Surface-enhanced Raman scattering of R6G dimerization during self-healing of gel.

Traditional surface-enhanced Raman scattering (SERS) substrates seeking uniformity and reproducibility of the Raman signal often assume and require that hot spots remain consistently stable during Raman testing. Recently, the non-uniform accumulation in SERS sample pre-concentration strategies have inspired the direct use of self-healing noble metal aerogels (NMAs), as the sample pretreatment presented in this work, and uncovered more diverse Raman information of substances during the dynamic process of laser irradiation. Rare characteristic peaks such as 820 cm⁻ for R6G within a specific concentration range were observed, and potential processes including R6G dimerization and desorption were analyzed.

One-Step Preparation of High-Stability CsPbX/CsPbX Composite Microplates with Tunable Emission.

The core-shell structure is an effective means to improve the stability and optoelectronic properties of cesium lead halide (CsPbX (X = Cl, Br, I)) perovskite quantum dots (QDs). However, confined by the ionic radius differences, developing a core-shell packaging strategy suitable for the entire CsPbX system remains a challenge. In this study, we introduce an optimized hot-injection method for the epitaxial growth of the CsPbX substrate on CsPbX surfaces, achieved by precisely controlling the reaction time and the ratio of lead halide precursors.

Ultrastable CsPbBr@CsPbBr@TiO Composites for Photocatalytic and White Light-Emitting Diodes.

Although cesium halide lead (CsPbX, X = Cl, Br, I) perovskite quantum dots (QDs) have excellent photovoltaic properties, their unstable characteristics are major limitations to application. Previous research has demonstrated that the core-shell structure can significantly improve the stability of CsPbX QDs and form heterojunctions at interfaces, enabling multifunctionalization of perovskite materials. In this article, we propose a convenient method to construct core-shell-structured perovskite materials, in which CsPbBr@CsPbBr core-shell micrometer crystals can be prepared by controlling the ratio of Cs/Pb in the precursor and the reaction time.

Preparation of CsPb(Cl/Br)/TiO:Eu composites for white light emitting diodes.

The inherent single narrow emission peak and fast anion exchange process of cesium lead halide perovskite CsPbX (X = Cl, Br, I) nanocrystals severely limited its application in white light-emitting diodes. Previous studies have shown that composite structures can passivate surface defects of NCs and improve the stability of perovskite materials, but complex post-treatment processes commonly lead to dissolution of NCs. In this study, CsPb(Cl/Br) NCs was in-situ grown in TiO hollow shells doped with Eu ions by a modified thermal injection method to prepare CsPb(Cl/Br)/TiO:Eu composites with direct excitation of white light without additional treatment.

In Situ Fabrication of Lead-Free Double Perovskite/Polymer Composite Films for Optoelectronic Devices and Anticounterfeit Printing.

Lead-free double perovskites (DP) have the potential to become a rising star in the next generation of lighting markets by addressing the toxicity and instability issues associated with traditional lead-based perovskites. However, high concentrations of hydrochloric acid (HCl) were often employed as a solvent in the preparation of most DPs, accompanied by slow crystallization at high temperatures, which not only raised the risk and cost in the preparation process, but also had a potential threat to the environment. Here, an in situ fabrication strategy was proposed to realize the crystallization of DP in the polymer at low temperature with a mild dimethyl sulfoxide (DMSO) solvent, and subsequently obtained optically well-behaved CsNaAgBiCl/PMMA composite films (CFs) by doping with Ag, generating bright orange luminescence with a photoluminescence quantum yield (PLQY) of up to 21.

Preparation of ultra-stable and environmentally friendly CsPbBr@ZrO/PS composite films for white light-emitting diodes.

The working stability of perovskite light-emitting diodes (LEDs) has become an urgent bottleneck to be solved in the process of commercialization. Although lead halide perovskite CsPbX (X = Br, I, Cl) quantum dots (QDs) are considered rising stars in the lighting market owing to their excellent optoelectronic properties, they suffer from fluorescence quenching under thermal conditions. Unfortunately, the surfaces of electronic devices inevitably warm up under long-term energization, which is extremely detrimental to the appropriate functioning of CsPbX QDs.

Electrochemically driven optical and SERS immunosensor for the detection of a therapeutic cardiac drug.

