Microstructure and photoluminescence properties of ternary Cd<SUB>0.2</SUB>Zn<SUB>0.8</SUB>S quantum dots synthesized by mechanical alloying

Ternary Cd0.2Zn0.8S quantum dots with a mixture of both cubic (zinc blende) and hexagonal (Wurtzite) phases have been prepared by mechanical alloying, the stoichiometric mixture of Cd, Zn and S powders at room temperature in a planetary ball mill under Ar. The Rietveld analysis of the X-ray diffraction patterns gives an insight of the relative phase abundances of both cubic and hexagonal phases present in sample. Microstructure parameters like change in lattice parameters, the variation of lattice strain, particle size, stacking faults of different kinds are quantitatively determined. High resolution transmission electron microscopy (HRTEM) image analysis corroborates well with the results obtained from the Rietveld analysis. A core–shell structure has been found in HRTEM images where major cubic phase remains at the core and minor hexagonal phase constitutes the shell. Optical band gap measurement using UV–Vis spectroscopy confirms the quantum confinement effects. Steady-state and time-resolved photoluminescence study have also been carried out for better understanding the optical property of this material. Atomic structure modelling helps to reveal the structural changes happening during different milling times

Structural interpretation of SnO<SUB>2</SUB> nanocrystals of different morphologies synthesized by microwave irradiation and hydrothermal methods

The detailed understanding of the crystal structure and microstructure of nanomaterials is useful to predict the properties of nanomaterials. SnO2 nanocrystals of different shapes like particles, spheres, rods and pyramids are chemically synthesized. Here, we report the crystal structure and microstructure of SnO2 nanocrystals of different morphologies using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). It is interesting to note that the tetragonal phase is found in particle, sphere and rod shaped SnO2 nanocrystals and pyramid shaped nanocrystals are composed of two types of orthorhombic phases. The Rietveld method has been used for refining simultaneously the atomic structure and microstructure of different SnO2 nanocrystals, and the growth mechanisms in different shapes are found to be different due to different preferential growth. Structural defects such as oxygen vacancies, deformation of unit cell and more importantly texturing effects are associated with change in bond length, bond angle and crystallite morphology. Size and lattice strain of different kinds of SnO2 nanocrystals are also studied in detail by using the Rietveld method of analysis and transmission electron microscopy (TEM)

Open Data for the publication "Reducing indium dependence by heterostructure design in SnO2–In2S3 nanocomposites" by Sloman et al. in Mater. Chem. Phys.

In this work, synthetic data report the synthesis of SnO2 nanowedges and In2S3 nanoparticles using literature techniques and SnO2–In2S3 heterostructures by approaches as fully described in the paper. The following supporting data are deposited. Powder X-ray diffraction (PXRD) data (20–80° 2θ) using Ni-filtered Cu Kα (λ = 0.15418 nm) radiation (40 kV and 40 mA) and a data step size of 0.033° 2θ. Data are in raw (Excel) format. Scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX) evaluated morphology of nanocomposites. Analysis was on a field emission (FE) TESCAN MIRA 3 SEM (accelerating voltage 30 kV) at low resolution. EDX data were obtained using a Horiba EX-400 and identified Sn, In and S content in the entirety of the corresponding SEM image. Transmission electron microscopy (TEM) analysis was on a FEI Tecnai 20 (accelerating voltage 200 keV, 70 μm objective aperture). Samples were sonicated in EtOH (15 min) then drop-cast onto 400 mesh lacey carbon on copper (Agar Scientific). Low magnification brightfield imaging (scale bars 500 nm) were employed to obtain an idea of nanocomposite size and coating. High-resolution (HR) brightfield imaging (see ESI) was done on In2S3 (scale bar 5 nm). Rietveld analysis used MAUD software with Rietveld whole profile fitting. Correction used a specially processed Si standard. Cagliotti parameters, Gaussianity parameters and asymmetry of the instrument were kept constant during refinements. Peaks were modelled using a pseudo-Voigt function with asymmetry compensating for broadening caused by particle size and strain. The background of diffraction patterns was fitted with a 4° polynomial and peak positions were corrected by refining the zero-shift error. For inductively coupled plasma-optical emission spectroscopy (ICPOES), a Thermo Scientific iCAP 7400 ICP-OES analyser was used. 2–10 mg of sample was mixed with 10x Na2CO3, ground, and transferred to Haldenwanger Al2O3 combustion boats, sputter coated (4 × 10 nm Pt) with a Quorum Technologies Q150T ES Turbo-Pumped Sputter Coater. Glass slides for use as crucible lids were likewise sputter coated. X-ray photoelectron spectroscopy (XPS) is presented in raw (Excel) formats. XPS signals were referenced using the C1s peak at 284.6 eV. Raman data used a Horiba LabRAM HR Evolution microscope with a 532 nm laser, a 600/mm grating, and a 50% ND filter. Each spectrum had an acquisition time of 5 s and 15 accumulations and data can be opened with OriginPro. A Varian Cary-50 UV–Vis spectrophotometer with a Harrick Video-Barrelino diffuse reflectance probe was used for UV-DRS. A cylindrical sample holder (4 × 10 mm) sat under the DRS probe. Again, use OriginPro. Photocatalytic activity was analysed in triplicate by degrading methyl orange under simulated solar irradiation (150 W Xenon lamp AM 1.5 G filter, 1 sun illumination, 100 mW cm-2). 5 mg of catalyst was added to 25 ml of 4.6 x 10–5 M aqueous dye at pH 7. The mixture was stirred in the dark for up to 120 mins. 2.0 ml aliquots were withdrawn and centrifuged. The 464 nm absorption for the dye was used to determine the dye concentration before photocatalysis (on a PerkinElmer Lamda 750 spectrophotometer). The remaining solution was kept on ice and then irradiated. 2 ml aliquots were obtained at 30, 60, 120 mins. and studied by UV-vis spectroscopy. Reference experiments with irradiation using SnO2, In2S3 or Degussa P25 are reported as are reference experiments without catalyst. Photocatalytic data can be viewed in Excel. To show hydroxyl radical photoformation a terephthalic acid (TA) probe was used. Catalyst (5 mg) was dispersed 30 ml TA (5 × 10−4 M), NaOH (2 × 10−3 M). During irradiation, 3.0 ml aliquots were withdrawn, centrifuged, and the fluorescence emission of the supernatant measured (excitation at 315 nm, emission at 425 nm for hydroxylated TA) with an Edinburgh Instruments FLS980 PL spectrometer. Data can be viewed in OriginPro

