Changshui Huang

Mesoporous NiCo2O4 nanoflakes as electrocatalysts for rechargeable Li–O2 batteries

Herein, we report the facile synthesis of mesoporous NiCo(2)O(4) nanoflakes and their application in nonaqueous Li-O(2) batteries as cathode catalysts. The assembled Li-O(2) batteries presented lower overpotentials and enhanced cyclability, which should be attributed to the superior electrocatalytic activity and the mesoporous nanostructure of NiCo(2)O(4).

Ordered Nanosphere Alignment of Porphyrin for the Improvement of Nonlinear Optical Properties

There is currently an intensive effort to develop methods for producing materials with two-dimensionally (2D) or threedimensionally (3D) structured patterns and arrays, which are of great importance and interest because of their potential applications in the development of optoelectronic and microelectronic devices, [ 1–4 ] and the fabrication of chemical and biological sensors. [ 5 , 6 ] In the most recent developments, the fabrication of 2D or 3D structured patterns and arrays via colloidal self-assembly is particularly attractive. [ 7–15 ] In addition to being inexpensive, this method offers relative ease of processing and requires short processing time, compared to the stepwise manner of microfabrication techniques. [ 16–20 ] Typical building blocks of these self-assembly are polystyrene (PS) or poly(methyl methacrylate) (PMMA) latex spheres, poly(dimethyl siloxane) (PDMS), silica spheres, emulsion droplets with narrow size distribution. [ 9 , 21–23 ]

One-step, solution-processed formamidinium lead trihalide (FAPbl((3-x))Cl(x)) for mesoscopic perovskite-polymer solar cells

Formamidinium (FA) lead triiodide perovskite with chlorine addition (NH2CH=NH2PbI(3-x)Clx) is employed as a light harvester in mesoscopic solar cells for the first time. It is demonstrated that a phase-pure FAPbI(3-x)Clx perovskite layer can be synthesized using a one-step solution-process at 140 °C, and the resultant solar cells deliver a maximum power conversion efficiency of 7.51%, which is the most efficient formamidinium-lead-halide perovskite mesoscopic solar cell employing a polymer hole-transporting layer. The effects of the thermal annealing temperature on the quality/morphology of the perovskite layer and the solar cells performance are discussed. The advantages offered by the one-step solution-processing method and the reduced bandgap make FAPbI(3-x)Clx perovskites an attractive choice for future hybrid photovoltaics.

Molybdenum nitride/n-doped carbon nanospheres for lithium-o2 battery cathode electrocatalyst.

Molybdenum nitride/N-doped carbon nanospheres (MoN/N-C) are synthesized by hydrothermal method followed by ammonia annealing. The as-prepared MoN/N-C nanospheres manifest considerable electrocatalytic activity toward oxygen reduction reaction in nonaqueous electrolytes because of its nanostructure and the synergetic effect between MoN and N-C. Furthermore, the MoN/N-C nanospheres are explored as cathode catalyst for Li-O2 batteries with tetra-(ethylene glycol) dimethyl ether as the electrolyte. The assembled batteries deliver alleviated overpotentials and improved battery lifespan, and their excellent performances should be attributed to the unique hierarchical structure and high fraction of surface active sites of cathode catalyst.

Self-catalyzed Growth of Large-Area Nanofilms of Two-Dimensional Carbon

The graphdiyne (GD), a carbon allotrope with a 2D structure comprising benzene rings and carbon–carbon triple bonds, can be synthesized through cross-coupling on the surface of copper foil. The key problem is in understanding the dependence of layers number and properties, however, the controlled growth of the layers numbers of GD film have not been demonstrated, its controlled growth into large-area and high ordered films with different numbers of layers is still an important challenge. Here, we show that a new strategy for synthesizing GD films with 2D nanostructures on ZnO nanorod arrays through a combination of reduction and a self-catalyzed vapor–liquid–solid growth process, using GD powder as the vapor source and ZnO nanorod arrays as the substrate. HRTEM shows the distance between pairs of streaks being approximately 0.365 nm by different thicknesses of GD films. The approach enables us to construct large-area ordered semiconductive films with high-quality surfaces showing high conductivity (up to 2800 S cm−1). FETs were fabricated based on the well ordered films; we prepared and measured over 100 devices. Devices incorporating these well-ordered and highly conductive GD films exhibited field-effect mobility as high as 100 cm2 V−1 s−1.

