Small Crystal Size Research Articles

The Origin of Synergetic Effect in Mixed Mn-Co Oxide with Spinel Structure for Catalytic Oxidation of CO

In this work, the origin of the synergetic effect in mixed MnxCo3-xO4 oxides with the spinel structure in the CO oxidation reaction was tested. A series of MnxCo3-x oxide catalysts were synthesized by the coprecipitation method with further calcination at 600 °C and varying manganese content from x = 0 to x = 3. The catalysts were characterized using XRD, TEM, N2 adsorption, TPR, EXAFS, and XPS. The catalytic activity of MnxCo3-x oxide catalysts was tested in CO oxidation reactions. The addition of manganese to cobalt oxide results in the formation of mixed Mn-Co oxides based on a cubic or tetragonal spinel structure, a change in microstructural properties, such as surface area and crystal size, as well as local distortions and a decrease in the surface concentration of Co ions and Co in the octahedral sites in spinel structure; it also decreases catalyst reducibility. For all catalysts, the activity of CO oxidation decreases as follows: Mn0.1Co2.9 > Co3O4~Mn0.3Co2.7 > Mn0.5Co2.5 > MnOx > Mn0.7Co2.3 > Mn0.9Co2.1~Mn1.1Co1.9~Mn2.5Co0.5 > Mn2.9Co0.1 > Mn1.7Co1.3 > Mn2.1Co0.9 > Mn1.3Co1.7~Mn1.5Co1.5~Mn2.3Co0.7. The Mn0.1Co2.9 catalyst displays the best catalytic activity, which is attributed to its small crystal size and the maximum surface ratio between Co3+ and Co2+. A further increase in the manganese content (x > 0.3) provokes drastic changes in the catalytic properties due to a decrease in the cobalt content on the surface and in the volume of mixed oxide, changes in the oxidation states of cations, and structure transformation.

Synthesis of High-Quality TS-1 Zeolites Using Precursors of Diol-Based Polymer and Tetrapropylammonium Bromide for 1-Hexene Epoxidation

To synthesize high-quality TS-1 zeolites with enhanced catalytic performance for 1-hexene epoxidation is highly attractive for meeting the increased need for sustainable chemistry. Herein, we report that a series of framework Ti-enriched TS-1 zeolites with high crystallinity can be effectively synthesized by the hydrothermal crystallization of a composite precursor composed of diol-based polymer (containing titanium and silicon) and tetrapropylammonium bromide (TPABr). The pre-addition of a certain amount of TPABr into the polymer-based precursor plays a very positive role in maintaining the high crystallinity and framework Ti incorporation rate of TS-1 zeolites under the premise that a relatively low concentration of tetrapropylammonium hydroxide (TPAOH) template is adopted in the following hydrothermal crystallization process. The condition-optimized TS-1 zeolite with a smaller particle size (300–500 nm) shows excellent catalytic activity, selectivity, and recyclability for the epoxidation of 1-hexene with H2O2 as an oxidant, which can achieve a 75.4% conversion of 1-hexene and a 99% selectivity of epoxide at a reaction temperature of 60 °C, which is much better than the TS-1 zeolites reported in the previous literature. The relatively small particle size of the resultant TS-1 crystals may enhance the accessibility of the catalytically active framework Ti species to reagents, and the absence of non-framework Ti species, like anatase TiO2, and low polymerized six-coordinated Ti species could effectively inhibit the ineffective decomposition of H2O2 and the occurrence of side reactions, leading to an improvement in the catalytic efficiency for the epoxidation of 1-hexente with H2O2.

