Energy Sources for Road Transport in the Future

Energy Sources for Road Transport in the Futur

Tuning the Optical Property and Photocatalytic Performance of Titanate Nanotube toward Selective Oxidation of Alcohols under Ambient Conditions

Titanate nanotube (TNT) represents one class of novel one-dimensional semiconducting nanomaterials that can be used as photocatalyst for given applications. However, TNT is only UV-light photoactive because of its intrinsic limitation of light absorption in the UV region. Here, we report a facile approach to tune the optical property and photocatalytic performance of TNT by doping various metal ions (Cu²⁺, Co²⁺, Ni²⁺, Fe²⁺, and Mn²⁺) via an ion-exchange method in an aqueous phase. The optical properties of TNT can be finely tuned by incorporating different kinds of metal ions into its tubular framework. In particular, the incorporation of metal ions into the matrix of TNT is able to extend its light absorption to the visible-light region, thus making TNT have the visible-light photoactivity. Activity testing on photocatalytic selective oxidation of a variety of benzylic and allylic alcohols under mild conditions demonstrates that these metal-ion-doped TNTs exhibit markedly enhanced catalytic performance as compared to the undoped TNTs under both the irradiation of UV light and visible light. Such an enhancement of photocatalytic activity with regard to metal-ion-doped TNT is primarily attributed to the prolonged lifetime of photogenerated electron–hole pairs in comparison with that of undoped TNT. Our current research work demonstrates the tunable optical property of TNT by doping metal ions and, more significantly, opens promising prospects of one-dimensional nanotubular TNT or TNT-based materials as visible-light-driven photocatalyst in the area of selective transformation using molecular oxygen as benign oxidant under ambient conditions

Table1_Neonatal cholestasis as the onset symptom of McCune–Albright syndrome: case reports and a literature review.pdf

AimThis study aimed to summarize and show the characteristics and evolutionary process of neonatal cholestasis caused by McCune–Albright syndrome (MAS), as neonatal cholestasis may be the initial manifestation of MAS before other classic clinical features appear.MethodsThe clinical characteristics, treatment methods, and outcomes of three neonatal cholestasis cases caused by MAS in our center were retrospectively studied. In addition, all the reported cases of MAS combined with cholestasis were reviewed and summarized to show the cholestatic features in them.ResultsWe have confirmed three MAS cases in our center, presenting onset symptoms of jaundice, pale stool, and neonatal cholestasis soon after birth. The cholestasis subsided spontaneously at around the sixth month. The literature review showed that the levels of total bilirubin, conjugated bilirubin, ALT, AST, and GGT in neonatal MAS cholestasis cases were 207 μmol/L (range 65–445 μmol/L), 162 μmol/L (range 46–412 μmol/L), 821 U/L (range 85–3,597 U/L), 532 U/L (range 127–3,633 U/L), and 244 U/L (range 79–3,800 U/L), respectively. Liver histology showed canalicular and hepatocellular cholestasis, giant hepatic cell transformation, and bile paucity. Extrahepatic manifestations such as café-au-lait pigmented skin lesions, Cushing's syndrome, hyperthyroidism, renal tubular dysfunction, and skeletal abnormalities could occur simultaneously when jaundice occurred. GNAS mutations had a high positive rate (83.3%–100%) in liver tissue with cholestasis. Neonatal cholestasis caused by MAS could be self-resolved, but hepatic lesions persist and have malignant potential.ConclusionMAS can be one of the causes of neonatal cholestasis, which may be the first manifestation of the disease. Extrahepatic coexisting symptoms of MAS and liver histology can help to distinguish MAS from other etiology of cholestasis. Detecting GNAS mutations in liver tissue may shorten diagnostic time and is of particular interest in the partial and atypical forms of MAS with neonatal cholestasis. Neonatal cholestasis in children with MAS can self-resolve, but liver dysfunction and malignant lesions persist.</p

Graphene Transforms Wide Band Gap ZnS to a Visible Light Photocatalyst. The New Role of Graphene as a Macromolecular Photosensitizer

