Dioxide Hybrid Research Articles

Terahertz metamaterials for broadband, high modulation depth modulator, and tunable dual-band absorber based on metal-vanadium dioxide hybrid structure

Terahertz metamaterials for broadband, high modulation depth modulating, and tunable dual-band absorbing are designed based on the similar composite structure of metal and vanadium dioxide film arrays. By using external excitation to induce the insulator-metal phase transition of the vanadium dioxide layer, the transmission characteristics of the metamaterial can be manipulated. High modulation depths of more than 80% are achieved in the range of 0.2–0.8 THz, and the bandwidth width with modulation depths exceeding 60% is up to 140%. By increasing the dielectric thickness and adding a metal ground, the initial broadband modulator can be switched to a dual-band absorber when the vanadium dioxide is in the metal phase. Furthermore, the modulation effect and the absorption performance exhibit insensitive characteristics to the polarization angle of incident waves. This work provides potential applications in broadband modulation of terahertz communication as well as dual-band absorption for terahertz detection.

Comparative Study of ZnO-and-TiO2-Nanoparticles-Functionalized Polyvinyl Alcohol/Chitosan Bionanocomposites for Multifunctional Biomedical Applications.

This study aimed to synthesize chitosan/polyvinyl alcohol (CS/PVA)-based zinc oxide (ZnO) and titanium dioxide (TiO2) hybrid bionanocomposites (BNCs) and observe their comparative accomplishment against the skin cancer cell line, A431, and antioxidant potential. CS was blended with PVA to form polymeric films reinforced with the immobilization of ZnO and TiO2 nanoparticles (NPs), separately. The optimization of the BNCs was done via physicochemical studies, viz. moisture content, swelling ratio, and contact angle measurements. The free radical scavenging activity was observed for 1,1-diphenyl-2-picryl-hydrazyl, and the antibacterial assay against the Escherichia coli strain showed a higher zone of inhibition. Furthermore, the anticancer activity of the synthesized BNCs was revealed against the skin cancer cell line A431 under varying concentrations of 50, 100, 150, 200, and 300 μg/mL. The anticancer study revealed a high percent of cancerous cell inhibition (70%) in ZnO BNCs as compared to (61%) TiO2 BNCs in a dose-dependent manner.

Preparation of Polyacrylamide Titanium Dioxide Hybrid Nanocomposite by Direct Polymerization and Its Applicability in Removing Crystal Violet from Aqueous Solution

Preparation of Polyacrylamide Titanium Dioxide Hybrid Nanocomposite by Direct Polymerization and Its Applicability in Removing Crystal Violet from Aqueous Solution

Multi-functional silver nanoprism-titanium dioxide hybrid nanoarrays for trace-level SERS sensing and photocatalytic removal of hazardous organic pollutants

Owing to the excellent optoelectronic properties of metal nanoparticle-semiconductor interfaces; hybrid substrates with superior catalytic and sensing properties can be designed. In the present study, we have attempted to evaluate anisotropic silver nanoprisms (SNP) functionalized titanium dioxide (TiO2) particles for multifunctional applications such as SERS sensing and photocatalytic decomposition of hazardous organic pollutants. Hierarchical TiO2/SNP hybrid arrays have been fabricated via facile and low-cost casting techniques. The structural, compositional, and optical characteristics of TiO2/SNP hybrid arrays were well elucidated and correlated to SERS activities. SERS studies revealed that TiO2/SNP nanoarrays possess almost 288 times enhancement compared to bare TiO2 substrates and 2.6 times enhancement than pristine SNP. The fabricated nanoarrays demonstrated detection limits down to 10-12 M concentration levels and lower spot-to-spot variability of ∼ 11%. The photocatalytic studies showed that almost 94 and 86% of rhodamine B and methylene blue were decomposed within 90 min of visible light exposure. Besides, two times enhancement in photocatalytic activities of TiO2/SNP hybrid substrates was also observed than bare TiO2. The highest photocatalytic activity was exhibited by SNP to TiO2 molar ratio of 1.5 × 10-3. The electrochemical surface area and the interfacial electron-transfer resistance were increased with the increment in TiO2/SNP composite load from 3 to 7 wt%. Differential Pulse Voltammetry (DPV) analysis revealed a higher RhB degradation potential of TiO2/SNP arrays than SNP or TiO2. The synthesized hybrids exhibited excellent reusability without any significant deterioration in photocatalytic properties over five successive cycles. TiO2/SNP hybrid arrays were proved to be multiple platforms for sensing and degrading hazardous pollutants for environmental applications.

