Titanium Dioxide Nanomaterials: Synthesis, Properties, Modifications, and Applications

Dye-sensitized solar cells (DSCs) offer the possibilities to design solar cells with a large flexibility in shape, color, and transparency. DSC research groups have been established around the worl ...

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Dye-Sensitized Solar Cells

Electrochemical measurements can distinguish between different types of energy storage materials and their underlying mechanisms.

/pdf/where-do-batteries-end-and-supercapacitors-begin-3ybpg4ralk.pdf

Where Do Batteries End and Supercapacitors Begin

Pseudocapacitance is commonly associated with surface or near-surface reversible redox reactions, as observed with RuO2·xH2O in an acidic electrolyte. However, we recently demonstrated that a pseudocapacitive mechanism occurs when lithium ions are inserted into mesoporous and nanocrystal films of orthorhombic Nb2O5 (T-Nb2O5; refs 1, 2). Here, we quantify the kinetics of charge storage in T-Nb2O5: currents that vary inversely with time, charge-storage capacity that is mostly independent of rate, and redox peaks that exhibit small voltage offsets even at high rates. We also define the structural characteristics necessary for this process, termed intercalation pseudocapacitance, which are a crystalline network that offers two-dimensional transport pathways and little structural change on intercalation. The principal benefit realized from intercalation pseudocapacitance is that high levels of charge storage are achieved within short periods of time because there are no limitations from solid-state diffusion. Thick electrodes (up to 40 μm thick) prepared with T-Nb2O5 offer the promise of exploiting intercalation pseudocapacitance to obtain high-rate charge-storage devices.

https://hal.archives-ouvertes.fr/hal-01159902/document

High-rate electrochemical energy storage through Li+ intercalation pseudocapacitance

-phenylenevinylene)s L4. Fluorene-Based Conjugated Polymers L4.1. Fluorene-Based Copolymers ContainingElectron-Rich MoietiesM4.2. Fluorene-Based Copolymers ContainingElectron-Deﬁcient MoietiesN4.3. Fluorene-Based Copolymers ContainingPhosphorescent ComplexesQ5. Carbazole-Based Conjugated Polymers R5.1. Poly(2,7-carbazole)-Based Polymers R5.2. Indolo[3,2-

https://ir.nctu.edu.tw:443/bitstream/11536/6508/1/000271856900020.pdf

Synthesis of Conjugated Polymers for Organic Solar Cell Applications

Electrochemical properties of Li+ ion insertion in nanoporous TiO2 (anatase) electrodes were studied by voltammetry. Linear and cyclic potential scans were recorded as a function of electrolyte con ...

Li+ Ion Insertion in TiO2 (Anatase). 2. Voltammetry on Nanoporous Films

The ability to generate homogeneous particulate thin films of highly oriented and highly porous microparticles of a post transition metal oxide onto polycrystalline and single-crystalline substrates, at low cost, by a template-free, aqueous low-temperature coating process is demonstrated by the fabrication of a large three-dimensional array of perpendicularly oriented hexagonal microtubes of crystalline zincite ZnO from an aqueous solution of zinc nitrate and methenamine.

Three-dimensional array of highly oriented crystalline ZnO microtubes

Nanocrystalline particles of ZnO and TiO2 of approximately equal size (∼15 nm) were used to prepare mesoporous electrodes for dye-sensitized solar cells. Electron transport in the solar cells was studied using intensity-modulated photocurrent spectroscopy and revealed very similar results for ZnO and TiO2. Apparent activation energies for electron transport in nanostructured ZnO of ≤0.1 eV were calculated from the temperature dependence of transport times under short-circuit conditions. The lifetime of electrons in the nanostructured semiconductors was evaluated from open-circuit voltage decay and intensity-modulated photovoltage spectroscopy. Significantly longer lifetimes were obtained with ZnO. Despite the reduced recombination, ZnO-based solar cells performed worse than TiO2 cells, which was attributed to a lower electron injection efficiency from excited dye molecules and/or a lower dye regeneration efficiency. The internal voltage in the nanostructured ZnO film under short-circuit conditions was abo...

Comparison of Dye-Sensitized ZnO and TiO2 Solar Cells: Studies of Charge Transport and Carrier Lifetime

Nanostructured NiO film was prepared by depositing nickel hydroxide slurry on conducting glass and sintering at 500 °C to a thickness of about 1 μm. The photocurrent−voltage (IV) characteristics of the plain nanostructured NiO electrode recorded potentiostatically in a standard three-electrode setup upon UV illumination demonstrate p-type behavior, while the IV characteristics of a dye-sensitized nanostructured NiO electrode coated with erythrosin B show cathodic photocurrent under visible light illumination. The highest incident photon-to-current conversion efficiencies of tetrakis(4-carboxyphenyl)porphyrin (TPPC) and erythrosin B-coated NiO films were 0.24% and 3.44%, respectively. In sandwich solar cells with a platinized conducting glass as counter electrode exposed to light from a sun simulator (light intensity:  68 mW/cm2), a short-circuit cathodic photocurrent density (ISC) of 0.079 mA/cm2 and an open-circuit voltage (VOC) of 98.5 mV for TPPC-coated NiO electrode were achieved. Similarly, ISC = 0.2...

Dye-Sensitized Nanostructured p-Type Nickel Oxide Film as a Photocathode for a Solar Cell

Four Zn(II)-tetra(carboxyphenyl)porphyrins in solution and bound to metal oxide (TiO2, ZnO, and ZrO2) nanoparticle films were studied to determine the effect of the spacer length and anchoring grou ...

https://www.chem.ccu.edu.tw/~joyce/seminar/96_I/J.%20Am.%20Chem.%20Soc.%202007,%20129,%204655%20-4665.pdf

and Anders Hagfeldt

Papers

Li+ Ion Insertion in TiO2 (Anatase). 2. Voltammetry on Nanoporous Films

Three-dimensional array of highly oriented crystalline ZnO microtubes

Comparison of Dye-Sensitized ZnO and TiO2 Solar Cells: Studies of Charge Transport and Carrier Lifetime

Dye-Sensitized Nanostructured p-Type Nickel Oxide Film as a Photocathode for a Solar Cell

Tetrachelate Porphyrin Chromophores for Metal Oxide Semiconductor Sensitization: Effect of the Spacer Length and Anchoring Group Position