Muhammad Sher

A chemodosimetric approach for the selective detection of Pb2+ ions using a cesium based perovskite

We report the preparation of a lead free inorganic perovskite by a facile wet-chemical method using HCl as a solvent at room temperature. The cesium perovskite CsCuCl3 material was characterized by powdered X-ray diffraction (p-XRD), field emission scanning electron microscopy (FESEM), and energy dispersive X-ray (EDX) spectroscopy. Ultraviolet/Visible (UV-Vis) and steady state photoluminescence (PL) spectroscopy were also carried out on the material. CsCuCl3 showed promising optical properties with a band gap of 2.6 eV. The material was tested as a fluorescent sensor for the detection of metal ions and as a selective fluorescent chemodosimeter for Pb2+ ions. The substitution of Cu2+ ions by Pb2+ in CsCuCl3 proves the success of the chemodosimetry approach for the detection of Pb2+ ions.

Synthesis of Ag-NPs impregnated cellulose composite material: its possible role in wound healing and photocatalysis

Cellulose is the natural biopolymer normally used as supporting agent with enhanced applicability and properties. In present study, cellulose isolated from citrus waste is used for silver nanoparticles (Ag-NPs) impregnation by a simple and reproducible method. The Ag-NPs fabricated cellulose (Ag-Cel) was characterised by powder X-rays diffraction, Fortier transform infrared spectroscopy and scanning electron microscopy. The thermal stability was studied by thermo-gravimetric analysis. The antibacterial activity performed by disc diffusion assay reveals good zone of inhibition against Staphylococcus aureus and Escherichia coli by Ag-Cel as compared Ag-NPs. The discs also displayed more than 90% reduction of S. aureus culture in broth within 150 min. The Ag-Cel discs also demonstrated minor 2,2-diphenyl 1-picryl-hydrazyl radical scavenging activity and total reducing power ability while moderate total antioxidant potential was observed. Ag-Cel effectively degrades methylene-blue dye up to 63.16% under sunlight irradiation in limited exposure time of 60 min. The Ag-NPs impregnated cellulose can be effectively used in wound dressing to prevent bacterial attack and scavenger of free radicals at wound site, and also as filters for bioremediation and wastewater purification.

Bis(selenobenzoato)dibutyltin(IV) as a single source precursor for the synthesis of SnSe nanosheets and their photo-electrochemical study for water splitting

A new organo-tin complex has been synthesized and used as a single source precursor for the synthesis of SnSe nanosheets by the hot injection method and thin films by the aerosol assisted chemical vapor deposition (AACVD) method. The films were deposited on glass substrates at three different temperatures. The textural quality and preferential growth were found to be significantly altered by changes in the deposition temperature. Oleylamine capped nanosheets and the as-deposited thin films by AACVD were characterized by powder X-ray diffraction (p-XRD) and microscopic techniques. The thin films were also studied by Raman spectroscopy. The stoichiometry is marginally affected by temperature, and all films were slightly selenium deficient. The synthesized material was also evaluated for the photoelectrochemical (PEC) splitting of water. The PEC study revealed the bifunctional nature of the material, which can be applied for both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), by switching the applied potential.

Cesium Lead Halide Perovskite Nanostructures: Tunable Morphology and Halide Composition

Inorganic halide perovskite (CsPbX3 ) nanostructures have gained considerable interest in recent years owing to their enhanced stability and optoelectronic applications. Recent developments in the synthesis of nanostructures are reviewed. The impact of the precursor and ligand nature, temperature and growth time on the morphology and shape tuning of CsPbX3 nanostructures is described in relation to their optical properties. The presynthetic and postsynthetic anion exchange strategies to retain pre-existing crystal phase and shape are discussed in this minireview.

Synthesis of sterically encumbered biaryls based on a ‘copper(I)-catalyzed arylation/[3+3] cyclocondensation’ strategy

Sterically encumbered biaryls are prepared in two steps by CuI-proline-catalyzed arylation of acetylacetone to give 3-arylpentane-2,4-diones and subsequent formal [3+3] cyclization of the latter with 1,3-bis(trimethylsilyloxy)-1,3-dienes.

Fabrication of planar heterojunction CsPbBr2I perovskite solar cells using ZnO as an electron transport layer and improved solar energy conversion efficiency

Inorganic lead halide perovskite solar cells with mixed halides have achieved reasonable power conversion efficiency with the advantage of enhanced stability. In this work, we report the fabrication of an all-inorganic cesium lead bromoiodide based planar perovskite solar cell with a ZnO electron transport layer. The method described herein includes the use of one step spin coating solution processing using a solvent mixture (DMF + DMSO) to avoid the solubility issues of CsPbBr2I perovskite in DMF. The substrate temperature during spin coating was found to be a critical parameter to generate the required crystalline morphology of the perovskite thin films. Post-annealing of the as-deposited perovskite film at 275 °C led to the formation of the cubic phase of CsPbBr2I with an optical band gap of 2.06 eV. Interestingly, cubic shaped CsPbBr2I morphology was obtained via single-step spin-coating processing that otherwise required two-step solution deposition of the hybrid perovskite. The best performing devices achieved 4.8% power conversion efficiency with minimal hysteresis and enhanced thermal and photo-stability. Owing to enhanced thermal and photo-stability, inorganic perovskites appear as viable alternatives to hybrid organic–inorganic perovskites for solar cell applications.

1-(3,5-Dinitro-benzo-yl)-3,3-dipropyl-thio-urea.

The title thiourea derivative, C14H18N4O5S, features two substantial twists between its component fragments: the dihedral angle between the SN2C (thiourea) and ONC2 (amide) residues is 48.89 (7)° and that between the benzene ring and the amide residue is 30.27 (7)°. In the crystal, molecules are linked by bifurcated N—H⋯(O,S) hydrogen bonds, generating [001] supramolecular chains.

3-Cyclo-hexyl-1-(3,5-dinitro-benzo-yl)thio-urea.

The structure of the title thiourea derivative, C14H16N4O5S, features an almost planar central C2N2OS fragment (r.m.s. deviation = 0.005 Å), an arrangement stabilized by an intramolecular N—H⋯O hydrogen bond. The terminal rings are twisted out of this plane, the dihedral angle formed with the benzene ring being 33.22 (10)°. The cyclohexyl ring is disordered, with two orientations (50:50) being resolved. The mean plane passing through the atoms of each disordered component forms dihedral angles of 65.7 (2) and 82.4 (3)° with the central plane. Centrosymmetric dimers mediated by an eight-membered {⋯HNC=S}2 synthon occur in the crystal.

Organometal Lead Halide Perovskite

Abstract The chemistry of organometal lead halides has been established since early 20th century. In 1970, for the first time, Weber has reported the synthesis and physical properties of CH3NH3PbX3 (X=Cl, Br, I) organometal lead halide perovskite. Today, the organometal lead halide perovskites have been emerged as the promising candidate as light harvesters in the solar cell with the first solar cell reported in 2009.

Broadband emission in a new lead free all-inorganic 3D CsZnCl2I perovskite

This contribution reports the deposition of new zinc based lead free all inorganic 3D CsZnCl2I perovskite thin films using aerosol assisted chemical vapour deposition (AACVD) at 100 °C. Room tempertaure optical measurements performed on the as-deposited thin films showed two absorption peaks. Upon 325 nm excitation, the CsZnCl2I perovskite thin film showed broad band white light emission having two peaks, which cover the entire visible range of the spectrum. This is the first example of white light emission from 3D all-inorganic lead free mixed halide CsZnCl2I perovskites.