A promising photocathode for green hydrogen generation from sanitation water without external sacrificing agent: silver-silver oxide/poly(1H-pyrrole) dendritic nanocomposite seeded on poly-1H pyrrole film

Abstract A novel photocathode has shown promise for generating green hydrogen from sanitation water at a rate of 50 µmol/h per 10 cm², using waste water as an electrolyte in a three-electrode cell. This photocathode is composed of two layers: a poly(1H-pyrrole) seeding layer topped with a silver-silver oxide/poly(1H-pyrrole) (Ag-Ag2O-P1HP) dendritic nanocomposite. The nanocomposite exhibits broad light absorption up to 660 nm and possesses a bandgap of 1.8 eV. SEM images reveal that the Ag-Ag2O-P1HP nanocomposite consists of well-ordered semi-spherical nanoparticles, with an average size between 80 and 100 nm. These spherical nanoparticles offer a large surface area, which enhances photon absorption and trapping efficiency. Additionally, the crystalline structure is characterized by a small crystal size of 32 nm, further contributing to the material’s efficiency. Hydrogen generation performance was evaluated by measuring the current density (J ph) under white light and monochromatic light, compared to the dark current (J o). The photocathode’s sensitivity was tested using four different monochromatic wavelengths: 540, 440, 340, and 730 nm. The first three wavelengths – 540, 440, and 340 nm – resulted in high J ph values of −0.19, −0.20, and −0.21 mA/cm², respectively, indicating significant hydrogen production. Conversely, the 730 nm wavelength produced a lower J ph value of −0.17 mA/cm², as the energy at this wavelength is insufficient to induce significant bond vibrations, resulting in limited hydrogen production. The high efficiency, combined with the straightforward fabrication of this photocathode, suggests that it could be scaled up as a prototype for industrial hydrogen generation applications.

Study on the formation mechanism and effective manipulation of polymorphs and solvates in Osimertinib-Caffeic acid multi-component crystal with distinct properties.

Investigating the formation mechanism and effective manipulation of multi-component crystal polymorphs is crucial for facilitating industrial drug development. Herein, five novel Osimertinib-caffeic acid forms were first strategically tailored by varying solvent selection. Theoretical analysis demonstrated this polymorphism is correlated with multiple hydrogen bond donors-acceptors within multi-component system, which provides manipulation space for reconfiguration of intermolecular interactions and structural competition, while solvent further induced or involved in hydrogen-bonded rearrangements. Molecular dynamics simulation and solvent characterization revealed strong solute-solvent interaction and hydrogen bond donor propensity promoted the generation of hydrate. Small molecular size or large cavity of crystal facilitated solvent entry, resulting in the generation of channel-type solvates. Higher solvation free energy implied faster reaction rate and poorer solvent removal ability for solvates. Thermal analysis confirmed removal of the solvent occupying crystal channels for precursor solvates led to polymorph formation while maintaining the structure. Properties assessments revealed multi-component crystals significantly enhanced the physicochemical properties of Osimertinib. Polymorphs and hydrate exhibited remarkable distinctions in solubility, dissolution rate and physical stability. Nanoindentation and tableting tests confirmed distinct mechanical properties of different forms. Overall, this exploration has the potential to reshape the landscape of multi-component crystal polymorph development, paving the way for manipulating intermolecular interactions.

Ligand‐Mediated Quantum Yield Enhancement in 1‐D Silver Organothiolate Metal–Organic Chalcogenolates

AbstractX‐ray free electron laser (XFEL) microcrystallography and synchrotron single‐crystal crystallography are used to evaluate the role of organic substituent position on the optoelectronic properties of metal–organic chalcogenolates (MOChas). MOChas are crystalline 1D and 2D semiconducting hybrid materials that have varying optoelectronic properties depending on composition, topology, and structure. While MOChas have attracted much interest, small crystal sizes impede routine crystal structure determination. A series of constitutional isomers where the aryl thiol is functionalized by either methoxy or methyl ester are solved by small molecule serial femtosecond X‐ray crystallography (smSFX) and single crystal rotational crystallography. While all the methoxy examples have a low quantum yield (0‐1%), the methyl ester in the ortho position yields a high quantum yield of 22%. The proximity of the oxygen atoms to the silver inorganic core correlates to a considerable enhancement of quantum yield. Four crystal structures are solved at a resolution range of 0.8–1.0 Å revealing a collapse of the 2D topology for functional groups in the 2‐ and 3‐ positions, resulting in needle‐like crystals. Further analysis using density functional theory (DFT) and many‐body perturbation theory (MBPT) enables the exploration of complex excitonic phenomena within easily prepared material systems.

