Zhiwei Tong

A Photoactivated Artificial Muscle Model Unit: Reversible, Photoinduced Sliding of Nanosheets

A novel photoactivated artificial muscle model unit is reported. Here we show that organic/inorganic hybrid nanosheets reversibly slide horizontally on a giant scale and the interlayer spaces in the layered hybrid structure shrink and expand vertically by photoirradiation. The sliding movement of the system on a giant scale is the first example of an artificial muscle model unit having much similarity with that in natural muscle fibrils. In particular, our layered hybrid molecular system exhibits a macroscopic morphological change on a giant scale (~1500 nm) relative to the molecular size of ~1 nm by means of a reversible sliding mechanism.

Highly Efficient All-Solution-Processed Fluorescent Organic Light-Emitting Diodes Based on a Novel Self-Host Thermally Activated Delayed Fluorescence Emitter

Here, we conveniently designed and synthesized a self-host thermally activated delayed fluorescence (TADF) emitter, which can not only form a uniform thin film through wet-process, but also allow the subsequently deposition of electron transporting layer (ETL) by orthogonal solvent. By using this self-host material as emitter, the all-solution-processed multilayer TADF organic light emitting diodes (OLEDs) was successfully fabricated. The maximum current, power and external quantum efficiencies of this nondoped device are 46.3 cd A-1, 39.3 lm W1- and 15.5%, respectively, which are much higher than the values of all-solution-processed OLEDs based on tranditional fluorescence and even comparable to the TADF devices with vacuum-deposited ETL. Moreover, the device maintains the high efficiency of 42.9 cd A-1 and 39.0 cd A-1 at the luminance of 100 cd m-2 for display and 1000 cd m-2 for practical lighting. The high efficiency and small efficiency roll-off of the all-solution-processed fluorescent OLEDs can be attributed to the superiority of the newly designed self-host TADF emitter, which possesses the perfect electroluminescent property and sufficient solvent resistance at the same time.

Supported ionic-liquid layer on polystyrene–TEMPO resin: a highly efficient catalyst for selective oxidation of activated alcohols with molecular oxygen

We report a facile, efficient procedure for selective oxidation of activated alcohols by use of a novel supported ionic-liquid catalyst produced by coating polystyrene–TEMPO resin with the ionic liquid [bmim]PF6 and CuCl2. The oxidation affords aldehydes or ketones in excellent yield and with high selectivity. It is worthy of note that the supported ionic-liquid layer substantially enhances catalytic activity, and the catalyst can easily be recycled.Graphical abstract

High Durable Ternary Nanodendrites as Effective Catalysts for Oxygen Reduction Reaction

Exploiting high catalytic activities and superior durability is significant for the lifetime and the cost of electro-catalysts for oxygen reduction reaction (ORR). Pt-Ni nanocrystals have attracted considerable attention owing to their exceptionally catalytic performance. However, the durability of Pt-Ni nanoparticles in acid media is still far below satisfaction. Consequently, improving the durability is extremely urgent for the application of Pt-Ni catalysts. To this end, we herein develop Pt-Ni-Ir ternary nanocrystals with dendritic shape, which are synthesized through a facile one-pot strategy. Such nanostructures featured with multibranches show an area specific activity of 1.58 mA cm(-2), seven times more than that of the commercial Pt/C catalyst (0.21 mA cm(-2)). More importantly, the dendritic Pt-Ni-Ir catalyst displays extraordinarily high durability. In contrast to the commercial Pt/C counterparts, which exhibit losses of 53.2% in EASA and 41% in area specific activity after 12 000 cycles of sweeping in the potential range of 0.6-1.1 V, only respective losses of 5.5% and 6% are detected for our dendritic Pt-Ni-Ir catalyst. The high activity and remarkable durability are mainly attributed to the dendritic morphology and the introduction of Ir. This work demonstrates that the Pt-Ni-Ir dendritic nanostructures are promising electro-catalysts for ORR.

One-Pot Synthesis of Concave Platinum–Cobalt Nanocrystals and Their Superior Catalytic Performances for Methanol Electrochemical Oxidation and Oxygen Electrochemical Reduction

Exploring highly efficient electro-catalysts is of significant urgency for the widespread uptake of the direct methanol fuel cells (DMFCs). Pt-Co nanocrystals have attracted considerable attentions because of their superior catalytic performance toward both methanol oxidation and oxygen reduction in the preliminary assessments. This Research Article presents a Pt-Co bimetal catalyst that is synthesized through a facile coreduction strategy. The Pt-Co nanocrystals have concave cubic shape with a high uniform size of 7-9 nm and Pt-rich surfaces. The catalysis of the concave cubic Pt-Co nanoparticles toward both methanol electrochemical oxidation reaction (MOR) and oxygen electrochemical reduction reaction (ORR) is evaluated. In comparison with the commercial Pt/C catalyst (Johnson Matthey), the present concave cubic Pt-Co catalyst displays superior performances in not only catalytic activity but also durability. The concave Pt-Co catalyst also shows higher activities than spherical and cubic Pt-Co nanoparticles. The dramatic enhancement is mainly attributed to its alloyed composition, Pt-rich surface and the concave nanostructure. The results of our research indicate that the concave Pt-Co nanocrystal could be a promising catalyst for both MOR and ORR. The present work might also raise more concerns on exploiting morphology and composition of nanocrystal catalysts, which are expected to provide high catalytic performance in electrochemical reactions.