High Conductive Two-Dimensional Covalent Organic Framework for Lithium Storage with Large Capacity

A high conductive 2D COF polyporphyrin (TThPP) linked by 4-thiophenephenyl groups was synthesized through an in situ chemical oxidative polymerization on the surface of copper foil. The TThPP films were used as the anode of lithium-ion battery, which exhibited high specific capacities, excellent rate performances, and long cycle lives due to the alignment of 2D polyporphyrin nanosheets, and they (i) can highly efficiently adsorb Li atoms, (ii) have short-ended paths for the fast lithium ion diffusion, and (iii) open nanopores holding electrolyte. The reversible capacity is up to 666 mAh/g. This is the first example of an organic 2D COF for an anode of lithium-ion battery and represents an important step toward the use of COFs in the next-generation high-performance lithium-ion battery.

Conjugated microporous polymers with excellent electrochemical performance for lithium and sodium storage

Conjugated microporous polymers, which exhibit high specific capacity, superior cycle stability and remarkable rate capability, are explored as high-performance electrode materials for lithium and sodium storage. Their excellent electrochemical performance can be attributed to their conductive frameworks, plentiful redox-active units, high specific surface area and homogeneous microporous structure.

Spectroscopic properties of nanotube-chromophore hybrids.

Recently, individual single-walled carbon nanotubes (SWNTs) functionalized with azo-benzene chromophores were shown to form a new class of hybrid nanomaterials for optoelectronics applications. Here we use a number of experimental and computational techniques to understand the binding, orientation, and nature of coupling between chromophores and the nanotubes, all of which are relevant to future optimization of these hybrid materials. We find that the binding energy between chromophores and nanotubes depends strongly on the type of tether that is used to bind the chromophores to the nanotubes. The pyrene tethers form a much stronger attachment to nanotubes compared to anthracene or benzene rings, resulting in more than 80% retention of bound chromophores post-processing. Density functional theory (DFT) calculations show that the binding energy of the chromophores to the nanotubes is maximized for chromophores parallel to the nanotube sidewall, even with the use of tethers; optical second harmonic generation measurements show that there is nonetheless a partial radial orientation of the chromophores on the nanotubes. We find weak electronic coupling between the chromophores and the SWNTs, consistent with noncovalent binding. This weak coupling is still sufficient to quench the chromophore fluorescence through a combination of static and dynamic processes. Photoluminescence measurements show a lack of significant energy transfer from the chromophores to isolated semiconducting nanotubes.

Nitrogen-Doped Graphdiyne Applied for Lithium-Ion Storage.

The elemental N emerged uniformly in graphdiyne (GDY) after heat treatment under NH3 atmosphere to form N-doping GDY. The interplanar N-GDY distance decreased slightly, which may be ascribed to the smaller atom radius of N than C. Compared with GDY, the introduction of N atoms in N-GDY created numerous heteroatomic defects and active sites, thus achieving enhanced electrochemical properties, including higher reversible capacity, improved rate performance, and superior cycling stability. In addition, N-doping might be advantageous to minimize the surface side reactions and form stable interfaces, hence improving the electrochemical cycling stability of N-GDY electrodes. These results indicate N-doping is also an efficient way for improving the electrochemical performance of GDY materials.

Morphological tuning and conductivity of organic conductor nanowires

We report the synthesis of small-molecule organic conductor nanowires of TTF-TCNQ by selective inducement in a two-phase method by pi-pi stacking interaction. The morphologies of TTF-TCNQ, from straight nanowires to helical nanowires and to complicated helical dendrite structures, have been controlled by adjusting the experimental conditions. The technique has been applied to the synthesis of AgTCNQ/CuTCNQ nanowires in a two-phase system of acetonitrile/hexane. I-V characterization of an individual nanowire indicated that the conductivity along the b-axis of the TTF-TCNQ helical nanowire is much better than that along other directions. The synthetic procedure presented is a general approach for producing controlled organic conductor/semiconductor nanowires.