Enhanced Ultraviolet Photoresponse Characteristics of Indium Gallium Zinc Oxide Photo-Thin-Film Transistors Enabled by Surface Functionalization of Biomaterials for Real-Time Ultraviolet Monitoring.

Indium gallium zinc oxide (IGZO) is one of the most promising materials for diverse optoelectronic applications based on thin-film transistors (TFTs) including ultraviolet (UV) photodetectors. In particular, the monitoring of UV-A (320-400 nm) exposure is very useful for healthcare applications because it can be used to prevent various human skin and eye-related diseases. However, the relatively weak optical absorption in the UV-A range and the persistent photoconductivity (PPC) arising from the oxygen vacancy-related states of IGZO thin films limit efficient UV monitoring. In this paper, we report the enhancement of the UV photoresponse characteristics of IGZO photo-TFTs by the surface functionalization of biomolecules on an IGZO channel. The biomaterial/IGZO interface plays a crucial role in enhancing UV-A absorption and suppressing PPC under negative gate bias, resulting in not only increased photoresponsivity and specific detectivity but also a fast and repeatable UV photoresponse. In addition, turning off the device without external bias completely eliminates PPC due to the internal electric field induced by the surface functionalization of biomaterials. Such a volatile feature of PPC enables the fast and repeatable UV photoresponse. These results suggest the potential of IGZO photo-TFTs combined with biomaterials for real-time UV monitoring.

Polycyclodextrin as a linker for nanomedicine fabrication and synergistic anticancer application.

Polycyclodextrin (denoted PCD) composed of cyclodextrin monomer units and 1,3-diethoxypropan-2-ol containing many hydroxyl groups with lone pairs of electrons, easily coordinated with transition metals with empty orbitals. The CD unit can also provide host-guest binding sites for functional molecules. This article utilizes this feature of PCD for the first time as a "linker" to combine transition metal nanomaterials with synergistic functional molecules. We synthesized PCD with 50% CD monomer by epichlorohydrin cross-linking method. Utilizing the coordination effect of the hydroxyl group in PCD and the iron ion in photothermal nanoparticles (PB-Yb), the PCD is coated on its surface; simultaneously, CD in PCD can form a host-guest complex with adamantane-modified zinc phthalocyanine (Pc) photosensitizer. Using PCD as a "linker", PB-Yb and Pc (denoted PYPP) were combined to improve the solubility of PB-Yb, reduce the aggregation degree of Pc to increase their activity, and achieve photothermal and photodynamic synergistic tumor therapy.

Hitchhiking Nanoparticles: Mesenchymal Stem Cell-Mediated Delivery of Theranostic Nanoparticles.

Nanotechnology has emerged as a promising solution to permanent elimination of cancer. However, nanoparticles themselves lack specificity to tumors. Due to enhanced migration to tumors, mesenchymal stem cells (MSCs) were suggested as cell-mediated delivery vehicles of nanoparticles. In this study, we have constructed a complex composed of photoluminescent quantum dots (QDs) and a photosensitizer chlorin e6 (Ce6) to obtain multifunctional nanoparticles, combining cancer diagnostic and therapeutic properties. QDs serve as energy donors-excited QDs transfer energy to the attached Ce6 via Förster resonance energy transfer, which in turn generates reactive oxygen species. Here, the physicochemical properties of the QD-Ce6 complex and singlet oxygen generation were measured, and the stability in protein-rich media was evaluated, showing that the complex remains the most stable in protein-free medium. In vitro studies on MSC and cancer cell response to the QD-Ce6 complex revealed the complex-loaded MSCs' potential to transport theranostic nanoparticles and induce cancer cell death. In vivo studies proved the therapeutic efficacy, as the survival of tumor-bearing mice was statistically significantly increased, while tumor progression and metastases were slowed down.

Energy funnelling within multichromophore architectures monitored with subnanometre resolution.