Preparation and photochemical behavior of polyfluorinated cationic azobenzene-titanoniobate intercalation compounds

A novel photofunctional material composed of polyfluorinated cationic azobenzene and layered potassium titanoniobate was synthesized and its photochemical behavior was investigated. Although polyfluorinated cationic azobenzene could not be intercalated into the interlayer region of layered potassium titanoniobate directly, the intercalation compound was obtained by guest–guest-exchange with the hexylammonium-TiNbO5 intercalation compound. X-Ray diffraction, TGA, IR, TEM, UV-visible spectroscopy and elemental analysis results indicated that the polyfluorinated cationic azobenzene was intercalated into the interlayer spaces of the potassium titanoniobate. The AFM image for the intercalated compound with a basal spacing of 3.90 nm was consistent with the X-ray diffraction data. The spectral properties as well as X-ray diffraction results have revealed that the adsorbed polyfluorinated cationic azobenzene molecules form J-like aggregates with bi-layers in the interlayer space of the potassium titanoniobate. The intercalation compound exhibited an excellent reversible cis–transphotoisomerization by successive illumination with UV light at 365 nm and visible light at 458 nm. The basal spacing changed reversibly upon photoisomerization of the intercalated polyfluorinated cationic azobenzene.

Preparation of polyaniline modified BiOBr with enhanced photocatalytic activities

The polyaniline/bismuth oxybromide (PANI/BiOBr) hybrids materials have been synthesized hydrothermally in the presence of PANI. The PANI/BiOBr hybrids materials were confirmed by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy and ultraviolet–visible diffuse reflectance spectroscopies. Among the hybrid photocatalysts, PANI/BiOBr-0.2 showed the highest photocatalytic properties for the degradation of rhodamine B (RhB), and the increased photocatalytic properties could be due to photosensitization and the inhibited electron–hole recombination.

SOLVOTHERMAL PREPARATION OF CeO2 NANOCUBES AND THEIR CATALYTIC PROPERTIES

Cubic-like CeO2 nanocrystals about 11 nm long were successfully synthesized via an ethanolamine-assisted hydrothermal route using (NH4)Ce(NO3)4 as a precursor at 180°C for 24 h. The CeO2 nanocubes were modified onto the glassy carbon electrode by adsorption to fabricate the modified electrode. The reliability and stability of the CeO2 NC/GC electrode offer a good possibility for applying the technique on routine analysis of ascorbic acid (AA) in clinical use. In addition, the catalytic effect of the CeO2 nanocubes for thermal decomposition of ammonium perchlorate (AP) was investigated by DTA and TG. The catalytic performance of CeO2 nanocubes is superior to that of commercial CeO2 powder.

Synthesis and photocatalytic performance of Bi2S3/SnS2 heterojunction

Bi2S3/SnS2 heterostructured photocatalysts were synthesized from BiOI, SnCl4⋅5H2O and NH2CSNH2 using an economic and simple hydrothermal method. The as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy and ultraviolet-visible diffuse reflectance spectroscopy. The photodegradation activities of the Bi2S3/SnS2 heterostructured photocatalysts were estimated by degrading rhodamine B under simulated sunlight supplied by irradiating with a 350W Xe lamp. Bi2S3/SnS2 photocatalysts were prepared using varying percentages of Bi2S3. The sample containing 13% Bi2S3 had the most efficient photocatalyst performance among the tested samples. The photocatalytic mechanism involves heterojunctions formed in the Bi2S3/SnS2, which promoted effective separation of photoinduced electrons and holes.

Fabrication and characterisation of MnOOH and β-MnO2 nanorods with rectangular cross-sections

MnOOH nanorods with rectangular cross-sections have been successfully prepared in high yield via a hydrothermal reduction process at a low temperature. After the subsequent heat treatment of the as-prepared MnOOH nanorods at 350°C for 6 h in air, β-MnO2 nanorods with rectangular cross-section that retained the similar morphologies of MnOOH nanorods were obtained. The products were characterised by powder X-ray diffraction and field-emission scanning electron microscopy. The influences of different degrees of pH on the morphology and phase of the final products under hydrothermal conditions are discussed.