High-resolution TOF-DOI PET detectors through the implementation of dual-ended readout with SiPM arrays of different pixel sizes on the two ends.

Anorgan-specific Positron emission tomography (PET) scanner can achieve the same sensitivity with much fewer detectors as compared to a whole-body PET scanner, thereby substantially reducing the system cost. It can also achieve much better spatial resolution as compared to a whole-body PET scanner since the photon noncollinearity effect is reduced by using smaller detector ring diameter. Consequently, the development of organ-specific PET scanners with high spatial resolution, high sensitivity, and low cost has been a major focus of international research in PET instrument development for many years. The focus of this work is to develop high-resolution depth encoding PET detectors with high timing resolution and a reduced number of signal processing electronic channels. Consequently, PET scanners tailored for specific organs can be developed with high spatial and timing resolutions, enhanced sensitivity, and affordable cost. An 8×8 silicon photomultiplier (SiPM) array with a pixel size of 3×3 mm2 and a multiplexed signal readout circuit is coupled to one end of the lutetium yttrium orthosilicate (LYSO) array with a glass light guide between them to achieve a good crystal identification of small crystals by using only four position-encoding energy signals. A 4×4 SiPM array with a pixel size of 6×6 mm2 and an individual readout circuit is coupled to the other end of the crystal array without a light guide to achieve a good coincidence timing resolution (CTR). The depth of interaction (DOI) of the detector is measured by ratio of the energies measured by the two SiPM arrays and can be used to correct the depth dependency of the timing. The flood histograms, energy resolutions (ERs), DOI resolutions, and CTRs of two detectors utilizing LYSO arrays with different crystal sizes were measured with each of the two SiPM arrays alternately placed at the front of the detectors. A better flood histogram was obtained by placing the 8×8 SiPM array in front of the detector. The depth dependency of timing was larger when the 4×4 SiPM array was placed at the front of the detector. A better CTR was obtained by placing the 4×4 SiPM array at the back of the detector as compared to placing it at the front of the detector if the depth-dependent timing correction was not performed. If the depth-dependent timing correction was performed, a better CTR can be obtained by placing the 4×4 SiPM array at the front of the detector. The first detector using a 12×12 LYSO crystal array with a crystal size of 1.95×1.95×20 mm3 provided a flood histogram with all crystals clearly resolved, an ER of 11.7%, a DOI resolution of 2.9mm, and a CTR of 275ps with the depth-dependent timing correction. The second detector using a 23×23 LYSO crystal array with a crystal size of 0.95×0.95×20 mm3 provided a flood histogram with all but the edge crystals clearly resolved, an ER of 17.6%, a DOI resolution of 2.3mm, and a CTR of 293ps with the depth-dependent timing correction. PET detectors with small crystal cross-sectional sizes, good DOI and timing resolutions and a reduced number of electronics channels were developed. The detectors can be used to develop high performance organ-specific PET scanners.

High-throughput extraction of cellulose nanofibers from Imperata cylindrica grass for advanced bio composites