Cardiovascular diseases pose a serious health risk and have a high mortality rate of 31% worldwide. Digoxin is the most commonly prescribed pharmaceutical preparation to cardiovascular patients particularly in developing countries. The effectiveness of the drug critically depends on its presence in the therapeutic range (0.

Strong violet emission from ultra-stable strontium-doped CsPbCl superlattices.

Among the lead halide perovskites, the photoluminescence quantum yields (PLQYs) of perovskite quantum dots (PQDs) in the violet region are the very lowest. This is an obstacle to the optical applications across the entire visible area based on perovskite materials. Herein, we report a novel strontium (Sr)-substitution along with chlorine passivation strategy to enhance the PLQYs of CsPbCl PQDs.

Tuning optical properties of CsPbBrby mixing Ndtrivalent lanthanide halide cations for blue light emitting devices.

In recent years, significant progress has been made in the red and green perovskite quantum dots (PQDs) based light-emitting devices. However, a scarcity of blue-emitting devices that are extremely efficient precludes their research and development for optoelectronic applications. Taking advantage of tunable bandgaps of PQDs over the entire visible spectrum, herein we tune optical properties of CSPbBrby mixing Ndtrivalent lanthanide halide cations for blue light-emitting devices.

Trioctylphosphine-Assisted Pre-protection Low-Temperature Solvothermal Synthesis of Highly Stable CsPbBr/TiO Nanocomposites.

Lead halide perovskite quantum dots (PQDs) are reported as a promising branch of perovskites, which have recently emerged as a field in luminescent materials research. However, before the practical applications of PQDs can be realized, the problem of poor stability has not yet been solved. Herein, we propose a trioctylphosphine (TOP)-assisted pre-protection low-temperature solvothermal synthesis of highly stable CsPbBr/TiO nanocomposites.

A versatile approach for shape-controlled synthesis of ultrathin perovskite nanostructures.

Very recently, ultrathin perovskite nanostructures, with the advantages of perovskite and ultrathin properties, have received an enormous level of interest due to their many fascinating properties, such as a strong quantum confinement effect and a large specific surface area. In spite of this incredible success of perovskite nanocrystals (NCs), the development of perovskite NCs is still in its infancy, and the production of high-quality ultrathin perovskite nanostructures has been a hot topic in the fields of nanoscience and nanotechnology. Herein, we demonstrate that ultrathin CsPbBr3 perovskite nanosheets (NSs) can be obtained by a simple mixing of precursor-ligand complexes under ambient conditions.

Pressure-Driven Transformation of CsPbBrI Nanoparticles into Stable Nanosheets in Solution through Self-Assembly.

Very recently, two-dimensional (2D) perovskite nanosheets (PNSs), taking the advantages of perovskite as well as the 2D structure properties, have received an enormous level of interest throughout the scientific community. In spite of this incredible success in perovskite nanocrystals (NCs), self-assembly of many nanostructures in metal halide perovskites has not yet been realized, and producing highly efficient red-emitting PNSs remains challenging. In this Letter, we show that by using CsPbBrI perovskite nanoparticles (NPs) as a building block, PNSs can emerge spontaneously under high ambient pressure via template-free self-assembly without additional complicated operation.

The adverse role of excess negative ions in reducing the photoluminescence from water soluble MAA-CdSe/ZnS quantum dots in various phosphate buffers.

The use of CdSe/ZnS quantum dots in making biosensors or biomarkers requires them to be water soluble, which can be achieved by conjugating with MAA. We report observation of modulation in the photoluminescence intensities of MAA conjugated CdSe/ZnS QDs (MAA-QDs) that depended strongly on the types and quantity of negative ions present in various kinds of phosphate buffers. The deterioration of PL was attributed to the presence of excess ions in the media that altered the energy and occupation of HOMO and LUMO levels of MAA.

Role of Au(NPs) in the enhanced response of Au(NPs)-decorated MWCNT electrochemical biosensor.

Background: The combination of Au-metallic-NPs and CNTs are a new class of hybrid nanomaterials for the development of electrochemical biosensor. Concentration of Au(nanoparticles [NPs]) in the electrochemical biosensor is crucial for the efficient charge transfer between the Au-NPs-MWCNTs modified electrode and electrolytic solution.

Methods: In this work, the charge transfer kinetics in the glassy carbon electrode (GCE) modified with Au(NPs)-multiwalled carbon nanotube (MWCNT) nanohybrid with varied concentrations of Au(NPs) in the range 40-100 nM was studied using electrochemical impedance spectroscopy (EIS).

