Zinc Oxide Microspheres Research Articles

Enhanced photocatalytic performance of SnS2/ZnO Z-scheme composite photocatalysts for efficient environmental remediation

Photocatalysts based on zinc oxide (ZnO) are promising for environmental applications, but their weak photoresponse and low photocarrier separation efficiency limit their practical use. To tackle this issue, we constructed Z-scheme composite photocatalysts of ZnO to boost its photocatalytic performance. We achieved the Z-scheme structure by hydrothermal modification of SnS2 nanoparticles onto ZnO microspheres. Its photocatalytic performance was evaluated through the degradation of Rhodamine B (RhB) under visible light with the assistance of magnetic stirring. The composite photocatalyst exhibited superior performance compared to individual ZnO and SnS2, achieving an optimal degradation rate of 0.0706 min⁻¹. This rate was 15.08 times higher than that of individual ZnO and 10.51 times higher than individual SnS2. Free radical trapping experiments showed that ·O2⁻ and ·OH radicals played a key role in RhB degradation. The Z-scheme composite structure established novel charge transport pathways, guided the migration of photogenerated carriers, and improved spatial separation, thereby enhancing photocatalytic performance. This study provides valuable insights into the design of highly efficient photocatalysts for environmental remediation, offering a promising solution for addressing challenges in pollution control and wastewater treatment.

Biomimetic Nanozyme-Decorated Smart Hydrogel for Promoting Chronic Refractory Wound Healing.

Chronic refractory wounds have become a serious threat to human health and are characterized by prolonged inflammation, recurrent bacterial infections, and elevated ROS levels. However, current therapeutic strategies usually target a unilateral healing function and are unable to tackle the complexity and sensitivity of chronic refractory wound healing. This study fabricated a biomimetic nanozyme based on rhein (Cu-rhein NSs), which effectively mimics the activity of superoxide dismutase (SOD) for scavenging various free radicals. Additionally, zinc oxide microspheres (ZnO MSs) were prepared to enhance the antibacterial activity and mechanical properties of the modified hydrogel. Cu-rhein NSs and ZnO MSs were comodified onto an extracellular matrix-mimetic dual-network smart hydrogel constructed from oxidized sodium alginate, gelatin, and borax via dynamic borate and Schiff base bonds. The smart hydrogel presented the good biocompatibility and targeted the unique acidic microenvironment with high oxidative stress of chronic refractory wounds, intelligently releasing bionic nanozymes to effectively eliminate bacteria, reduce inflammatory responses, and scavenge multiple free radicals for reducing ROS. In vivo experiments on the rat model based on diabetic infection showed that the smart hydrogel could effectively eliminate bacteria, promote vascular regeneration and collagen deposition, reduce inflammatory response, and accelerate the healing of diabetic-infected wounds (almost complete healing within 14 days). The advantages of an intelligent, biomimetic tissue regeneration cascade management strategy against diabetic infected wound healing are highlighted.

Boolean Circuits in Colloidal Mixtures of ZnO and Proteinoids.

Liquid computers use incompressible fluids for computational processes. Here, we present experimental laboratory prototypes of liquid computers using colloids composed of zinc oxide (ZnO) nanoparticles and microspheres containing thermal proteins (proteinoids). The choice of proteinoids is based on their distinctive neuron-like electrical behavior and their similarity to protocells. In addition, ZnO nanoparticles are chosen for their nontrivial electrical properties. Our research demonstrates the successful extraction of 2-, 4-, and 8-bit logic functions in ZnO proteinoid colloids. Our analysis shows that each material has a distinct set of logic functions and that the complexity of the expressions is directly related to each material present in a mixture. Our study shows that 2-, 4-, and 8-bit logic functions can be successfully extracted from ZnO proteinoid colloids. These findings provide a basis for the development of future hybrid liquid devices capable of general-purpose computing.