We report the assembly of nanosized ZnS particles on the 2D platform of a graphene oxide (GO) sheet by a facile two-step wet chemistry process, during which the reduced graphene oxide (RGO, also called GR) and the intimate interfacial contact between ZnS nanoparticles and the GR sheet are achieved simultaneously. The ZnS–GR nanocomposites exhibit visible light photoactivity toward aerobic selective oxidation of alcohols and epoxidation of alkenes under ambient conditions. In terms of structure–photoactivity correlation analysis, we for the first time propose a new photocatalytic mechanism where the role of GR in the ZnS–GR nanocomposites acts as an organic dye-like macromolecular “photosensitizer” for ZnS instead of an electron reservoir. This novel photocatalytic mechanism is distinctly different from all previous research on GR–semiconductor photocatalysts, for which GR is claimed to behave as an electron reservoir to capture/shuttle the electrons photogenerated from the semiconductor. This new concept of the reaction mechanism in graphene–semiconductor photocatalysts could provide a new train of thought on designing GR-based composite photocatalysts for targeting applications in solar energy conversion, promoting our in-depth thinking on the microscopic charge carrier transfer pathway connected to the interface between the GR and the semiconductor

A Unique Silk Mat-Like Structured Pd/CeO₂ as an Efficient Visible Light Photocatalyst for Green Organic Transformation in Water

The charm embedded in nature is its inherent power to create a myriad of materials, for example, a spider web and lotus leaf, with ordinary composition but exhibiting fascinating functional property owing to their unique structures. Such intricate natural designs inspire immense research in synthesizing materials with controlled structure and morphology toward achieving novel or enhanced properties for target applications. Herein, we report a rotary vacuum evaporation and support-driven nanoassembly of tiny Pd noble metal particles on nanosized CeO₂, which features a remarkable unique silk “mat-like” morphology with significant anti-aggregation of Pd nanoparticles during a high temperature calcination process, whereas the obvious aggregation phenomenon of Pd nanoparticles occurs when using commercial CeO₂ as a support. This nanocomposite with unique structural and morphology composition is able to act as a highly selective and active visible light photocatalyst toward organic redox transformations in water, including aerobic oxidation of alcohols and anaerobic reduction of nitro-compounds under ambient conditions, representing a typical tenet of photocatalytic green chemistry

Graphene Oxide as a Surfactant and Support for In-Situ Synthesis of Au–Pd Nanoalloys with Improved Visible Light Photocatalytic Activity

Traditional ways for the synthesis of bimetallic alloyed nanoparticles involve successive or simultaneous reduction of metallic precursors either in an organic solvent phase or in an aqueous phase. However, these two approaches generally require the use of surfactants or polymers, dendrimers, or ligands as protecting or capping agents in order to achieve stable colloidal bimetallic nanoalloys for potential use, for example, loading them onto supports as heterogeneous catalysts. Here, we report the direct synthesis of stabilizing-molecules-free bimetallic Au–Pd nanoalloys promoted by graphene oxide (GO) in an aqueous phase. Formation of Au–Pd nanoalloys and loading onto the reduced GO (denoted as GR) are accomplished simultaneously. Controlled experiments suggest that GO vividly acts as a unique “solution processable macromolecular surfactant” and 2D “flat-mat” support to promote formation and loading of alloyed Au–Pd bimetallic nanoparticles onto the GR sheet. The as-formed Au–Pd/GR exhibits higher photocatalytic activity than both monometallic Au/GR and Pd/GR, prepared by the same approach toward degradation of dye, Rhodamine B (RhB), which thus demonstrates the promising potential of bimetallic nanoalloys rather than the monometallic one in promoting visible light photocatalysis. It is anticipated that our work could boost further interest for harnessing the versatile soft materials features of GO in solution to synthesize other bimetallic alloy catalysts and exploring their applications in photocatalysis

Synthesis of Titanate Nanotube–CdS Nanocomposites with Enhanced Visible Light Photocatalytic Activity

CdS–1D titanate nanotubes (CdS/TNTs) nanocomposites have been synthesized via a facile one-step in situ hydrothermal method. The structure and properties of CdS/TNTs nanocomposites have been characterized by X-ray diffraction, UV–vis diffuse reflectance spectra, transmission electron microscopy, photoluminescence spectra, nitrogen adsorption–desorption, and electron spin resonance spectra. The results show that (i) as compared to blank-CdS, it is found that the morphology of CdS in the CdS/TNTs nanocomposites can be finely tuned by TNTs formed during the one-step in situ hydrothermal process; and (ii) the CdS/TNTs nanocomposites exhibit remarkably much higher visible light photocatalytic activity than both blank-CdS and blank-TNT toward aerobic selective oxidation of alcohols under mild conditions. Three integrative factors lead to such a drastic photoactivity enhancement for CdS/TNTs nanocomposites. The first one is the different morphology of CdS in the CdS/TNTs nanocomposites from blank-CdS. The second one is the prolonged lifetime of photogenerated electron–hole pairs from CdS in CdS/TNTs nanocomposites under visible light irradiation. The third one is the higher surface area and adsorption capacity of CdS/TNTs nanocomposites than blank-CdS. In addition, the possible reaction mechanism for photocatalytic selective oxidation of alcohols over CdS/TNTs nanocomposites has also been investigated using the radical scavengers technique. It is hoped that this work could promote further interest in fabrication of various 1D TNT-based composite materials and their application to visible-light-driven photocatalytic selective organic transformations