The funnelling of energy within multichromophoric assemblies is at the heart of the efficient conversion of solar energy by plants. The detailed mechanisms of this process are still actively debated as they rely on complex interactions between a large number of chromophores and their environment. Here we used luminescence induced by scanning tunnelling microscopy to probe model multichromophoric structures assembled on a surface. Mimicking strategies developed by photosynthetic systems, individual molecules were used as ancillary, passive or blocking elements to promote and direct resonant energy transfer between distant donor and acceptor units. As it relies on organic chromophores as the elementary components, this approach constitutes a powerful model to address fundamental physical processes at play in natural light-harvesting complexes.

Three-dimensional dose-distribution measurement of therapeutic carbon-ion beams using a ZnS scintillator sheet.

The accurate measurement of the 3D dose distribution of carbon-ion beams is essential for safe carbon-ion therapy. Although ionization chambers scanned in a water tank or air are conventionally used for this purpose, these measurement methods are time-consuming. We thus developed a rapid 3D dose-measurement tool that employs a silver-activated zinc sulfide (ZnS) scintillator with lower linear energy transfer (LET) dependence than gadolinium-based (Gd) scintillators; this tool enables the measurement of carbon-ion beams with small corrections. A ZnS scintillator sheet was placed vertical to the beam axis and installed in a shaded box. Scintillation images produced by incident carbon-ions were reflected with a mirror and captured with a charge-coupled device (CCD) camera. A 290 MeV/nucleon mono-energetic beam and spread-out Bragg peak (SOBP) carbon-ion passive beams were delivered at the Gunma University Heavy Ion Medical Center. A water tank was installed above the scintillator with the water level remotely adjusted to the measurement depth. Images were recorded at various water depths and stacked in the depth direction to create 3D scintillation images. Depth and lateral profiles were analyzed from the images. The ZnS-scintillator-measured depth profile agreed with the depth dose measured using an ionization chamber, outperforming the conventional Gd-based scintillator. Measurements were realized with smaller corrections for a carbon-ion beam with a higher LET than a proton. Lateral profiles at the entrance and the Bragg peak depths could be measured with this tool. The proposed method would make it possible to rapidly perform 3D dose-distribution measurements of carbon-ion beams with smaller quenching corrections.

Stimuli-responsive azobenzene-quantum dots for multi-sensing of dithionite, hypochlorite, and azoreductase.

A new fluorescence turn-on sensing platform has been developed applicable for sensitive profiling of multiple chemical and biological analytes, using azobenzene-quantum dot as a new stimuli-responsive optical nanoprobe. An azobenzene-carrying compound bis [4, 4'-(dithiophenyl azo)-1, 3-benzenediamine] (DTPABDA) is for the first time reported to be used for conjugation with CdSe/ZnS core/shell quantum dots (QDs) via the ligand exchange reaction. Due to the photo-induced electron-transfer (PET) effect, the electron-withdrawing azobenzene groups of DTPABDA can significantly cause the photoluminescence (PL) of QDs quenched. The QDs' PL can be subsequently reignited by the removal of azo moiety cleavable through three types of specific reactions: the dithionite reduction, hypochlorite oxidation, and azoreductase enzymatic catalysis, respectively. By monitoring of reaction-induced recovery of FL signals at 560 nm with an excitation of 450 nm, such azobenzene-QDs conjugates served as a new nanoprobe enabling the fluorescence turn-on sensing of dithionite, hypochlorite, and azoreductase with high sensitivity, broad linear range, and good selectivity. The successful detection of target analytes in real samples reveals the potential of our method in practical applications, such as biosensing, environmental and industrial monitoring. Graphical abstract A new stimuli-responsive fluorescence probe is reported for the sensitive detection of sodium dithionite, hypochlorite, and azoreductase. The probe consists of QDs with an azobenzene-carrying compound as a ligand. The fluorescence of QDs could be quenched by the azo group and subsequently recovered via the removal of azo group by these three compounds, resulting in the "turn-on" sensing of these compounds with high sensitivity, broad linear range, and good selectivity. The successful detection of azoreductase in serum samples reveals the practical use of this method.