Enhanced Photocatalytic Degradation of Rhodamine B Using ZnO Microspheres Decorated with Ag Nanoparticles

Zinc oxide (ZnO) has demonstrated significant potential as a photocatalyst for the wastewater treatment. However, its wide bandgap leads to inefficient light utilization and rapid carrier recombination, which inhibits its photocatalytic activity. To overcome these limitations, we employed a hydrothermal method to synthesize Ag/ZnO composite microspheres with different concentrations of Ag nanoparticles. By utilizing Ag complexed with ZnO, the Ag/ZnO composite photocatalysts were made to have a narrower bandgap and a broadened light response range, as well as the red-shift phenomenon at the absorption edge. In addition, Ag nanoparticles can act as electron traps to efficiently capture electrons and minimize the recombination of photoexcited carriers for improved photocatalytic performance. Compared with other concentrations of ZnO microspheres and pure ZnO microspheres, the 5% Ag/ZnO composite microspheres exhibited excellent degradation performance when exposed to a xenon lamp, with 90.1% degradation of rhodamine B (RhB) solution in 100[Formula: see text]min. Incorporating trapping agents in experimental studies has indicated that the RhB degradation process is significantly influenced by •O[Formula: see text], while the impact of •OH and h[Formula: see text] were relatively weak. Thus, Ag/ZnO nanocomposites hold great promise as materials for use in wastewater treatment.

Self-powered TENG probe for scanning surface charge distribution

Triboelectric nanogenerators are remarkable devices that show great potential in harvesting energy from mechanical work and are generally used for sensing purposes. Here we report a novel method for the fabrication of ZnO microspheres and the formation of TENG based on ZnO/PDMS composite. The zinc oxide microspheres with needle decorated structure via thermal oxidation of metallic zinc was grown at 500 °C. The TENG was then fabricated using ZnO/PDMS composite with Au sputtered electrode. While PDMS is a good triboelectric material, its output power density is low. Embedding ZnO micro/nanostructures in PDMS increases the output power of PDMS-based TENG manifolds. ZnO with a high dielectric constant exhibits semiconductor properties as well as piezoelectric properties. This combines with the triboelectric properties of PDMS and gives a significant boost to the TENG performance. This composite structure is used for the fabrication of high output power density TENG using contact separation mode, where the power density of 27Wm−2 was achieved. Consequently, a novel device application to detect surface charge density through the fabricated TENG is reported and the subsequent reconstruction of surface charge topology based on the detected surface charge density on large surfaces is presented. This technique may be used for the study of surface charge morphology, electrostatics, triboelectric constants, and various other material properties for characterization and application purposes.

Injective Programmable Proanthocyanidin-Coordinated Zinc-Based Composite Hydrogel for Infected Bone Repair.

Effectively integrating infection control and osteogenesis to promote infected bone repair is challenging. Herein, injective programmable proanthocyanidin (PC)-coordinated zinc-based composite hydrogels (ipPZCHs) are developed by compositing antimicrobial and antioxidant PC-coordinated zinc oxide (ZnO) microspheres with thioether-grafted sodium alginate (TSA), followed by calcium chloride (CaCl2 ) crosslinking. Responsive to the high endogenous reactive oxygen species (ROS) microenvironment in infected bone defects, the hydrophilicity of TSA can be significantly improved, to trigger the disintegration of ipPZCHs and the fast release of PC-coordinated ZnOs. This together with the easily dissociable PC-Zn2+ coordination induced fast release of antimicrobial zinc (Zn2+ ) with/without silver (Ag+ ) ions from PC-coordinated ZnOs (for Zn2+ , > 100 times that of pure ZnO) guarantees the strong antimicrobial activity of ipPZCHs. The exogenous ROS generated by ZnO and silver nanoparticles during the antimicrobial process further speeds up the disintegration of ipPZCHs, augmenting the antimicrobial efficacy. At the same time, ROS-responsive degradation/disintegration of ipPZCHs vacates space for bone ingrowth. The concurrently released strong antioxidant PC scavenges excess ROS thus enhances the immunomodulatory (in promoting the anti-inflammatory phenotype (M2) polarization of macrophages) and osteoinductive properties of Zn2+ , thus the infected bone repair is effectively promoted via the aforementioned programmable and self-adaptive processes.

