Application of Bimetallic Heterojunction Nanoparticle-Based Multishelled Porous Hollow Microspheres as a Two-in-One Inorganic UV Filter

Zinc oxide (ZnO) and titanium dioxide (TiO2), two inorganic UV filters, have taken the center stage in the talks of photoprotection. These days, sunscreens incorporate ZnO and TiO2 nanoparticles that are generally less than 100 nm in size. Concerned about the adverse effects of nanoparticles (NPs) on human health and the environment, we have synthesized TiO2@ZnO porous hollow multishelled microspheres (PHMMs) through a sequential template procedure (STP) and employed them as a two-in-one inorganic UV filter. For better understanding, we also compared their performances with TiO2 and ZnO NPs. Morphological characterization showed that TiO2 NPs are well equipped with ZnO NPs and formed a type II heterojunction structure. After 5 h of UV irradiation, we assessed the toxicity and photostability of these compounds. The TiO2@ZnO PHMMs show significant photostability with no significant cytotoxicity, whereas the ZnO and TiO2 NPs show significantly less photostability with cytotoxicity. The band gap widening in TiO2@ZnO PHMMs resulted in excellent UV absorption, and the recombination center of the photogenerated e–/h+ pair leads to reduced production of H2O2 and OH (ROS). Besides, the microspheres’ highly porous nature decreases visible light reflection, which results in less skin whitening. The formulated sunscreen with TiO2@ZnO PHMMs revealed higher SPF values with low photodegradation

<i>In Situ</i> Construction of Binder-Free Stable Battery-Type Copper Cobaltite and Copper Oxide Composite Electrodes for All-Solid-State Asymmetric Supercapacitors: Cation Concentration and Morphology-Dependent Electrochemical Performance

Binder-free electrode materials offer high active material mass loading and usage rate, excellent connectivity between active materials and current collectors, and efficient electron and ion transport inside the electrodes. Herein, we demonstrate a binder-free in situ synthesis of microstructures of CuCo2O4/CuO composites grown on the Ni foam (CCO/NF) by wet chemical methods. Two different morphologies of microspheres (CCO/NF-IPA) and cross-linked microsheets (CCO/NF-DIW) result from solvents of isopropyl alcohol and deionized water, respectively. Using X-ray techniques, the nonstoichiometry of Cu, Co, and O in composites is measured. In the backdrop of the supercapacitor application, even though both electrodes have consistent electrochemical performance, the Co-excess of the CCO/NF-IPA composite has a higher specific capacity (369.6 C g–1 at 1 A g–1) and an extended cyclic performance (98% retention after 5000 cycles) compared to the other. The all-solid-state CCO/NF-IPA//activated carbon (AC) asymmetric supercapacitor (ASC) device with a full operating potential window of 0–1.5 V has exhibited a high specific capacity of 162.6 C g–1 at 1 A g–1. The ASC device retains its initial capacity of 97% over 5000 cycles and renders a notable energy density of 43.7 Wh kg–1 at 752.4 W kg–1 power density

Effect of Potassium Ions on the Formation of Crystalline Manganese Oxide Nanorods via Acidic Reduction of Potassium Permanganate

Uniformly grown manganese oxides nanorods are synthesized via a simple and rapid process through an acidic reduction of potassium permanganate followed by heat treatment. The as-produced manganese oxides nanorods are characterized with X-ray diffraction, energy dispersive X-ray analysis, scanning electron microscopy, and transmission electron microscopy. The crystallinity of the nanostructure is found to have a dominant Mn₂O₃ phase. The compositional and microstructural analyses reveal that the potassium concentration within the as-prepared material has a profound effect on the morphological conversion of manganese oxide nanoparticles to nanorods. Potassium ions are believed to act as a template for the formation of nanorods and the conversion efficiency increases with the increasing content of potassium. Also the morphology of products is found to depend strongly on the annealing time. The mechanism of nanorod growth with respect to different potassium contents and annealing times is discussed

