Aqueous Solution-based Method Research Articles

Aqueous synthesis of stable Zn alloyed manganese halides for efficient backlit display

Metal halide perovskite has been widely researched in the field of wide color gamut backlight due to its excellent luminescence properties. However, the toxicity of lead and thermal stability issue greatly hindered its practical application. In this regard, environmentally friendly manganese halide perovskites has intrigued great attention. Herein, facile yet robust preparation of highly emissive all-inorganic manganese halides is presented via a one-step pure aqueous solution-based method without using corrosive acid solution. The introduction of Zn2+ cation-alloying enables the weakly luminescent Cs3MnCl5 to exhibit exceptionally efficient green emission at 521 nm. The alloyed Cs3MnxZn(1-x)Cl5 exhibits superior optical properties as well as improved thermal stability. In particular, alloyed Cs3MnxZn(1-x)Cl5 still retained 74% of the initial fluorescence intensity when the heating temperature was raised up to 225 °C. Furthermore, within the protective encapsulation of polydimethylsiloxane (PDMS) matrix, the prepared Cs3MnxZn(1-x)Cl5@PDMS films demonstrates excellent air, water and blue-light stability, which can be readily applied as light conversion films in backlit display. The as-prepared Cs3MnxZn(1-x)Cl5@K2SiF6: Mn4+@PDMS films displayed excellent quality and the color gamut was over 113% of the NTSC 1953 standard. This work provides a simple and effective pure aqueous-based strategy for the development of environment-friendly perovskite materials for the application of wide color gamut backlit display.

Role of Seed Layer Crystalline Quality in Photoresponse Performance of Hydrothermally Grown ZnO Nanorods.

We investigated the effects of the crystalline state for seed layers (SLs) on the growth morphology and material characteristics for hydrothermally grown ZnO nanorods (NRs). For this, preheating (PH) at different temperatures (100–300 °C) and O2 plasma treatment (PT) for 9 min were performed during the growth of SLs on p-Si by the aqueous solution-based method to provide the characteristic change on the NR growth platform. An improvement in material properties was achieved from the ZnO NRs grown on the SL crystals of enhanced crystalline quality in terms of the increased preferred orientation (002), the higher UV emission with suppressed deep-level emissions, the recovery of O/Zn stoichiometry, and the reduction of various intrinsic defects. Ultraviolet photodiodes of a p-Si/n-ZnO-NR structure fabricated under the SL conditions of O2 PT and PH at 100 °C showed a significantly enhanced on-off current ratio of ~90 at +5 V and faster photoresponse characteristics presenting a reduction in the fall time from 16 to 9 s.

Comparison between conventional solvothermal and aqueous solution-based production of UiO-66-NH2: Life cycle assessment, techno-economic assessment, and implications for CO2 capture and storage

Metal-organic frameworks (MOFs) are a new class of materials that has shown great potential in catalysis, sensing, separations, and carbon capture and storage. Conventionally, MOFs are synthesized at lab-scale using organic solvent-based systems, leading to high environmental burdens and high operating costs, which ultimately hinders the large-scale production and application of MOFs. Aqueous synthesis of MOFs overcomes such difficulty by eliminating the organic solvent, which makes it an environmental-friendlier and economically-favorable alternative to the current production method. However, further quantitative analysis is required to compare the environmental and economic performances of the two methods. Here, we used life cycle assessment (LCA) coupled with techno-economic analysis (TEA) to evaluate the environmental and economic performances of different UiO-66-NH2 production methods. When the solvothermal method was replaced by the aqueous solution-based method, the LCA and TEA results suggest the environmental burdens and cost of UiO-66-NH2 production were reduced by up to 91% and 84%, respectively. By using aqueous solution-based method, the cradle to gate carbon footprint, and production cost of UiO-66-NH2 were estimated to be 43 kg CO2 eq/kg, and $15.8/kg, respectively. We further applied our LCA results to reassess the role of UiO-66-NH2 in carbon capture and storage (CCS) and compare its environmental performance with current benchmark (amine-based solvent). Our results show that electricity produced from UiO-66-NH2 CCS system could potentially have better environmental performance (lower Global Warming Potential (GWP)) than that of the amine-based CCS system if the sorbent loss is less than 0.0017 tonne/tonne CO2 captured. This work is the first comprehensive LCA-TEA study that quantifies the substantial environmental and economic benefits of using the aqueous solution-based systems to produce UiO-66-NH2, and the analysis in this work is intended to be a starting point for further systematic studies on the full life-cycle impacts of MOFs.