Sonoelectrochemical Nanoarchitectonics of Crystalline Mesoporous Magnetite @ Manganese Oxide Nanocomposite as an Alternate Anode Material for Energy-Storage Applications

In this report, the synergetic sonoelectrochemical method was utilized to produce magnetite nanoparticles was doped with MnO2 with the assistance of ultrasound to form nanoarchitectonic magnetic crystals with a mesoporous magnetite @ manganese dioxide (m-Fe3O4@MnO2) hybrid nanostructure. The hybrid nanocomposite was rapidly produced based on the nucleation and growth of pure iron-oxide nanocrystals in the electrochemical system. The nanocomposite was pure, highly amorphous, and mesoporous in nature; the magnetite was spherical in shape, with an average diameter of 45 ± 10 nm and a MnO2-plane length of 420 ± 30 nm. The stability of the pure m-Fe3O4 was enhanced from 89.61 to 94.04% with negligible weight loss after adding manganese dioxide and the stable formation of the hybrid nanostructure. Based on the superior results of the material, it was utilized as an anode material in Li-ion batteries. The m-Fe3O4@MnO2 hybrid nanostructure had a highly active surface area, which enhanced the interfacial interaction between the Li-ion and the metal surface; it delivered 1513 mAh g−1 and 1290 mAh g−1 as the first specific discharge and charge capacity, respectively, with 85% coulombic efficiency, and it showed an excellent cyclic reversibility of 660 mAh g−1 with a coulombic efficiency of almost 99% at current density of 1.0 A g−1.

Tunable broadband terahertz properties in an architecture optimized ITO/VO2 hybrid metamaterial

This article proposes an architecture optimized indium-tin-oxide (ITO)/vanadium dioxide (VO2) hybrid metamaterial with optically transparent and tunable broadband terahertz properties. By changing the architecture of subunits, a broadband (∼1 THz) absorption with average absorptivity of 80.0 % has been achieved in an optimized ITO metamaterial at first. With adding strong correlated electron oxide VO2 film, the tunability is introduced in the ITO/VO2 hybrid structures. The most striking finding here is that the position of the VO2 layers in the hybrid structure can efficiently affect both the THz properties and the modulation functionality. In an optimized ITO/VO2 hybrid structure, 84.5 % reflection modulation and 78.9 % absorption modulation within a broadband (0.2 ∼1.0 THz) range are obtained. These findings highlight the architecture optimization for the THz properties in hybrid metamaterials, which is expected to have a great technological impact on the design of optically transparent THz tunable absorbers.

Dynamically switchable multifunctional terahertz absorber based on graphene and vanadium dioxide hybrid metamaterials

A multifunctional terahertz absorber based on a hybrid configuration of vanadium dioxide ( V O 2 ) and graphene is proposed, which is enabled to dynamically switch between ultrabroadband and double-narrowband absorption characteristics using the phase-shifting property of V O 2 . When V O 2 is in the metallic phase and the Fermi energy level of graphene is 0.01 eV, ultrabroadband absorption from 3.04 THz to 8.78 THz can be achieved. The absorption can be continuously adjusted from 0.7% to 99.9% by changing the conductivity of the V O 2 through temperature. When V O 2 is in the insulating phase and Fermi energy level of graphene is 0.4 eV, the proposed absorber exhibits a double-narrowband absorption characteristic, achieving 99.8% and 97.3% absorption at 1.79 THz and 4.62 THz, respectively. Since graphene is an electronically controlled material, it is able to dynamically modulate the resonant frequency and absorption intensity by changing the Fermi energy level of graphene. In addition, the physical mechanism of the multifunctional absorber is revealed using electric field distribution and the impedance-matching theory. The proposed absorber has potential applications in optical switching, image processing, and stealth technology.