Synthesis of Amourphous and Crystalline Hollow Manganese Oxide Nanotubes with Highly Porous Walls Using Carbon Nanotube Templates and Enhanced Catalytic Activity

A novel rapid fabrication method was developed for the first time to prepare hollow manganese oxide nanotubes with porous walls, using sacrificial carbon nanotube templates. Multiwalled carbon nanotubes (CNTs) are coated with amorphous manganese oxide layers by acidic reduction of potassium permanganate solution. The rapid synthesis process with the evolution of gaseous byproduct yields very high porosity in the coated manganese oxide layers. Subsequent heat treatment leads to the removal of CNT templates, resulting in the formation of amorphous and crystalline hollow manganese oxide nanotubes with highly porous walls. The porous hollow nanotubes were found to provide excellent catalytic performances in the degradation of organic dye at ambient conditions by virtue of the very high surface reaction sites within the porous hollow tubular structures. These novel nanostructures of hollow nanotubes with porous walls are promising for a series of applications such as hydrogen storage, sensing, supercapacitance, and catalysis, among others

<i>N</i>-Isocyaniminotriphenylphosphorane (Ph₃PNNC) as a metal-free catalyst for the synthesis of functionalized isoindoline-1-ones

<p>A novel application in the field of <i>N</i>-isocyaniminotriphenylphosphorane (Ph₃PNNC) chemistry has been introduced in this work. A series of substituted isoindolin-1-one ring systems has been successfully synthesized through a novel and efficient multicomponent reaction of methyl 2-formylbenzoate and primary amines in the presence of <i>N</i>-isocyaniminotriphenylphosphorane (Ph₃PNNC) as a catalyst. This one-pot three component reaction (3-CR) gives high yield using <i>N</i>-isocyaniminotriphenylphosphorane (Ph₃PNNC) as a metal-free catalyst under mild conditions.</p

<i>N</i>-isocyaniminotriphenylphosphorane (Ph₃PNNC) as an efficient reagent for the synthesis of ferrocene-containing 1,3,4-oxadiazole derivatives

<p>Reaction of N-isocyaniminotriphenylphosphorane (Ph₃PNNC) with an aromatic aldehyde in the presence of ferrocene carboxylic acid and a secondary amine proceeds smoothly at room temperature under neutral conditions to afford sterically congested ferrocene-containing 1,3,4-oxadiazole derivatives in high yields. The reaction progresses smoothly and clearly under mild conditions and no side reactions were observed.</p

Engineering Rich-Cation Vacancies in CuCo₂O₄ Hollow Spheres with a Large Surface Area Derived from a Template-Free Approach for Ultrahigh Capacity and High-Energy Density Supercapacitors

Intriguing cationic defects with hollow nano-/microstructures are a critical challenge but a potential strategy to discover electrochemical energy conversion and storage devices with improved electrochemical performances. Herein, we successfully produced a highly porous, and large surface area of self-templated CuCo2O4 hollow spheres (CCOHSs) with cationic defects via a solvothermal route. We hypothesized that the inside-out Ostwald ripening mechanism of the template-free strategy was the framework for forming the CCOHSs. Cationic defects (Cu) within the CCOHSs were identified by employing various analytical techniques, including energy-dispersive X-ray spectroscopy analysis of both scanning and transmission electron microscopy, X-ray photon spectroscopy, and inductively coupled plasma–atomic emission spectroscopy. The resulting CCOHSs had significant properties, such as a high specific surface area of 98.32 m2 g–1, rich porosity, and battery-type electrode behavior in supercapacitor applications. Notably, the CCOHSs demonstrated an outstanding specific capacity of 1003.7 C g–1 at 1 A g–1, with excellent structural integrity and cycle stability. Moreover, the fabricated asymmetric CCOHS//activated carbon device exhibited a high energy density of 65.2 Wh kg–1 at a power density of 777.8 W kg–1

A Novel Rapid One-Step Synthesis of Manganese Oxide Nanoparticles at Room Temperature Using Poly(dimethylsiloxane)

