Showing papers by "Michael Grätzel published in 1993"
TL;DR: In this article, the anatase structure of n-TiO2 (anatase) was obtained by anodic oxidative hydrolysis of acidic aqueous TiCl3 solutions, and the performance of an I-I2 regenerative photocell based on a thus prepared TiO2 photoanode was considerably improved.
282 citations
01 Jan 1993
TL;DR: A.K. Kalyanasundaram et al. as discussed by the authors discuss the evolution of Inorganic and Organometallic Photochemistry and their application in photoelectrochemical cells.
Abstract: Preface. Evolution of Inorganic and Organometallic Photochemistry. Historical Perspectives and Commentary A.W. Adamson. Intermolecular Energy and Electron Transfer Processes V. Balzani, M. Maestri. Photocatalysis: Definitions and Classifications H. Hennig, R. Billing, H. Knoll. Charge Transfer Excitation of Coordination Compounds. Generation of Reactive Intermediates A. Vogler, H. Kunkely. Photoredox and Sensitization Processes involving Transition Metal Polypyridine Complexes K. Kalyanasundaram. Intramolecular Energy and Electron Transfer in Polynuclear Complexes F. Scandola, C.A. Bignozzi, M.T. Indelli. Photocatalysis: Reduction of CO2 and Water-Gas Shift Reaction catalysed by 2,2'-bipyridine or 1,10-phenanthroline Co(II), Ru(II), Re(I) and Ir(III) complexes R. Ziessel. Metal Complexes as Photosensitizers in Photoelectrochemical Cells M. Gratzel, K. Kalyanasundaram. Photosensitization by (Metallo)porphyrins: Formation and Photophysical Properties of Porphyrin Assemblies A. Harriman. Photocatalytic and Photoredox Properties of Polyoxometalate Systems C.L. Hill, C.M. Prosser-McCartha. Photocatalytic Transformations of Organic Substrates using INorganic Salts and Complexes U. Kolle. Photocatalytic Reactions involving Metal Carbonyls P.C. Ford, W. Boese, B. Lee, K.L. MacFarlane. Photocatalysis - C-H Activation R.H. Crabtree. Electron Donor-Acceptor Interactions and Photoinduced Electron Transfer of Organometallic Compounds T.M. Bockman, J.K. Kochi. Index.
264 citations
15 Oct 1993
TL;DR: In this article, the temperature dependence of highly exoergic interfacial electron transfer processes from the conduction band of nanocrystalline titanium dioxide to the cation radicals of three different sensitizers, i.e alizarin, a merocyanine and a coumarin dye, is investigated.
Abstract: Measurements have been performed of the temperature dependence of highly exoergic interfacial electron transfer processes from the conduction band of nanocrystalline titanium dioxide to the cation radicals of three different sensitizers, i.e alizarin, a merocyanine and a coumarin dye. Although these reactions fall deep into the inverted Marcus region, they show practically no activation energy. The results are interpreted in terms of a quantum mechanical model for non-adiabatic electron transfer including the treatment of high frequency molecular vibrations of the adsorbed sensitizer. This analysis provides apart from the electronic matrix coupling elements separate values for the internal and solvent reorganization energies. The behavior of the alizarin/TiO 2 chelate is unusual in as much as the solvent reorganization does not appear to contribute significantly to the interfacial redox process.
191 citations
TL;DR: A reusable piezoelectric immunosensor has been developed for the detection of viruses and bacteria, playing an important role in acute diarrhea in early childhood as discussed by the authors, and three different methods for antibody immobilization to the gold electrode were tested.
Abstract: A reusable piezoelectric immunosensor has been developed for the detection of viruses and bacteria, playing an important role in acute diarrhea in early childhood. Three different methods for antibody immobilization to the gold electrode were tested. Coating the electrode with protein A gave the best results in terms of stability, sensitivity and reproducibility. Worse results were observed when coating the electrode with γ-amino propyltriethoxy silane and polyethyleneimine. Applying an antibody layer via protein A immobilization onto a 10-MHz AT-cut crystal resulted for 1 × 106 to 1 × 1010 virus cells and for 1 × 106 to 1 × 108 bacteria in a linear frequency change. The modified crystal was stable for six weeks when stored desiccated at +4°C.
