Jianming Zhao

Synthesis of Convex Hexoctahedral Palladium@Gold Core–Shell Nanocrystals with {431} High-Index Facets with Remarkable Electrochemiluminescence Activities

Convex hexoctahedral nanocrystals have been synthesized through fast growth kinetics and the use of cetylpyridinium chloride as a capping agent. Monodisperse convex hexoctahedral Pd@Au core-shell nanocrystals with {431} high-index facets are obtained at high reaction rates by using high concentrations of ascorbic acid in the presence of cetylpyridinium chloride. In contrast, octahedral nanocrystals with {111} low-index facets and their {100}-truncated counterparts are formed at low ascorbic acid concentrations. The substitute of cetylpyridinium chloride with cetyltrimethylammonium chloride leads to the generation of concave trisoctahedral Pd@Au core-shell nanocrystals with {331} high-index facets, indicating that cetylpyridinium plays an important role in the formation of convex hexoctahedral nanocrystals. The as-prepared convex hexoctahedral Pd@Au core-shell nanocrystals exhibit remarkable catalytic performances toward electrochemiluminescence compared with truncated octahedral and concave trisoctahedral Pd@Au core-shell nanocrystals.

Electrochemical cholesterol sensor based on carbon nanotube@molecularly imprinted polymer modified ceramic carbon electrode.

A monolithic molecular imprinting sensor based on ceramic carbon electrode (CCE) has been reported. The sensor can be renewed simply by smoothing. It was fabricated by thoroughly mixing multiwalled carbon nanotube@molecularly imprinted polymer (MWCNT@MIP), graphite powder, and silicon alkoxide, and then packing the resulting complex mixture of components firmly into the electrode cavity of a Teflon sleeve. The incorporated MWCNT@MIP in CCEs functioned as a recognition element for cholesterol determination. The MWCNT@MIP-CCEs were tested in the presence or absence of cholesterol by cyclic voltammetry and linear sweep voltammetry. The cholesterol sensor has excellent sensitivity with a linear range of 10-300nM and a detection limit of 1nM (S/N=3). The monolithic molecular imprinting sensor exhibits good stability, high sensitivity, and user-friendly reusability for cholesterol determination. This study shows that CCE is a promising matrix for MIP sensors.

Facile surfactant-free synthesis and characterization of Fe3O4@3-aminophenol–formaldehyde core–shell magnetic microspheres

Fe3O4@3-aminophenol–formaldehyde (Fe3O4@APF) core–shell resin polymer magnetic nanocomposites were synthesized using a straightforward surfactant-free methodology. The shell quickly formed within 5 min and could be easily size tunable in the range from 15 to 137 nm by changing the concentrations of 3-aminophenol and formaldehyde. The morphology, composition and magnetic properties of the resulting magnetic microspheres were characterized by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis measurements. The magnetic microspheres were uniform in morphology and can be converted into Fe3O4@carbon magnetic nanocomposites because of their excellent thermal stability. Moreover, Fe3O4@APF magnetic microspheres have excelling adsorption properties in the removal of methyl blue.

Facile Synthesis of Porous PtM (M=Cu, Ni) Nanowires and Their Application as Efficient Electrocatalysts for Methanol Electrooxidation

Porous Pt75Cu25 and Pt73Ni27 nanowires were successfully synthesized by a one‐step wet chemical solution method without the use of any template for the first time. The combination of porous and one‐dimensional features and the addition of a second cheap metal offer high catalyst utilization, excellent catalytic activity, and better durability for the methanol oxidation reaction. Porous Pt75Cu25 and Pt73Ni27 nanowires showed mass current densities of 390 (at 0.69) and 503 mA mg−1 (at 0.70 V), respectively. These mass current densities are much higher than that of Pt nanowires (356 mA mg−1 at 0.73 V) and commercial Pt black (195 mA mg−1 at 0.73 V). During the entire 2000 s current–time test, the porous Pt75Cu25 and Pt73Ni27 nanowires also exhibited higher stability for the methanol oxidation reaction than Pt nanowires and commercial Pt black.

Synthesis and electrochemical applications of nitrogen-doped carbon nanomaterials

Abstract Nitrogen doping is an effective way to tailor the properties of the shaped carbon materials, including the nanotubes, nanocups, nanofibers, as well as the nanorods, and render their potential use for various applications. The common bonding configurations obtained on the N insertion is the pyridinic N and pyrrolic N, which impart the characteristic properties to these carbon materials. This review will focus on the nitrogen-doped carbon materials, the doping effect on the electrochemistry of the doped nanomaterials, and the various synthetic methods to introduce N into the carbon network. The potential applications of the N-doped materials are also reviewed on the basis of the experimental and theoretical studies in electrochemistry.

