S. Karuthapandian

Novel CuO/chitosan nanocomposite thin film: facile hand-picking recoverable, efficient and reusable heterogeneous photocatalyst

The present work demonstrates a new simple hand-picking technique for the 100% recovery of a photocatalyst. CuO nanospheres were synthesized by a simple wet chemical method and were subsequently embedded into the biopolymer matrix (chitosan) under mild conditions by the solution cast method and its photocatalytic application towards the degradation of organic pollutants was measured for the first time. The crystal structure, optical properties, surface and bulk morphology were discussed in detail. ICP-OES analysis showed 3.025% copper embedded in the chitosan (CS) matrix. Efficiency of the CuO/chitosan was evaluated against the degradation of rhodamine B dye as a probe. The combination of CuO nanospheres with chitosan leads to the higher efficiency of up to 99% degradation of the dye with 60 minutes of irradiation. This may be attributed to many features such as the slow electron hole pair recombination rate of nanosized CuO in the biopolymer matrix, the large surface area of the CuO and the high adsorption efficiency of the chitosan. The major advantage of this present protocol is that it is not only restricted to azo type dyes but can also be adopted for different kinds of organic pollutants. For all the types of organic contaminants tested, the CuO/chitosan nanocomposite thin film photocatalyst showed excellent activity. The facile hand-picking recovery and recyclability of this novel thin film likely opens up a new straightforward strategy in the effective photocatalytic degradation of organic contaminants.

CdO/ZnO nanohybrids: facile synthesis and morphologically enhanced photocatalytic performance

A series of CdO/ZnO nanohybrids of different compositions were synthesized by a wet chemical method and investigated in detail. The nanohybrids were characterized by various techniques such as wide angle X-ray diffraction (XRD), diffuse reflectance UV-vis spectroscopy, transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The results revealed that the crystal structure and optical properties of the nanohybrids were almost the same for all the compositions. FE-SEM images showed that the morphology of CdO/ZnO was hexagonal like microspheres, and the 0.75 : 1 Cd/Zn sample had a well-proportioned morphology. Three different dyes viz crystal violet, congo red and rhodamineB were used for the photocatalytic studies in a photoreactor and monitored with a UV-visible spectrometer. The nanohybrids showed excellent photocatalytic degradation compared to pure CdO and ZnO. In particular, nanohybrids with 0.75 : 1 (Cd : Zn) composition ratio exhibited better results compared to all other CdO/ZnO nanohybrids, which may be attributed to the improved charge separation at the heterojunction interface.

Controllable synthesis of SnO2 photocatalyst with superior photocatalytic activity for the degradation of methylene blue dye solution

ABSTRACT SnO2 photocatalyst was successfully synthesised by novel chemical route in hydrothermal environment and annealed at two different temperatures viz 550 and 600 °C, respectively. The crystal structure, optical properties, surface and bulk morphology have been characterised using various tools like X-ray diffraction (XRD), UV visible spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscope (TEM) and scanning electron microscope (SEM). Cubic, spheres and porous like morphology of SnO2 photocatalyst was successfully confirmed using SEM micrographs and TEM. In addition to this the photocatalytic activity was evaluated towards the degradation of methylene blue dye solution. SnO2 photocatalyst annealed at 600 °C exhibits excellent photocatalytic efficiency which may be attributed to the unique morphology, high crystalline nature and charge separation. The photocatalyst efficiency was further tested towards the concentration of dye, catalyst dosage and pH of the dye. The involvement of •OH in the photocatalytic reaction was evidenced using trapping experiment by employing different scavengers. The photocatalyst was moderately active, stable upto its fifth usage and stability of the photocatalyst before and after the photocatalytic reaction was also been studied using XRD and SEM.

Design and Fabrication of a Novel Metal-Free SiO 2 /g-C 3 N 4 Nanocomposite: A Robust Photocatalyst for the Degradation of Organic Contaminants

AbstractDevelopment of novel and efficient nanostructured materials for the waste water treatment is a great challenge for the researchers. In this regard, we report a novel SiO2/g-C3N4 nanocomposites were tailored via simple solvothermal route and characterized by various spectroscopic and microscopic techniques such as XRD, FT-IR, UV–Vis DRS, SEM, TEM and XPS. The photocatalytic performances of the as-prepared SiO2/g-C3N4 nanocomposites were evaluated for the removal of hazardous rhodamine B (RhB) and crystal violet (CV) organic dyes in aqueous solution under visible light irradiation. Interestingly, the UV–Visible spectroscopy results revealed that the as-synthesized SiO2/g-C3N4 nanocomposite showed superior photocatalytic activity for the degradation of RhB and CV dyes could degrade 99 and 98% under visible-light irradiation respectively. The enhanced photocatalytic activity of SiO2/g-C3N4 nanocomposites could be mainly attributed to the proficient separation of photo-induced charge carriers. A plausible degradation mechanism for the controlled visible-light photocatalytic activity of SiO2/g-C3N4 nanocomposites was strongly evidenced by the trapping experiment by employing different scavengers. The present research findings may open up a new platform for the g-C3N4 based photocatalyst for the degradation of organic pollutants.Graphical AbstractProposed degradation mechanism of the SiO2/g-C3N4 photocatalyst.