Open Data for publication "Visible light photocatalysts from low-grade iron ore: the environmentally benign production of magnetite/carbon (Fe3O4/C) nanocomposites" by Periyasamy et al. in Environmental Science and Pollution Research (https://doi.org/10.1007/s11356-021-15972-2)

Synthetic data report the ball-milling of mined iron ore tailings (IOTs) dried at 100°C. These were milled using a laboratory ball mill (internal diameter 300 mm and length 300 mm, using 150 steel alloy balls and an ore-to-ball ratio of 0.5 with a milling time of 30 min). Conversion of the resulting ≤50 μm IOTs to aqueous (soluble) FeCl3 removed insoluble Al-, Si-, Mg- and Ca-based minerals. This was done by the described sequential heating and filtering protocol. The conversion of FeCl3 to magnetite nanoparticles (NPs) by reduction with excess dextrose is described. Conditions of pH control, heating and washing are included. Powder X-ray diffraction (PXRD) data (obtained for 20–75° 2θ using Ni-filtered Cu Kα (λ = 0.15418 nm) radiation and a data step size of 0.02° 2θ and counting time of 2 s per step) of the resulting magnetite is presented in graphical (OriginPro) and raw (Excel) formats. Scanning electron microscopy (SEM) was combined with energy dispersive X-ray spectroscopy (EDX) to evaluate morphology and size distribution of IOTs and magnetite. IOTs analysed by SEM on a Hitachi S3400N (accelerating voltage 15 kV) and magnetite analysed on a field emission (FE) TESCAN MIRA 3 SEM (accelerating voltage 30 kV) at high (scale bar 100-200 nm) and low magnification (scale bar 1-100 μm). EDX data were obtained using a Horiba EX-400 identified Fe content (at%) at the red spot indicated in the corresponding SEM image. Transmission electron microscopy (TEM) followed sample sonication in EtOH and then drop-casting onto holey carbon copper grids. Magnetite NPs only were analysed using a FEI Philips Tecnai 20 with an accelerating voltage 200 KeV and a 70 μm objective aperture. Low magnification brightfield imaging (scale bars 10-100 nm) were employed to obtain a mean size distribution based on 100 NPs. High-resolution (HR) brightfield imaging and combined High-angle annular dark-field (HAADF) scanning TEM (STEM) and EDX analysis used a Thermo Scientific Talos F200X G2 TEM fitted with a Super-X EDS detector system. EDX detected Fe content (at%) in the white square panels indicated in representative HAADF images. Selected-area electron diffraction (SAED) data for magnetite were obtained with a 40 μm aperture. X-ray photoelectron spectroscopy (XPS) is presented in processed (OriginPro) and raw (Excel) formats. XPS signals were referenced using the C1s peak at 284.6 eV. FT-Infrared spectra of magnetite NPs were measured using a JASCO FT/IR-4000 in the range 400–4000 cm–1 and raw and processed data are reported. Thermogravimetric analysis (TGA) data were obtained for magnetite coated with dextrose on a TA Instruments TGA 500. Data acquisition was in the range 25-750 °C in N2 (ramp rate 10 °C min–1). UV-vis diffuse reflectance spectroscopy (UV-vis DRS) of magnetite was collected on a Varian Cary-50 UV-vis spectrophotometer with a Harrick Video-Barrelino diffuse reflectance probe. Photoluminescence (PL) and excitation (PLE) spectra of magnetite required dispersion in ethanol (1.0 × 10–5 M concentration of magnetite). PL spectra were recorded using Perkin-Elmer LS 55 fluorescence spectrometer. Magnetization of both IOTs and magnetite NPs were Recorded on a SQUID magnetometer (Quantum DesignMPMS XL-7) at 300 K in the range +/-30 kOe. Photocatalytic activity was analysed by degrading bodactive red BNC-BS dye in aqueous H2O2 under simulated solar irradiation (100 W Xenon lamp fitted with a UV cut-off filter, Solar Simulator-Royal Enterprise, 1 sun illumination, 100 mW cm-2). For testing, 25 mg of magnetite NPs were added to 50 ml of 1.0 x 10–5 M aqueous dye. The mixture was kept in the dark for 45 mins. before a 5.0 ml aliquot was withdrawn and centrifuged. The 418 nm absorption for the dye was used to determine the dye concentration before photocatalysis. The remaining suspension was treated with H2O2 (250 µl) and then irradiated. Dye degradation was monitored in triplicated experiments over 180 mins. by UV-vis spectroscopy. The solution was kept ice-cold throughout. Reference experiments without irradiation in the presence of catalyst but without H2O2 and with light irradiation in the absence of catalyst but presence of H2O2 were also done. To show hydroxyl radical photoformation a terephthalic acid (TA) probe was used. Catalyst (25 mg) was dispersed 30 ml TA (5 × 10−4 M), NaOH (2 × 10−3 M) and 0.15 ml H2O2. During irradiation, 3.0 ml aliquots were withdrawn at 30 min. intervals, centrifuged, and the fluorescence emission of the supernatant measured (excitation at 315 nm, emission at 425 nm for hydroxylated TA)