Facile fabrication of SiC/ZnO composite and its enhanced sensitivity for detection of NO

Zinc oxide (ZnO) is an attractive material for gas sensors, and various ZnO-based sensors have been developed to detect gas pollution. In this work, a series of SiC/ZnO composites were fabricated by incorporating silicon carbide nanocrystals (SiC NCs) into ZnO microspheres by a grinding method. The SiC/ZnO composite exhibited a significantly enhanced gas sensitivity response toward NO gas in comparison to ZnO. The test revealed that the response of the composite was 251.1 for 100 ppm of nitrogen monoxide (NO), and the detection limit was as low as 100 ppb. Through spectral and comparative analyses, it has been indicated that the active functional groups of the SiC NCs have a substantial impact on the detection of NO, and the corresponding mechanism is studied and discussed. This work offers a simple strategy for the fabrication of SiC/ZnO material with enhanced sensitivity in sensing applications.

Construction of ZnSe protective layer on zinc oxide for ultra-stable cycling of zinc-nickel batteries at high rates

Zinc anodes suffer from self-corrosion, deformation and dendrite growth, which greatly limit the commercial application of zinc-nickel batteries. For this purpose, zinc oxide microspheres with porous surfaces are synthesized by a simple hydrothermal method, and ZnSe protective layer is constructed on their surfaces. The uniform coverage of ZnSe improves the corrosion resistance of the anode material and alleviates the polarization phenomenon during the cycle, thus ensuring the stability of the electrode material. Moreover, the prominent specific surface area optimizes the interface contact between anode and electrolyte, improving the ion transport efficiency while homogenizing the current distribution around the interface. Therefore, the discharge specific capacity of ZnO@ZnSe electrode can still reach 577.5 mAh·g−1 after 1460 cycles at a high rate. There is almost no attenuation compared with the initial discharge capacity, demonstrating an extremely excellent electrochemical performance.

Degradation of methylene blue and rhodamine B by hollow ZnO microspheres formed of radially oriented nanorods

It is crucial to find effective solutions to environmental contamination that are also ecologically friendly. Zinc oxide (ZnO) is well-known as a good photocatalyst. In this work, ZnO microspheres were synthesized using the solvothermal technique. X-ray diffraction (XRD), UV-Vis, and scanning electron microscopy(SEM) were used to evaluate the structural, optical, and morphological features of ZnO microspheres . The hexagonal structure of ZnO was determined using XRD analysis. The crystal size of ZnO was calculated using XRD patterns and was found to be 44.27 nm by the Debye-Scherrer equation, 32.39 nm using the Williamson Hall model, and 9.92 nm by the Modified Scherrer formula. The SEM pictures of the manufactured ZnO revealed that it has a shape in the form of microspheres formed by the conjunction of hexagonal nanorods. The average diameter of these microspheres is 5.16 μm. ZnO has a band gap energy of 3.1 eV. The photocatalytic activities of ZnO microspheres against methylene blue and Rhodamine B dyes were examined. Under sunlight, photocatalytic removal rates for methylene blue after 90 minutes and Rhodamine B after 120 minutes were 98.95% and 98.62%, respectively.

Demonstrating the In Vitro and In Situ Antimicrobial Activity of Oxide Mineral Microspheres: An Innovative Technology to Be Incorporated into Porous and Nonporous Materials.

The antimicrobial activity of surfaces treated with zinc and/or magnesium mineral oxide microspheres is a patented technology that has been demonstrated in vitro against bacteria and viruses. This study aims to evaluate the efficiency and sustainability of the technology in vitro, under simulation-of-use conditions, and in situ. The tests were undertaken in vitro according to the ISO 22196:2011, ISO 20473:2013, and NF S90-700:2019 standards with adapted parameters. Simulation-of-use tests evaluated the robustness of the activity under worst-case scenarios. The in situ tests were conducted on high-touch surfaces. The in vitro results show efficient antimicrobial activity against referenced strains with a log reduction of >2. The sustainability of this effect was time-dependent and detected at lower temperatures (20 ± 2.5 °C) and humidity (46%) conditions for variable inoculum concentrations and contact times. The simulation of use proved the microsphere's efficiency under harsh mechanical and chemical tests. The in situ studies showed a higher than 90% reduction in CFU/25 cm2 per treated surface versus the untreated surfaces, reaching a targeted value of <50 CFU/cm2. Mineral oxide microspheres can be incorporated into unlimited surface types, including medical devices, to efficiently and sustainably prevent microbial contamination.

