Enhanced performance of dye-sensitized solar cells by utilization of an external, bifunctional layer consisting of uniform ß-NaYF4:Er³âº/Yb³âº nanoplatelets.

Uniform ß-NaYF(4):Er(3+)/Yb(3+) hexagonal nanoplatelets were synthesized via a modified hydrothermal route, and the nanoplatelets were applied as an external, bifunctional layer in a novel DSC configuration consisting of only one internal TiO(2) transparent layer. Approximately 10% enhancements of photocurrent and overall DSC efficiency are demonstrated by the addition of the external layer, which exhibits two functions of light reflecting and near-infrared (NIR) light harvesting. The novel DSC configuration not only simplifies the DSC fabrication process but also eliminates charge recombination induced by the conducting up-converting nanocrystals when used internally thus opening the path for other more efficient up-converting nanocrystals to be designed and applied.

Near-infrared sunlight harvesting in dye-sensitized solar cells via the insertion of an upconverter-TiO2 nanocomposite layer.

Er(3+),Yb(3+) co-doped LaF3-TiO2 nanocomposites (UC-TiO2) are inserted as a middle layer in a novel tri-layer photoanode design (see Figure) of a dye-sensitized solar cell (DSSC). The Er(3+),Yb(3+) co-doped LaF3 part of the nanocomposite helps capture near-infrared (NIR) light by converting it into visible light absorbable by the dye hence opening the road for the development of DSSCs with higher conversion efficiency and photocurrent output.

The synthesis of aqueous-dispersible anatase TiO2 nanoplatelets.

Aqueous well-dispersed and phase-pure anatase TiO(2) truncated octahedron nanoplatelets (NPLs) were prepared via controlled hydrolysis of titanium tetrachloride (TiCl(4)) in ethylene glycol at 240 degrees C. Two shapes, square and hexagon, were observed by microscopy, exactly corresponding to the truncated octahedron NPLs. Ethylene glycol was found to produce water in situ that reacts with TiCl(4) to produce TiO(2) and HCl-the latter promoting TiO(2) colloid peptization. TiO(2) truncated octahedron NPLs are formed under the stabilizing action of ethylene glycol thermolysis derivatives, such as aldehydes. Crystal growth of the TiO(2) NPLs was affected by the reaction temperature that determines the water production rate and HCl-assisted peptization. TGA and FT-IR results showed approximately 1.2% ethylene glycol thermolysis derivatives are attached to the surface of the TiO(2) NPLs, which prevents their agglomeration, hence making them easily dispersible in aqueous media. HR-TEM and SAED results showed that the TiO(2) NPLs are well crystallized and that the SAED patterns of the single TiO(2) NPL changes with its size and shape. XRD patterns showed that the TiO(2) NPLs are phase-pure anatase and the percentage of the [101] plane in the TiO(2) NPLs to be only 18%-a structural feature that renders the TiO(2) NPLs with enhanced UV absorption and reactivity properties.

Immobilization of Pseudomonas delafieldii with magnetic polyvinyl alcohol beads and its application in biodesulfurization.

Pseudomonas delafieldii was immobilized in magnetic polyvinyl alcohol (PVA) beads using a hydrophilic magnetic fluid, which was prepared by a co-precipitation method. The beads had distinct super-paramagnetic properties and were compared with immobilized cells in non-magnetic PVA beads. Their desulfurizing activity was increased slightly from 8.7 to 9 mmol sulfur kg(-1) (dry cell) h(-1). The main advantages was that the magnetic immobilized cells maintain a high desulfurization activity and remain in good shape after 7 times of repeated use, while the non-magnetic immobilized cells could only be used for 5 times. Furthermore, the magnetic immobilized cells could be easily collected or separated magnetically from the biodesulfurization reactor.