A Platinum Highly Concave Cube with one Leg on each Vertex as an Advanced Nanocatalyst for Electrocatalytic Applications

Platinum highly concave cubes with one leg on each vertex (HCCLV) enclosed by {7 5 0} facets were conveniently synthesized for the first time through a one‐pot solvothermal method in a mixed solvent of oleylamine and isopropanol containing platinum(II) acetylacetonate. This method can also be extended to the synthesis of Pt dendrite nanocubes at shorter reaction times. Preferential overgrowth may facilitate the formation of Pt HCCLV in the presence of oleylamine and isopropanol. The Pt HCCLV exhibit excellent electrocatalytic activity for the oxidation of methanol (7.76×) and ethanol (5.46×) compared to commercial Pt black. Furthermore, the Pt HCCLV show higher stability than Pt dendrite nanocubes and commercial Pt black. The Pt HCCLV also remarkably improve the electrochemiluminescence activity of the luminol/H2O2 system.

One-pot synthesis of gold nanorods using binary surfactant systems with improved monodispersity, dimensional tunability and plasmon resonance scattering properties

A facile seedless growth method for high-yield synthesis of monodisperse gold nanorods using binary surfactant mixtures is reported for the first time. In comparison with other seedless methods, the present method enables the preparation of gold nanorods with much better monodispersity. Moreover, the present seedless growth method enables the preparation of not only thin gold nanorods but also thick gold nanorods which cannot be prepared by other reported seedless methods. Dark-field microscopy measurements of a single gold nanorod indicate that the thicker gold nanorod shows enhanced scattering properties.

Pd@Au core–shell nanocrystals with concave cubic shapes: kinetically controlled synthesis and electrocatalytic properties

A new type of concave cubic Pd@Au core-shell nanocrystals is synthesized through a kinetically controlled growth process. Pd nanocubes of 56 nm are used as the inner core, and CTAC and Br(-) are used as the capping agent and selective adsorbent, respectively. A suitable ratio of HAuCl4 and cubic Pd seeds and the presence of Br(-) anions are critical to the growth of the concave cubic Pd@Au core-shell nanocrystals. The fast deposition rate on the corners of the cubic Pd seeds promotes the overgrowth of the Au outer shell along the <111> direction, leading to the formation of concave cubic nanostructures. The reduction process is monitored by the surface plasmon resonance spectra of the nanocrystals, and the extinction band became broader and red shifted as the nanocrystals became larger. The electrocatalytic properties of the concave cubic Pd@Au core-shell nanocrystals were investigated with the cathodic electrochemiluminescence reaction of luminol and H2O2. A possible electrocatalytic mechanism was proposed and analyzed.

Fluorescent silica nanoparticle-based probe for the detection of ozone via fluorescence resonance energy transfer

A fluorescence resonance energy transfer (FRET) platform for the detection of ozone was developed by combining the overlap of the fluorescence spectrum of Ru(bpy)3(2+)-doped silica nanoparticles with the absorption spectrum of indigo carmine at around 600 nm. This FRET system can be used to detect ozone simply within 10 min. Simple qualitative ozone detection methods using cotton swabs or paper were also developed.

Fabrication of biomembrane-like films on carbon electrodes using alkanethiol and diazonium salt and their application for direct electrochemistry of myoglobin

Alkanethiols generally form self-assembled monolayers on gold electrodes and the electrochemical reduction of aromatic diazonium salts is a popular method for the covalent modification of carbon. Based on the reaction of alkanethiol with aldehyde groups covalently bound on carbon surface by the electrochemical reduction of aromatic diazonium salts, a new strategy for the modification of carbon electrodes with alkanethiols has been developed. The modification of carbon surface with aldehyde groups is achieved by the electrochemical reduction of aromatic diazonium salts in situ electrogenerated from a nitro precursor, p-nitrophenylaldehyde, in the presence of nitrous acid. By this way, in situ electrogenerated p-aminophenyl aldehyde from p-nitrophenylaldehyde immediately reacts with nitrous acid, effectively minimizing the side reaction of amine groups and aldehyde groups. The as-prepared alkanethiol-modified glassy carbon electrode was further used to make biomembrane-like films by casting didodecyldimethylammonium bromide on its surface. The biomembrane-like films enable the direct electrochemistry of immobilized myoglobin for the detection of hydrogen peroxide. The response is linear over the range of 1-600μM with a detection limit of 0.3μM.