Facile synthesis of triple-hybrid organosilica/manganese dioxide hybrid nanoparticles for glutathione-adaptive shape-morphing and improving cellular drug delivery

BackgroundGreat attention has been received for the synthesis of multi-hybrid mesoporous organosilica nanomaterials (MONs), which can integrate multiple functions of organic saline groups into one nanoplatform. However, shape-morphing is absent in most previously reported multi-hybrid MONs. MethodsHerein, a glutathione-adaptive shape-morphing nanoplatform was constructed by facile doping of manganese dioxide in MONs frameworks. FindingThe size of the environmentally adaptive shape-morphing nanoplatform can be successfully regulated by the contents of cetyltrimethylammonium bromide (CTAB) and organic silanes, showing a controlled range of 153∼271 nm, and 271∼354 nm, respectively. Importantly, all these series of environmentally adaptive shape-morphing nanoparticles with different sizes can achieve isotropic-to-anisotropic morphology transition under a tumor-mocked environment containing glutathione (GSH). In addition, the statistical analysis of the cell proliferation test shows that the GSH-adaptive shape-morphing nanoparticles possess good biocompatibility and show significantly increased cellular drug delivery efficiency due to the doping of manganese dioxide. This study provides a facile strategy for the synthesis of environmentally adaptive shape-morphing micro-/nanoparticles, and exhibits a promising method for enhancing drug delivery efficiency for better tumor therapeutic effect.

THz broadband and dual-channel perfect absorbers based on patterned graphene and vanadium dioxide metamaterials.

This paper proposes a novel and perfect absorber based on patterned graphene and vanadium dioxide hybrid metamaterial, which can not only achieve wide-band perfect absorption and dual-channel absorption in the terahertz band, but also realize their conversion by adjusting the temperature to control the metallic or insulating phase of VO2. Firstly, the absorption spectrum of the proposed structure is analyzed without graphene, where the absorption can reach as high as 100% at one frequency point (f = 5.956 THz) when VO2 is in the metal phase. What merits attention is that the addition of graphene above the structure enhances the almost 100% absorption from one frequency point (f = 5.956 THz) to a wide frequency band, in which the broadband width records 1.683 THz. Secondly, when VO2 is the insulating phase, the absorption of the metamaterial structure with graphene outperforms better, and two high absorption peaks are formed, logging 100% and 90.7% at f3 = 5.545 THz and f4 = 7.684 THz, respectively. Lastly, the adjustment of the Fermi level of graphene from 0.8 eV to 1.1 eV incurs an obvious blueshift of the absorption spectra, where an asynchronous optical switch can be achieved at fK1 = 5.782 THz and fK2 = 6.898 THz. Besides, the absorber exhibits polarization sensitivity at f3 = 5.545 THz, and polarization insensitivity at f4 = 7.684 THz with the shift in the polarization angle of incident light from 0° to 90°. Accordingly, this paper gives insights into the new method that increases the high absorption width, as well as the great potential in the multifunctional modulator.

Enhanced quantum efficiency of silicon solar cell via TRGO-MnO2 hybrid

In this study, thermally reduced graphene oxide-manganese dioxide (TRGO-MnO2) hybrid was synthesized via in-situ thermal-chemical method. MnO2 nanoparticles (NPs) with the size of 20–30 nm are homogenously dispersed on TRGO nanosheets. The results of the I-V characteristics revealed that the deposition of MnO2 NPs on TRGO significantly improves performance of the silicon solar cells. The incorporation of MnO2 NPs reduced the emission, enhancing the quantum efficiency from 5.8 % to 9.5 %. These findings suggest that the TRGO and TRGO-MnO2 hybrid improve the solar cell efficiency due to the down-shifting properties. It is expected that TRGO-MnO2 hybrid could be a promising candidate material as a highly efficient heterocontact for silicon solar cells.

Hybrid Polymer Composites Based on Polystyrene (PS) Used in the Melted and Extruded Manufacturing Technology.

