Chemical synthesis of p-type nanocrystalline copper selenide thin films for heterojunction solar cells

Nanocrystalline thin films of copper selenide have been grown on glass and tin doped-indium oxide substrates using chemical method. At ambient temperature, golden films have been synthesized and annealed at 200 °C for 1 h and were examined for their structural, surface morphological and optical properties by means of X-ray diffraction (XRD), scanning electron microscopy and UV-vis spectrophotometry techniques, respectively. Cu_2−xSe phase was confirmed by XRD pattern and spherical grains of 30 ± 4 - 40 ± 4 nm in size aggregated over about 130 ± 10 nm islands were seen by SEM images. Effect of annealing on crystallinity improvement, band edge shift and photoelectrochemical performance (under 80 mW/cm² light intensity and in lithium iodide electrolyte) has been studied and reported. Observed p-type electrical conductivity in copper selenide thin films make it a suitable candidate for heterojunction solar cells.     

Green synthesis and characterization of silver nanoparticles by Allium cepa L. to produce silver nano‐coated fabric and their antimicrobial evaluation

This research work was proposed to study the antimicrobial activity of the silver nanocoated fabric with the purpose of producing good dressing and clothing material. We synthesized simple, ecofriendly, cost‐effective and sustainable silver nanoparticles by using the aqueous extract of Allium cepa L. Here, A. cepa L. acts as a good reducing and capping agent that produced stable silver nanoparticles having particle size of range 36 ± 1 to 98 ± 2 nm, Poly dispersiblity index 0.234 ± 0.61 to 1.023 ± 0.33 and Zeta potential ‐12 ± 1.5 mV to ‐26 ± 1.2 mV. The effect of temperature and extract volume used was considered for optimization of synthetic procedure. The nanocoated fabric was characterized for morphological study, size (using transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE‐SEM) and zeta‐potential (Zeta Potentiometer). The presence of functional groups were observed by using attenuated total reflection‐Fourier transform infrared (ATR‐FTIR) and Raman spectroscopy. The crystallinity and structural property of the synthesized silver nanoparticles were studied in terms of Powder X‐ray diffraction (PXRD). An IC₅₀ value and zone of inhibition was studied which demonstrate that the silver nanocoated fabric have an excellent antibacterial property against Gram‐negative (Escherichia coli) and Gram‐positive (Staphylococcus aureus) bacteria. Further nanocoated fabric material was washed (with function of time 0, 10, 25, and 50 laundry cycles) and still retained their anti‐bacterial activity towards both strain. Initially there was 52 μg/ml of silver nanoparticles on the cotton fabric but after 50 laundry cycle in 500 ml of distilled water the fabric showed 92% efficiency against gram positive and 90% efficacy toward gram negative bacteria. It was found that 4.16 μg/ml nano particles leached in case of S. Aureus and 5.2 μg/mL silver nanoparticles leached in case of E. coli. Nanocoated fabric material synthesized using green synthesis was found to be economical with good resistance to washing.     

Total synthesis of attenols A and B

A concise approach for the total synthesis of attenols A and B is described involving MacMillan’s α-aminooxylation, Evan’s asymmetric alkylation, Brown’s allylation, and spiro-ketalization as key steps. This approach has successfully demonstrated the α-aminooxylation protocol for the construction of the anti-1,3-diol unit.     

An efficient protocol for the synthesis of 2-amino-4,6-diphenylpyridine-3-carbonitrile using ionic liquid ethylammonium nitrate

Chalcones on condensation with malononitrile and ammonium acetate in the presence of ionic liquid ethylammonium nitrate affords the corresponding 2-amino-4, 6-diphenylpyridine-3-carbonitrile in excellent yield. The ionic liquid is recycled and reused several times.     

1-Decanethiol, a new reagent for the odorless deprotection of aryl methyl ethers

1-Decanethiol has been found to be an excellent reagent for the deprotection of aryl methyl ethers. This newly developed protocol afforded the corresponding phenols in good to excellent yields. A clear advantage of 1-decanethiol over the more commonly used thiols is the easy extraction of both the deprotecting reagent and the reaction byproduct into the aqueous phase, which allows an essentially odorless work-up.     

A Facile Diversity‐Oriented Multicomponent One‐Pot Synthesis of 3‐Amino‐6,7‐dihydrobenzo[c]thiophen‐4(5H)‐one Derivatives from α‐Oxo‐N,S‐ketene Acetal

A convenient one‐pot multicomponent method for the preparation of 3‐amino‐6,7‐dihydrobenzo[c]thiophen‐4(5H)‐one derivative has been developed. Reaction of 1,3‐cyclohexanedione and phenyl isothiocynate gave α‐oxo‐N,S‐ketene acetal that were reacted in situ with 2‐chloromethylquniazoline‐4‐one derivatives, in the presence of sodium hydride to afford the target compound in reasonable overall yields.     

Oxidative fragmentation of oxiranes to nitriles with hypervalent iodine(V) reagents in aqueous ammonia

Oxiranes undergo oxidative fragmentation when treated with hypervalent iodine(V) reagents particularly o-iodoxybenzoic acid in aqueous ammonia to give nitriles. The reaction goes via the formation of 1, 2-amino alcohols as intermediates followed by C-C bond cleavage.     

A simple CdS nanoparticles cascading approach for boosting N3 dye/ZnO nanoplates DSSCs overall performance

Enhanced photosensitization in presence of CdS nanoparticles is achieved in electrochemically deposited ZnO nanoplates and N3 loaded dye-sensitized solar cells. Chemically embedded CdS nanoparticles act as a sandwiching layer between ZnO nanoplates and dye molecules by overcoming current limiting serious Zn²⁺/dye insulating complex formation and CdS photo-corrosion issues. The X-ray diffraction and the scanning electron microscopy confirm the ZnO with vertically aligned nanoplates, perpendicular to the substrate surface. Amorphous CdS is monitored using electron dispersive X-ray analysis. The low and high resolution transmission electron microscope images confirm the presence of CdS nanoparticles over ZnO nanoplates which later is supported by an increase in optical absorbance and shift in band edge. About 400% increase in solar conversion efficiency with this cascade arrangement is achieved when compared with without CdS which could be fascinating while designing solid state solar cells in presence of suitable p-type layer.     

Addition of multiwalled carbon nanotube and graphene nanosheet in cobalt oxide film for enhancement of capacitance in electrochemical capacitors

In order to enhance the capacitance of electrochemical capacitors, multiwalled carbon nanotubes (MWCNTs) and graphene nanosheets (GNS) were added to cobalt oxide (Co₃O₄) paste. The composite film based on Co₃O₄/MWCNT/GNS (95:4:1 wt%) exhibited a capacitance of 294 F/g while the capacitance of Co₃O₄/MWCNT (95:5 wt%) and pure Co₃O₄ film is 205 and 163 F/g, respectively. The enhanced capacitance of Co₃O₄/MWCNT/GNS composite film was attributed to the electrochemical contributions of the Co₃O₄ nanoparticle attached to the GNS as well as their significantly increased specific surface areas by MWCNTs. Furthermore, the composite films showed faradaic redox capacitive behavior to double-layer capacitive behavior due to the different nanostructures of the composites.