Influence of size and shape on the photocatalytic properties of SnO<SUB>2</SUB> nanocrystals

Tuning the functional properties of nanocrystals is an important issue in nanoscience. Here, we are able to tune the photocatalytic properties of SnO<SUB>2</SUB> nanocrystals by controlling their size and shape. A structural analysis was carried out by using X-ray diffraction (XRD)/Rietveld and transmission electron microscopy (TEM). The results reveal that the number of oxygen-related defects varies upon changing the size and shape of the nanocrystals, which eventually influences their photocatalytic properties. Time-resolved spectroscopic studies of the carrier relaxation dynamics of the SnO<SUB>2</SUB> nanocrystals further confirm that the electron–hole recombination process is controlled by oxygen/defect states, which can be tuned by changing the shape and size of the materials. The degradation of dyes (90 %) in the presence of SnO<SUB>2</SUB> nanoparticles under UV light is comparable to that (88 %) in the presence of standard TiO<SUB>2</SUB> Degussa P-25 (P25) powders. The photocatalytic activity of the nanoparticles is significantly higher than those of nanorods and nanospheres because the effective charge separation in the SnO2 nanoparticles is controlled by defect states leading to enhanced photocatalytic properties. The size- and shape-dependent photocatalytic properties of SnO<SUB>2</SUB> nanocrystals make these materials interesting candidates for photocatalytic applications

Facile synthesis of SnO2-PbS nanocomposites with controlled structure for applications in photocatalysis.

Recent studies have shown that SnO2-based nanocomposites offer excellent electrical, optical, and electrochemical properties. In this article, we present the facile and cost-effective fabrication, characterization and testing of a new SnO2-PbS nanocomposite photocatalyst designed to overcome low photocatalytic efficiency brought about by electron-hole recombination and narrow photoresponse range. The structure is fully elucidated by X-ray diffraction (XRD)/Reitveld refinement, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area analysis, and transmission electron microscopy (TEM). Energy-dispersive X-ray spectroscopy (EDX) spectrum imaging analysis demonstrates the intermixing of SnO2 and PbS to form nanocomposites. A charge separation mechanism is presented that explains how the two semiconductors in junction function synergistically. The efficacy of this new nanocomposite material in the photocatalytic degradation of the toxic dye Rhodamine B under simulated solar irradiation is demonstrated. An apparent quantum yield of 0.217 mol min(-1) W(-1) is calculated with data revealing good catalyst recyclability and that charge separation in SnO2-PbS leads to significantly enhanced photocatalytic activity in comparison to either SnO2 or PbS.A. K. and D. R. acknowledge support from the Royal Society’s Newton International Fellowship scheme. D.R would also like to thank Prof. Paul Midgley for access to the TEM at the University of Cambridge and Prof. Gianluigi Botton for access to the CCEM, a national facility supported by NSERC, the Canada Foundation for Innovation and McMaster University. B. R. K. thanks the UK EPSRC for financial support (EP/J500380/1). Thanks go also to Drs. Tim Jones and Jill Geddes of Schlumberger Gould Research for help with the acquisition of Raman and X-ray photoelectron spectra and to Dr. Zlatko Saracevic of the Department of Chemical Engineering and Biotechnology (University of Cambridge) for help with BET surface area analysis. The authors would also like to thanks Miss Georgina Hutton (University of Cambridge) for valuable discussions and input. Unprocessed data for this paper are available at the University of Cambridge data repository (see https://www.repository.cam.ac.uk/handle/1810/252973). These include some data in the file format .dm3 (HRTEM data), which can be opened using the software program Gatan Digital Micrograph 3.6.5 or similar.This is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5NR07036

