOC detection.

Large Area, Multilayer Graphene Films as a Flexible Electronic Material.

Chemically reduced graphene oxide possesses unique properties and leads to a secure processing method for many applications. The electrical and optical properties of graphene oxide are strongly dependent on the chemical and atomic structure. In the present work, the reduction of synthesized multilayer graphene oxide sheets by both chemical and thermal methods to use them as a substrate in the field of molecular electronic device fabrication is reported. 1-Dodecanethiol molecules are used to covalently bond on the surface atoms of reduced graphene oxide to constitute molecular electronic devices. The metal-organic molecules-reduced graphene oxide-metal junctions show a significant reduction in current levels and weak diode behavior. The observations confirm the tunneling as the conduction mechanism. The sheets are low cost, highly flexible, and can be used as a substrate to build the molecular electronic junctions.