Double-shell ZnO hollow microspheres prepared by template-free method for ethanol detection

Oxide semiconductors with multi-shell hollow architecture are considered favorable candidates as sensing materials for applications in high-performance gas sensors. Herein, the solid, core-shell, and double-shell zinc oxide (ZnO) microspheres were successfully prepared via a facile template-free method. Compared with solid and core-shell spheres, the gas sensor based on double-shell sphere exhibited the highest response to 100 ppm ethanol at 275 °C (∼ 47.4), which was about 4.8-fold higher than that of the solid sphere (∼ 9.8) under the same conditions. Furthermore, the detection limit of the double-shell ZnO microsphere could reach 1 ppm. The enhancement mechanism of the ethanol gas-sensing performance was systematically discussed.

Co-doped zinc oxide microspheres as photocatalysts for enhanced uranium extraction

Co-doped zinc oxide microspheres as photocatalysts for enhanced uranium extraction

Ultrasensitive flexible ultraviolet detectors based on electrochemically deposited ZnO microspheres synthesized by the assembly of nanoplatelets

Zinc oxide microspheres synthesized by the assembly of nanoplatelets have been deposited on seeded polycarbonate substrates using the electrochemical deposition technique with the assistance of glycerol. An electrochemical cell with platinum mesh as anode and the seeded substrates as cathode was employed to deposit ZnO microspheres. A computer-controlled potentiostat was used to supply sufficient current for the growth of ZnO nanoplatelets. Zinc chloride was used as a Zn source, and glycerol was applied to assist in the formation of microspheres. The average diameter of formed microspheres was 4 µ m, and the average size of nanoplatelets that formed the microspheres was a few nanometers. The morphology of the nanostructures indicated the formation of ZnO nanoplatelets with various orientations, which can significantly increase the entrapment of incident photons. X-ray diffraction analysis showed a dominant peak related to (002) as a reflection corresponding to the hexagonal ZnO structure. The enhanced photoluminescence (PL) intensity revealed improvement in the light-capturing ability due to the multiple scattering of light in the nanostructures. The quantum confinement phenomenon in the ZnO crystallites was evident from the blue shift of the PL peak position. A flexible photodetector was fabricated using the metallization of ZnO nanostructures to investigate the capability of ZnO microspheres in light sensing. The optoelectrical properties of fabricated devices were tested under ultraviolet radiation. The devices based on ZnO microspheres exhibited high sensitivity to the incident photons and showed stable photoelectric behavior under various bending conditions. • Zinc oxide microspheres were synthesized by the assembly of nanoplatelets • The role of glycerol in the aggregation of ZnO nanoplatelets was investigated • The improved PL properties of microspheres revealed enhanced light-capturing ability • Flexible photodetectors were fabricated based on ZnO microspheres and nanoplatelets • The ZnO spheres showed stable photoelectric behavior under various bending conditions

Fabrication of a waste cotton fabrics-based nanosystem for simultaneous removal of Cu(II) and Pb(II)

Herein, a waste cotton fabrics-based nanosystem was fabricated to simultaneously remove copper (Cu(II)) and lead ions (Pb(II)) from water and soil. Therein, carboxyl-functionalized zinc oxide microsphere (ZnO–COOH) with peanut shape was carried by cotton fabric (CF) to get CF/ZnO–COOH nanosystem. CF/ZnO–COOH with a good foldable property possessed a high removal capacity for Cu(II) and Pb(II) via electrostatic attraction and chelation. The result indicated that their removal efficiencies of CF/ZnO–COOH could reach over 95% after 2 h. The adsorption process was consistent with Langmuir (R2 = 0.9905 of Cu(II) and R2 = 0.9846 of Pb(II)) and pseudo-second-order kinetic models (R2 = 0.9999 of Cu(II) and R2 = 0.9999 of Pb(II)). The thermodynamic data showed that the adsorption process was spontaneous and exothermic. Additionally, CF/ZnO–COOH also possessed a high fixation ability for Cu(II) and Pb(II) in sand-soil column, especially for Pb(II) (15 cm, 0.4 μg kg−1). Therefore, this wok provides an environmentally friendly and efficient way to remove Cu(II) and Pb(II) from water and soil concurrently.