Smart pH-Regulated Switchable Nanoprobes for Photoelectrochemical Multiplex Detection of Antibiotic Resistance Genes.

Antibiotic resistance, encoded via particular genes, has become a major global health threat and substantial burden on healthcare. Hence, the facile, low-cost, and precise detection of antibiotic resistance genes (ARGs) is crucial in the realm of human health and safety, especially multiplex sensing assays. Here, a smart pH-regulated switchable photoelectrochemical (PEC) bioassay has been created for ultrasensitive detection of two typical subtypes of penicillin resistance genes bla-CTX-M-1 (target 1, labeled as TDNA1) and bla-TEM (target 2, labeled as TDNA2), whereby pH-responsive antimony tartrate (SbT) complex-grafted silica nanospheres are ingeniously adopted as signal DNA1 tags (labeled as SDNA1-SbT@SiO2NSs). The operations of the PEC bioassay depend on the switchable dissociation of the pH-responsive SDNA1-SbT@SiO2NSs complex under the external pH stimuli, thus initiating the pH-regulated release of ions pre-embedded in sandwich-type DNA nanoassemblies. At acidic conditions, the dissociation of SDNA1 tags (ON state) triggers the release of the embedded SbO+. Under alkaline conditions, the dissociation of SDNA1 tags is inhibited (OFF state). The detection of TDNA2 was achieved via DNA hybridization-triggered metal ion release. The unwinding of the introduced hairpin T-Hg2+-T fragment, hybridized with the second anchored signal DNA (SDNA2), ignites the release of Hg2+. The released SbO+ or Hg2+ ions would trigger the formation of Sb2S3/ZnS or HgS/ZnS heterostructure through ion-exchange with the photosensitive ZnS layer, giving rise to the amplified photocurrents and eventually realizing the ultrasensitive detection of penicillin resistance genes subtypes, bla-CTX-M-1 and bla-TEM. The as-fabricated pH-regulated PEC bioassay, smartly integrating the pH-responsive intelligent unit as SDNA tags, pH-regulated release of embedded ions, and the subsequent ion-exchange-based signal amplification strategy, exhibits high sensitivity, specificity, low-cost, and ease of use for multiplex detection of ARGs. It can be successfully used for measuring bla-CTX-M-1 and bla-TEM in real E. coli plasmids, demonstrating great promise for developing a new class of genetic point-of-care devices.

An immunosensor for sensitive photoelectrochemical detection of Staphylococcus aureus using ZnS-Ag2S/polydopamine as photoelectric material and Cu2O as peroxidase mimic tag.

We report here sensitive photoelectrochemical immunosensing of Staphylococcus aureus (S. aureus) using ZnS-Ag2S/polydopamine (PDA) as a novel photoelectric material and Cu2O as the peroxidase mimic tag. ZnS-Ag2S heterojunctions were prepared on indium tin oxide (ITO) via electrodeposition of ZnS nanoparticles, followed by silver ion exchange. To prepare a PDA/ZnS-Ag2S/ITO, the ZnS-Ag2S/ITO electrode was coated with PDA by self-polymerization of dopamine. The photocurrent of the PDA/ZnS-Ag2S/ITO is 1.55 times that of the ZnS-Ag2S/ITO and 7.87 times that of the ZnS/ITO, indicating a high-performance photoelectric material. A sandwiched-type photoelectrochemical immunosensor was constructed by using PDA/ZnS-Ag2S/ITO as the photoelectrode and Cu2O nanocubes as the labels. Cu2O nanocubes can serve as peroxidase mimic to generate catalytic precipitates on the immunoelectrodes, and both the Cu2O nanocubes and the generated precipitates can decrease the photocurrents of the immunoelectrodes, so a photoelectrochemical immunosensor for detecting S. aureus was constructed, showing a linear range between 10 and 107 CFU mL-1 and a low detection limit of 2 CFU mL-1. Owing to the signal amplification of Cu2O labeling, the sensitivity of the Cu2O-labeled immunosensor is 4 times that of a label-free immunosensor for detecting S. aureus, and the detection limit (2 CFU mL-1) is lower than that of a label-free immunosensor (10 CFU mL-1). This work not only provides a new and efficient photoelectric material but also demonstrated an efficient signal-amplification strategy for photoelectrochemical biosensing.

