Simple Aqueous Solution Method Research Articles

AX·(H2SeO3)n (A = K, Cs; X = Cl, Br; n = 1, 2): A Series of Ionic Cocrystals as Promising UV Birefringent Materials with Large Birefringence and Wide Band Gap.

The design and syntheses of new birefringent crystals will be of great importance in commercial applications and materials science. A series of ultraviolet (UV) birefringent crystals, AX·(H2SeO3)n (A = K, Cs; X = Cl, Br; n = 1, 2), with large sizes up to 23 × 6 × 3 mm3, was successfully synthesized by simple aqueous solution method. These four compounds belong to three different space groups. Isomorphic KCl·(H2SeO3)2 and CsCl·(H2SeO3)2 crystallize in the space group, while CsBr·(H2SeO3)2 and CsCl·H2SeO3 crystallize in the P21/m and P21/c space groups, respectively. They exhibit cocrystal structures composed of [2(H2SeO3)]∞ and [AX]∞ frameworks, ingeniously inheriting the large optical anisotropy of selenite and the wide band gap of alkali metal halide. And it proves that these compounds indeed possess large birefringence (0.1-0.17 at 532 nm) and short UV cutoff edges (227-239 nm), achieving a balance of optical properties. This research affords a simple and viable strategy for the design and syntheses of new UV birefringent crystals. Besides, it is also found that the n value and ionic size (A and X ions) have important influences on the crystal structures and optical properties of AX·(H2SeO3)n. And this will promote further understanding of the alkali metal halide selenite family.

Interfacial oxygen vacancy modulated ZIF-8-derived ZnO/CuS for the photocatalytic degradation of antibiotic and organic pollutants: DFT calculation and degradation pathways

Fabricating oxygen vacancies (Vo) is an effective approach to enhance photocatalytic performance, but its effect on the interfacial charge transfer pathway remains unelucidated to date. In this study, we used the simple aqueous solution method to create an oxygen-defected ZIF-8-derived CuS/ZnO (CZ) heterostructure, and various characterization techniques were used to investigate the prepared catalysts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS) were used to determine the surface defects caused by the CuS nanoparticles in the ZnO matrix generated from ZIF-8. The optimized CuS/ZnO (CZ-2) catalyst exhibited efficient photocatalytic performance by effectively increasing the charge separation rate of the photogenerated electrons. The photocatalytic performances of methylene orange (MO) and ciprofloxacin (CIP) using the CZ heterostructure were 99.76 % and 94.59 %, respectively, with the corresponding rate constants of 0.0695 and 0.0312 min−1 at 40 min. The electron spin resonance and scavenger tests have established that •O2− is the primary oxidative radical species involved in photocatalytic activity. In addition, the density functional theory calculations were performed to determine the degradation mechanism of CIP, and the possible pathways of CIP degradation were investigated using liquid chromatography–mass spectroscopy. This study provides new insights into the development of metal–organic frameworks and metal sulfide-based heterostructures for environmental degradation applications.

NaCl·CH4N2O·H2O: An Organic-Inorganic Hybrid Ultraviolet Nonlinear Optical Crystal with Optimized Comprehensive Properties.

Ultraviolet (UV) nonlinear optical (NLO) crystals are a vital component in laser systems to modulate frequency. Organic groups have the advantages of easy synthesis, structural diversity, and large hyperpolarizations (β), which can be combined with inorganic groups to form unique organic-inorganic hybrid NLO crystal materials. Herein, a urea-containing crystal NaCl·CH4N2O·H2O is screened out and large-size crystals have been grown by a simple aqueous solution method. Compared with most reported organic-inorganic hybrid NLO materials, it has optimized comprehensive properties including a large SHG effect of 1.53 × KDP, a moderate birefringence (0.084@1064 nm), and a short UV cutoff edge of 209 nm. First-principles studies reveal that the dominant contributor to the linear and nonlinear optical properties is the urea molecule.

