Lichun Dong

Nanostructured Polyaniline-Decorated Pt/C@PANI Core–Shell Catalyst with Enhanced Durability and Activity

We have designed and synthesized a polyaniline (PANI)-decorated Pt/C@PANI core-shell catalyst that shows enhanced catalyst activity and durability compared with nondecorated Pt/C. The experimental results demonstrate that the activity for the oxygen reduction reaction strongly depends on the thickness of the PANI shell and that the greatest enhancement in catalytic properties occurs at a thickness of 5 nm, followed by 2.5, 0, and 14 nm. Pt/C@PANI also demonstrates significantly improved stability compared with that of the unmodified Pt/C catalyst. The high activity and stability of the Pt/C@PANI catalyst is ascribed to its novel PANI-decorated core-shell structure, which induces both electron delocalization between the Pt d orbitals and the PANI π-conjugated ligand and electron transfer from Pt to PANI. The stable PANI shell also protects the carbon support from direct exposure to the corrosive environment.

Enhanced dispersion and durability of Pt nanoparticles on a thiolated CNT support

High dispersion Pt nanoparticles supported on surface thiolation functional carbon nanotubes (SH-CNTs) is presented and electrochemical measurements confirm that the Pt/SH-CNTs catalyst shows good durability and excellent ORR activity.

Dual-porosity Mn2O3 cubes for highly efficient dye adsorption

Dual-porosity materials containing both macropores and mesopores are highly desired in many fields. In this work, we prepared dual-porosity Mn2O3 cube materials with large-pore mesopores, in which, macropores are made by using carbon spheres as the hard templates, while the mesopores are produced via a template-free route. The attained dual-porosity Mn2O3 materials have 24nm of large-pore mesopores and 700nm of macropores. Besides, the achieved materials own cubic morphologies with particle sizes as large as 6.0μm, making them separable in the solution by a facile natural sedimentation. Dye adsorption measurements reveal that the dual-porosity materials possess a very high maximum adsorption capacity of 125.6mg/g, much larger than many reported materials. Particularly, the adsorbents can be recycled and the dye removal efficiency can be well maintained at 98% after four cycles. Adsorption isotherm and kinetics show that the Langmuir model and the pseudo-second-order kinetics model can well describe the adsorption process of Congo Red on the dual-porosity Mn2O3 cube materials. In brief, the reported dual-porosity Mn2O3 demonstrates a good example for controlled preparation of dual-porosity materials with large-pore mesopores, and the macropore-mesopore dual-porosity distribution is good for mass transfer in dye adsorption application.

A Novel Solid-acid Catalyst Using Sulfonated Crosslinked Chitosan Resin

Sulfonated crosslinked chitosan resins (SCCRs) were prepared by firstly crosslinking chitosan to crosslinked chitosan resins (CCRs) using a reverse emulsion crosslinking method, followed by sulfonating CCRs with concentrated H 2 SO 4 as the sulfonation agent. The properties and application of SCCRs as solid acid catalysts were studied. The acidic sites in SCCRs, including C 6 –O and C 2 –N sulfate groups, are all weak acidic sites. SCCRs of higher crosslinking degrees have a higher sulfonation rate of the C 6 primary hydroxyl groups, thus more C 6 –O sulfate groups. High-temperature treatment and TG analysis verified that the crosslinking can improve the thermostability of both SCCR backbone and its acidic groups, and a higher crosslinking degree leads to better thermostability. Catalytic esterification of citric acid with butanol and propionic acid with n-butyl alcohol demonstrated that SCCRs have good catalytic activity and can be repetitively used as efficient solid acid catalysts.

A vinyl flanked difluorobenzothiadiazole–dithiophene conjugated polymer for high performance organic field-effect transistors

Fluorine containing conjugated polymers have been widely applied in high performance organic solar cells, but their use in field-effect transistors is still quite limited. In this work, a conjugated polymer PTFBTV based on difluorobenzothiadiazole (DFBT) and dithiophene was synthesized, utilizing multiple vinylene as linkers. The polymer exhibits a relatively high hole mobility up to 2.0 cm2 V−1 s−1 compared with the reported DFBT–oligothiophene based polymers, yet its structural complexity is much simpler. The polymer thin film exhibits a typical ‘face on’ molecular orientation. A single crystal of its monomer revealed a non-covalent intramolecular contact between fluorine and the neighbouring proton, which strengthens the backbone co-planarity. Meanwhile an intermolecular F⋯F contact was also observed, which might cause rather scattered lamellar crystallinity for PTFBTV in the solid state.

Vinylene spacer effects of benzothiadiazole–quarterthiophene based conjugated polymers on transistor mobilities

In this work we aim to investigate the relationships among the ratios of vinyl linker, crystallinity and charge carrier mobility in a series of benzothiadiazole–quarterthiophene based conjugated polymers. Four polymers, PB4TV0, PB4TV1, PB4TV2 and PB4TV3, containing 0 to 3 vinyl linkers in the repeating unit were synthesized, and their corresponding bottom gate/bottom contact organic field effect transistors were fabricated and examined. The results manifest escalating hole mobilities along the increasing ratio of vinyl linker, with PB4TV3 reaching a high hole mobility up to 0.36 cm2 V−1 s−1. On the other hand, further investigations have revealed a gradual reduction in the crystallinity with rising vinyl ratio after a slight enhancement at first. The difference between the mobility and crystallinity variation tendency is caused by the combined influences of intra-chain charge transport enhancement and the conformational isomerization nature of the vinyl linker, which could provide new thoughts in designing high performance conjugated polymers for OFETs in future.

Boosted Visible Light Photodegradation Activity of Boron doped rGO/g-C3N4 Nanocomposites: The Role of C-O-C Bonds

Heteroatom doping has been demonstrated to be an effective way to tune the properties of nanomaterials including chemical reactivity and electronic and optical performance. In this study, rGO/g-C3N4 and boron doped rGO/g-C3N4 (B-rGO/g-C3N4) nanocomposites were fabricated via a rapid plasma treatment method, and their photocatalytic performance under visible light radiation was examined. The results showed that the photocatalytic efficiency of B-rGO/g-C3N4 for rhodamine B degradation can be 50% higher than that of rGO/g-C3N4 at an optimum rGO loading of 5 wt%. XPS and FTIR analyses indicated the enhanced C–O–C covalent bonding between rGO and g-C3N4 in B-rGO/g-C3N4, and the optical characterization demonstrated that it could further improve the separation of the photo-generated chargers and narrow the bandgap of the nanocomposite. This work provides an idea that boron doping could be an effective way to promote the chemical interaction between different components in composite materials, which is important in designing and developing new functional nanomaterials.

High Carbon-Resistance Ni@CeO 2 Core–Shell Catalysts for Dry Reforming of Methane

Ni@CeO2 core–shell catalysts were synthesized via a facile surfactant-assisted hydrothermal method and their catalytic performance in the dry reforming of methane (DRM) reaction was evaluated. A variety of techniques including XRD, N2 adsorption–desorption, SEM, TEM, TPO, TGA were employed to characterize the prepared or spent catalysts. The encapsulation by the CeO2 shell, on one side, can restrict the sintering and growth of Ni nanoparticles under harsh reaction conditions. On the other side, compared to the conventional shell material of SiO2, CeO2 can provide more lattice oxygens and vacancies, which is helpful to suppress coke deposition. Consequently, the Ni@CeO2 core–shell catalysts exhibited better catalytic activity and stability in the DRM reaction with respect to the referenced Ni@SiO2 core–shell catalysts and Ni/CeO2 supported catalysts.