83 citations
Patent•
12 Mar 1993
TL;DR: In this article, a regenerating photoelectrochemical cell with a first transparent substrate (1) and a second transparent substrate(2, 4) was shown to have a sintered colloidal particle structure in the form of a porous nanostructure, and a compact continuous semiconductor oxide layer (20) extending between the second transparent electrode (8) and the first semiconductor layer (10).
Abstract: A regenerating photoelectrochemical cell (1) is disclosed having a first transparent substrate (2) which has thereon a first transparent electrode (6), a second transparent substrate (4) which has thereon a second transparent electrode (8) on which is deposited a first layer (10) of a photoelectrochemically active semiconductor oxide in the form of a porous nanostructure of sintered colloidal particles, the substrates (2, 4) being so disposed in relation to one another as to define a space filled with electrolyte (16), said electrolyte (16) impregnating the said porous structure in a manner such that it is in contact on the one hand with the first transparent electrode (6) disposed on the first transparent substrate (2) and on the other hand with the second transparent electrode (8) disposed on the second transparent substrate (4), and said second transparent substrate also having a second compact continuous semiconductor oxide layer (20) extending between the second transparent electrode (8) and the first semiconductor oxide layer (10).
77 citations
TL;DR: A reusable piezoelectric immunosensor was developed for the detection of purified human erythrocytes and ery Throcytes in whole human blood and gave the best results in terms of stability, sensitivity and reproducibility.
61 citations
TL;DR: This poster presents a poster presenting a probabilistic procedure to characterize the response of the immune system to chemotherapy-like injuries to treat central giant cell granuloma.
42 citations
TL;DR: A reusable piezoelectric immunosensor was developed for the detection of purified human T-lymphocytes and of T- lymphocytes in whole human blood and gave the best results in terms of stability, sensitivity and reproducibility.
37 citations
33 citations
TL;DR: In this paper, a monolayer-on-oxide substrate was studied by Raman spectroscopy; the laser light must stimulate the charge transfer in the Ti-molecule surface complex.
Abstract: Surface modification by suitable dyes of electrodes used in photoelectrochemical cells allows noticeable increase of their photo‐to‐electrical conversion efficiency. Several bis or trisbipyridylruthenium(II) complexes, containing different functional groups (in particular, carboxylation of the pyridine ring is necessary to obtain a strong adsorption) were studied. All of them were identified by "normal" (without any "artificial" enhancement) ex situ Raman spectroscopy. The differences (in peak position and intensity) of their spectra, typical of the pyridine rings, carboxylated or not, yields the position of the molecule with respect to the oxide surface. It is the first time that such a monolayer‐on‐oxide substrate was studied by Raman spectroscopy; the laser light must stimulate the charge transfer in the Ti‐molecule surface complex.
31 citations
TL;DR: To improve the reusability of a recently developed piezoelectric immunosensor a synthetic peptide corresponding to the human glycophorin A sequence of the amino acids 27–39 was used for competition with the bound antigen.
TL;DR: In this article, a reusable piezoelectric immunosensor for human granulocytes was developed, and three different methods for immobilization of the anti-CD 18 antibody on the gold electrode of the immunosensors were tested.
Abstract: We have developed a reusable piezoelectric immunosensor for human granulocytes. Three different methods for immobilization of the anti-CD 18 antibody on the gold electrode of the immunosensor were tested. The methods showed some differences in terms of stability and sensitivity. Applying an anti-CD 18 antibody layer onto a 10-MHz AT-cut crystal resulted for 2 × 103 to 3 × 105 cells on the surface in a linear frequency change. The modified crystal was stable for eight weeks when stored desiccated at room temperature.