Si@C Core–Shell Nanostructure-Based Anode for Li-Ion Transport

Silicon-based anode materials are gaining popularity in lithium-ion battery research due to their high theoretical specific capacity compared to the conventional graphite anode. However, the commercialization of silicon-based anode materials has been hampered by their limited electronic conductivity and significant volume expansion. To address these challenges, our strategy was conducted to prepare porous silicon@carbon (p-Si@C) nanocomposites as an anode material using a simple aqueous solution method. In this work, nitrogen-containing p-phenylenediamine was chosen as the carbon source for synthesizing the nanostructured p-Si@C composites. The excellent electrochemical performance can be achieved, with over 100 cycles, a specific capacity of 624 mAh g–1, and a high Coulombic efficiency of 97.2%. These promising results were attributed to efficient Li-ion transport and low volume expansion, which are confirmed by the distribution function of relaxation time plots coupled with impedance spectroscopy technique, followed by the calculation of the expansion rate obtained from the SEM cross-sectional image. Hence, our work not only clearly provides a simple yet valuable method for the preparation of nanostructured silicon-based anode material with good electrochemical performance but also demonstrates its potential for industrial battery-grade development.

Flow boiling heat transfer enhancement via micro-pin-fins/ZnO nanorods hierarchical surface

In this study, ZnO nanorods were synthesized on micro-pin-fins by a simple and inexpensive aqueous solution method for flow boiling heat transfer enhancement. The morphology, chemical composition and wickability of the micro/nano hierarchical surface (PF+NR) were characterized. The heat transfer performance of PF+NR was investigated under various flow velocities together with a micro-pin-finned surface (PF), a ZnO nanorod-coated surface (NR) and a smooth surface (S). The results indicated that the boiling performance is improved significantly by the hierarchical surface and demonstrated a synergism between the microstructure and the nanostructure. The maximum boiling heat transfer coefficient of PF+NR is increased by 63%, 76%, and 158% compared with PF, NR and S, respectively. The critical heat flux is also increased by 31%, 33%, and 74%, respectively. The onset of nucleate boiling temperature of PF+NR is decreased compared with that of the other surfaces. The comprehensive improvement of boiling heat transfer performance is attributed to the cooperation of structures in different scales: the nanorods provide abundant nucleation sites, and the micro-pin-fins improve the liquid replenishment capacity and suppress the lateral coalescence of large bubbles at high heat fluxes.

Amorphous calcium phosphate nanoparticles using adenosine triphosphate as an organic phosphorus source for promoting tendon\u2013bone healing

BackgroundRotator cuff tear (RCT) is a common problem of the musculoskeletal system. With the advantage of promoting bone formation, calcium phosphate materials have been widely used to augment tendon-bone healing. However, only enhancing bone regeneration may be not enough for improving tendon–bone healing. Angiogenesis is another fundamental factor required for tendon–bone healing. Therefore, it’s necessary to develop a convenient and reliable method to promote osteogenesis and angiogenesis simultaneously, thereby effectively promoting tendon–bone healing.MethodsThe amorphous calcium phosphate (ACP) nanoparticles with dual biological activities of osteogenesis and angiogenesis were prepared by a simple low-temperature aqueous solution method using adenosine triphosphate (ATP) as an organic phosphorus source. The activities of osteogenesis and angiogenesis and the effect on the tendon–bone healing of ACP nanoparticles were tested in vitro and in a rat model of acute RCT.ResultsThe ACP nanoparticles with a diameter of tens of nanometers were rich in bioactive adenosine. In vitro, we confirmed that ACP nanoparticles could enhance osteogenesis and angiogenesis. In vivo, radiological and histological evaluations demonstrated that ACP nanoparticles could enhance bone and blood vessels formation at the tendon–bone junction. Biomechanical testing showed that ACP nanoparticles improved the biomechanical strength of the tendon–bone junction and ultimately promoted tendon–bone healing of rotator cuff.ConclusionsWe successfully confirmed that ACP nanoparticles could promote tendon–bone healing. ACP nanoparticles are a promising biological nanomaterial in augmenting tendon–bone healing.Graphic abstract

PbSe/sulfur-doped carbon nanocube composites prepared from Pb-MOF precursors as anode materials for lithium and sodium-ion batteries

PbSe/sulfur-doped carbon (SC) nanocube composites were successfully synthesized by a simple two-step method. Firstly, the lead-based metal organic framework (Pb-MOF) materials were synthesized by a simple room-temperature aqueous solution method. Then the Pb-MOF materials were used as precursor to react with selenium powder to prepare PbSe/SC nanocube composites in a vacuum quartz tube under high temperature. As the anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs), the PbSe/SC nanocube composites exhibit excellent electrochemical performance, because the special microporous nanocube structure can provide more active sites for redox reaction and effectively reduce the volume expansion of PbSe materials, and sulfur-doped carbon can increase the electronic conductivity of the material. The PbSe/SC nanocube composites showed excellent high-rate performance (818.5 mAh g−1 after 800 cycles in LIBs at 2000 mA g−1) and cyclic performance (717.1 mAh g−1 in LIBs and 313.6 mAh g−1 in SIBs after 100 cycles at 100 mA g−1). The results show that PbSe/SC nanocube composites have great potential as anode materials for LIBs and SIBs.