Extracting high-quality cellulose nanofibers (CNFs) with superior yield and purity particularly due to the cost and efficiency limitations inherent in current extraction methods. In this study, we present a novel and cost-effective approach for extracting cellulose nanofibers (ECNFs) from naturally available Imperata cylindrica grass using an optimized chemical process. This process involves tailoring adjusting acid-base ratios and bleaching conditions to successfully extract CNFs with a uniform diameter (90 nm), length (11 μm), high crystallinity (71.64 %), and a small average crystal size (2.06 nm). These characteristics were confirmed using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy analyses. To evaluate the potential of ECNFs in enhancing polymer mechanical properties, ECNFs-reinforced chitosan (CS) composite films were fabricated via a simple solution casting process. The addition of 2 wt% ECNFs significantly improved the Young's modulus by 402 % (reaching 1.37 GPa) and the tensile strength by 748 % (reaching 16.77 MPa) compared to pristine CS films (0.27 GPa and 1.98 MPa), underscoring their effectiveness as reinforcement agents. Furthermore, to expand the functionality of the CS composites, cost-effective graphene nanoplatelets (GNPs) were incorporated. These hybrid ECNFs/CS/GNP composites exhibited remarkable improvements in thermal stability, flame retardancy, and electromagnetic interference (EMI) shielding compared to pure CS films. In conclusion, this study presents a facile and cost-effective method for extracting high-quality CNFs. The ECNFs-reinforced CS composites demonstrate superior mechanical properties, while the incorporation of GNPs further enhances their functionality by improving thermal stability, reducing flammability, and providing effective EMI shielding. These findings could facilitate the development of high-performance green composites with diverse applications across various industries.

Study on the surface modification of regenerated and repaired LiNi0.5Co0.2Mn0.3O2 single crystal

Due to the relatively small particle size of single crystals, the high specific surface area increases the side reactions between the electrode and the electrolyte. Without proper surface modification, single-crystal particles tend to interact directly with the electrolyte, leading to side reactions that impair the electrochemical performance of the material. To address this issue, constructing a coating layer on the material's surface is one effective solution. In this study, a wet-coating technique was employed to co-coat single-crystal LiNi0.5Co0.2Mn0.3O2 cathode material with vanadium (V) and samarium (Sm). SEM and TEM tests revealed the presence of a V-Sm coating layer with a thickness of approximately 1–3 nm on the surface of the coated samples. The coated material demonstrated a capacity retention rate of 86.5 % after 450 cycles at a 1 C rate (1 C = 160 mA h g−1), which represents an improvement of about 6.7 % compared to the original material. EIS results indicated that the V-Sm coating stabilized the surface SEI film of the material and inhibited the growth of charge transfer resistance (Rct). XPS analysis of the electrodes after cycling showed that the V-Sm coating effectively protected the material by isolating it from direct contact with the electrolyte, suppressing the decomposition of the electrolyte during cycling, and reducing adverse side reactions between the material and the electrolyte, thereby enhancing the overall electrochemical performance of the material.

Effect of co-addition of Nb/Zr on the microstructure and soft magnetic properties of Fe77.5Si11.5B7NbxZr3-xCu1 nanocrystalline alloys

Soft magnetic nanocrystalline alloys, exemplified by FINEMET (Fe73.5Si13.5B9Nb3Cu1), are essential in electronics due to their low coercivity and high permeability. However, demand for miniaturization and enhanced efficiency in power conversion devices necessitates materials with increased saturation magnetization. Given the limited saturation magnetization (1.23 T) of FINEMET alloy, which is attributed to its lower iron content, there has been growing interest in exploring alternative alloys that potentially offer higher saturation magnetization values. The present research introduces a new alloy system that builds on FINEMET by increasing the iron content and meticulously incorporating Nb and Zr in a controlled manner, aiming for a composition that delivers enhanced soft magnetic properties. Alloy ribbons with a newly designed composition of Fe77.5Si11.5B7NbxZr3-xCu1 (x = 0–3 at%) were fabricated via rapid-quenching melt spinning followed by nanocrystallization thermal annealing, and the impact of Nb/Zr content on the magnetic microstructure and magnetic properties was investigated. Strategically distributing both Zr and Nb has been found to effectively suppresses grain growth, enhancing permeability and reducing coercivity and core loss. Remarkably, the Fe77.5Si11.5B7Nb1Zr2Cu1 nanocrystalline ribbon annealed at 580 °C for 10 min demonstrates outstanding soft-magnetic properties with a coercivity of 1.64 A/m and a saturation magnetization of 170.31 emu/g (1.59 T). Furthermore, a high-resolution TEM analysis revealed an impressively small average crystal size of 9.69 nm. It is anticipated that Fe77.5Si11.5B7NbxZr3-xCu1 (x = 0–3 at%) soft magnetic alloys will be broadly applied in power conversion devices such as inductors and transformers, contributing significantly to efficiency and performance enhancements.

