•ZSM-5/KIT-1 composites were synthesized using an ionic liquid as a template.•The ZSM-5/KIT-1 composites show a crystalline MFI framework and a three-dimensional network of worm-like channels.•The ratio of ZSM-5 and KIT-1 could be simply adjusted by controlling the pre-crystalline time.ZSM-5/KIT-1 composites were synthesized using an ionic liquid as a template. The structures and morphologies of as-obtained products were characterized using an infrared spectroscopy, X-ray diffractometer, N2 adsorption/desorption, scanning electron microscopy and transmission electron microscopy. The resultant zeolites show a fully crystalline microporous MFI zeolite framework and a three-dimensional network of short worm-like channels. Mesopores and microspores of 4.2 and 0.8 nm in diameter coexist in the zeolite composites. Moreover, the ratio of ZSM-5 and KIT-1 could be simply adjusted by controlling the pre-crystalline time. We believe that the strategy for fabricating ZSM-5/KIT-1 through a simple method could potentially promote the large-scale production of zeolite composites.

A novel nanocomposite of Co0.85Se nanotubes with reduced graphene oxide (Co0.85Se/RGO) is prepared by a facile hydrothermal approach coupled with in situ selenization, which is applied as counter electrode in dye-sensitized solar cells. Electrochemical analysis shows that the Co0.85Se/RGO composite displays a higher electrocatalytic activity for the reduction of triiodide respect to its single components due to the unique hollow structure of Co0.85Se as well as the synergistic effects of high catalytically active Co0.85Se and conductive RGO. As a consequence, the dye-sensitized solar cell (DSSC) fabricated with the Co0.85Se/RGO electrode presents a high photovoltaic conversion efficiency of 7.81%, exceeding the cell based on a Pt electrode (7.55%). Moreover, a considerable electrochemical stability is also achieved when the material was used as a counter electrode in a I−/I3− electrolyte. Therefore, the Co0.85Se/RGO exhibits a huge potential as efficient and low-cost Pt-free counter electrode material to replace Pt allowing for large-scale fabrication of DSSCs.Download high-res image (250KB)Download full-size image

A novel sandwich-like hierarchical structure composed of reduced graphene oxide (RGO) and uniform cobalt disulfide (CoS2) octahedrons is successfully prepared by a simple one-step solvothermal process, in which Co2+ cations attracted into graphene framework by the electrostatic adsorption induce the growth of octahedral CoS2 nanoparticles between the layers of graphene. The fascinating sandwich-like structured CoS2/RGO hybrid inherits excellent electrical conductivity of graphene skeletons. Meanwhile, CoS2 octahedrons intercalated between the layers of graphene provide both rich inner active sites for the reduction of triiodide and abundant mesoporous structure for effective electrolyte diffusion. Benefit from the synergistic effects of CoS2 octahedrons and RGO, the dye-sensitized solar cell (DSSC) assembled with this CoS2/RGO counter electrode (CE) manifests excellent photoelectric conversion efficiency (7.69%), even higher than that of DSSC with conventional noble metal Pt CE (7.38%). Furthermore, CoS2/RGO composite displays outstanding electrochemical stability in I3−/I− redox electrolyte. Overall, this design provides a new strategy for the development of alternative Pt-free counter electrode materials in a DSSC system.Download high-res image (332KB)Download full-size image

