Keywords : CdS

Eggshell Membrane Assisted CdS Nanoparticles for Manganese Removal in Water Treatment  

Anurag Roy; Sasireka Velusamy; Tapas K. Mallick; Senthilarasu Sundaram

Advanced Materials Letters, 2021, Volume 12, Issue 3, Pages 1-7
DOI: 10.5185/amlett.2021.031609

Domestic food waste chicken eggshells can produce naturally abundant protein-based eggshell membranes (ESMs), which is used as a less-explored source of sulphur to synthesize hexagonal CdS nanoparticles (NPs) under 365 nm (UVA) light irradiation. The perspective of CdS NPs synthesis in the way of UVA light irradiation soakage technique using ESM is distinctive compare to other traditional methods. Various physicochemical methods were employed to validate the formation of CdS NP using ESM assisted process. The obtained NPs exhibit an average particle size of ~5 nm as obtained from the transmission electron microscopy study. The capability of the synthesized CdS NPs was further explored in the catalysis reaction for the decomposition of KMnO4, considered as toxic Mn VII (violet) ion source at room temperature. The degradation results as monitored by UV-Vis spectrophotometry analysis confirms the CdS NPs exhibit excellent catalytic activity towards the reduction of KMnO4, toxic Mn VII (violet) ion to MnO2 as non-toxic Mn IV (brownish yellow) ion in aqueous solution (pH 7.0) at room temperature by 50 min. The KMnO4 decomposition reaction follows a pseudo-first-order reaction having the rate constant value of 1.9 x 10 -2 min -1 . This study encourages the potential use of natural waste materials for wastewater treatment.

Growth and characterization of graphite doped CdTe/CdS thin film heterojunction

Muhammad Asghar; Ya Hong Xie; M. Asif Nawaz; Hammad M. Arbi; M. Y. Shahid; F. Iqbal; Waqas Khalid

Advanced Materials Letters, 2017, Volume 8, Issue 8, Pages 878-882
DOI: 10.5185/amlett.2017.7094

Doping is a notable factor to improve the performance of CdTe/CdS heterojunction solar cell. Graphite doped CdTe/CdS heterojunction on Si (1 1 1) substrate has systematically fabricated by thermal evaporator method under medium vacuum (10 -4 torr) condition. Characterization of doped CdTe/CdS film was carried out by various diagnostic techniques such as X-ray diffraction (XRD) exhibits the polycrystalline structure of cubic phase CdTe and hexagonal phase CdS, scanning electron microscopy (SEM) shows the smoothening of the film, energy dispersive X-ray (EDX) confirm the elemental composition found in the film and current-voltage (I-V) analysis suggests the diode like properties where the current is slightly increased by the doping of graphite into CdTe/CdS heterojunction compared to the reported literature. Analysis of I-V characteristics has been made to investigate the current conduction mechanism in CdTe/CdS heterojunction. 

Determination of optimum cation to anion (Cd:S) ratio for the synthesis of mono sized CdS quantum dots through optical properties

Jai Kumar B; Sumanth Kumar D; Mahesh H. M

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 386-392
DOI: 10.5185/amlett.2017.6918

The CdS quantum dots (QDs) were synthesized using double injection aqueous method and systematic studies were carried to determine optimum cation to anion (Cd:S) ratio to obtain mono sized CdS QDs. An efficient and convenient method is designed by utilizing the optical properties (absorbance and transmission spectra) as qualitative tool. CdS QDs was synthesized by varying cadmium and sulfur concentration from 0.01M to 0.1M and 0.01M to 0.05M respectively keeping MPA and other precursors constant. Through Concentration Optimization by Optical Spectra (COOS) method, it was found that for 0.02M sulfur and 0.04M MPA, 0.03 to 0.05M cadmium was the most favorable concentration and similarly for 0.04M cadmium and MPA the optimum concentration of sulfur was 0.02M. CdS QDs optical band gap varied from 3.09 eV to 3.69 eV with quantum dots size decreasing from 3.22 nm to 2.45 nm, respectively for Cadmium concentration from 0.02M to 0.07M. For Sulfur concentration variation, band gap varied from 3.55 eV to 3.03 eV, with size of QDs increasing from 2.58 nm to 3.33 nm, respectively for concentration 0.01M to 0.05M. All this results shows that synthesized quantum dots were well under quantum confinement effect. Further, the proposed COOS method can be extended to all QDs synthesis to obtain the optimum cation to anion ratio to synthesis QDs with narrow size distribution.