As part of the work, innovative hybrid polymer composites dedicated to rapid prototyping, especially for 3D printing with the melted and extruded manufacturing (MEM) technique, were developed. For this purpose, the influence of modified fillers, such as alumina-modified silica, bentonite modified with quaternary ammonium salt, and lignin/silicon dioxide hybrid filler, on the functional properties of polystyrene-based composites was investigated. The introduced additives were selected to improve the processing properties of polystyrene (PS), in particular its thermal stability, while maintaining good mechanical properties. In the first part of the work, using the proprietary technological line, filaments from unfilled PS and its composites were obtained, which contain modified fillers in the amount of 1.5% to 3.0% by weight. Samples for testing functional properties were obtained by 3D printing in MEM technology and injection technique. The rheological properties-mass melt flow rate (MFR), viscosity, and mechanical properties-are presented in the further part of the work. The size and the respective dispersion in the polystyrene polymer matrix of the fillers used were determined by scanning electron microscopy with energy dispersion spectroscopy (SEM/EDS). The correct dispersion of additives in PS was also confirmed by wide-angle X-ray analysis (WAXS). A significant improvement in the thermal stability of the obtained composites after the introduction of fillers into the polymer matrix was confirmed on the basis of thermogravimetric analysis (TGA). The remaining tests of physicochemical properties, differential scanning calorimetry (DSC), and infrared spectroscopy with Fourier transform (FT-IR) allowed us to state no significant changes in relation to polystyrene. The obtained test results allowed us to conclude that the amount and type of fillers used in the PS polymer matrix significantly affect the performance properties of the tested hybrid composites. The composites obtained as part of the work can be successfully used in rapid prototyping technologies, especially for the production of details originally designed from PS, which are required to have higher thermal stability than is guaranteed only by the polymer matrix.

Investigation of mechanical properties of UHMWPE composites reinforced with HAP+TiO2 fabricated by solvent dispersing technique

This work seeks to contribute to solving the problems of inadequate artificial joint design from the mechanical perspective in total joint replacement (TJR) surgery. Ultra-high molecular weight polyethylene (UHMWPE)/hydroxyapatite (HAP) + titanium dioxide (TiO2) hybrid composites were fabricated and tested for use as artificial cartilages in the total joint prosthesis. Different amounts of TiO2 (1–10 wt%) and fixed amount of HAP (20 wt%) were dispersed in UHMWPE-based nanocomposites due to obtaining a material easy to be processed, inexpensive, with remarkable mechanical properties, and good cells interaction. The UHMWPE/HAP + TiO2 composites were prepared by using the solvent dispersing technique and twin-screw mixer, followed by hot compression molding, then mechanical testing was performed. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) are used to study the effect of the additives and the dispersion quality of the composites. The solvent dispersing technique shows better dispersion of the additives in the polymer matrix. The composites show an increase in Young's modulus, hardness, and flexural strength, by 71%, 33%, and 95% respectively concerning neat UHMWPE. The composite contains 3 wt% TiO2 showing the best enhancement percentage.

Tailoring surface electronic properties of GO-TiO2 hybrid nanostructures through interface modifications

The tailoring of electronic properties in carbon-based hybrid functional materials is essential for improving their overall physicochemical behavior. In this work, graphene oxide (GO)-titanium dioxide (TiO2) hybrid nanostructures are irradiated with 120 MeV Ag9+ swift heavy ions (SHI) for tailoring its surface electronic properties through defect-mediated interface modifications. The microscopic and spectroscopic characterizations indicate a gradual reduction of GO into reduced graphene oxide (rGO) with increasing ion dose. The work function (WF) measurement of GO-TiO2 by scanning Kelvin probe microscopy (SKPM) exhibits systematic variation with the ion fluence and agrees well with the variation in the Fermi energy of GO obtained from the Raman spectroscopy. Moreover, the semiconducting behavior of GO can be effectively tuned by TiO2-controlled Fermi level modulation in GO-TiO2 hybrid nanostructures with ion fluence. The Monte Carlo-based simulations, stopping range of ions in matter (SRIM) and transport of ions in matter (TRIM) codes, reveal that the mutual interplay of defects created in the nanostructures, substrate, and their interfacial regions are responsible for the systematic modulation of the WF in the GO-TiO2.