•The h-CoFe2O4@CNTs are successfully prepared by in-situ chemical vapor deposition.•The h-CoFe2O4@CNTs is applied as counter electrode for the reduction of triiodide.•The catalytic mechanism of h-CoFe2O4@CNTs/PPy is investigated.•The h-CoFe2O4@CNTs/PPy CE shows the optimal photovoltaic performance of 6.55%.•The h-CoFe2O4@CNTs/PPy CE is a good potential substitute for platinum electrode.The composites of hollow CoFe2O4 and carbon nanotubes (h-CoFe2O4@CNTs) are successfully prepared by using a simple hydrothermal process coupling with the in-situ chemical vapor deposition (CVD) as electrocatalytic materials for counter electrode of dye-sensitized solar cells. The CNTs are uniformly grown on the surface of hollow CoFe2O4 particles verified by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) measurements. The electrochemical performances of hollow CoFe2O4@CNTs composites are evaluated by the EIS, Tafel polarization and CV measurements, and exhibiting high electrocatalytic performance for the reduction of triiodide. The presence of conductive polypyrrole nanoparticles could further improve the conductivity and catalytic performance of the resultant composites. Controlling the thickness of composites film, the optimum photovoltaic conversion efficiency of 6.55% is obtained, which is comparable to that of the cells fabricated with Pt counter electrode (6.61%). In addition, the composites exhibit a good long-term electrochemical stability in I3−/I− electrolyte.

Magnetic CoFe2O4 nanoparticles supported basic poly(ionic liquid)s catalysts were successfully synthesized, and the catalysts prepared through the surface grafting method showed a higher loading amount of ionic liquids, better stability and excellent paramagnetism than that prepared by the conventional co-polymerization method. The catalytic activities for the transesterification and for the Knoevenagel condensation were evaluated, and the catalysts showed an excellent catalytic performance as opposed to the sample prepared using the copolymerization method. The yields of the objective products in transesterification and Knoevenagel condensation were 93 and 97 %, respectively. Moreover, the catalysts could be easily recovered with the assistance of an external magnetic field and after being reused four times, they retained about 76.1 and 68.5 % of their catalytic performance, respectively.

Brønsted acid ionic liquids with different alkyl group carbon chain lengths and an alkane sulfonic acid group were synthesized through bromoalkane, imidazole and 1,4-butane sultone as raw materials. The structures and properties of the ionic liquids were experimentally characterized. Catalytic reaction of methylal (DMM) with trioxane (TOX) for preparation of polyoxymethylene dimethyl ethers (PODMEn, CH3O(CH2O)nCH3, where n > 1) was investigated in various Brønsted acid ionic liquids with different carbon chain length of alkyl groups. The carbon chain length of alkyl groups and activity correlation for the ionic liquids was studied. It was found that the structures of ionic liquids were consistent with the designed structure and their purities were high. They possessed high thermal stability and wide liquid range. The hydrophobicity of ionic liquids became stronger with the increase of carbon chain length. With increasing the carbon chain length of ionic liquids, the selectivity of PODME3–8 is increased at first and then decreased. Among all the ionic liquids, [C6ImBS][HSO4] shows the best catalytic performance and the selectivity of PODME3–8 is 57.85%.

A novel basic polymerized ionic liquid (BPIL): polymeric 1-[(4-ethenylphenyl)methyl]-3-propylimidazolium imidazolide was synthesized and characterized by Fourier transform infrared (FT-IR), nuclear magnetic resonance (NMR) and electron spray ionization mass spectrometry (ESI-MS). The BPIL was used as an efficient catalyst for aqueous Knoevenagel condensations with extended substrates. In comparison with common base catalysts, the BPIL showed high catalytic activity, which was ascribed to the cooperation between the strong basicity and the high surface activity. Moreover, the BPIL with high molecular weight has high surface activity and low catalytic activity. In addition, the BPIL was easily recovered and maintained high catalytic activity after five cycles of use in the system using benzaldehyde and malononitrile as substrates.

To improve the magnetic properties and MRI contrast effect of Fe3O4 superparamagnetic nanoparticles (NPs), a series of oleate-capped, Mn-doped MnxFe(1−x)Fe2O4 (x ≤ 0.4) NPs was prepared via a thermal decomposition method and subsequently assembled into nanoclusters by the carboxylic silane. The effects of Mn doping and clustering on the magnetization, relaxivity and contrast enhancement of the MnxFe(1−x)Fe2O4 (x ≤ 0.4) NPs were studied. Our results revealed that the MnxFe(1−x)Fe2O4 NPs exhibited the highest saturation magnetization of 82.55 emu g−1 when x = 0.05. Correspondingly, the assembled Mn0.05Fe(1−0.05)Fe2O4 nanoclusters showed the highest relaxivity value of 528 (Mn + Fe) mM−1 s−1 and an enhanced MRI contrast in mouse liver. In addition, the MTT and H&E analysis confirmed that Mn0.05Fe(1−0.05)Fe2O4 nanoclusters were non-toxic. Therefore, the biocompatible Mn0.05Fe(1−0.05)Fe2O4 nanoclusters with superior relaxometric properties hold great potential in serving as a novel MRI nanoprobe.