Synthesis Of C/ZnO/CdS Nanocomposite With Enhanced Visible Light Photocatalytic Activity  

Yuvraj S. Malghe; Atul B. Lavand

Advanced Materials Letters, 2016, Volume 7, Issue 3, Pages 239-245
DOI: 10.5185/amlett.2016.6130

C/ZnO/CdS nanocomposite was synthesized using microemulsion method. Thermal stability of precursor was studied with TG and DTA techniques. Structural and optical properties of composite were studied using various characterization techniques like X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), energy dispersive x-ray spectroscopy (EDX), transmission electron microscopy (TEM) and  UV-visible absorption spectroscopy  and photoluminescence spectroscopy. XRD study indicates that ZnO and CdS are having wurtzite and cubic phase in the composite sample. SEM and TEM study indicates formation of CdS nanospheres on ZnO nanorods. C doping and CdS coupling are responsible for red shift and shifting of absorption edge of ZnO from UV to visible region. C/ZnO/CdS nanocomposite exhibits better visible light photocatalytic activity for degradation of methylene blue (MB). Stability of photocatalyst was studied using recovered photocatalyst up to third cycle and it was found that photocatalyst prepared in the present work is stable and reusable.   

 Influence Of Laser Irradiation On The Optical Properties Of As40Se45Sb15 Thin Films By Thermal Evaporation Technique

Ramakanta Naik

Advanced Materials Letters, 2015, Volume 6, Issue 6, Pages 531-537
DOI: 10.5185/amlett.2015.5753

 The present paper highlights the optical properties change in thermally evaporated As40Sb15Se45 amorphous film of 800 nm thickness with laser irradiation. The as-prepared and illuminated films were studied by X-ray diffraction, Energy dispersive X-ray analysis. The optical properties were calculated from the transmission spectra obtained from Fourier Transform Infrared Spectroscopy. The band gap is decreased by 0.22 eV due to photo induced effects causing photo darkening. The refractive index is found to be increased due to increase in structural disordering. These optical properties changes are due to the change of homopolar bond densities which can be seen from the core level peak shifting in XPS spectra. The optical constants such as refractive index, band gap of the material plays a major role in the preparation of the device for a particular wavelength. Selecting suitable pairs of chalcogenide glasses with different optical gaps, one can modify the parameters of the light sensitive layers and use them for optical recording.  

Synthesis Of Mercaptopropionic Acid Stabilized CdS Quantum Dots for Bioimaging In Breast Cancer

P. Kumar; D. Kukkar; A Deep; S.C. Sharma; L.M. Bharadwaj

Advanced Materials Letters, 2012, Volume 3, Issue 6, Pages 471-475
DOI: 10.5185/amlett.2012.icnano.296

Semiconductor inorganic nanocrystals or quantum dots (QDs) are nowadays extensively used for imaging and analysis of bio-molecules owing to their superior optical properties over conventional organic fluorophores. They have excellent potential for synthesizing molecular probes against various biological markers such as free antigens, cell surface markers/antigens, bacteria, viruses and tissues. Traditional synthesis protocols of the QDs generally lead to the formation of hydrophobic nanocrystals. For biological applications, post-synthesis modifications need to be introduced to render required hydrophilicity. However, such additional steps make the tiny QDs structures bulky, which is unwanted in subsequent in-vivo executions. The present work reports a simple method for the direct synthesis of hydrophilic carboxyl (–COOH) functionalized CdS QDs using mercaptopropionic acid as a sulfur source and stabilizer. This aqueous synthesis route avoids the requirement of extra surface modification steps. The size and surface morphology of the synthesized CdS QDs were studied by electron microscopy. The average diameter of the QDs has been found to be in the range of 2-3.5nm. Spectral studies confirmed the grafting of –COOH terminal on the synthesized nanocrystals. Band gap energy and the theoretical size of the particles were calculated and found in good agreement with the experimental analysis. Due to the size quantization effect, the estimated band gap energy (2.6eV) of the QDs was on a higher side than that reported (2.4eV) for the bulk material. The synthesized nanocrystals can be further conjugated with bio-molecules for high-throughput drug screening, clinical immunological assays and protein-protein interaction studies.