Outstanding supercapacitive properties of Mn-doped TiO2 micro/nanostructure porous film prepared by anodization method

Innovatively feasible wet incipient method for preparing Cu doped TiO2 nanocomposite: Electro-optical measurement supported by quantitative quantum and classical calculations

The Cu-doped titanium oxide (Cu/TiO2) nanocomposite was systematically prepared using the innovatively feasible incipient wet impregnation method. Notably, the samples were derived from the raw materials through water dilution only. The successful formation of the host anatase TiO2 phase was confirmed by the characteristic peaks observed in the acquired X-ray powder diffraction (XRD) spectrum, which displayed intense peaks attributed to Cu2+ scattering sites, indicating the formation of crystallite Cu/TiO2 nanostructures. Dielectric measurements revealed that Cu/TiO2 possesses a higher dielectric permittivity compared to undoped TiO2. The conductivity for both structures exhibited a decreasing trend with increasing temperature. Interestingly, the measured optical properties indicated that Cu/TiO2 exhibited the minimum energy gap and maximum refractive index. This was further validated by qualitative time-dependent density functional calculation on a stable structural model, which was confirmed through semi-empirical molecular dynamic calculations. Thus, we have demonstrated the capability of our innovatively feasible synthesis method to produce the industrially important Cu-doped TiO2.

Multi-Functional Materials Based on Cu-Doped TiO2 Ceramic Fibers with Enhanced Pseudocapacitive Performances and Their Dielectric Characteristics

In this work, pure TiO2 and Cu (0.5, 1, 2%)-doped TiO2 composites prepared by electrospinning technique followed by calcination at 900 °C, and having high pseudocapacitive and dielectric characteristics were reported. These nanocomposites were characterized by scanning electron microscopy, X-ray diffraction, and dynamic water sorption vapor measurements. The structural characterization of these nanostructures highlighted good crystallinity including only the rutile phase. The electrochemical characteristics were investigated by cyclic voltammetry and galvanostatic charge-discharge measurements, which were performed in a KOH electrolyte solution. Among the Cu-doped TiO2 nanostructures that were prepared, the one containing 0.5% Cu exhibited superior electrochemical properties, including high specific gravimetric capacitance of 1183 F·g-1, specific capacitance of 664 F·g-1, energy density of 45.20 Wh·kg-1, high power density of 723.14 W·kg-1, and capacitance retention of about 94% after 100 cycles. The dielectric investigation shows good dielectric properties for all materials, where the dielectric constant and the dielectric loss decreased with the frequency increase. Thus, all the interconnected studies proved that these new materials show manifold ability and real applicative potential as pseudocapacitors and high-performance dielectrics. Future work and perspectives are anticipated for characterizing electrochemical and dielectric properties for materials including larger amounts of Cu dopant.

Mixed oxide nanotubes in nanomedicine: A dead-end or a bridge to the future?

Nanomedicine has seen a significant rise in the development of new research tools and clinically functional devices. In this regard, significant advances and new commercial applications are expected in the pharmaceutical and orthopedic industries. For advanced orthopedic implant technologies, appropriate nanoscale surface modifications are highly effective strategies and are widely studied in the literature for improving implant performance. It is well-established that implants with nanotubular surfaces show a drastic improvement in new bone creation and gene expression compared to implants without nanotopography. Nevertheless, the scientific and clinical understanding of mixed oxide nanotubes (MONs) and their potential applications, especially in biomedical applications are still in the early stages of development. This review aims to establish a credible platform for the current and future roles of MONs in nanomedicine, particularly in advanced orthopedic implants. We first introduce the concept of MONs and then discuss the preparation strategies. This is followed by a review of the recent advancement of MONs in biomedical applications, including mineralization abilities, biocompatibility, antibacterial activity, cell culture, and animal testing, as well as clinical possibilities. To conclude, we propose that the combination of nanotubular surface modification with incorporating sensor allows clinicians to precisely record patient data as a critical contributor to evidence-based medicine.

