S. Padmaja

Bio: S. Padmaja is an academic researcher from PSG College of Technology. The author has contributed to research in topics: Fourier transform infrared spectroscopy & Nanocomposite. The author has an hindex of 2, co-authored 3 publications receiving 13 citations.

CdS:PMMA nanocomposite solid films with enhanced properties

Abstract: Size tunability and enhanced optical properties of cadmium sulphide (CdS) nanoparticles entrapped in polymethyl methacrylate (PMMA) matrix were presented in this paper. The three-dimensional quantum confinement of CdS in the PMMA matrix was achieved by the in situ technique. X-ray diffraction results show the presence of CdS in the PMMA matrix for higher concentration of CdS nanoparticles (1:20). The particle size and energy band gap were determined by UV–visible spectroscopy. The photoluminescence spectrum shows broadened surface trapped emissions that are shifted towards the blue region. The formation of CdS and its stoichiometric ratio has been confirmed using X-ray photoelectron spectroscopy. The transmission electron microscope results reveal the uniform distribution of nanometre sized particles in the PMMA matrix. The size distribution of CdS nanoparticles in the nanocomposite was carried out by atomic force microscope.

Review on the photocatalytic activity of various composite catalysts

Abstract: Nano sized semiconductor photocatalysts have a great scope for removal of large organic molecules like dyes and pesticides in an eco-friendly and sustainable manner. The photocatalytic decomposition of dyeing industrial wastewater produces negligible amount of solid by products. The problem associated with the existing catalysts are, their high band gap. Doping one catalyst with other suitable metals and metal oxides will enhance the efficiency of the photocatalyst and also makes the catalyst to be active in the visible region. The photocatalytic activity of the composite catalysts were highly improved through the modification in the crystallinity, micro structures, band gap, morphology, particle size and the surface area of the catalyst. This paper reviews the recent developments in the synthesis and application of composite photocatalysts. The role of synthetic pathways on the structure and activity of composite catalyst derived from TiO2, CdS, WO3, SnS and ZnO were analyzed. This paper will be more helpful for the scientists working in the field of nano sized photocatalysis.

Tailoring cadmium sulfide-based photocatalytic nanomaterials for water decontamination: a review

Abstract: Global energy demand and pollution are calling for advanced materials such as visible light semiconductor photocatalysts. In particular, cadmium sulfide (CdS) appears promising due to its tunable bandgap, high absorption of visible light and excellent optical properties. Here we review the photocatalytic mechanism, properties, synthesis and application to wastewater treatment of CdS photocatalysts. Strategies to improve photocatalytic performance include heteroatom doping, heterojunction formation, morphology and crystallinity modification, hybridization with co-catalysts and the use of carbon materials.

Flexible photocatalytic membrane based on CdS/PMMA polymeric nanocomposite films: multifunctional materials.

Abstract: In this study, poly(methyl methacrylate) with different doping nano-cadmium sulfide (CdS/PMMA) is prepared and characterized. CdS/PMMA polymeric nanocomposite films were synthesized using solution casting methodology. SEM and XRD are used for structure analysis for the studied nanocomposite films. XRD revealed the amorphous domains of PMMA polymer, which increased with increasing CdS nanoparticle contents. SEM revealed the CdS dispersion within the PMMA matrix. CdS nanoparticles in the PMMA matrix are expected to be aggregated due to the casting technique. The optical energy gap is found to be decreased after the CdS addition. e′ and e″ have the same behavior with the applied frequency. Maxwell-Wagner interfacial polarization is the responsible factor for higher values of e′–e″ at the higher frequencies. Electrical conductivity behavior σAC tends to obtain a constant value at lower frequencies that approach from its DC conductivity values. After doping PMMA with nano-CdS, an exponential increase after a critical frequency value and the values of σAC was also increased. Besides, a significant reduction in laser energy power is identified by the reduction of the output power. CdS/PMMA can attenuate the laser power due to its nonlinear effect. CdS/PMMA nanocomposite can act as a photocatalyst to improve the performance of the photodegradation of Rhodamine B (RhB). Among the different CdS/PMMA nanocomposite films, 3.33 wt% CdS/PMMA demonstrates the highest efficiency in visible photocatalysis of Rhodamine B. CdS/PMMA can be utilized as multifunctional materials use like laser optical limiting to reduce the power of laser sources and as a photocatalyst membranes.

Photocatalytic degradation of organic dyes by UV light, catalyzed by nanostructured Cd-doped ZnO synthesized by a sonochemical method

Abstract: ZnO and Cd-doped ZnO photocatalysts were successfully synthesized by use of a sonochemical method. The as-synthesized ZnO and Cd-doped ZnO photocatalysts were characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Brunauer–Emmett–Teller analysis, inductively couple plasma-optical emission spectrometry, and X-ray photoelectron spectroscopy. The as-synthesized ZnO and Cd-doped ZnO photocatalysts were pure wurtzite hexagonal ZnO phase. The Raman-active E 2H mode of ZnO, located at 437 cm−1, corresponded to the characteristic band of the hexagonal wurtzite phase. The photocatalytic activity of the pure ZnO and Cd-doped ZnO photocatalysts was investigated by studying the degradation of methylene blue (MB) and methyl orange (MO), in solution, under UV irradiation. Compared with pure ZnO, 3 % Cd-doped ZnO reduced the amounts of MB and MO by 65 % and 45 %, respectively, within 300 min. The results indicated that Cd dopant substantially increased the photocatalytic activity of ZnO.