Yang Shengyuan

Facile Fabrication of TiO2–Graphene Composite with Enhanced Photovoltaic and Photocatalytic Properties by Electrospinning

We report the fabrication of one-dimensional TiO(2)-graphene nanocomposite by a facile and one-step method of electrospinning. The unique nanostructured composite showed a significant enhancement in the photovoltaic and photocatalytic properties in comparison to TiO(2) as demonstrated in dye-sensitized solar cells and photodegradation of methyl orange.

A simple recipe for an efficient TiO2 nanofiber-based dye-sensitized solar cell.

Development of highly efficient dye-sensitized solar cells (DSSCs) with good photovoltaic parameters is an active research area of current global interest. In this article, we provide a simple recipe for the fabrication of electrospun TiO(2) nanorod-based efficient dye-sensitized solar cell using a Pechini-type sol. The Pechini-type sol of TiO(2) nanofibers produces a highly porous and compact layer of TiO(2) upon doctor-blading and sintering without the need for an adhesion and scattering layers or TiCl(4) treatment. The best nanofiber DSSCs with an area of ~0.28 cm(2) shows an efficiency of ~4.2% under standard test conditions (100 mW/cm(2), 25°C and AM1.5 G) and an incident photon-to-electron conversion efficiency (IPCE) of ~50%. Impedance measurements show lower charge transfer resistance that improved the fill factor. We believe that simple approaches such as the present one to develop nanofiber DSSCs would open up enormous possibilities in effective harvesting of solar energy for commercial applications, considering the fact that electrospinning is a cost-effective method for the mass scale production of nanofibers and nanorods.

Rice grain-shaped TiO2 mesostructures by electrospinning for dye-sensitized solar cells

Nanofibers, produced by electrospinning a solution containing titanium tetra(IV) isopropoxide, polyvinyl acetate and acetic acid in N,N-dimethyl acetamide, upon sintering at 500 °C produce rice grain-shaped TiO(2) mesostructures. Each rice grain-shaped TiO(2) has a mixed crystal structure and high porosity and the mesostructures are found to have applications in dye-sensitized solar cells.

Rice grain-shaped TiO2 mesostructures—synthesis, characterization and applications in dye-sensitized solar cells and photocatalysis

We report the synthesis, characterization and applications in dye-sensitized solar cells and photocatalysis of novel “rice grain-shaped” TiO2 mesostructures by electrospinning, which is a well-established and cost-effective technique for large-scale production of 1-D nanostructures. The porous and crystalline rice grain-like structures produced at 500 °C are uniformly distributed with a high surface area of ∼60 m2 g−1 and with mixed crystal structure. The origin of the unique morphology is traced to the microscale phase separation between TiO2 and the polymer during solvent evaporation owing to the solubility difference between the two. The morphology is excellently reproducible over a wide range of concentrations of the precursors and spinning conditions. Evolution of the unique morphology from fiber structures is probed by scanning electron microscopy analyses of systematically heated electrospun fibers. The rice grain morphology is stable up to 600 °C and with further increase in temperature, the shape distorts with accompanying changes to the anatase–rutile proportion and complete dominance of the rutile phase at 1000 °C. A comparison of the photovoltaic and photocatalytic performance of the material with P-25 TiO2 showed that the rice grain-shaped structures are superior to commercially available P-25. We anticipate that the material would have wide range of applications in other areas too such as photonic crystals, chemical sensors, self-cleaning materials, UV-blockers, etc.

Electrospun TiO2 nanorods assembly sensitized by CdS quantum dots: a low-cost photovoltaic material†

An easily processable nanostructure comprising a TiO2 nanorod (NR) core and CdS quantum dot (QD) shell is fabricated by electrospinning and a successive ionic layer adsorption and reaction (SILAR) method, respectively. The composite material is successfully assembled to photovoltaic devices for efficient solar energy conversion. Stable photovoltaic parameters of a short-circuit photocurrent density of 3.62 mA cm−2, an open-circuit voltage of 0.482 V, a fill factor of 0.30, and an overall power conversion efficiency of over 0.5% are obtained in the presence of a polysulfide electrolyte under standard 1 sun illumination of 100 mW cm−2. Without any elaborate and complicated fabrication procedures, the present methodology is believed to provide a promising mass production means for alternative low-cost solar cells as both electrospinning and SILAR are simple and scalable techniques.

Highly anisotropic titanates from electrospun TiO2–SiO2 composite nanofibers and rice grain-shaped nanostructures

We report a low temperature alkali-mediated conversion of nanofiber-and rice grain-shaped TiO2–SiO2 composites into highly anisotropic fiber (decorated with thorn-like features on surfaces)/sponge-shaped titanates of the formula Na2−xHxTi2O4(OH)2. The titanates were thoroughly characterized by spectroscopy and microscopy. Control experiments with the respective TiO2 analogues revealed that the unique open and highly porous morphologies were the result of structural rearrangement of TiO2 coupled with the in situleaching of SiO2 from the composites by the alkali. Effect of concentration of the alkali and the reaction temperature on the morphology of the titanates was also probed. Evolution of the unique morphologies from the respective starting materials was studied by scanning electron microscopy analyses of the systematically withdrawn samples during the course of the reaction. The materials utilized in dye-sensitized solar cells showed excellent photovoltaic parameters amongst the category of titanates.

Electrospun TiO 2 nanorods assembly sensitized by mercaptosuccinic acid-capped CdS quantum dots for solar cells: Subtitle as needed (paper subtitle)

CdS quantum dots (QDs) capped with mercaptosuccinic acid (MSA) as the surface passivating ligand were anchored to electrospun TiO2 nanorod surfaces using the terminal carboxylic acid groups present on MSA. The as-synthesized materials and the dye-sensitized solar cells were characterized by spectroscopy, microscopy and photocurrent measurements, respectively. Best solar cells fabricated by the method showed an efficiency of 0.07%. We believe that the simple, one-pot fabrication of the QDs and their assembly into solar cells are significant steps in QD-sensitized solar cell research.