Design and synthesis of robust Z-scheme ZnS-SnS2 n-n heterojunctions for highly efficient degradation of pharmaceutical pollutants: Performance, valence/conduction band offset photocatalytic mechanisms and toxicity evaluation.

Petal-like ZnS-SnS2 heterojunctions with Z-scheme band alignment were prepared by one-pot solvothermal strategy. The optimal (1:1) ZnS-SnS2 can degrade 93.46 % of tetracycline and remove 73.9 % COD of pharmaceutical wastewater under visible-light irradiation due to the efficient production of H, O2-, h+ and OH. The toxicity evaluation by ECOSAR prediction and the growth of E. coli indicates efficient toxicity reduction of tetracycline by photocatalysis and the non-toxicity of ZnS-SnS2. The attacked sites on tetracycline by reactive species were analyzed according to Fukui index, and two degradation pathways of tetracycline were inferred via the identification of intermediate products. Tetracycline degradation efficiency and the energy consumption in different water bodies were compared, and it was found that the electrical energy per order (EE/O) was the lowest in Ganjiang River. The valence band offset (ΔEVBO) and conduction band offset (ΔECBO) of ZnS-SnS2 were 1.02 eV and 0.22 eV, respectively. The probable photocatalytic mechanism of ZnS/SnS2 heterojunctions with Z-scheme band alignment based on ΔEVBO and ΔECBO was first presented.

MoS2 nanosheets anchored on porous ZnSnO3 cubes as an efficient visible-light-driven composite photocatalyst for the degradation of tetracycline and mechanism insight.

In this study, MoS2/ZnSnO3 (MS-ZSO) composite photocatalyst with loading MS nanosheets onto the surface of porous ZSO microcubes was synthesized using a simple hydrothermal route. The prepared MS-ZSO composite can be easily excited under visible light, and 3 % MS-ZSO exhibits an outstanding photo-degradation (>80 % in 60 min) and mineralization performance (>42 % in 60 min) of the tetracycline. A remarkable improvement in the photocatalytic activity of MS-ZSO composite derived from a positive synergistic effect of well-matched energy level positions, increasement the absorption of visible light, prolonged life time decay and improved interfacial charge transfer between MS and ZSO. In-depth investigation on charge carrier separation mechanism toward MS/ZSO composite under visible light was proposed, which was further evidenced by capture experiments and electron spin resonance (ESR) techniques. Furthermore, the corresponding intermediates of tetracycline degradation over MS-ZSO composites were inspected by liquid chromatography-mass spectrometry (LC-MS) analysis, and the possible degradation paths were proposed.

Construction of novel Z-scheme Ag/ZnFe2O4/Ag/BiTa1-xVxO4 system with enhanced electron transfer capacity for visible light photocatalytic degradation of sulfanilamide.