Photocatalytic properties of ZnO thin film with different morphologies from seed, array to grass

ZnO thin film with different morphologies from seed, array to grass was grown by simple aqueous solution method under room temperature. The morphologies, structure, optical properties and photocatalytic properties of the samples were characterised by transmission electron microscope, scanning electron microscope, X-ray diffraction, fluorescence spectrometer, UV-Vis spectrophotometer and photocurrent response. The results showed that the ZnO arrays and grassy ZnO were both hexagonal wurtzite with uniform distribution and regular growth on the glass substrate. ZnO thin film with different morphologies affected the utilisation efficiency of the ultraviolet light. Multiple light reflections inside the grassy ZnO greatly increase the light efficiency. The methyl blue degradation rate of grassy ZnO photocatalyst was superior under the UV light compared to the other ZnO morphologies. Grassy ZnO showed favourable stability after five cycles. The comparison of the ZnO semiconductor in different dimensions is helpful for further research on other photocatalysts as well as their potential application.

PHOTODEGRADATION OF RhB UNDER VISIBLE LIGHT BY PT/TIO2 NANOPARTICLES PREPARED THROUGH PHOTOREDUCTIVE DEPOSITION PROCESS

Pt/TiO2 nanoparticles were prepared by a simple two-step aqueous solution method, which consists of a low temperature hydrothermal step and a photoreduction deposition step. The as-prepared samples were characterized by XRD, TEM, XPS, UV-vis, and BET techniques. The as-prepared samples exhibited enhanced photocatalytic activity towards the degradation of rhodamine B (RhB) under visible light irradiation. With increasing Pt content from 0.25 to 1 wt.%, the band gap energies shift from 2.32 to 1.64 eV. The 0.75 wt.% Pt/TiO2 sample showed the best photocatalytic activity, which could be ascribed to the formation of a Schottky barrier and the localized surface plasmon resonance effect of Pt nanoparticles. And the as-prepared samples also displayed excellent stability and reusability in multiple experimental cycles.

Photocathodic Protection of Cobalt Doped ZnO Nanorod Arrays for 316 Stainless Steel and Q235 Carbon Steel in 3.5 wt.% NaCl Solution

In this work, cobalt-doped ZnO nanorod arrays with anticorrosion function were successfully prepared on fluorine-doped tin oxide (FTO) substrates by a simple aqueous solution method. The XRD patterns and the energy-dispersive X-ray spectroscopy (EDX) analysis indicate the doped Co2+ were successfully incorporated into the ZnO crystal lattice. The photocurrent density and open circuit potential (OCP) results indicate the photocathodic protection performance for 316 stainless steel (316 SS) and Q235 carbon steel in a 3.5 wt.% NaCl solution under a Xe lamp with a power of 300 W was enhanced with the increase of cobalt concentration, and the photoanode with a 15% Co/Zn ratio had the optimal photocathodic protection effect. The mechanism of enhancement may be result from the narrowed band gap, the lower recombination rate of the photogenerated electron-hole pairs, the intermediate impurity level, and the split of the hypo-outer shell of cobalt ions.

Optoelectronic properties of hybrid diodes based on vanadyl- phthalocyanine and zinc oxide nanorods thin films

Herein, we report the optoelectronic properties of hybrid diodes fabricated using vanadyl phthalocyanine (VOPc) and zinc oxide nanorods (ZNR) with the configuration: ITO/ZNR/VOPc/MoO3/Al. Vertically aligned ZnO nanorods were grown using a simple aqueous solution (AS) method as a function of growth temperature. The correlation between the morphology of ZNR films and the optoelectronic properties of the ZNR/VOPc hybrid devices was investigated. The results show that the hybrid diodes with ZNR films grown at 120 °C offer the best optoelectronic properties. The higher photocurrent responsivity, Rph, (16.28 A/W) was achieved for devices with ZNR films grown at 120 °C. This value is 25 times higher than the Rph value obtained for the devices made with ZnO nanoparticle films that were reported earlier.