Efficient seed-mediated method for the large-scale synthesis of Au nanorods.

Seed-mediated methods are widely followed for the synthesis of Au nanorods (NRs). However, mostly dilute concentrations of the Au precursor (HAuCl) are used in the growth solution, which leads to a low final concentration of NRs. Attempts of increasing the concentration of NRs by simply increasing the concentration of HAuCl, other reagents in the growth solution and seeds lead to a faster growth kinetics which is not favourable for NR growth.

Significance of postgrowth processing of ZnO nanostructures on antibacterial activity against gram-positive and gram-negative bacteria.

In this work, we highlighted the effect of surface modifications of one-dimensional (1D) ZnO nanostructures (NSs) grown by the vapor-solid mechanism on their antibacterial activity. Two sets of ZnO NSs were modified separately - one set was modified by annealing in an Ar environment, and the second set was modified in O2 plasma. Annealing in Ar below 800°C resulted in a compressed lattice, which was due to removal of Zn interstitials and increased O vacancies.

Anomalous optical and magnetic behavior of multi-phase Mn doped Zn(2)SiO(4) nanowires: a new class of dilute magnetic semiconductors.

We present the synthesis of Mn doped Zn(2)SiO(4) dense nanowire bundles using the VLS mode of growth with unusual optical and magnetic properties. The synthesized Zn(2)SiO(4) nanowires were identified with two phases, α-Zn(2)SiO(4) as the major phase and β-Zn(2)SiO(4) as the minor phase. XPS studies confirmed that Zn(2)SiO(4) nanowires were Zn rich and Mn doped.

Electrochemical immunosensor for prostate-specific antigens using a label-free second antibody based on silica nanoparticles and polymer brush.

In this paper, we propose a sensitive electrochemical immunosensor synthesized using a surface-initiated atom transfer radical polymerization process for the detection of prostate-specific antigen (PSA). Electrochemical immunosensors based on polymer brush [oligo(ethylene glycol)methacrylate-co-glycidyl methacrylate] (OEGMA-co-GMA) were grown on plane Au and nanostructured (NS) Au electrodes, characterized and compared for their sensitivity to detect PSA. Due to a large capacity for antibody loading and high resistance to nonspecific antibody adsorption of POEGMA-co-GMA brush, the Au-NS immunosensor exhibited detection in a wide dynamic range of five orders of magnitude with an improved lower limit of detection of 2pgml(-1), which was better than the synthesized immunosensor with the polymer brush grown on plane Au electrode.

Optical analysis of hafnium oxide-aluminum multilayer structures for transparent heat mirrors.

We report on HfO2/Al/HfO2 multilayer thin films for heat mirror applications prepared on corning glass substrates by electron beam evaporation. Films fabricated at a substrate temperature of 100 °C show nano-polycrystals of HfO2 embedded in a disordered lattice according to X-ray diffraction results. Atomic force microscopy revealed that HfO2/Al/HfO2 layers possess smooth surface that is appropriate for optical heat mirror applications.

Removal of micrometer size morphological defects and enhancement of ultraviolet emission by thermal treatment of Ga-doped ZnO nanostructures.

Mixed morphologies of Ga-doped Zinc Oxide (ZnO) nanostructures are synthesized by vapor transport method. Systematic scanning electron microscope (SEM) studies of different morphologies, after periodic heat treatments, gives direct evidence of sublimation. SEM micrographs give direct evidence that morphological defects of nanostructures can be removed by annealing.

Synthesis of ZnO nanostructures for low temperature CO and UV sensing.

In this paper, synthesis and results of the low temperature sensing of carbon monoxide (CO) gas and room temperature UV sensors using one dimensional (1-D) ZnO nanostructures are presented. Comb-like structures, belts and rods, and needle-shaped nanobelts were synthesized by varying synthesis temperature using a vapor transport method. Needle-like ZnO nanobelts are unique as, according to our knowledge, there is no evidence of such morphology in previous literature.

Measurement of soil radioactivity levels and radiation hazard assessment in southern Rechna interfluvial region, Pakistan.

Rechna interfluvial region is one of the main regions of Punjab, Pakistan. It is the area which is lying between River Ravi and River Chenab, alluvial-filled. Radioactivity levels in soil samples, collected from southern Rechna interfluvial region, Pakistan, have been estimated by using gamma-ray spectrometric technique.