A novel Z-scheme system, Ag/ZnFe2O4/Ag/BiTa1-xVxO4 with enhanced electron transfer capacity was constructed for degrading sulfanilamide (SAM) using solar light. The photocatalytic activity of Ag/ZnFe2O4/Ag/BiTa1-xVxO4 was investigated. The effects of the mass ratio (ZnFe2O4:BiTaO4), doped V dose, Ag wt.% content, and irradiation time on the catalytic performance were evaluated. The reasonable mechanism of Ag/ZnFe2O4/Ag/BiTa1-xVxO4 solar photocatalytic degradation was also presented. These results reveal Ag/ZnFe2O4/Ag/BiTa1-xVxO4 possesses enhanced photocatalytic performance. The loaded Ag as electron mediator increases the electron transfer rate. Particularly, the doped V and the Fe ions from ZnFe2O4 form a powerful electron driving force, which enhances the electron transfer capacity. Ag/ZnFe2O4/Ag/BiTa1-xVxO4 shows optimal photocatalytic performance at 2.0 wt.% Ag and 0.5% doped V dose (ZnFe2O4:BiTaO4 = 1.0:0.5). Also, Ag/ZnFe2O4/Ag/BiTa1-xVxO4 exhibits high stability and repeatability in photocatalytic degradation. Several active species (•OH, •O2-, and h+) are produced in the Z-scheme photodegradation of SAM. These results on the enhanced photocatalytic activity of Ag/ZnFe2O4/Ag/BiTa1-xVxO4 are ascribed to synergistic photocatalytic effects of ZnFe2O4 and BiTa1-xVxO4 mediated through Ag and driven by doped V and Fe ions. Therefore, the Z-scheme Ag/ZnFe2O4/Ag/BiTa1-xVxO4 photocatalytic technology proves to be promising for the solar photocatalytic treatment of antibiotics under solar light.

Left Ventricular Function Assessment Using 2 Different Cadmium-Zinc-Telluride Cameras Compared with a γ-Camera with Cardiofocal Collimators: Dynamic Cardiac Phantom Study and Clinical Validation.

UNLABELLED: This study compared two SPECT cameras with cadmium-zinc-telluride (CZT) detectors to a conventional Anger camera with cardiofocal collimators for the assessment of left ventricular (LV) function in a phantom and patients. METHODS: A gated dynamic cardiac phantom was used. Eighteen acquisitions were processed on each CZT camera and the conventional camera. The total number of counts within a myocardial volume of interest varied from 0.25 kcts to 1.5 Mcts. Ejection fraction was set to 33%, 45%, or 60%. Volume, LV ejection fraction (LVEF), regional wall thickening, and motion (17-segment model) were assessed. One hundred twenty patients with a low pretest likelihood of coronary artery disease and normal findings on stress perfusion SPECT were retrospectively analyzed to provide the reference limits for end-diastolic volume (EDV), end-systolic volume (ESV), ejection fraction, and regional function for each camera model. RESULTS: In the phantom study, for each ejection fraction value, volume was higher for the CZT cameras than for the conventional camera, resulting in a decreased but more accurate LVEF (all P < 0.001). In clinical data, body-surface-indexed EDV and ESV (mL/m(2)) were higher for one of the CZT cameras (Discovery NM 530c) than for the other (D-SPECT) or the conventional camera (respectively, 40.5 ± 9.2, 37 ± 7.9, and 35.8 ± 6.8 for EDV [P < 0.001] and 12.5 ± 5.3, 9.4 ± 4.2, and 8.3 ± 4.4 for ESV [P < 0.001]), resulting in a significantly decreased LVEF: 70.3% ± 9.1% vs. 75.2% ± 8.1% vs. 77.8% ± 9.3%, respectively (P < 0.001). CONCLUSION: The new CZT cameras yielded global LV function results different from those yielded by the conventional camera. LV volume was higher for the Discovery NM 530c than for the D-SPECT or the conventional camera, leading to decreased LVEF in healthy subjects. These differences should be considered in clinical practice and warrant the collection of a specific reference database.

Photocatalytic properties of zinc sulfide nanocrystals biofabricated by metal-reducing bacterium Shewanella oneidensis MR-1.