Target-Triggered Assembly of Nanogap Antennas to Enhance the Fluorescence of Single Molecules and Their Application in MicroRNA Detection.

Nanogap antennas are plasmonic nanostructures with a strong electromagnetic field generated at the gap region of two neighboring particles owing to the coupling of the collective surface plasmon resonance. They have great potential for improving the optical properties of fluorophores. Herein, nanogap antennas are constructed using an aqueous solution-based method to overcome the defects of weak fluorescence and photobleaching associated with traditional organic dyes, and a highly sensitive nanogap antenna-based sensing strategy is presented for the detection of low-abundance nucleic acid biomarkers via a target-triggered strand displacement amplification (SDA) reaction between two DNA hairpins that are tagged to the tips of gold nanorods (Au NRs). In the presence of targets, end-to-end Au NR dimers gradually form, and the fluorophores quenched by the Au NRs exhibit a dramatic fluorescence enhancement due to the plasmon-enhanced fluorescence effect of nanogap antennas. Meanwhile, the SDA reaction results in secondary amplification of fluorescence signals. Combined with single-molecule counting, this method applied in miRNA-21 detection can achieve a low detection limit of 97.2 × 10-18 m. Moreover, accurate discrimination between different cells through miRNA-21 imaging demonstrates the potential of this method in monitoring the expression level of low-abundance nucleic acid biomarkers.

Synthesis of organo tin halide perovskites via simple aqueous acidic solution-based method

Abstract Organometal halide perovskites have been studied extensively during the last ten years for their interesting applications in solar cells and optoelectronics. One drawback of these materials is the presence of lead inside the compound, thus limiting their practical applications. Replacing lead with tin has been one of the implemented approaches for lead-free perovskites. In this paper, we report on the synthesis of organo tin mixed halide perovskites CH3NH3SnBrxCl3-x at room temperature in an aqueous acidic mixture between HCl and H3PO2 without the need of protecting perovskites against moisture. X-ray diffraction patterns show that the tin mixed halide perovskites adopt the trigonal phase. A detailed analysis of Raman scattering measurements has identified several low frequency Sn-Cl and Sn-Br modes of these perovskites. These results show that the high-quality CH3NH3SnBrxCl3-x crystals have been successfully synthesized by this aqueous solution-based method, demonstrating a low-cost approach to replace lead in organo metal halide perovskites for photovoltaic and optoelectronic applications.

Biotemplating rod-like viruses for the synthesis of copper nanorods and nanowires

BackgroundIn the past decade spherical and rod-like viruses have been used for the design and synthesis of new kind of nanomaterials with unique chemical positioning, shape, and dimensions in the nanosize regime. Wild type and genetic engineered viruses have served as excellent templates and scaffolds for the synthesis of hybrid materials with unique properties imparted by the incorporation of biological and organic moieties and inorganic nanoparticles. Although great advances have been accomplished, still there is a broad interest in developing reaction conditions suitable for biological templates while not limiting the material property of the product.ResultsWe demonstrate the controlled synthesis of copper nanorods and nanowires by electroless deposition of Cu on three types of Pd-activated rod-like viruses. Our aqueous solution-based method is scalable and versatile for biotemplating, resulting in Cu-nanorods 24–46 nm in diameter as measured by transmission electron microscopy. Cu2+ was chemically reduced onto Pd activated tobacco mosaic virus, fd and M13 bacteriophages to produce a complete and uniform Cu coverage. The Cu coating was a combination of Cu0 and Cu2O as determined by X- ray photoelectron spectroscopy analysis. A capping agent, synthesized in house, was used to disperse Cu-nanorods in aqueous and organic solvents. Likewise, reactions were developed to produce Cu-nanowires by metallization of polyaniline-coated tobacco mosaic virus.ConclusionsSynthesis conditions described in the current work are scalable and amenable for biological templates. The synthesized structures preserve the dimensions and shape of the rod-like viruses utilized during the study. The current work opens the possibility of generating a variety of nanorods and nanowires of different lengths ranging from 300 nm to micron sizes. Such biological-based materials may find ample use in nanoelectronics, sensing, and cancer therapy.