Dioxide Microspheres Research Articles

Template-free synthesis of hollow titanium dioxide microspheres and amorphous titanium dioxide microspheres with superior lithium and sodium storage performance

Hierarchical hollow TiO2 microspheres (H-TiO2) and amorphous solid TiO2 microspheres (A-TiO2) were synthesized using a template-free method. Initially, quasi-monodisperse solid TiO2 microspheres (A-TiO2) were obtained by controlled thermal hydrolysis of titanium sulfate, forming aggregates of amorphous particles, followed by solvothermal treatment to convert the solid structure into a hollow and crystalline H-TiO2 structure. SEM and TEM images revealed that the morphological evolution from A-TiO2 to H-TiO2 conforms precisely to the inside-out Ostwald ripening mechanism. The unique hollow layered structure endows H-TiO2 with a large specific surface area of 93.3 m2/g and a rich porous structure. When used as an anode material for LIBs and SIBs, H-TiO2 exhibits superior cycling stability and rate performance compared to A-TiO2. For LIBs, H-TiO2 achieves a reversible capacity of 342.2 mA h g−1 at a 0.2C charge/discharge rate and retains unprecedented long-term stability at high current densities (258.5 mA h g−1 after 1000 cycles at 5C and 220.4 mA h g−1 after 1000 cycles at 10C). For SIBs, H-TiO2 exhibits a reversible capacity of 271.7 mA h g−1 at 0.2C, with specific capacities of 173.4 mA h g−1 after 1000 cycles at 1C and 101.4 mA h g−1 after 2000 cycles at 5C. Furthermore, kinetic calculations demonstrate that H-TiO2 possesses higher Li+ and Na+ diffusion rates, adsorption capacities, and conductivity, further explaining its excellent electrochemical performance.

Methyltrimethoxysilane modified tin dioxide microspheres with hydrophobic networks and abundant adsorbed oxygen for efficient solid-phase microextraction of polychlorinated biphenyls.

Methyltrimethoxysilane (MTMS) modified tin dioxide microspheres (MTMS/SnO2) were prepared by a facile hydrothermal method and heated reflux reaction strategy. The characterization results indicate that the modification of MTMS induced the formation of a hydrophobic network within the composites, while maintaining abundant adsorbed oxygen species. Subsequently, the MTMS/SnO2 microspheres were used as a solid-phase microextraction (SPME) coating for the efficient extraction and sensitive determination of trace polychlorinated biphenyls (PCBs) in aqueous solutions coupled to gas chromatography-mass spectrometry. MTMS/SnO2 coating exhibited superior extraction performances for PCBs compared withcommercial SPME and pure SnO2 microspheres coatings, owing to the hydrophobic crosslinking and adsorbed oxygen-enhanced hydrogen bonding. The proposed analytical method presented respectable linearity in the concentration range 0.25-1000ng L-1, with low limits of detection varying from 0.036 to 0.14ng L-1 for seven PCBs and excellent precision, with relative standard deviations of 5.7-9.8% for a single fiber and 8.2-13.1% for five fibers. Finally, the proposed method was successfully used for determination of PCBs in real water with recoveries ranging from 75.8 to 115.6%. This study proposed a new type SPME coating of MTMS/SnO2 microspheres, which extended the potential of SnO2 in capturing and determining organic pollutants.

One-step preparation of Z-scheme g-C3N4 nanorods/TiO2 microsphere with improved photodegradation of antibiotic residue

Graphitic carbon nitride nanorods/titanium dioxide microspheres (g-C3N4 NRs/TiO2 MSs) Z-scheme heterojunctions were simply prepared by a one-step hydrothermal method, which showed improved visible-light-induced photocatalytic activity for the degradation of tetracycline hydrochloride (TC-HCl). The photodegradation activity of g-C3N4 NRs/TiO2 MSs is 6.6 and 1.9 times better than that of pristine g-C3N4 and TiO2, which is assigned to the unique morphology and formed heterojunction. Hydroxyl radical (⋅OH) and superoxide radical (⋅O2−) were the main species for TC-HCl photodegradation according to capture experiments, and a possible mechanism is proposed. This study provides an effective reference for the preparation of binary heterostructures with excellent photocatalytic activity from a simplified process.