A Theoretical Proposal for an Actively Controlled Ultra-Wideband Absorber Based on Vanadium Dioxide Hybrid Metamaterials

In this study, an ultra-wideband actively tunable terahertz absorber composed of four identical arc-shaped structures made of phase transition material vanadium dioxide (VO2) is presented. A metal ground plane is placed at the bottom and an insulating spacer (quartz) as the middle dielectric layer. Simulation results demonstrate 90% absorption with a broad bandwidth spanning 3 THz (2.7 THz–5.7 THz) under normal incidence. The proposed structure transforms from a reflector to an absorber by changing the conductivity from 200 S/m to 2 × 105 S/m; the absorbance at peak frequencies can be consistently tuned from 4% to 100%. Absorption spectra demonstrate that the polarization angle does not affect the response of the proposed structure. Power loss density (PLD) and impedance-matching theory are further analyzed to learn more about the physical origin of ultra-wide absorption. The ultra-wide operating bandwidth, high absorption efficiency, active tunability, and independence of polarization make the proposed structure an excellent candidate for integration into profound THz applications such as sensors, modulators, and optic-electro switches.

Toughening and Heat-Resistant Modification of Degradable PLA/PBS-Based Composites by Using Glass Fiber/Silicon Dioxide Hybrid Fillers.

In this paper, to enhance the toughness and heat resistance properties of polylactic acid (PLA)/polybutylene succinate (PBS) composites, the PLA/PBS matrix was modified by different glass fiber (GF), GF/SiO2, and GF/(Polyaluminium chloride) PAC fillers. Additionally, the effect of filler type, filler content, components interaction and composite structure on the mechanical and thermal properties of the PLA/PBS composites was researched. The results showed that the addition of GF, GF/SiO2 and GF/PAC make the PLA/PBS composites appear significantly higher mechanical properties compared with the pristine PLA/PBS composite. Among the different inorganic fillers, the 10%GF/1%SiO2 fillers showed excellent strengthening, toughening and heat resistant effects. Compared with the pristine PLA/PBS matrix, the tensile strength, elastic modulus, flexural strength, flexural modulus and Izod impact strength improved by 36.28%, 70.74%, 67.95%, 66.61% and 135.68%, respectively. Considering the above, when the weight loss rate was 50%, the thermal decomposition temperature of the 10%GF/1%SiO2 modified PLA/PBS composites was the highest 412.83 °C and its Vicat softening point was up to 116.8 °C. In a word, the 10%GF/1%SiO2 reinforced PLA/PBS composites exhibit excellent mechanical and thermal properties, which broadens the application of biodegradable materials in specific scenarios.

Microwave-assisted Synthesis of Functionalized Multiwalled Carbon Nanotube–Titanium Dioxide Hybrid Structure and Photodegradation

Decoration of a functionalized multiwalled carbon nanotube (f-MWCNT) surface with titanium dioxide (TiO2) was designed to improve its photocatalytic degradation performance. Structural decoration was achieved by microwave heating at various mass ratios (1:2; 1:4; 1:8; 1:16 wt.%) of titanium (IV) isopropoxide as precursor. The hybrid structure of TiO2/f-MWCNT was characterized by scanning electron microscope and transmission electron microscope (TEM). The crystallite form of the TiO2 nanoparticles was further studied by X-ray diffraction (XRD) and HR–TEM. We report the conformation of high-density TiO2 coated on an f-MWCNT surface at a mass ratio of 1:16 wt.%. XRD analysis revealed a structural transformation from mixture phase (anatase–brookite) at mass ratios of 1:2 and 1:4 wt.% to fully anatase phase for mass ratios of 1:8 and 1:16 wt.%. The transformation was also confirmed by selected area electron diffraction (SAED) and HR–TEM analysis. Our results showed that anatase phase plays a significant role in photodegradation activity.