Reservoir characteristics and distribution of the Majiagou Formation in the Fuxian area of Ordos Basin, China

The Majiagou Formation in the Fuxian area of the southeastern Ordos Basin has undergone a complex diagenetic evolution history under the influence of eustacy and the Caledonian karstification, resulting in several complex reservoir types. Through analyses of mineralogy, petrology, and reservoir geology, three major types of dolomite reservoirs with different genetic mechanisms, including anhydritic moldic-dissolved pore type, dolomitic intercrystalline-pore type, and fractured type were identified, and their formation mechanisms and distribution patterns were examined. The aphanocrystalline to very fine-crystalline anhydritic dolomite was resulted from Sabhak dolomitization, and is characterized by small size of crystals and high content of anhydrite. Dolomite reservoirs of anhydritic moldic-dissolved pore type were developed in multi-stage dissolution processes and mainly distributed at higher positions of the paleogeomorphology where the filling was weak. The very fine to fine-crystalline dolomite of shoal facies was formed under seepage-reflux dolomitization, and characterized by larger sizes of crystals and well-developed intercrystalline pores. Dolomite reservoirs of intercrystalline-pore type were mainly developed at the lower positions of the paleogeomorphology where bedding-parallel karst dissolution was strong. The fractured dolomite reservoirs, generated by the anhydrite swelling and karst cave collapse, occur in multiple horizons but within limited areas due to multi-stage fillings.

Composition Determination of Heterometallic Trinuclear Clusters via Anomalous X-ray and Neutron Diffraction.

Anomalous X-ray diffraction (AXD) and neutron diffraction can be used to crystallographically distinguish between metals of similar electron density. Despite the use of AXD for structural characterization in mixed metal clusters, there are no benchmark studies evaluating the accuracy of AXD toward assessing elemental occupancy in molecules with comparisons with what is determined via neutron diffraction. We collected resonant diffraction data on several homo and heterometallic clusters and refined their anomalous scattering components to determine metal site occupancies. Theoretical resonant scattering terms for Fe0, Co0, and Zn0 were compared against experimental values, revealing theoretical values are ill-suited to serve as references for occupancy determination. The cluster featuring distinct cation and anion metal compositions [CoCp2*][(tbsL)Fe3(μ3-NAr)] was used to assess the accuracy of different f' references for occupancy determination (f'theoretical ± 15-17%; f'experimental ± 10%). This methodology was applied toward calculating the occupancy of three different clusters: (tbsL)Fe2Zn(py) (6), (tbsL)Fe2Zn(μ3-NAr)(py) (7), and [CoCp*2][(tbsL)Fe2Zn(μ3-NAr)] (8). The first two clusters maintain 100% Fe/Zn site isolation, whereas 8 showed metal mixing within the sites. The large crystal size of 8 enabled collection of neutron diffraction data which was compared against the results found with AXD. The ability of AXD to replicate the metal occupancies as determined by neutron diffraction supports the AXD occupancy methodology developed herein. Furthermore, the advantages innate to AXD (e.g., smaller crystal sizes, shorter collection times, and greater availability of synchrotron resources) versus neutron diffraction further support the need for its development as a standard technique.