Mechanistic insights into temperature hysteresis in CO oxidation on Cu-TiO2 mesosphere

This study employs in-situ X-ray absorption spectroscopy (XAS) and operando Raman to explore the reaction mechanism of copper/titanium dioxide microspheres (CuTMS) in CO oxidation. A temperature-dependent hysteresis behavior was observed during catalytic CO oxidation, which can be divided into two distinct regions. In the low-temperature region, the transformation of CuO → Cu2O → Cu2O/Cu on the surface of CuTMS is detected via in-situ XAS, highlighting the pivotal role of surface-adsorbed oxygen in initiating this conversion process. Conversely, in the high-temperature region, analysis of Raman peak areas suggests a variation in the {001} and {101} facets of anatase. Specifically, a decrease in the {001} facets from 17% to 10% indicates TiO2-mediated oxygen transportation, which facilitates the reoxidization of reduced Cu species. This integrated approach showcases significant potential for unraveling the mechanistic studies of catalytic reaction mechanisms in copper/titanium systems, including surface copper valence state changes, oxygen replenishment, and crystal structure distortion.

Remote focusing optical tweezers for 3D imaging.

We present a remote focusing optical tweezer utilizing a 4f symmetrical optical system to compensate the high-order aberration during annular light refocusing. The position of the optical trap can be adjusted beyond the range of one hundred micrometers in the axial direction by means of tuning the position of the mirror placed in the focal region of the illumination objective lens. This optical tweezer can be combined with a sectioning microscope to realize three-dimensional (3D) imaging, e.g., a confocal microscope using a single water immersion objective lens. All optical elements are placed in one side of the sample, which is very useful for application in fields such as radiation biology, where radiation or magnetism disturbance must be introduced on the other side of the sample. In the experiment, a 10 µm diameter silicon dioxide microsphere and pollen cells immersed in the water are translated along the axis using the optical tweezer and, meanwhile, the sectioning images are obtained using the confocal microscope.

Polyaniline composited with rGO wrapped-SiO2 microsphere ammonia sensor with fast response/recovery and high sensitivity for pig healthy breeding

Ammonia detection is important in pig healthy breeding due to its big threat to pig health, and it is still a challenge to detect ammonia rapidly and sensitively. Therefore, an ammonia sensor based on polyaniline composited with reduced graphene oxide wrapped-silicon dioxide microsphere (PANI@rGO@SiO2) is proposed. Firstly, the sensor has fast response/recovery characteristic and the response/recovery time is only 1.09/1.81 s, while its sensing response to 100 ppm ammonia can reach 211%. The supporting effect of SiO2 microsphere can inhibit the stacking of rGO and agglomeration of PANI, providing more adsorption and desorption paths for ammonia. Secondly, the sensor shows high sensitivity of 3.85% ppm−1 in 1–50 ppm ammonia range. The enhanced protonation, high specific surface area and synergistic effect of PANI@rGO@SiO2 can improve its sensitivity. Besides, the sensor has good repeatability, stability and selectivity. As a result, the sensor is used to detect the ammonia released from pig manures and its accuracy is verified by comparing with the commercial detector. Finally, based on the fast response and high sensitivity of the sensor, it realizes the real-time ammonia detection and timely warning in pig house which can provide a reliable method for pig healthy breeding application.

