Cheng-Yong Su

Construction of Covalent Organic Framework for Catalysis: Pd/COF-LZU1 in Suzuki-Miyaura Coupling Reaction

Covalent organic frameworks (COFs) are crystalline porous solids with well-defined two- or three-dimensional molecular structures. Although the structural regularity provides this new type of porous material with high potentials in catalysis, no example has been presented so far. Herein, we report the first application of a new COF material, COF-LZU1, for highly efficient catalysis. The easily prepared imine-linked COF-LZU1 possesses a two-dimensional eclipsed layered-sheet structure, making its incorporation with metal ions feasible. Via a simple post-treatment, a Pd(II)-containing COF, Pd/COF-LZU1, was accordingly synthesized, which showed excellent catalytic activity in catalyzing the Suzuki-Miyaura coupling reaction. The superior utility of Pd/COF-LZU1 in catalysis was elucidated by the broad scope of the reactants and the excellent yields (96-98%) of the reaction products, together with the high stability and easy recyclability of the catalyst. We expect that our approach will further boost research on designing and employing functional COF materials for catalysis.

Oriented hierarchical single crystalline anatase TiO2 nanowire arrays on Ti-foil substrate for efficient flexible dye-sensitized solar cells

Hierarchical anatase TiO2 nanowire (HNW) arrays consisting of long single crystalline nanowire trunks and short single crystalline nanorod branches have been synthesized on Ti-foil substrate via a two-step hydrothermal growth process. The formation of the HNW arrays based on anatase TiO2 nanowire (NW) arrays can be ascribed to the crystallographic relationship between trunk and branch. The power conversion efficiency of dye-sensitized solar cells (DSSCs) based on such a HNW photoelectrode (4.51%) shows a significant enhancement compared to TiO2 nanowire (NW) array photoelectrode (3.12%) with similar thickness (∼15 μm in nanowire length), which can be attributed to more dye loading, superior light scattering ability and comparable electron transport rate for the former. Furthermore, flexible DSSC using TiO2 HNW arrays on Ti substrate as working electrode and transparent PEDOT/ITO-PET prepared via in situelectrodeposition as counter electrode shows a comparable photovoltaic performance to the rigid Pt/FTO-glass cell. A power conversion efficiency as high as 4.32% (Jsc = 7.91 mA cm−2, Voc = 796 mV, FF = 0.69) is obtained for the first time for fully flexible DSSC based on hierarchical TiO2 nanowire arrays and Pt-free counter electrode.

Recent Advances in Supramolecular Design and Assembly of Silver(I) Coordination Polymers

The supramolecular chemistry of Ag(i) coordination assemblies continues to attract attention due to their versatile structural diversity and potential physical and chemical functions. This article provides a short review of recent advances in the design and construction of Ag(i) coordination polymers with special emphasis on the Ag(i) ion coordination geometry, ligand functionality, and supramolecular interactions. The potential functions of Ag(i) coordination polymers are briefly summarized.

Hydrothermal fabrication of hierarchically anatase TiO2 nanowire arrays on FTO glass for dye-sensitized solar cells.

Hierarchical anatase TiO2 nano-architecture arrays consisting of long TiO2 nanowire trunk and numerous short TiO2 nanorod branches on transparent conductive fluorine-doped tin oxide glass are successfully synthesized for the first time through a facile one-step hydrothermal route without any surfactant and template. Dye-sensitized solar cells based on the hierarchical anatase TiO2 nano-architecture array photoelectrode of 18 μm in length shows a power conversion efficiency of 7.34% because of its higher specific surface area for adsorbing more dye molecules and superior light scattering capacity for boosting the light-harvesting efficiency. The present photovoltaic performance is the highest value for the reported TiO2 nanowires array photoelectrode.

Tri-functional hierarchical TiO2 spheres consisting of anatase nanorods and nanoparticles for high efficiency dye-sensitized solar cells

Hierarchical anatase TiO2 spheres consisting of nanorods and nanoparticles are successfully prepared via a simple acid thermal method using titanium n-butoxide and acetic acid, which will overcome the kinetic and light-scattering limitations of nanoparticles and the surface area limitations of one-dimensional nanostructures, as photoelectrodes for dye-sensitized solar cells. The as-prepared and calcined hierarchical spheres were characterized by transmission electron microscopy, scanning electron microscopy and X-ray powder diffraction. The DSSC based on hierarchical TiO2 spheres as the photoelectrode shows a highly efficient power conversion efficiency (10.34%) accompanied by 18.78 mA cm−2 in short-circuit photocurrent density and 826 mV in open-circuit voltage. The great improvements of photocurrent density and power conversion efficiency for hierarchical TiO2 spheres compared to P25 nanoparticle photoelectrodes are mainly attributed to a considerable surface area, a higher light scattering ability, and faster electron transport rates and slower recombination rates for the former.