We report for the first time a novel rapid synthesis method for manganese oxide (MO) nanoparticles by a reaction between acidic permanganate and poly­(dimethylsiloxane) (PDMS). In contrast to the existing traditional methods for synthesis of MO nanoparticles, the new method has the advantage of shorter reaction time (∼2 h) at room temperature (∼25 °C). The produced MO nanoparticles are characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM, HRTEM). The material produced is semicrystalline silicon-doped MnO2 with homogeneous size and morphology with an average particle size around 300 nm. Other products of the reactions include Cl2, silicon dioxide sheets on PDMS, and CO2. A mechanism for this reaction is proposed. The prepared MO was successfully used as a catalyst for the rapid and highly efficient degradation of a water pollutantRhodamine B (RhB)

Enhanced Electrochemical Performance of Rare-Earth Metal-Ion-Doped Nanocrystalline Li₄Ti₅O₁₂ Electrodes in High-Power Li-Ion Batteries

A comprehensive and comparative exploration research performed, aiming to elucidate the fundamental mechanisms of rare-earth (RE) metal-ion doping into Li4Ti5O12 (LTO), reveals the enhanced electrochemical performance of the nanocrystalline RE-LTO electrodes in high-power Li-ion batteries. Pristi ne Li4Ti5O12 (LTO) and rare-earth metal-doped Li4–x/3Ti5–2x/3LnxO12 (RE-LTO with RE = Dy, Ce, Nd, Sm, and Eu; x ≈ 0.1) nanocrystalline anode materials were synthesized using a simple mechanochemical method and subsequent calcination at 850 °C. The X-ray diffraction (XRD) patterns of pristine and RE-LTO samples exhibit predominant (111) orientation along with other characteristic peaks corresponding to cubic spinel lattice. No evidence of RE-doping-induced changes was seen in the crystal structure and phase. The average crystallite size for pristine and RE-LTO samples varies in the range of 50–40 nm, confirming the formation of nanoscale crystalline materials and revealing the good efficiency of the ball-milling-assisted process adopted to synthesize nanoscale particles. Raman spectroscopic analyses of the chemical bonding indicate and further validate the phase structural quality in addition to corroborating with XRD data for the cubic spinel structure formation. Transmission electron microscopy (TEM) reveals that both pristine and RE-LTO particles have a similar cubic shape, but RE-LTO particles are better interconnected, which provide a high specific surface area for enhanced Li+-ion storage. The detailed electrochemical characterization confirms that the RE-LTO electrodes constitute promising anode materials for high-power Li-ion batteries. The RE-LTO electrodes deliver better discharge capacities (in the range of 172–198 mAh g–1 at 1C rate) than virgin LTO (168 mAh g–1). Among them, Eu-LTO provides the best discharge capacity of 198 mAh g–1 at a 1C rate. When cycled at a high current rate of 50C, all RE-LTO electrodes show nearly 70% of their initial discharge capacities, resulting in higher rate capability than virgin LTO (63%). The results discussed in this work unfold the fundamental mechanisms of RE doping into LTO and demonstrate the enhanced electrochemical performance derived via chemical composition tailoring in RE-LTO compounds for application in high-power Li-ion batteries

Four-component synthesis of ferrocene-containing 1,3,4-oxadiazoles from <i>N</i>-isocyaniminotriphenylphosphorane (Ph₃PNNC), a primary amine, a cyclic ketone and ferrocene carboxylic acid

<p>The 1:1 imine intermediate created by the addition of a primary amine to a cyclic ketone is trapped by N-isocyaniminotriphenylphosphorane (Ph₃PNNC) in the presence of ferrocene carboxylic acid and the corresponding iminophosphorane intermediate was formed. Afterwards, ferrocene containing 1,3,4-oxadiazole derivatives are formed via intramolecular aza-Wittig reaction of the iminophosphorane intermediate. The reaction proceeded under mild conditions at room temperature.</p