Photoswitching and thermoresponsive properties of conjugated multi-chromophore nanostructured materials

Conjugated multi-chromophore organic nanostructured materials have recently emerged as a new class of functional materials for developing efficient light-harvesting, photosensitization, photocatalysis, and sensor devices because of their unique photophysical and photochemical properties. Here, we demonstrate the formation of various nanostructures (fibers and flakes) related to the molecular arrangement (H-aggregation) of quaterthiophene (QTH) molecules and their influence on the photophysical properties. XRD studies confirm that the fiber structure consists of >95% crystalline material, whereas the flake structure is almost completely amorphous and the microstrain in flake-shaped QTH is significantly higher than that of QTH in solution. The influence of the aggregation of the QTH molecules on their photoswitching and thermoresponsive photoluminescence properties is revealed. Time-resolved anisotropic studies further unveil the relaxation dynamics and restricted chromophore properties of the self-assembled nano/microstructured morphologies. Further investigations should pave the way for the future development of organic electronics, photovoltaics, and light-harvesting systems based on π-conjugated multi-chromophore organic nanostructured materials

Research data supporting 'Facile synthesis of SnO2-PbS nanocomposites with controlled structure for applications in photocatalysis'.

This research data supports the publication "Facile Synthesis of SnO2-PbS Nanocomposites with Controlled Structure for Visible Light Photocatalysis", which is published in 'Nanoscale'. Synthetic and analytical data for SnO2 nanoparticles, PbS nanocubes and SnO2-PbS nanocomposites prepared in Cambridge in 2014-2015. Analysis includes X-ray diffraction data and Rietveld refinement, transmission electron microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, Brunauer-Emmett-Teller (BET) surface area analysis. Photocatalytic data is presented for each material for the degradation of Rhodamine B in aqueous solution.This work was supported by the Royal Society [grant number NF130808 (RS)], the EPSRC grant number [EP/J500380/1 (EPSRC)] and the Canada Foundation for Innovation

Visible light photocatalysts from low-grade iron ore: the environmentally benign production of magnetite/carbon (Fe3O4/C) nanocomposites

Magnetite (Fe3O4) nanoparticles coated with dextrose and gluconic acid possessing both super-paramagnetism and excellent optical properties have been productively synthesized through a straightforward, efficient and cost efficient hydrothermal reduction route using Fe3+ as sole metal precursor acquired from accumulated iron ore tailings - a mining waste that usually represents a major environmental threat. Fe3O4/C nanocomposites were fully elucidated by FEGSEM and TEM, revealing a combination of platelets (<1 µm) capped by particles (<10 nm) and magnetite was verified by XPS, which demonstrated also oxygen deficiency. A dextrose/gluconic acid coating was elucidated by Fourier transform-infrared (FT-IR) spectroscopy and Thermogravimetric analysis (TGA). The Fe3O4/C nanocomposites were found to be superparamagnetic at room temperature. Meanwhile, their optical properties were investigated by UV-visible Diffuse reflectance Spectroscopy (UV-vis DRS) and photoluminescence (PL) spectroscopy; an Eg of 1.86 eV was determined and emissions at 612 and 650 nm (ex. 250 nm) were consistent with the XPS identification of oxygen vacancies. The efficacy of the as-synthesized magnetically recoverable magnetite/carbon (Fe3O4/C) nanocomposites has been exhibited in the photocatalytic degradation of the toxic textile (industrial) dye bodactive red BNC-BS

Research data supporting "Morphological effects on the photocatalytic properties of SnO2 nanostructures"

Data collection primarily supported by RS Newton Fellowship Ref. NF130808 and associated NF Alumni Follow-on funding for Dr. A. Kar. See 'List of uploaded data' file for information regarding dataset contents