Constructing Ternary CdS–Graphene–TiO₂ Hybrids on the Flatland of Graphene Oxide with Enhanced Visible-Light Photoactivity for Selective Transformation

The ternary CdS–graphene–TiO₂ hybrids (CdS–GR–TiO₂) have been prepared through an in situ strategy on the flatland of graphene oxide (GO). The structure and properties have been characterized by a series of techniques, including X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), transmission scanning electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), UV–vis diffuse reflectance spectra (DRS), electrochemical analysis, photoluminescence spectra (PL), nitrogen adsorption–desorption, and electron spin resonance spectra (ESR). Combined with our previous results, it is found that the introduction of the third-component TiO₂ can maintain the morphology and porosity of the samples, whereas it is able to tune the energy band, increase the surface area, and facilitate the electron transfer, thus prolonging the lifetime of photogenerated carriers. Taking photocatalytic selective oxidation of various alcohols to their corresponding aldehydes as model reactions, the ternary CdS–GR–TiO₂ hybrid exhibits enhanced photocatalytic activity compared with its foundation matrix binary CdS–GR. The improved photocatalytic performance can be attributed to the combined interaction of the longer lifetime of photogenerated electron–hole pairs, faster interfacial charge transfer rate, and larger surface area. In addition, a possible reaction mechanism has been proposed. This work indicates that the careful design of graphene–based composites by coupling graphene to suitable, multiple semiconductors allows the achievement of more efficient photocatalysts, which may have the great potential to improve the capacity for photocatalytic processes significantly. As a proof-of-concept, it is expected that this work could offer new inroads into exploration and utilization of graphene–based nanocomposites as a fertile ground for energy conversion

Syntheses, crystal structures, electrochemical studies, and antioxidant activities of zinc(II) and copper(II) complexes with bis(2-benzimidazolyl) aniline derivatives

<div><p>Two ligands, bis(benzimidazol-2-ylmethyl) aniline (bba) and bis(<i>N</i>-methyl-benzimidazol-2-ylmethyl) aniline (Mebba), and their transition metal complexes [Zn(bba)(Br)₂]·2DMF (<b>1</b>) and [Cu(Mebba)(Br)₂]·2DMF (<b>2</b>) have been synthesized and characterized by elemental analyses, molar conductivities, UV–vis spectra, IR spectra, NMR spectroscopy, and X-ray crystallography. The structure around Zn(II) can be described as distorted tetrahedral. Complex <b>2</b> can be described as distorted trigonal bipyramidal. Cyclic voltammograms of <b>2</b> indicate a quasireversible Cu²⁺/Cu⁺ couple. Additionally, the antioxidant activities of the free ligands and their complexes were determined by the superoxide and hydroxyl radical scavenging methods <i>in vitro</i>. Complexes <b>1</b> and <b>2</b> possess potent hydroxyl radical scavenging activity and better than standard antioxidants such as vitamin C and mannitol. Complex <b>2</b> possesses excellent superoxide radical activity.</p></div

Graphene Oxide Directed One-Step Synthesis of Flowerlike Graphene@HKUST‑1 for Enzyme-Free Detection of Hydrogen Peroxide in Biological Samples

A novel metal–organic framework (MOF)-based electroactive nanocomposite containing graphene fragments and HKUST-1 was synthesized via a facile one-step solvothermal method using graphene oxide (GO), benzene-1,3,5-tricarboxylic acid (BTC), and copper nitrate (Cu­(NO₃)₂) as the raw materials. The morphology and structure characterization revealed that the GO could induce the transformation of HKUST-1 from octahedral structure to the hierarchical flower shape as an effective structure-directing agent. Also, it is interesting to find out that the GO was torn into small fragments to participate in the formation of HKUST-1 and then transformed into the reduction form during the solvothermal reaction process, which dramatically increased the surface area, electronic conductivity, and redox-activity of the material. Electrochemical assays showed that the synergy of graphene and HKUST-1 in the nanocomposite leaded to high electrocatalysis, fast response, and excellent selectivity toward the reduction of hydrogen peroxide (H₂O₂). Based on these remarkable advantages, satisfactory results were obtained when the nanocomposite was used as a sensing material for electrochemical determination of H₂O₂ in the complex biological samples such as human serum and living Raw 264.7 cell fluids