A lignin-based epoxy/TiO2 hybrid nanoparticle for multifunctional bio-based epoxy with improved mechanical, UV absorption and antibacterial properties

Lignin, as a natural polymer material, has the advantages of green safety, renewable, and pollution-free. It has a wide application prospect in the field of thermosetting. However, it has been attractive but a huge challenge to design high performance and high added-value lignin-based epoxy resin. Herein, lignin-based epoxy (LEP) was synthesized from moso bamboo-derived lignin, and then lignin-based epoxy/titanium dioxide (LEP/TiO2) hybrid nanoparticle was synthesized via liquid deposition method for modifying lignin-based epoxy resin to prepare multifunctional bio-based epoxy. The results show that the LEP/TiO2 hybrid nanoparticle exhibits a stable topological surface shape and good dispersion and uniformity. By adding 10 wt% LEP/TiO2 hybrid nanoparticles, the multifunctional bio-based epoxy exhibits good mechanical strength and toughness, and the tensile strength and fracture toughness reach 36 MPa and 1.26 MPa·m1/2, respectively. In addition, the thermal stability, UV absorption and antibacterial properties of the multifunctional bio-based epoxy are further improved. This study provides a facile and efficient method for the preparation of high-performance multifunctional bio-based epoxy composite and a novel solution for the utilization of lignin.

Slippery omniphobic covalently attached liquid coatings mitigate carbon deposition by autoxidation of jet fuel

The decomposition of jet fuel at elevated temperatures leads to fuel fouling and deposit formation on metallic walls. Here, we develop and study an innovative sol-gel silicon dioxide (SiO 2 ) hybrid anti-fouling coating to mitigate fuel fouling. Our coating has low surface roughness (<1 nm) and low surface energy (<12 mJ/m 2 ), reducing the heterogeneous nucleation rate during deposition. The sol-gel SiO 2 , which forms the base coating, further minimizes exposure of the metal substrate to the fuel, which can act as a catalyst and increase the decomposition reaction rate. We tested the fouling behavior in a custom-built fuel fouling test loop. Tests were able to characterize the efficacy of our coatings and to benchmark performance with bare copper, stainless steel, and Inconel 600 metals as well as commercial anti-fouling coatings, such as alumina and SilcoTek. Our coating demonstrated reduced fouling rates of at least 96% when compared with bare samples. • Hybrid low surface energy and smooth coating for carbon deposition mitigation • Scalable coating methodology applicable for complex heat exchangers • Reduced jet fuel autoxidation by reduction of metal surface catalytic effects • Comparison with jet fuel fouling on copper, stainless steel, and alumina The autoxidation of jet fuel results in carbon deposition on metals. Khodakarami et al. use a scalable hybrid coating to combine SiO2 and a slippery omniphobic covalently attached liquid to mitigate carbon deposition by eliminating the interface between the fuel and substrate and to provide a low surface energy smooth interface.

MXene framework‐supported F, S, and Co ternary‐doped tin dioxide hybrid structures for ultrafast and stable lithium‐ion batteries

<scp>MXene</scp> framework‐supported F, S, and Co ternary‐doped tin dioxide hybrid structures for ultrafast and stable lithium‐ion batteries

Multifield Controlled Terahertz Modulator Based on Silicon‐Vanadium Dioxide Hybrid Metasurface

AbstractDespite flourishing and deepening trend in the terahertz (THz) field, there are still challenges in high‐performance active system components, such as THz modulators. Present THz modulators are typically limited to a single external driving field and the fixed switching speed, hindering the ability to flexibly manipulate THz waves. Here, an optically and thermally controlled THz modulator based on silicon (Si) and vanadium dioxide (VO2) hybrid metasurface is proposed to overcome these limitations. The modulator enables the dynamical control of the transmitted amplitude in the range of 0.4–1.8 THz. Under thermal management, a maximum modulation depth (MD) of 97.2% at 0.9 THz can be acquired, thanks to the phase transition of VO2. Once excited with an 800 nm pump light at 1600 µJ cm−2, the device achieves a maximum MD of 91.5% at 0.87 THz accomplished with an ultrafast speed of 2 ps, resulting from photogenerated carriers in the Si substrate. Furthermore, the findings of this study propose a promising strategy for developing multifield controlled active THz components, which would be a new paradigm to design switchable metasurface devices.