Parallel Alignment of π-Conjugated Anions in Hydroisocyanurates Enhancing Optical Anisotropy.

Birefringent crystals with optical anisotropy, which are employed to modulate the polarization of light, play a vital role in many fields of the optical industry. In this Communication, two mixed alkali metal hydroisocyanurates, RbLi(H2C3N3O3)2·2H2O (I) and CsLi(H2C3N3O3)2·2H2O (II), were synthesized by a simple aqueous solution method, and they feature layered structures composed of ∞2[H2C3N3O3]- ribbons through hydrogen bonds with the separation of water molecules and alkali cations. They exhibit a simultaneously short ultraviolet cutoff and giant birefringence, resulting from the perfect parallel alignment of π-conjugated (H2C3N3O3)- anions. Interestingly, the first-principles calculations elucidated that the electronic states and optical properties are slightly different owing to the distinct p-π interaction between alkaline metals and the (H2C3N3O3)- group despite the isostructural crystallographic lattice.

In-situ creating elastic lattice O O bonds over semicrystalline yellow TiO2 nanoparticles for significantly enhanced photocatalytic H2 production

Atomic defects (e.g., Ti3+, oxygen vacancies) have been intenstively investigated for modifying TiO2 in order to reach visible light active photocatalytic H2 production. However, the atomic defects within TiO2 could easily act as photo-generated charge-carrier recombination centers, resulting in relatively low H2 conversion efficiency. In this paper, semicrystalline yellow TiO2 nanoparticles rich of superoxide ions are new synthesized by a simple aqueous solution method. Instead of introducing atomic defects, we show for the first time that catalytic performance can also be significantly improved via in-situ creating lattice OO bonds within metastable semicrystalline TiO2. The synthesized semicrystalline yellow TiO2 exhibits significantly enhanced photocatalytic activity for H2 production after cycle tests. The formaldehyde in aqueous solution is used as target pollutant to simulate industrial wastewater. In-situ created elastic lattice OO bonds are proposed to improve catalytic performance through facilitating the breakage of CH bonds of HCHO. A series of internally consistent reaction equations is proposed that describes the role of in-situ created lattice OO bonds for improving the catalytic performance. This is strongly supported by that the H2 production rate at the end of the fourth cycle test is significantly more than that of the beginning of the first cycle test.

Fabrication and Characterization of Aluminum-Doped ZnO Nanosheets for Field Emitter Application

The field emission characteristics of Al-doped ZnO nanosheets (AZO) were investigated. The AZO nanosheets were synthesized on a glass substrate by using a simple aqueous solution method. As demonstrated by the X-ray diffraction patterns, the AZO nanosheets display the hexagonal wurtzite structure with preferential orientation along the (0 0 2) crystal plane. The ZnO and AZO nanosheets exhibit turn-on fields of 4.2 and 3.8 V/μm, respectively, and field enhancement factors (β) of 2698 and 4760, respectively. These results can be attributed to the well-aligned nanosheet array and better conductivity with the AZO nanosheets.

Controllable Synthesis of Bandgap‐Tunable CuSxSe1−x Nanoplate Alloys

Composition engineering is an important approach for modulating the physical properties of alloyed semiconductors. In this work, ternary CuS(x)Se(1-x) nanoplates over the entire composition range of 0≤x≤1 have been controllably synthesized by means of a simple aqueous solution method at low temperature (90 °C). Reaction of Cu(2+) cations with polysulfide/-selenide ((S(n)Se(m))(2-)) anions rather than independent S(n)(2-) and Se(m)(2-) anions is responsible for the low-temperature and rapid synthesis of CuS(x)Se(1-x) alloys, and leads to higher S/Se ratios in the alloys than that in reactants owing to different dissociation energies of the Se-Se and the S-S bonds. The lattice parameters 'a' and 'c' of the hexagonal CuS(x)Se(1-x) alloys decrease linearly, whereas the direct bandgaps increase quadratically along with the S content. Direct bandgaps of the alloys can be tuned over a wide range from 1.64 to 2.19 eV. Raman peaks of the S-Se stretching mode are observed, thus further confirming formation of the alloyed CuS(x)Se(1-x) phase.