Influence of copper and iron transition metals in the photocatalytic activity of titanium dioxide microspheres

This work proposes the combined sol–gel/solvothermal synthesis method to prepare Cu-doped TiO2 and Fe-doped TiO2 microstructures, and further study their photocatalytic activity in the degradation of Eriochrome Black T (EBT) at neutral conditions using a simulated sunlight source. TiO2:at%M (at%=0.25, 0.5, and 1.0; M = Cu or Fe) catalysts were characterized by X-ray diffractometry, Scanning electron microscopy, Diffuse reflectance UV–Vis spectroscopy, Raman spectroscopy, and Brunauer-Emmett-Teller surface area analysis. All synthesized catalysts showed TiO2 anatase phase with spherical morphology and average particle size of 4 to 8 μm. Transition metal doping did not modify the TiO2 anatase phase. TiO2:at%M catalysts exhibited lower bandgap energies than pure TiO2. TiO2:0.5at%Fe showed the lowest bandgap energy (2.87 eV). TiO2 catalysts with a transition metal content of 0.25at% showed a higher surface area compared to the rest of dopant concentrations. The inclusion of the metallic elements in the TiO2 structure enhances the photocatalytic efficiency of the TiO2 anatase under visible light. TiO2:0.25at%Cu showed the highest EBT degradation yields of 90% color removal, 61% total organic carbon (TOC) reduction, and 87% chemical oxygen demand decrease at 180 min. TiO2:0.25at%Cu and TiO2:0.50at%Fe microspheres retained good degradation efficiency for color and TOC removals even after being reused for three cycles.

Fabrication of Patchy Silica Microspheres with Tailor-Made Patch Functionality using Photo-Iniferter Reversible-Addition-Fragmentation Chain-Transfer (PI-RAFT) Polymerization.

Their inherent directional information renders patchy particles interesting building blocks for advanced applications in materials science. In this study, a feasible method to fabricate patchy silicon dioxide microspheres is demonstrated, which they are able to equip with tailor-made polymeric materials as patches. Their fabrication method relies on a solid-state supported microcontact printing (µCP) routine optimized for the transfer of functional groups to capillary-active substrates, which is used to introduce amino functionalities as patches to a monolayer of particles. Acting as anchor groups for polymerization, photo-iniferter reversible addition-fragmentation chain-transfer (RAFT) is used to graft polymer from the patch areas. Accordingly, particles with poly(N-acryloyl morpholine), poly(N-isopropyl acrylamide), and poly(n-butyl acrylate) are prepared as representative acrylic acid-derived functional patch materials. To facilitate their handling in water, a passivation strategy of the particles for aqueous systems is introduced. The protocol introduced here, therefore, promises a vast degree of freedom in engineering the surface properties of highly functional patchy particles. This feature is unmatched by other techniques to fabricate anisotropic colloids. The method, thus, can be considered a platform technology, culminating in the fabrication of particles that possess locally precisely formed patches on particles at a low µm scale with a high material functionality.

Conformal poly 3,4-ethylene dioxythiophene skin stabilized ε-type manganese dioxide microspheres for zinc ion batteries with high volumetric energy density

Manganese dioxide (MnO2) is an important active material for energy storage. Constructing microsphere-structured MnO2 is key for practical application due to the high tapping density for high volumetric energy density. However, the unstable structure and poor electrical conductivity hinder the development of MnO2 microspheres. Herein, Poly 3,4-ethylene dioxythiophene (PEDOT) is painted conformally on ε-MnO2 microspheres to stabilize the structure and enhance the electrical conductivity via in-situ chemical polymerization. When used for Zinc ion batteries (ZIBs), the obtained material (named MOP-5) with high tapping density (1.04 g cm−3) delivers a superior volumetric energy density (342.9 mWh cm−3) and excellent cyclic stability (84.5% after 3500 cycles). Moreover, we find the structure transformation of ε-MnO2 to ZnMn3O7 during the initial few cycles of charge and discharge, and the ZnMn3O7 provides more reaction sites for Zinc ions from analysis of the energy storage mechanism. The material design and theoretical analysis of MnO2 in this work may provide a new idea for future commercial applications of aqueous ZIBs.

