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K Tennakone

Publications and source records attributed to K Tennakone.

9 recordsLinked to original sources
PubMed2005

Chromopore-linked conducting polymers attached to semiconductor surfaces: a strategy for development of dye-sensitized solar cells.

It is suggested that attaching chromopores to a conducting polymer chain anchored to a semiconductor surface is a good strategy for development of dye-sensitized solar cells. A model system that illustrates this principle is constructed by bonding mercurochrome to poly(vinyl alcohol) films adsorbed onto nanocrystalline TiO2 films. The dye-polymer structure enables transport of electrons (released in excitation of the dye) along the polymer chain to TiO2 as states in the lowest unoccupied molecular orbital of the polymer. By attaching several chromopores to a polymer chain, panchromatic sensitization can be achieved in principle by avoiding concentration quenching and the insulation by thick dye layers.

Journal Article↗
PubMed2005

Molecular rectification: application in dye-sensitized solar cells.

A dye-sensitized heterojunction of configuration n-TiO2/PD-CuPC-MV/p-CuSCN (where PD = 3,4-pyridinedicarboxylic acid anchored to TiO2, CuPC = copper(II) phthallocyanine tetrasulfonic acid ionically linked to PD, and MV = Methyl Violet complexed to CuPC) is developed to demonstrate the applicability of molecular rectification to dye-sensitized solar cells as a strategy of suppressing recombination. Short-circuit photocurrent, open-circuit voltage, energy conversion efficiency, and incident photon to photocurrent conversion of this system are higher than that of the heterojunctions of configurations n-TiO2/PD-MV/p-CuSCN, n-TiO/CuPC-MV/p-CuSCN, and n-TiO2/MV/p-CuSCN. The impressively high rectification ratio and the mode of anchorage of CuPC toTiO2 are suggested as the cause of superior photovoltaic action of the cell TiO2/PD-CuPC-MV/p-CuSCN.

Journal Article↗
PubMed2004

Sensitization of nanostructured TiO2 by electrostatic coupling of ionic dyes to ionic absorbates.

It is shown that an ionic dye Y can be electrostatically bonded to an ionic molecule X of opposite charge anchored to a TiO2 surface via suitable ligands. Dye-sensitized solid-state photovoltaic cells of the configuration n-TiO2/X-Y/p-CuSCN were constructed with X = trihydroxybenzoic acid or mercurochrome and Y = methyl violet. Cells of this configuration were found to be more efficient and delivered higher short-circuit photocurrents and open-circuit photovoltages compared to the cells based only on methyl violet or mercurochrome. It is suggested that this technique would be a means of extending the spectral response of dye-sensitized photovoltaic devices. The formation of a wider barrier by coupling of anionic and cationic species also improves the cell performance by suppression of recombination.

Journal Article↗
PubMed2003

Sensitization of aluminum chloride adsorbed tin(IV) oxide nanocrystalline films with Rose Bengal.

The anionic dye Rose Bengal was found to surface chelate more strongly to SnO2 nanocrystalline films previously kept immersed in a solution of washed and dried AlCl3. Dye-sensitized photoelectrochemical cells made from such films exhibit enhanced quantum and energy conversion efficiencies. The result is explained as caused by binding of AlCl3 to SnO2 surface by elimination of Cl atoms and stronger bonding of Rose Bengal to Al, enhancing dye adsorption and suppression of back electron transfer by bridging of an Al atom between Sn and the dye molecule.

Journal Article↗
PubMed2002

Composite tin and zinc oxide nanocrystalline particles for enhanced charge separation in sensitized degradation of dyes.

Composite ZnO/SnO2 catalyst has been studied for the sensitized degradation of dyes e.g. Eosin Y (2', 4', 5', 7'-tetrabromofluorescein disodium salt) in relation to efficient charge separation properties of the catalyst. Improved photocatalytic activity was observed in the case of ZnO/SnO2 composite catalyst compared to the catalytic activity of ZnO, SnO2 or TiO2 powder. The suppression of charge recombination in the composite ZnO/SnO2 catalyst led to higher catalytic activity for the degradation of Eosin Y. Degradation of Eosin follows concomitant formation of CO2 and formation of CO2 followed a pseudo-first-order rate. Photoelectrochemical cells constructed using SnO2, ZnO, ZnO/SnO2 sensitized with Eosin Y showed V(oc) of 175, 306, 512 mV/cm2 and I(sc) of 50, 70, 200 microA/cm2 respectively. A higher irreversible degradation of Eosin Y and higher V(oc) observed on composite ZnO/SnO2 than ZnO and SnO2 separately can be considered as a proof of enhanced charge separation of ZnO/SnO2 catalyst. Eosin Y showed a higher emission decreases on ZnO/SnO2 composite than on individual ZnO, SnO2 or TiO2 indicating dominance of the charge injection process. Photoinjected electrons are tunneled from ZnO to SnO2 particles accumulating injected electrons in the conduction bands allowing wider separation of excited carriers.

Catalysis↗
PubMed1989

Photocatalytic oxidation of nitrite in water to nitrate.

It is found that the nitrite in water is converted into nitrate by irradiation in the presence of oxygen and titanium dioxide which acts as a catalyst. As nitrate is a less hazardous contaminant, this method might be worth investigating further for the treatment of water.

Journal Article↗
PubMed1988

Aluminium contamination from fluoride assisted dissolution of metallic aluminium.

Trace amounts (microg g(-1) quantities) of fluoride ion are found to catalyse the dissolution of metallic aluminium in very slightly acidic or alkaline aqueous media. Possibly hazardous levels of aluminium could get leached from cooking utensils if fluoridated water or fluoride rich foodstuffs are used. The fluoride assisted corrosion of aluminium is most dramatic in oxalic, tartaric acids or sodium bicarbonate. Carbon dioxide also corrodes aluminium in the presence of the fluoride ion, generating colloidal hydrated aluminium oxide which is readily soluble in dilute organic and mineral acids.

Journal Article↗