Developing a novel toffee-type soft candy process by sonocrystallization: A preliminary study

This study aimed to evaluate the applicability of sonocrystallization, an innovative process, as a low-cost and time-efficient alternative for the crystallization of confectionery dough, which is a crucial step in the production of conventional toffee-type soft candy. In this regard, according to the design plan, sonocrystallization time and current were selected as independent variables. The samples (36 run) nucleated by sonocrystallization using the optimum conditions (1600 and 2400 mA, 20 min) were allowed to aging under different times (0, 2, 4, 6, 8, and 10 min) and temperatures (60, 65, and 70 °C) in order to determine crystal growth. According to the texture profile analysis results, all parameters except for cohesiveness were significantly affected by both the sonocrystallization and aging conditions (p < 0.05), and dramatically higher hardness values were obtained for samples sonocrystallized at 2400 mA. Micrographs showed the formation of a crystalline network with more crystals of smaller size, fragmentation of larger crystals, and a more homogenous crystallization, especially in the samples sonocrystallized at 2400 mA and allowed to aging at >65 °C for durations of >6 min. The targets of the study were achieved by subjecting the samples to sonocrystallization at 2400 mA and aging at 70 °C for 8 min for crystal growth.

Preparation of nano magnesium oxide by mechanochemical method using magnesium chloride

Magnesium chloride is a magnesium resource that is widely present in seawater and salt lakes. Therefore, the use of magnesium chloride is of great significance for the low-cost preparation of high-performance magnesium materials. In this work, mechanical ball milling was used for the preparation of magnesium oxide nanoparticles from magnesium chloride. Ball milling improves the unevenness of the reaction process and generates magnesium oxide with a more uniform particle size distribution. First, a magnesium chloride complex was obtained by heating and evaporating a mixture of magnesium chloride and ethanol with a mass ratio of 1:2 at 110 °C. Next, pure magnesium hydroxide with a smaller crystal size was obtained by ball milling the prepared magnesium chloride complex with calcium hydroxide at 600 rpm for 3 h. Finally, the magnesium hydroxide was calcined at 1000 °C for 60 min to obtain nano magnesium oxide particles with a particle size of 670 nm.

Study on the homologous effects on the performance of alkali metal-doping MgO-based adsorbents for CO2 capture

In this article, MgO-based adsorbents with different structure and surface property were prepared by combustion of the colloids containing Mg and alkali metal. At the same time, CO2 adsorption performance tests are conducted to compare the doping effect of alkali metal on MgO adsorbents. As confirmed, the introduction of lithium, sodium, and potassium can reduce the grain size of MgO and enhance the basicity, especially increasing the concentration of oxygen vacancies on MgO surface which exposed more basic adsorption active sites and was more conducive to CO2 adsorption. Among them, the one doped with 0.5 % K which had more electron shell numbers showed larger surface area and smaller crystal size. Most importantly, it provided more number of basic sites along with the improved strength of surface basicity due to the more oxygen vacancies. As a result, the maximum CO2 uptake (1.09 mmol/g) at the adsorption time of 60 min can be obtained which still remained at 0.67 mmol/g after 16 cycles of CO2 adsorption–desorption. With the aid of N2 physical adsorption, inductively coupled plasma-optical emission spectroscopy, powder X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy, electron paramagnetic resonance, and chemical adsorption, the relationship between CO2 adsorption capacity of MgO-based adsorbent and homologous regularity of alkali metal was disclosed. In other words, by comparing the CO2 adsorption performance of MgO adsorbents prepared by doping different alkali metals, CO2 adsorption capacity increased with the increase of electron shell numbers. Such a configuration is in favor of the electron supply of the p-orbitals and weakens the Mg–O bonds which promoted the formation of oxygen vacancies. The found will provide in-depth understanding for the modification and performance improvement of MgO-based adsorbents.

Optimization of three-dimensional electron diffuse scattering data acquisition

The diffraction patterns of crystalline materials with local order contain sharp Bragg reflections as well as highly structured diffuse scattering. In this study, we quantitatively show how the diffuse scattering in three-dimensional electron diffraction (3D ED) data is influenced by various parameters, including the data acquisition mode, the detector type and the use of an energy filter. We found that diffuse scattering data used for quantitative analysis are preferably acquired in selected area electron diffraction (SAED) mode using a CCD and an energy filter. In this study, we also show that the diffuse scattering in 3D ED data can be obtained with a quality comparable to that from single-crystal X-ray diffraction. As electron diffraction requires much smaller crystal sizes than X-ray diffraction, this opens up the possibility to investigate the local structure of many technologically relevant materials for which no crystals large enough for single-crystal X-ray diffraction are available.