Bifunctional Zinc Oxide Nanoburger Aggregates as the Dye-Adsorption and Light-Scattering Layer for Dye-Sensitized Solar Cells

A novel burger-like aggregate nanostructure assembled from ZnO nanocrystals was synthesized by using a simple aqueous solution method at a low temperature (80°C). The burger-shaped nanostructure consists of two bun-like exterior layers joined together via a disk-shaped middle layer. Each exterior layer has a thickness of 200 to 300nm and a diameter of 400 to 600nm, while the relatively small middle layer has a thickness of 20 to 50nm and a diameter approximately 80nm smaller than the exterior layer. The nanoburger-based dye-sensitized solar cells (DSSCs) achieved a higher light-to-electricity conversion efficiency of 4.03% than those made of commercial ZnO nanoparticles (3.07%). The superior photovoltaic performance of the nanoburger-based DSSCs can be ascribed primarily to the enhanced dye adsorption ability of the aggregates. Because of their submicron sizes, the burger-like aggregates may also generate prominent light scattering, thereby improving the photoanode's optical absorption. Furthermore, the low-temperature heat-treatment process (150°C) used to fabricate the photoanode film provides opportunities to utilize polymeric substrates in flexible DSSCs.

Controlled Growth of ZnO with Different Morphologies on Zn Foils by a Simple Aqueous Solution Method

Nanostructured ZnO with versatile morphologies has great potential applications in many fields. In this work, ZnO materials with different morphologies were deposited on Zn foils by a simple aqueous solution method, and the shape of ZnO can be controlled by the concentration of Cl ions in the solution. Rods, spheres and platelets were obtained respectively with the concentration of Cl ions increase. The competition between Cl ions and growth units in the solution results the formation of ZnO materials with different morphologies. At the same time, the preferential orientation of the crystal plane is also changed by the concentration of Cl ions. The different morphologies of ZnO grown form this kind of solution method was also explained.

A cobalt-based polyoxometalate catalyst for efficient visible-light-driven H2 evolution from water splitting

A cobalt-based polyoxometalate, Na7H10[Co6(H2O)2(PW9O34)2(PW6O26)]·30H2O, was synthesized by a simple aqueous solution method. It showed catalytic activity for the visible-light-driven H2 evolution from water splitting with eosin Y as the photosensitizer and triethanolamine as the electron donor. The initial rate of the H2 evolution was 141μmolh−1, which was higher than that of Co2+ cations (55μmolh−1). The efficient catalytic activity was attributed to that the [B-PW9O34]9− units in the sample act as electron transmitters to accelerate charge transfer. Moreover, a possible mechanism was proposed to explain the H2 evolution from water splitting in the present system.

Facile synthesis of biocompatible cysteine-coated CuS nanoparticles with high photothermal conversion efficiency for cancer therapy.

The semiconductor compounds have been proven to be promising candidates as a new type of photothermal therapy agent, but unsatisfactory photothermal conversion efficiencies limit their widespread application in photothermal therapy (PTT). Herein, we synthesized cysteine-coated CuS nanoparticles (Cys-CuS NPs) as highly efficient PTT agents by a simple aqueous solution method. The Cys-CuS NPs have a good biocompatibility owing to their biocompatible cysteine coating and exhibit a strong absorption in the near-infrared region due to the localized surface plasma resonances of valence-band free carriers. The photothermal conversion efficiency of Cys-CuS NPs reaches 38.0%, which is much higher than that of the recently reported Cu9S5 and Cu(2-x)Se nanocrystals. More importantly, tumor growth can be efficiently inhibited in vivo by the fatal heat arising from the excellent photothermal effect of Cys-CuS NPs at a low concentration under the irradiation of a 980 nm laser with a safe power density of 0.72 W cm(-2). Therefore, the Cys-CuS NPs have great potential as ideal photothermal agents for cancer therapy.

Synthesis of ZnO nanowires on aluminum flake by aqueous method

ZnO nanowires are grown on aluminum flake at low temperature by using a simple aqueous solution method. X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscope (TEM) are applied to determine the as-grown ZnO nanowires morphology and crystal structures. The results show that the ZnO nanowires have wurtzite structure, and the diameter and length of the nanowire are 30 nm and more than 1.5 μm, respectively. Photoluminescence spectroscopy (PL) and Raman spectrum reveal the nanowires have good optical properties with low tensile stress. Meanwhile, photoelectrochemical cell (PEC) study verifies that ZnO nanowires as photoanodes are relatively stable in the photo-oxidation process, which could be a promising technique for practical applications.