Oxygen vacancies-enriched and porous hierarchical structures of ZnO microspheres with improved photocatalytic performance

Controlling the morphology and surface defects is an effective strategy for enhancing photocatalytic performance. In this paper, we have successfully prepared zinc oxide (ZnO) microspheres with oxygen vacancies-enriched and porous hierarchical structures by hydrothermal annealing. The porous hierarchical structure of the ZnO microspheres was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and other analytical techniques, and their photocatalytic properties were studied by the decomposition of methylene blue, tetracycline and phenol in condition simulated sunlight. The porous hierarchical structure of ZnO–SO42- microspheres showed higher photocatalytic activity compared to ZnO–Cl- and ZnO–NO3- (ZnO from different sources of zinc as ZnO-X, where X is SO42−, Cl− and NO3−, respectively.). Under sunlight, the photocatalytic removal rates of methylene blue, tetracycline and phenol by ZnO–SO42- were 98%, 100% and 83%, respectively. Meanwhile, the photoelectrochemical tests showed that the porous hierarchical structures of ZnO–SO42- microspheres had the best photocurrent response and the lowest charge transfer resistance. After five cycles of photocatalytic degradation of phenol, the synthesized ZnO microspheres also showed good durability and stability. In addition, superoxide radicals (•O2−) and hydroxyl radicals (•OH) were identified as the active species by the trapping experiments. This study showed that the improvement of photocatalytic performance of ZnO microspheres could be owing to abundant oxygen vacancies and the porous hierarchical structures.

Enhanced treatment of organic matter in slaughter wastewater through live Bacillus velezensis strain using nano zinc oxide microsphere

Slaughter wastewater is an important and wide range of environmental issues, and even threaten human health through meat production. A high efficiency and stability microsphere-immobilized Bacillus velezensis strain was designed to remove organic matter and inhibit the growth of harmful bacteria in process of slaughter wastewater. Bacillus velezensis was immobilized on the surface of sodium alginate (SA)/Polyvinyl alcohol (PVA)/Nano Zinc Oxide (Nano-ZnO) microsphere with the adhesion to bio-carrier through direct physical adsorption. Results indicated that SA/PVA/ZnO and SA/ZnO microspheres could inhibit E.coli growth with adding 0.15 g/L nano-ZnO and not affect Bacillus velezensis strain, and the removal the chemical oxygen demand (COD) rates of SA/PVA/ZnO microsphere immobilized cells are 16.99%, followed by SA/ZnO (13.69%) and free bacteria (7.61%) from 50% concentration slaughter wastewater within 24 h at 37 °C, pH 7.0, and 120 rpm, a significant difference was found between the microsphere and control group. Moreover, when the processing time reaches 36 h, COD degradation of SA/PVA/ZnO microsphere is obviously higher than other groups (SA/PVA/ZnO:SA/ZnO:control vs 18.535 : 15.446: 10.812). Similar results were obtained from 30% concentration slaughter wastewater. Moreover, protein degradation assay was detected, and there are no significant difference (SA/PVA/ZnO:SA/ZnO:control vs 35.4 : 34.4: 36.0). The design of this strategy could greatly enhance the degradation efficiency, inhibit the growth of other bacteria and no effect on the activity of protease in slaughter wastewater. These findings suggested that the nano-ZnO hydrogel immobilization Bacillus velezensis system wastewater treatment is a valuable alternative method for the remediation of pollutants from slaughter wastewater with a novel and eco-friendly with low-cost investment as an advantage.

Ultra-highly sensitive detection of ppb-level acetone gas using novel multicore-shell porous zinc oxide microspheres

In this study, novel multicore-shell ZnO microspheres were synthesized via a simple solvothermal method based on the coordination of salicylic acid under the protection of polyvinylpyrrolidone (PVP). In this process, as an organic acid, salicylic acid with a benzene ring structure rich in hydroxyl and carboxyl functional groups can not only play a structure-oriented role, but also can etch materials to form a hollow structure. Compared with traditional basic synthesis methods, the diversity of coordination forms makes the structure more abundant. The multicore-shell ZnO was annealed at 450, 600, and 750 °C respectively. Under the driving force of reducing the surface free energy, part of the multi-nucleus inside the microspheres aggregated to form large particles, and the other part adhered to the shell layer to grow. The crystallinity, morphology and surface composition of the ZnO microspheres were characterized by XRD, SEM, TEM, XPS, BET and FT-IR analyses. The multicore-shell ZnO-based sensor that exhibited excellent sensitivity to acetone (2 ppm, SRa/Rg = 8.6) at an optimal working temperature of 240 °C, with a low limit of detection of 100 ppb with a SRa/Rg = 2.9. The annealed ZnO-based sensors also performed well, among them, the product annealed at 750 °C (ZnO-750) is the best, with a response of 6.4 to 2 ppm acetone. The sensors exhibited satisfactory selectivity and can detect acetone in the presence of other interfering gases, including NO, CO, NH3, HCHO, CH3OH and C2H5OH. The outstanding sensitivity of the multicore-shell ZnO sensor to acetone can be attributed to its large specific surface area and pore volume, which favors gas adsorption, penetration and diffusion. For the annealed ZnO, we speculated that the specific exposed crystal plane (002) plays a decisive role in the good adsorption and reaction of acetone.

