Stable Aqueous ZnO@Polymer Core−Shell Nanoparticles with Tunable Photoluminescence and Their Application in Cell Imaging

Stable Aqueous ZnO@Polymer Core−Shell Nanoparticles with Tunable Photoluminescence and Their Application in Cell Imagin

Polyether-Grafted ZnO Nanoparticles with Tunable and Stable Photoluminescence at Room Temperature

Polyether-Grafted ZnO Nanoparticles with Tunable and Stable Photoluminescence at Room Temperatur

Immobilization of Co–Al Layered Double Hydroxides on Graphene Oxide Nanosheets: Growth Mechanism and Supercapacitor Studies

Layered double hydroxides (LDHs) are generally expressed as [M²⁺_1–<i>x</i>M³⁺_<i>x</i> (OH)₂] [A^<i>n</i>–_{<i>x</i>/<i>n</i>}·<i>m</i>H₂O], where M²⁺ and M³⁺ are divalent and trivalent metal cations respectively, and A is <i>n</i>-valent interlayer guest anion. Co–Al layered double hydroxides (LDHs) with different sizes have been grown on graphene oxide (GO) via in situ hydrothermal crystallization. In the synthesis procedure, the GO is partially reduced in company with the formation of Co–Al LDHs. The morphology and structure of LDHs/GO hybrids are characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The growth mechanism of LDHs on GO nanosheets is discussed. Moreover, both LDHs and LDHs/graphene nanosheets (GNS) hybrids are further used as electrochemical supercapacitor materials and their performance is evaluated by cyclic voltammetry (CV) and galvanostatic charge/discharge measurements. It is shown that the specific capacitances of LDHs are significantly enhanced by the hybridization with GNS

Niobium-Doped Titanosilicate Sitinakite Anode with Low Working Potential and High Rate for Sodium-Ion Batteries

Titanosilicate sitinakite compound with an ideal formula of Na1.68H0.32Ti2O3SiO4·1.76H2O (NTSO) has been employed as a low intercalation potential anode for rechargable sodium ion batteries (SIBs), which exhibit low intercalation potential, low cost, and environmental friendliness. However, the NTSO suffers from shortcomings such as low electronic conductivity, which restricts its electrochemical performances. In this work, cation Nb-doped NTSO compounds have been synthesized and investigated systematically. The powder X-ray diffraction coupling with Rietveld refinement has been used to prove that the Nb has been successfully doped into the crystalline framework of NTSO. The electrochemical performances of Nb-doped NTSO (Na1.68H0.32(Ti1–xNbx)2O3SiO4·1.76H2O, 0 ≤ x ≤ 0.2) has been evaluated in SIBs. Compared to performances of pristine material, those of 10% Nb-doped samples exhibits enhanced electrochemical performances, which shows a stable capcaity of 124 mA h g–1 at a current density of 0.05 A g–1 and 55 mA h g–1 under a current density of 2.0 A g–1. First-principles calculations proved the formation of impurity bands and decrease of conductivity effective mass after Nb doped into the crystalline framework of NTSO with improvement in the electronic conductivity. These findings indicate that the cation doping is an effective way to modify the electrochemical performances of NTSO as an anode in SIBs

Nitrogen-Doped Graphene Nanoribbons as Efficient Metal-Free Electrocatalysts for Oxygen Reduction

Nitrogen-doped graphene nanoribbon (N-GNR) nanomaterials with different nitrogen contents have been facilely prepared via high temperature pyrolysis of graphene nanoribbons (GNR)/polyaniline (PANI) composites. Here, the GNRs with excellent surface integration were prepared by longitudinally unzipping the multiwalled carbon nanotubes. With a high length-to-width ratio, the GNR sheets are prone to form a conductive network by connecting end-to-end to facilitate the transfer of electrons. Different amounts of PANI acting as a N source were deposited on the surface of GNRs via a layer-by-layer approach, resulting in the formation of N-GNR nanomaterials with different N contents after being pyrolyzed. Electrochemical characterizations reveal that the obtained N_8.3-GNR nanomaterial has excellent catalytic activity toward an oxygen reduction reaction (ORR) in an alkaline electrolyte, including large kinetic-limiting current density and long-term stability as well as a desirable four-electron pathway for the formation of water. These superior properties make the N-GNR nanomaterials a promising kind of cathode catalyst for alkaline fuel cell applications