Titanium dioxide microspheres modified with cobalt stearate as a photocatalyst for the degradation of polyethylene films

The degradation of plastics is of great importance due to the ever-increasing concerns of environmental issues. Herein, we report a photocatalyst for the degradation of polyethylene (PE) films, that is, nano titanium dioxide (TiO2) nanoparticles modified with cobalt stearate, which was prepared by sol-gel method and surface modification. Its structure, morphology, and thermal stability were studied by powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. Then the prepared photocatalyst was added to the linear low-density polyethylene (LLDPE) resin, resulting in a novel PE/TiO2 composite film. The effects of the modified TiO2 on the plasticity of PE film and the degradation performance of the composite film under UV irradiation were investigated. The mechanical properties, molecular weight change, and melting index (MFR) of the film were measured. The results revealed that the degradation properties of PE films were significantly improved after the addition of modified nano TiO2 microspheres. Under UV irradiation for 96 h, the tensile elongation retention rate of the composite film dropped to 0. The peak at 1713 cm-1 attributable to the stretching vibration of CO in infrared spectra significantly increased and the weight-average molecular weight (Mw) of the film decreased from 1.2 × 105 g mol-1 to 0.85 × 104 g mol-1. The melt flow rate was enhanced to 194.2 g/10 min. These results suggest that the present modified TiO2 could be utilized as a promising photocatalyst candidate for the degradation of plastics.

New Method for Measuring the Scattering Phase Function of Micron/Nano Particles

The scattering phase function is crucial to analyze the light transport in the micron/nano particle suspensions. A new method including a liquid–particle system and reference system is proposed to measure the scattering phase function of the liquid–particle suspensions. In this method, a reference system of a standard particle is used to obtain the correction factor to compensate for the influence of the cuvette. Experimental validation was conducted for monodisperse silicon dioxide microspheres and monodisperse polystyrene microspheres. By considering the influence of the cuvette, both theoretical and experimental analyses prove that the proposed method can achieve a good result in the measurement of the scattering phase function of liquid–particle suspensions for particles with unknown size parameters and optical constants, especially when the size parameter of the particle is larger than 10. The correction factors of scattering light distribution of silicon dioxide microsphere suspensions with various mean particle sizes were obtained and analyzed. This method provides an alternative and simple way of measuring the scattering phase function of micron/nano particle suspensions.

Exploration of the Simple and Green Synthetic Route of Hollow Titanium Dioxide Microspheres for In-Depth Analysis of Phosphopeptides in the Serum of Nasopharyngeal Carcinoma Patients

Exploration of the Simple and Green Synthetic Route of Hollow Titanium Dioxide Microspheres for In-Depth Analysis of Phosphopeptides in the Serum of Nasopharyngeal Carcinoma Patients

Enhancement of titanium dioxide microspheres doped with transition metals: Characterization and photocatalytic evaluation

Enhancement of titanium dioxide microspheres doped with transition metals: Characterization and photocatalytic evaluation

Bioinspired Composite Hydrogel‐Coated Stainless Steel Screen for Efficient and Stable Gravity‐Driven Oil–Water Separation

The reasonable and efficient treatment of oily wastewater has attracted wide attention. Herein, a composite hydrogel‐modified filter screen, inspired by fish scales and marine mussels, is prepared via layer‐by‐layer modification to separate oil–water mixture even in harsh environments. First, a stainless steel filter screen is coated by a layer of silicon dioxide (SiO2) microspheres by the vapor deposition of polydimethylsiloxane. Then, a SiO2@polydopamine‐polyacrylamide composite hydrogel (SiO2@P–PGel)‐modified screen is prepared by dipping the screen into a prepolymer solution. Due to the special wettability and micronanostructures, the stable and high efficient water permeation in the air and oil repellency in water are achieved by the screen. A very effective oil–water separation rate of over 99% can be achieved for various types of oil–water mixtures. The separation efficiency and water flux remain stable even after 70 cycles. Another significant feature of the innovative screen is that it displays excellent underwater superoleophobicity in very salty, acidic, and alkaline solutions, suggesting that the screen has excellent oil–water separation performance and stability, even in corrosive aqueous media. This innovative screen is a potentially attractive candidate for the treatment and recovery of oily wastewater due to its high efficiency and stability.