A comparative study of crystal geometry, material, and reconstruction algorithms on MicroPET scanner performance

Small-animal PET, also known as microPET, has been developed to enhance image quality by improving spatial resolution and sensitivity due to its smaller ring and crystal size. However, the reduction of crystal size and the presence of gaps between cuboidal crystals could reduce sensitivity. MicroPET with tapered arrays has been developed to simultaneously improve sensitivity and spatial resolution. This study compared the performance of 14 × 14 and 28 × 28 array microPETs using LSO and CZT crystal materials. The impact of crystal design and reconstruction algorithms on image quality and performance parameters was investigated, using GATE Monte Carlo simulation toolkit. The findings showed that sensitivity increased with crystal thickness, particularly in LSO. The 14 × 14 arrays consistently exhibited higher sensitivity, while the 28 × 28 arrays had superior spatial resolution. NECR values increased with crystal thickness, with LSO outperforming CZT. Scatter and random fractions were low. Different reconstruction algorithms had negligible effects on FWHM and CNR but influenced SNR, with the COSEM algorithm achieving significantly reduced noise. The small size of crystals and tapered arrays contributed to improved sensitivity and spatial resolution. However, there was a trade-off between sensitivity and spatial resolution. LSO crystals showed better performance, but the choice between array sizes depended on specific imaging requirements. This study provides insights into optimizing microPET design for enhanced imaging capabilities.

Nanocarbons decorated TiO2 as advanced nanocomposite fabric for photocatalytic degradation of methylene blue dye and ciprofloxacin

In this research, C [graphene (Gr), multi-walled carbon nanotubes (MWCNTs), and single-walled carbon nanotubes (SWCNTs)] decorated TiO2 nanostructures were developed and further utilized to modify textile to achieve high-performance photocatalytic degradation of mixed water pollutants including methylene blue (MB) dye and pharmaceutical active compound, Ciprofloxacin (CPF) on solar radiation exposure (∼105 Lumens). The crystallite sizes of TiO2, TiO2-MWCNT, TiO2-SWCNT, and TiO2-Gr nanocomposites were observed in the 7.2–10.4 nm range. The bandgap, Eg of nanostructured C-TiO2, was observed in the 3.09–3.14 eV range. The photocatalytic performance of C-TiO2 showed almost complete removal of MB under the irradiation of the solar spectrum in just 120 min. Among C-based TiO2 nanocomposites, nanostructured TiO2-SWCNT showed the highest degradation efficiency of ∼98.86 % for MB dye. Further, the textile membrane showed a good degradation efficiency of 99.49 % for MB dye and 95.7 % for CPF within 120 min. An impressive removal efficiency of ∼93 % was observed for the mixture of MB and CPF solution due to a combination of several properties like surface groups (OH− & O2−), low charge recombination rate due to CNTs, and small crystal size. This proof-of-the-concept study can be the potential platform to manage water quality according to sustainability goals.

Effects of Rapid Heat Treatments on the Properties of Cu2O Thin Films Deposited at Room Temperature Using an Ammonia-Free SILAR Technique