Heteropoly acid (SiW12O40)-based ionic liquid (SWIL) and silica supported SiW12O40-based ionic liquid (SWIL/SiO2) catalysts with different contents of SWIL were designed and prepared. The structures of the catalysts were experimentally characterized and theoretically analyzed, and catalytic activities and reusability of the catalysts were evaluated through an esterification reaction between oleic acid and methanol. The results showed that SWIL had excellent activity and good reusability. SWIL dissolved in the reaction mixture during the reaction process and could be precipitated and separated from products at room temperature after methanol and water were removed. The fresh SWIL/SiO2 had high catalytic activity close to that of SWIL and could be easily separated from the reaction system just through simple filtration. However, the leaching of SWIL in the esterification reaction caused the deactivation of SWIL/SiO2. SWIL contents of SWIL/SiO2 played an important role on the catalytic activity and reusability of SWIL/SiO2.

Acidic ionic liquid ([BsAIm][OTf]) was immobilized on sulfhydryl-group-modified SiO2 (MPS-SiO2) via free radical addition reaction. The [BsAIm][OTf] loading on acidic ionic liquid-functionalized silica ([BsAIm][OTf]/SiO2) was controlled through tuning the sulfydryl (SH) content of MPS-SiO2. All the samples were characterized by FT-IR, elemental analysis, N2 adsorption-desorption measurements and TG-DTA. The catalytic performance of [BsAIm][OTf]/SiO2 in the esterification of oleic acid and the transesterification of glycerol trioleate for biodiesel production was investigated. The results showed that with the increase of [BsAIm][OTf] loading on SiO2 the specific surface area and pore volume of [BsAIm][OTf]/SiO2 decreased, and the pore diameter of [BsAIm][OTf]/SiO2 narrowed. In the esterificaiton of oleic acid, the oleic acid conversion increased with the increasing [BsAIm][OTf] loading. In the transesterification of glycerol trioleate, with the increasing [BsAIm][OTf] loading the glycerol trioleate conversion decreased and the selectivities to glycerol monooleate and methyl oleate increased.SiO2 supported ionic liquid catalysts with different ionic liquid loading were used in biodiesel production. Ionic liquid loading showed contrary influences on the catalytic activities in esterification of oleic acid and tranesterification of glycerol trioleate.Download full-size image

To improve the magnetic properties and MRI contrast effect of Fe3O4 superparamagnetic nanoparticles (NPs), a series of oleate-capped, Mn-doped MnxFe(1−x)Fe2O4 (x ≤ 0.4) NPs was prepared via a thermal decomposition method and subsequently assembled into nanoclusters by the carboxylic silane. The effects of Mn doping and clustering on the magnetization, relaxivity and contrast enhancement of the MnxFe(1−x)Fe2O4 (x ≤ 0.4) NPs were studied. Our results revealed that the MnxFe(1−x)Fe2O4 NPs exhibited the highest saturation magnetization of 82.55 emu g−1 when x = 0.05. Correspondingly, the assembled Mn0.05Fe(1−0.05)Fe2O4 nanoclusters showed the highest relaxivity value of 528 (Mn + Fe) mM−1 s−1 and an enhanced MRI contrast in mouse liver. In addition, the MTT and H&E analysis confirmed that Mn0.05Fe(1−0.05)Fe2O4 nanoclusters were non-toxic. Therefore, the biocompatible Mn0.05Fe(1−0.05)Fe2O4 nanoclusters with superior relaxometric properties hold great potential in serving as a novel MRI nanoprobe.