Synthesis of Dual-Response MnO2 Nanospheres as Multifunctional Drug Carriers

Recently, hollow structures have attracted much attention due to their high specific surface area, clear interior space, low density and good permeability. Among them, manganese dioxide (MnO2) hollow structure has also been widely studied for catalysis, drug delivery and energy storage. Based on the characteristics of low pH and high GSH concentration in tumor microenvironment, it is possible to develop an intelligent drug delivery system with pH/GSH response based on hollow mesoporous MnO2 nanospheres. In addition, the excellent physical and chemical properties of MnO2 nanomaterials provide conditions for its synergistic photothermal therapy. For example, Mn2+ released after manganese dioxide reacts with GSH can enhance T1-MAGNETIC resonance (MR) imaging. Meanwhile, manganese dioxide can also react with H2O2 in tumor microenvironment to release oxygen and alleviate tumor hypoxia. In order to prevent drug loss during delivery, a GSH-responsive hollow mesoporous manganese dioxide microsphere was selected as the drug carrier in this paper, and a series of studies were carried out on the performance of the carrier. Hollow mesoporous MnO2 nanospheres with particle size below 100 nm were prepared by hydrothermal method, and their response to tumor microenvironment was simulated in vitro. It has been proved that hollow mesoporous MnO2 nanospheres can be desorbed at low pH and GSH response, and can be used to deliver drugs or photothermal agents, as well as for collaborative cancer imaging and treatment.

An effective Z-scheme hybrid photocatalyst based on zinc porphyrin derivative and anatase titanium dioxide microsphere for carbon dioxide reduction

Photocatalysis is considered as one of the most promising technologies to convert carbon dioxide (CO2) into high-valued chemicals. Herein, a novel hybrid photocatalyst for effectively catalyzing CO2 reduction reaction (CO2RR) is synthesized using zinc(II)-tetra-(4-pyridyl) porphyrin (ZnPy4) and MnOx-decorated anatase titanium dioxide (TiO2) microspheres (Mn/AMS) as raw materials. The resultant ZnPy4-Mn/AMS hybrid material exhibits excellent photocatalytic CO2RR performance with methane (CH4)/ carbon monoxide (CO) yields of 44.1/20.9 μmol/(g∙h) and an overall photo-activity of 394.6 μmol/(g∙h), 6.5 times higher than that of anatase TiO2 microsphere (AMS) alone. The effects of ZnPy4/MnOx species on the light absorption, photo-induced charge separation, photo-electrochemical behavior, adsorption/activation capacity of reactants (CO2/H2O) and photocatalytic CO2RR performance of the AMS were studied, and it is found that a direct Z-scheme charge transfer mechanism proceeds in the hybrid material via H-bonding formed between the ZnPy4 and Mn/AMS components to boost the photocatalytic CO2RR activity. These results present an effective strategy for fabricating high-performance artificial photosynthesis for solar-driven CO2 conversion via the hybridization of semiconductor with porphyrin derivative.

In-situ growth of N@MoO2 microflowers on carbon cloth for high-performance anodes in microbial fuel cells

Anode is a crucial component enabling microbial fuel cells (MFCs) to achieve efficient and durable power generation; however, the preparation of high-performance and up-scaling anodes via facile methods remains a practical challenge. In this study, a nitrogen-doped carbon cloth grafted with molybdenum dioxide microspheres (N @ MoO2/CC) was fabricated using a facile two-step method: in situ polymerization and high-temperature carburization. N @ MoO2/CC exhibited excellent bioelectricity harvesting capacity owing to its dual function of promoting bacterial colonization while enriching electroactive bacteria. The synergy of N-doping and MoO2-grafting enabled the development of a biocompatible interface for bacterial adhesion, resulting in a high bacterial loading capacity. Furthermore, N-doping and MoO2-grafting modifications facilitated the enrichment of Geobacter, thereby enhancing the electrocatalytic activity of the electrode. MFC equipped with N @ MoO2/CC achieved a maximum power density of 3.01 ± 0.23 W·m−2, i.e., 1.43 times the power density achieved using a pristine carbon cloth (2.10 ± 0.04 W·m−2). Additionally, the physical and electrochemical characterizations confirmed that the as-prepared N @ MoO2/CC exhibited excellent operational stability. In summary, N @ MoO2/CC could significantly enhance bacterial colonization, enable electroactive bacteria to flourish, and boost charge transfer efficiency at the microbe–electrode interface, thus improving the electricity generation in MFCs.