Shaped-controlled growth of sphere-like ZnO on modified polyester fabric in water bath

A modified polyester fabric (MPF) was successfully coated with a sphere-like zinc oxide (ZnO) microstructures in water bath. The characterization of the finished fabric was carried out using SEM, XRD and EDS. UV–vis spectrophotometry was investigated for the UV-blocking property of the as-obtained sample, as well as the photocatalytic behaviour of ZnO/MPF radiated under UV-light. The findings revealed the excellent demonstration of the photocatalytic and UV-blocking properties of ZnO/MPF. The ZnO microspheres were successfully grown on the MPF, with about 87% degradation rate of Methylene blue (MB) under UV light irradiation for the duration of 60 min. The UPF of ZnO/MPF was 170.3. The strong bond existing between Zno/MPF ensured that it still retained its perfect photocatalytic and UV- blocking potential after been washed 10 times.

Rhodamine B Doped ZnO Monodisperse Microcapsules: Droplet-Based Synthesis, Dynamics and Self-Organization of ZnO Nanoparticles and Dye Molecules.

In the present work, droplet-based microfluidics and sol-gel techniques were combined to synthesize highly monodisperse zinc oxide (ZnO) microspheres, which can be doped easily and precisely with dyes, such as rhodamine B (RhB), and whose size can be finely tuned in the 10–30 μm range. The as-synthesized microparticles were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and confocal microscopy. The results reveal that the microspheres exhibit an excellent size monodispersity, hollow feature, and a porous shell with a thickness of about 0.6 μm, in good agreement with our calculations. We show in particular by means of fluorescence recovery after photobleaching (FRAP) analysis that the electric charges carried by ZnO nanoparticles primary units play a crucial role not just in the formation and structure of the synthesized ZnO microcapsules, but also in the confinement of dye molecules inside the microcapsules despite a demonstrated porosity of their shell in regards to the solvent (oil). Our results enable also the measurement of the diffusion coefficient of RhB molecules inside the microcapsules ( cm/s), which is found two order of magnitude smaller than the literature value. We attribute such feature to a strong interaction between dye molecules and the electrical charges carried by ZnO nanoparticles. These results are important for potential applications in micro-thermometry (as shown recently in our previous study), photovoltaics, or photonics such as whispering gallery mode resonances.

Mn-doped ZnO microspheres as cathode materials for aqueous zinc ion batteries with ultrastability up to 10 000 cycles at a large current density

Recently, aqueous zinc-ion batteries (ZIBs) are highly attractive due to high specific capacity of Zn, low-cost and safety, but the weak reaction kinetics and fast capacity attenuation still remain challenging. Herein, we adopt a temperature-regulation method to prepare rough Mn-doped zinc oxide microspheres. Such microsphere structure is rich in superfine nanoparticles and internal mesopores, which offers more Zn2+ diffusion channels and alleviates the stress and strain in the electrochemical process. Meanwhile, the doping of Mn into the ZnO structure can not only adjust the electronic structure, but also enhance the electrical conductivity, thereby upraising the reaction kinetics. Applied to ZIBs cathode, Mn-doped ZnO material presents appreciable rate performance, which obtains 268.1 mA h g−1 at 1 A g−1 and retains 163.8 mA h g−1 at 5 A g−1. Most importantly, high energy density (206.9 Wh kg−1), power density (6896.7 W kg−1) and superior cycle durability (~146.7% after 10 000 cycles relative to the first cycle) endow this material with more potential in energy storage.