Accumulation and utilization of heavy metals from wastewater by biological treatment system has aroused great interest. In the present study, a metal-reducing bacterium Shewanella oneidensis MR-1 was used to explore the biofabrication of ZnS nanocrystals from the artificial wastewater. The biogenic H2S produced via the reduction of thiosulfate precipitated the Zn(II) as sulfide extracellularly. Characterization by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), and field emission scanning electron microscope (FESEM) confirmed the precipitates as ZnS nanocrystals. The biogenic ZnS nanocrystals appeared spherical in shape with an average diameter of 5 nm and mainly aggregated in the medium and cell surface of S. oneidensis MR-1. UV-vis DRS spectra showed ZnS nanoparticles appeared a strong absorption below 360 nm. Thus, the photocatalytic activity of ZnS was evaluated by the photodegradation of rhodamine B (RhB) under UV irradiation. The biogenic ZnS nanocrystals showed a high level of photodegradation efficiency to RhB coupled with a significant blue-shift of maximum adsorption peak. A detailed analysis indicated the photogenerated holes, rather than hydroxyl radicals, contributed to the photocatalytic decolorization of RhB. This approach of coupling biosynthesis of nanoparticles with heavy metal removal may offer a potential avenue for efficient bioremediation of heavy metal wastewater.

Characterization and evaluation of the efficiency of SiO2/tetra-α-(2,4-di-tert-butylphenoxy)-phthalocyaninato zinc nanocomposite as photosensitizers for oxidation of 2,4,6-trichlorophenol.

A photosensitizer tetra-α-(2,4-di-tert-butylphenoxy)-phthalocyaninato zinc [ZnPc(OAr)4] was successfully encapsulated in SiO2 nanoparticle by the microemulsion method. The photosensitized composite nanoparticle was able to degrade 2,4,6-trichlorophenol (TCP) in aqueous solution. Under visible light irradiation, the nanoparticles efficiently generated reactive oxygen species; 95.4% of TCP was degraded after 270 min of reaction. Some aromatic compounds and aliphatic carboxylic acids were detected by mass spectrometry as the reaction intermediates. The results were different from those of previously reported photocatalytic reactions, in which valence band holes or hydroxyl radicals functioned as the main oxidants. The photosensitizing composite nanoparticle is potentially applicable to the oxidation of phenol.

Stimulated emission and lasing from CdSe/CdS/ZnS core-multi-shell quantum dots by simultaneous three-photon absorption.

Three-photon pumped stimulated emission and coherent random lasing from colloidal CdSe/CdS/ZnS core-multishell quantum dots are achieved for the first time. These results can offer new possibilities in biology and photonics, as well as at their intersection of biophotonics.

Vibration characteristics of aluminum surface subjected to ultrasonic waves and their effect on wetting behavior of solder droplets.

The vibration characteristics of an aluminum surface subjected to ultrasonic waves were investigated with a combination of numerical simulation and experimental testing. The wetting behavior of solder droplets on the vibrating aluminum surface was also examined. The results show that the vibration pattern of the aluminum surface is inhomogeneous. The amplitude of the aluminum surface exceeds the excitation amplitude in some zones, while the amplitude decreases nearly to zero in other zones. The distribution of the zero-amplitude zones is much less dependent on the strength of the vibration than on the location of the vibration source. The surface of the liquid solder vibrates at an ultrasonic frequency that is higher than the vibration source, and the amplitude of the liquid solder is almost twice that of the aluminum surface. The vibration of the surface of the base metal (liquid solder) correlates with the oxide film removal effect. Significant removal of the oxide film can be achieved within 2s when the amplitude of the aluminum surface is higher than 5.4 µm or when the amplitude of the liquid solder surface is higher than 10.2 µm.

Effect of pH on photocatalytic activity of capped ZnS nanoparticles.

In the present work, Zinc sulphide (ZnS) nanoparticles (NPs) capped with 2-Mercaptoethanol (2 ME) are synthesized via chemical precipitation method. Structural and morphological studies have been done using X Ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) techniques. Band gap of as prepared NPs is determined using UV-Visible spectroscopy. Photoluminescence spectra of the synthesized NPs was recorded to study the emission properties. After optimizing the capping concentration, ZnS NPs were synthesized at different pH viz. 5.62 (natural pH), 8, 10, and 12 at optimized capping concentration. These nanoparticles were further used as a catalyst to degrade crystal violet dye. It has been observed that catalyst synthesized at pH 12 is able to degrade dye to a larger extent as compared to samples synthesized at pH 5.62, 8, and 10. Possible reason for this observation is discussed. Reusability of catalyst shows better results of dye degradation. UV curing studies of ZnS surface with different irradiation times (0-180 min) are done in this context.

