Owing to wide-ranging industrial applications and fundamental importance, tailored synthesis of well-faceted single crystals of anatase TiO2 with high percentage of reactive facets has attracted much ...research interest. In this work, high-quality anatase TiO2 single-crystal nanosheets mainly dominated by {001} facets have been prepared by using a water−2-propanol solvothermal synthetic route. The synergistic functions of 2-propanol and HF on the growth of anatase TiO2 single-crystal nanosheets were studied by first-principle theoretical calculations, revealing that the addition of 2-propanol can strengthen the stabilization effect associated with fluorine adsorption over (001) surface and thus stimulate its preferred growth. By measuring the •OH species with terephthalic acid scavenger, the as-prepared anatase TiO2 single-crystal nanosheets having 64% {001} facets show superior photoreactivity (more than 5 times), compared to P25 as a benchmarking material.
Nitrogen-doped ZnO bundle-like nanoparticles were prepared by heating ZnOHF precursor at different temperatures under an ammonia atmosphere. ZnOHF gradually transformed to N-ZnO with the increase of ...the heating temperature, and the as-prepared N-ZnO nanoparticles preserved the original morphologies of ZnOHF at moderate heating temperature. The N-ZnO nanoparticles demonstrated drastically enhanced absorption in the visible region compared with the commercial ZnO and N-ZnO derived from commercial ZnO. Theoretical calculations indicated that the contribution of nitrogen to the top of the valence band (VB) of ZnO plays the major role of extending the absorption of ZnO to the visible region. The as-prepared N-ZnO showed high photocatalytic activity for the visible-light-induced water oxidation, and the activity can be further greatly enhanced by loading IrO2 cocatalyst. To our knowledge, this is the first report of realizing photocatalytic water oxidation on non-metal-doped ZnO under visible light without applied bias, thus adding new value to the band gap engineering of benchmark ZnO for efficient solar energy utilization.
Ammonia borane (AB) has attracted tremendous interest for on‐board hydrogen storage due to its low molecular weight and high gravimetric hydrogen capacity below a moderate temperature. However, the ...slow kinetics, irreversibility, and formation of volatile materials (trace borazine and ammonia) limit its practical application. In this paper, a new catalytic strategy involved lithium (Li) catalysis and nanostructure confinement in mesoporous carbon (CMK‐3) for the thermal decomposition of AB is developed. AB loaded on the 5% Li/CMK‐3 framework releases ∼7 wt % of hydrogen at a very low temperature (around 60 °C) and entirely suppresses borazine and ammonia emissions that are harmful for proton exchange membrane fuel cells. The possible mechanism for enhanced hydrogen release via catalyzed thermal decomposition of AB is discussed.
Synergistic effects of nano confinement within CMK3 and Li catalysis enhance the hydrogen release from ammonia borane (AB) to ∼7wt% at temperatures as low as 60oC (see figure), which satisfies the requirements of the US Department of Energy for hydrogen storage. The thermodynamics of hydrogen release from AB is modified via these synergistic effects and the release of undesirable volatile products, for example ammonia and borazine, is eliminated.
A unique ZnS branched architecture was fabricated by a facile thermal evaporation method. Stable UV emission at 327 nm and superior field emission with a low turn‐on field, a high field‐enhancement ...factor, a large current density, and small fluctuation were observed.
Room temperature simultaneous doping of reduced graphene oxide films with oxygen, nitrogen and chlorine was performed through anodic polarization in a neutral nitrogen-deaerated KCl electrolyte. The ...thermodynamic electrochemical windows of water, dissolved nitrogen and chlorine anions were analyzed on the basis of the Pourbaix diagram. Anode polarization demonstrated that the nitrogen, water and chlorine anions can be oxidized at an applied potential of 1.7V vs. NHE. The oxidative products, i.e. oxygen, nitrate anion and hypochlorous acid, can react with the reduced graphene oxide surface. X-ray photoelectron spectroscopy proved the chlorine–nitrogen co-doping of the treated film, along with an increase of oxygen groups. Surface structure evolution was also confirmed by Raman and Fourier-transform infrared spectroscopies. The anodic doping can be hindered by covering the reduced graphene oxide surface with sulfate anions or forming stable carbon–nitrogen bonds. Incorporation of oxygen, nitrogen and chlorine also helps to enhance the supercapacitance of the doped film.
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► One-pot preparation of MSA-capped CdTe/CdS QDs at neutral pH (6–7). ► High fluorescence quantum yield (84%) of MSA-capped QDs. ► High structural and chemical stability in pH 6–9 ...solution. ► Great potential of MSA-capped CdTe/CdS QDs for live cell imaging.
Water-soluble CdTe/CdS quantum dots (QDs) with tuneable emissions were prepared in aqueous solution at pH=6–7 via refluxing and hydrothermal treatment. The resultant CdTe/CdS QDs are stabilized with mercaptosuccinic acid (MSA) and show high fluorescence quantum yields (maximum QY is 84%). Characterization with UV–Vis, PL, XPS, XRD and TEM demonstrates a core (CdTe)–shell (CdS) structure, which leads to high fluorescence quantum yields. The effective protection from CdS shell and MSA enables CdTe QDs to be chemically stable in a pH range of 6–9 and less toxic. These merits make our CdTe/CdS QDs very promising for bio-imaging applications, as exemplified by labelling HEK 293 cells.
We demonstrate an efficient synthesis of novel layered double hydroxide mesoporous silica core-shell nanostructures (LDH@mSiO(2)) that have a hexagonal MgAl-LDH nanoplate core and an ordered ...mesoporous silica shell with perpendicularly oriented channels via a surfactant-templating method. Transmission electron microscopy, X-ray diffraction and N(2) sorption analyses confirmed that the obtained nanostructures have uniform accessible mesopores (∼2.2 nm), high surface area (∼430 m(2) g(-1)), and large pore volume (∼0.22 cm(3) g(-1)). Investigations of drug release and bio-imaging showed that this material has a slow release effect of ibuprofen and good biocompatibility. This work provides an economical approach to fabricate LDH@mSiO(2) core-shell nanostructures, which may have great potential in broad drug delivery and hyperthermia therapy applications.
Nanometer‐sized mesoporous silica particles of around 100‐nm diameter functionalized with a large amount of sulfonic acid groups are prepared using a simple and fast in situ co‐condensation ...procedure. A highly ordered hexagonal pore structure is established by applying a pre‐hydrolysis step in a high‐dilution synthesis approach, followed by adding the functionalization agent to the reaction mixture. The high‐dilution approach is advantageous for the in situ functionalization since no secondary reagents for an effective particle and framework formation are needed. Structural data are determined via electron microscopy, nitrogen adsorption, and X‐ray diffraction, proton conductivity values of the functionalized samples are measured via impedance spectroscopy. The obtained mesoporous SO3H‐MCM‐41 nanoparticles demonstrate superior proton conductivity than their equally loaded micrometer‐sized counterparts, up to 5 × 10−2 S cm−1. The mesoporosity of the particles turns out to be very important for effective proton transport since non‐porous silica nanoparticles exhibit worse efficient proton transport, and the obtained particle size dependence might open up a new route in rational design of highly proton conductive materials.
Mesoporous silica particles 100 nm in diameter functionalized with sulfonic acid groups are prepared using a simple and fast in situ co‐condensation procedure. The resulting SO3H‐MCM‐41 nanoparticles (see image) exhibit a highly ordered hexagonal pore structure and demonstrate very high proton conductivities. Superior proton conductivity values indicate a particle size dependence of the proton conductivity.