Roll-to-roll processed silver nanowire/silicon dioxide microsphere composite for high-accuracy flexible touch sensing application

Economical accurate resistive touch sensing panels (TSPs) is fabricated by means of full roll-to-roll (R2R) slot-die coating process. The fabricated TSPs have silver nanowire (Ag NW) random network and uniformly distributed silicone dioxide microspheres (SiO2 MSs) as conducting layer and spacer, respectively. The transparent conductive composite film of Ag NW and SiO2 MSs were R2R coated simultaneously on the flexible substrate, which simplified the manufacturing process. The parametric study was conducted by regulating the diameter and concentration of the SiO2 coating solution. The touch sensing performance was characterized by comparing output images qualitatively and by computing precision and accuracy from output images in response to reference input image. As results, R2R coated SiO2 MSs played a role of space successfully and touch sensing performance was improved with diameter of larger than 1000 nm and concentration of around 1 wt%. Furthermore, multi-functional TSP was fabricated with optimized coating condition and demonstrated to yield various operations in response to touch behavior.

Can Manganese Dioxide Microspheres be Used as Intermediaries to Alleviate Intervertebral Disc Degeneration With Strengthening Drugs?

Degenerative disc disease (DDD) is a pathological condition associated with intervertebral discs (IVDs) that causes chronic back pain. IVD degeneration has become a significant issue in contemporary society. To date, numerous biological therapies have been applied to alleviate the progression of DDD, among which therapeutic protein injection is the most direct and convenient. However, there are some limitations to applying direct protein injection therapy, the most significant being that the efficacy of this method has a short duration, which is a major factor in its effectiveness and the resulting patient satisfaction. How do we solve this problem? Or how can the effectiveness of the treatment be enhanced? It has been proved that manganese dioxide (MnO2) microspheres, widely used in environmental science, not only regulate the expression of cell genes and cytokines in the microenvironment, but also have the ability to release drugs slowly. We propose that direct injection of protein encapsulated in hollow MnO2 (h-MnO2) microspheres could solve the problem of rapid drug release. In addition, the use of a MnO2 and protein injection in the treatment of DDD may have a synergistic effect, which would be highly significant for the degradation of pro-inflammatory factors in the DDD microenvironment. Therefore, the combination of MnO2 and protein may provide a new therapeutic approach to alleviate the progression of DDD.

Hollow urchin-shaped manganese dioxide microspheres immobilized acetylcholinesterase for rapid screening inhibitors from traditional herbal medicines

Acetylcholinesterase (AChE) is generally considered to be a valuable therapeutic target for Alzheimer's disease (AD). To rapidly screen novel AChE inhibitors from Traditional Chinese medicines (TCMs), polydopamine (PDA) coated hollow urchin-shaped manganese dioxide microspheres (h-MnO2@PDA) were fabricated in this work. AChE was immobilized onto the surface of h-MnO2@PDA for the first time, and the prepared h-MnO2@PDA immobilized AChE coupled with capillary electrophoresis (CE) was applied to AChE inhibitor screening. The enzyme catalytic activity and kinetic performances of the immobilized AChE were determined by measuring the peak areas of 5-thio-2-nitrobenzoic acid (TNB), which was produced by the reaction of thiocholine (TCh) with 5,5-dithiobis-(2-nitrobenzoic acid) (DTNB). Inhibition kinetics for the immobilized AChE was performed by employing huperzine A as model inhibitor, and its inhibition constant and IC50 were determined. The constructed AChE immobilized h-MnO2@PDA presented outstanding pH, thermal and storage stability. Ultimately, the constructed strategy was applied to screen AChE inhibitors from 7 TCMs and Schisandrae Chinensis Fructus was screened out for its superior AChE inhibitory activity. Therefore, our work not only established a platform for efficiently screening novel AChE inhibitors from TCMs, but also provided inspiration for further exploration of Schisandrae Chinensis Fructus as a potential drug for AD.