Visible and near-infrared planar waveguide structure of polycrystalline zinc sulfide from C ions implantation.

We report the fabrication of a planar waveguide in polycrystalline zinc sulfide by 6.0 MeV C ions implantation with a fluence of 5 × 10¹4 ion/cm² at room temperature. The near-field light intensity profiles in the visible and near-infrared bands are measured by the end-face coupling method with different laser sources. Investigation of the Raman spectra demonstrates that the microstructure of the polycrystalline zinc sulfide has no significant change after C ion implantation. The absorption spectra show that the implantation processes have no influence on the visible and infrared bands.

Wurtzite CuInS2 and CuInxGa1-xS2 nanoribbons: synthesis, optical and photoelectrical properties.

Single crystalline wurtzite ternary and quaternary semiconductor nanoribbons (CuInS(2), CuIn(x)Ga(1-x)S(2)) were synthesized through a solution-based method. The structure and composition of the nanoribbons were characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), the corresponding fast Fourier transform (FFT) and nanoscale-resolved elemental mapping. Detailed investigation of the growth mechanism by monitoring the structures and morphologies of the nanoribbons during the growth indicates that Cu(1.75)S nanocrystals are formed first and act as a catalyst for the further growth of the nanoribbons. The high mobility of Cu(+) promotes the generation of Cu(+) vacancies in Cu(1.75)S, which will facilitate the diffusion of Cu, In or Ga species from solution into Cu(1.75)S to reach supersaturated states. The supersaturated species in the Cu(1.75)S catalyst, Cu-In-S and Cu-In-Ga-S species, start to condense and crystallize to form wurtzite CuInS(2) or CuIn(x)Ga(1-x)S(2) phases, firstly resulting in two-sided nanoparticles. Successive crystallizations gradually impel the Cu(1.75)S catalyst head forward and prolong the length of the CuInS(2) or CuIn(x)Ga(1-x)S(2) body, forming heterostructured nanorods and thus nanoribbons. The optical band gaps of CuIn(x)Ga(1-x)S(2) nanoribbons can be continuously adjusted between 1.44 eV and 1.91 eV, depending on the Ga concentration in nanoribbons. The successful preparation of those ternary and quaternary semiconductor nanoribbons provide us an opportunity to study their photovoltaic properties. The primary photoresponsive current measurements demonstrate that wurtzite CuIn(x)Ga(1-x)S(2) nanoribbons are excellent photoactive materials. Furthermore, this facile method could open a new way to synthesize other various nano-structured ternary and quaternary semiconductors, such as CuInSe(2) and CuIn(x)Ga(1-x)Se(2), for applications in solar cells and other fields.

Novel microwave assisted synthesis of ZnS nanomaterials.

A novel ambient pressure microwave assisted technique is developed in which silver and indium-modified ZnS is synthesized. The as-prepared ZnS is characterized by x-ray diffraction, UV-vis spectroscopy, x-ray photoelectron spectroscopy and luminescence spectroscopy. This procedure produced crystalline materials with particle sizes below 10 nm. The synthesis technique leads to defects in the crystal which induce mid-energy levels in the band gap and lead to indoor light photocatalytic activity. Increasing the amount of silver causes a phase transition from cubic blende to hexagonal phase ZnS. In a comparative study, when the ZnS cubic blende is heated in a conventional chamber furnace, it is completely converted to ZnO at 600 °C. Both cubic blende and hexagonal ZnS show excellent photocatalytic activity under irradiation from a 60 W light bulb. These ZnS samples also show significantly higher photocatalytic activity than the commercially available TiO(2) (Evonik-Degussa P-25).