Porous Pt-Ni-P Composite Nanotube Arrays: Highly Electroactive and Durable Catalysts for Methanol Electrooxidation

Porous Pt-Ni-P composite nanotube arrays (NTAs) on a conductive substrate in good solid contact are successfully synthesized via template-assisted electrodeposition and show high electrochemical activity and long-term stability for methanol electrooxidation. Hollow nanotubular structures, porous nanostructures, and synergistic electronic effects of various elements contribute to the high electrocatalytic performance of porous Pt-Ni-P composite NTA electrocatalysts.

Dynamic Study of Highly Efficient CdS/CdSe Quantum Dot-Sensitized Solar Cells Fabricated by Electrodeposition

An in situ electrodeposition method is described to fabricate the CdS or/and CdSe quantum dot (QD) sensitized hierarchical TiO(2) sphere (HTS) electrodes for solar cell application. Intensity modulated photocurrent spectroscopy (IMPS), intensity modulated photovoltage spectroscopy (IMVS) and electrochemical impedance spectroscopy (EIS) measurements are performed to investigate the electron transport and recombination of quantum dot-sensitized solar cells (QDSSCs) based on HTS/CdS, HTS/CdSe, and HTS/CdS/CdSe photoelectrodes. This dynamic study reveals that the CdSe/CdS cosensitized solar cell performs ultrafast electron transport and high electron collection efficiency (98%). As a consequence, a power conversion efficiency as high as 4.81% (J(SC) = 18.23 mA cm(-2), V(OC) = 489 mV, FF = 0.54) for HTS/CdS/CdSe photoelectrode based QDSSC is observed under one sun AM 1.5 G illumination (100 mW cm(-2)).

Single-crystal ZnO nanorod/amorphous and nanoporous metal oxide shell composites: Controllable electrochemical synthesis and enhanced supercapacitor performances

Single-crystal ZnO nanorod/amorphous and nanoporous metal oxide shell composites were facilely prepared by electrochemical deposition and tested as promising electrode materials for supercapacitor applications.

Multistack Integration of Three-Dimensional Hyperbranched Anatase Titania Architectures for High-Efficiency Dye-Sensitized Solar Cells

An unprecedented attempt was conducted on suitably functionalized integration of three-dimensional hyperbranched titania architectures for efficient multistack photoanode, constructed via layer-by-layer assembly of hyperbranched hierarchical tree-like titania nanowires (underlayer), branched hierarchical rambutan-like titania hollow submicrometer-sized spheres (intermediate layer), and hyperbranched hierarchical urchin-like titania micrometer-sized spheres (top layer). Owing to favorable charge-collection, superior light harvesting efficiency and extended electron lifetime, the multilayered TiO2-based devices showed greater J(sc) and V(oc) than those of a conventional TiO2 nanoparticle (TNP), and an overall power conversion efficiency of 11.01% (J(sc) = 18.53 mA cm(-2); V(oc) = 827 mV and FF = 0.72) was attained, which remarkably outperformed that of a TNP-based reference cell (η = 7.62%) with a similar film thickness. Meanwhile, the facile and operable film-fabricating technique (hydrothermal and drop-casting) provides a promising scheme and great simplicity for high performance/cost ratio photovoltaic device processability in a sustainable way.

A synthetic route to ultralight hierarchically micro/mesoporous Al(III)-carboxylate metal-organic aerogels

Developing a synthetic methodology for the fabrication of hierarchically porous metal-organic monoliths that feature high surface area, low density and tunable porosity is imperative for mass transfer applications, including bulky molecule capture, heterogeneous catalysis and drug delivery. Here we report a versatile and facile synthetic route towards ultralight micro/mesoporous metal-organic aerogels based on the two-step gelation of metal-organic framework nanoparticles. Heating represents a key factor in the control of gelation versus crystallization of Al(III)-multicarboxylate systems. The porosity of the resulting metal-organic aerogels can be readily tuned, leading to the formation of well-ordered intraparticle micropores and aerogel-specific interparticle mesopores, thereby integrating the merits of both crystalline metal-organic frameworks and light aerogels. The hierarchical micro/mesoporosity of the Al-metal-organic aerogels is thoroughly evaluated by N2 sorption. The good accessibility of the micro/mesopores is verified by vapour/dye uptake, and their potential for utilization as effective fibre-coating absorbents is tested in solid-phase microextraction analyses.