In situ growth of MnO@Na2Ti6O13 heterojunction nanowires for high performance supercapacitors

One-dimensional tunnel and layer frame crystal structure materials are extremely attractive for energy storage in electrode materials. The energy storage properties of the electrode materials depend on their conductivity. Furthermore, the conductivity of electrode materials can be tailored through combination or doping with other materials, which transforms their properties from semiconductor to semimetallic or metallic and allow them to show unequaled performance for storage devices. In this work, heterostructures of manganese oxide (MnO) and modified sodium titanate (Na₂Ti₆O₁₃) (MnO@Na₂Ti₆O₁₃) nanowires are attained by the in situ thermal decomposition method. The heterojunction between MnO and Na₂Ti₆O₁₃ allows the semiconductor properties of pure Na₂Ti₆O₁₃ to show remarkable metallic behavior for improving the electrochemical performance. The capacitance of MnO@Na₂Ti₆O₁₃ heterojunction nanowires can reach 272.3 F g^-1, a power intensity of 250 W kg^-1 at the energy density of 37.83 Wh kg^-1 and retain 5000 W kg^-1 at 6.67 Wh kg^-1 as well. The energy storage mechanism of the MnO@Na₂Ti₆O₁₃ heterostructure is studied by density functional theory. All of the results show that the MnO@Na₂Ti₆O₁₃ heterostructure material has the potential to be an excellent supercapacitor material in the future.

Unveiling the Effect of the Structure of Carbon Material on the Charge Storage Mechanism in MoS2-Based Supercapacitors

MoS₂ is a 2D material that has been widely used in supercapacitor applications because of its layered structure that provides a large surface area and allows for high electric double-layer charge storage. To enhance the cycling stability and capacitance of MoS₂, it is usually mixed with carbon materials. However, the dependence of the charge storage mechanism on the structure of the carbon material is still unclear in literature. Herein, the effect of the structure of the carbon material on the charge storage mechanism in 2H flower-shaped MoS₂ is investigated in detail. Specifically, 2H MoS₂ was mixed with either 8 nm-diameter carbon nanotubes (CNTs) or graphene nanoflakes (GNFs) in different weight ratios. Also, a composite of MoS₂, CNTs, and GNFs (1:1:1) was also studied. The charge storage mechanism was found to depend on the structure and content of the carbon material. Insights into the possible storage mechanism(s) were discussed. The MoS₂/CNT/GNF composite showed a predominant pseudocapacitive charge storage mechanism where the diffusion current was ∼89%, with 88.31% of the resulted capacitance being due to faradic processes.

Unraveling doping induced anatase–rutile phase transition in TiO2 using electron, X-ray and gamma-ray as spectroscopic probes

The present work reports the microscopic details of anatase (A) to rutile (R) phase transformation in a Mn-doped TiO₂ system.

Poly(Acrylic acid)⁻Based Hybrid Inorganic⁻Organic Electrolytes Membrane for Electrical Double Layer Capacitors Application

Nanocomposite polymer electrolyte membranes (NCPEMs) based on poly(acrylic acid)(PAA) and titania (TiO₂) are prepared by a solution casting technique. The ionic conductivity of NCPEMs increases with the weight ratio of TiO₂.The highest ionic conductivity of (8.36 ± 0.01) × 10^-4 S·cm^-1 is obtained with addition of 6 wt % of TiO₂ at ambient temperature. The complexation between PAA, LiTFSI and TiO₂ is discussed in Attenuated total reflectance-Fourier Transform Infrared (ATR-FTIR) studies. Electrical double layer capacitors (EDLCs) are fabricated using the filler-free polymer electrolyte or the most conducting NCPEM and carbon-based electrodes. The electrochemical performances of fabricated EDLCs are studied through cyclic voltammetry (CV) and galvanostatic charge-discharge studies. EDLC comprising NCPEM shows the specific capacitance of 28.56 F·g^-1 (or equivalent to 29.54 mF·cm^-2) with excellent electrochemical stability.