We report herein the analysis of the properties of copper(I) oxide thin films deposited by an optimized ammonium-free successive ion layer adsorption and reaction (SILAR) technique. The Cu2O thin film deposition process was carried out at room temperature using copper acetate monohydrate, sodium citrate as complexing agent, and hydrogen peroxide as precursors of copper and oxygen ions, respectively. The harmless and easy-to-handle sodium citrate replaces the volatile NH4OH commonly employed as complexing agent in the SILAR technique for the deposition of metal oxide thin films. The optical, structural, morphological, and electrical properties of the as-deposited Cu2O thin films were studied as a function of the number of cycles during deposition, as well as their modifications produced by the effect of rapid thermal annealing (RTA) in vacuum in a temperature range of 200–250°C for 1 min, 3 min, and 5 min. The as-deposited thin films had cubic crystalline structure corresponding to the Cu2O phase as determined by x-ray diffraction (XRD), with a direct energy bandgap of 2.43–2.51 eV depending on the number of cycles, and electrical resistivity of the order of 103 Ω cm. The XRD and x-ray photoelectron spectroscopy (XPS) analysis of the Cu2O thin films treated by RTA demonstrated an increase of the crystal size with time and temperature of the RTA and reduction effects from Cu2+ to Cu1+ oxidation states. On the other hand, the RTA treatments also decreased their energy bandgap to 2.38 eV and electrical resistivity to 102 Ω cm. The high energy bandgap values of the Cu2O thin films were attributed to quantum confinement effects produced by their small crystal size in the range of 3.6–8.6 nm.Graphical

Nanosized “rice ball” like hierarchical beta zeolites with inter-crystalline mesopores for efficient catalytic synthesis of lactide

A series of nanosized “rice ball” like hierarchical beta zeolite aggregates (RBZxAy, x = 6, 9, 12 or 15; y = 2, 4 or 6) with hierarchical structures are successfully synthesized via gel aging and hydrothermal method without mesoporous template. The as-prepared RBZxAy zeolites possess two ranges of inter-crystalline mesoporous that formed by zeolite nanoparticles aggregation compared to the non-aged samples (B12Z4). The effects of Si/Al ratio and crystallization time on the morphology, structure and surface acidic properties of RBZxAy were systematically investigated. Meanwhile, RBZxAy as catalysts were applied in the conversion of lactic acid (LA) to lactide (LT) to investigate their catalytic performance. Benefitting from smaller crystal size, hierarchical structures and higher acid content, the representative catalyst (RBZ12A4) exhibited outstanding catalytic activity that the LA conversion was high to 98 % and the LT yield up to 94 %. In addition, RBZ12A4 presented perfect regeneration ability after 10 times recycles. This work provides an effective and facile route to directly synthesis nanocrystals aluminosilicate zeolite with hierarchal structure, and constructs an approach for efficiently converting LA to LT, it has greatly significance for the development of polylactic acid industry.

Efficient electrochemical oxidation of antibiotic wastewater using a graphene-loaded PbO2 membrane anode: Mechanisms and applications

This paper aims to develop a flow-through electrochemical system with a series of graphene nanoparticles loaded PbO2 reactive electrochemical membrane electrodes (GNPs-PbO2 REMs) on porous Ti substrates with pore sizes of 100, 150, 300 and 600 μm, and apply them to treat antibiotic wastewater. Among them, the GNPs-PbO2 with Ti substrate of 150 μm (Ti-150/GNPs-PbO2) had superior electrochemical degradation performance over the REMs with other pore sizes due to its smaller crystal size, larger electrochemical active specific area, lower charge-transfer impedance and larger oxygen evolution potential. Under the relatively optimized conditions of initial pH of 5, current density of 15 mA cm−2, and membrane flux of 4.20 m3 (m2·h)−1, the Ti-150/GNPs-PbO2 REM realized 99.34% of benzylpenicillin sodium (PNG) removal with an EE/O of 6.52 kWh m−3. Its excellent performance could be explained as the increased mass transfer. Then three plausible PNG degradation pathways in the flow-through electrochemical system were proposed, and great stability and safety of Ti-150/GNPs-PbO2 REM were demonstrated. Moreover, a single-pass Ti-150/GNPs-PbO2 REM system with five-modules in series was designed, which could consistently treat real antibiotic wastewater in compliance with disposal requirements of China. Thus, this study evidenced that the flow-through electrochemical system with the Ti-150/GNPs-PbO2 REM is an efficient alternative for treating antibiotic wastewater.