TL;DR: Reference LPI-ARTICLE-1993-015View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12 as mentioned in this paper, created on 2016
Abstract: Reference LPI-ARTICLE-1993-015View record in Web of Science Record created on 2006-02-21, modified on 2017-05-12
TL;DR: In this article, the FTIR spectra of a Ru-RuOx/TiO2 catalyst obtained on co-adsorption of CO, CO2 and H2 in the temperature range of 300-500 K were found to be the sum total of corresponding spectra observed during methanation of individual oxides.
Abstract: FTIR spectra of a Ru-RuOx/TiO2 catalyst obtained on co-adsorption of CO, CO2 and H2 in the temperature range of 300–500 K were found to be the sum total of corresponding spectra observed during methanation of individual oxides. The two oxides compete for metal sites and at each temperature they reacted simultaneously to form distinct transient Ru(CO)n type species even though the nature, the stability and the reactivity of these species were different in the two cases. The monocarbonyl species formed during adsorption/reaction of CO alone or of CO + H2 were bonded more strongly than those formed during CO2 + H2 reaction.
TL;DR: Based on the selective resonance enhancement of the intensities of the Raman bands of the ligand biq by excitation within the lowest energy absorption band, the lowest excited states in the dinuclear complexes have been assigned unambiguously to Ru → biq charge transfer as discussed by the authors.
Abstract: In the ligand-bridged complexes [(bipy)2Ru(dpp)Ru(biq)2]4+ and [(biq)2Ru(dpp)Ru(biq)2]4+[dpp = 2,3-bis(2′-pyridyl)pyrazine, bipy = 2,2′-bipyridine and biq = 2,2′-biquinoline], the photophysical and redox properties do not allow differentiation of the low-energy charge-transfer transitions Ru → biq and Ru → dpp. Based on the selective resonance enhancement of the intensities of the Raman bands of the ligand biq by excitation within the lowest-energy absorption band, the lowest excited states in the dinuclear complexes have been assigned unambiguously to Ru → biq charge transfer.
01 Jan 1993
TL;DR: In this article, the electrochemical behavior of polyaniline and structurally modified polyaniliine has been studied in various nonaqueous media including solvents such as acetonitrile and propylene carbonate, together with LiClO 4 or other salts.
Patent•
12 Mar 1993
TL;DR: In this article, a regenerative photoelectrochemical cell including a first transparent substrate (2, 4) consisting of a transparent electrode (6), and a second transparent substrate(4) comprising a second opaque electrode (8), was constructed as a porous nanostructure of sintered colloidal particles.
Abstract: A regenerative photoelectrochemical cell (1) including a first transparent substrate (2) comprising a first transparent electrode (6), and a second transparent substrate (4) comprising a second transparent electrode (8) on which a first photoelectrochemically active semiconductor oxide layer (10) is deposited as a porous nanostructure of sintered colloidal particles (12). Said substrates (2, 4) are arranged so as to define a space filled with an electrolyte (16) impregnating said porous structure in such a way that it contacts both the electrode (6) on the first substrate (2) and the electrode (8) on the second substrate (4). The second substrate further comprises a second, continuous and dense semiconductor oxide layer (20) extending between the second electrode (8) and the first semiconductor oxide layer (10).
01 Jan 1993
TL;DR: In this paper, the performance of bis(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) type redox sensitizers was investigated.
Abstract: cis-X~Bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) complexes (X = C1-, Br, I-, CN-, and SCN-) were prepared and characterized with respct to their absorption, luminescence, and redox behavior. They act as efficient charge-transfer sensitizers for nanocrystalline Ti02 films (thickness 8-1 2 pm) of very high internal surface area (roughness factor ca. lOOO), prepared by sintering of 15-30-nm colloidal titania particles on a conducting glass support. The performance of cis-di(thiocyanato)bis(2,2'-bipyridyl-4,4'-dicarboxylate)ruthenium(II) (1) was found to be outstanding and is unmatched by any other known sensitizer. Nanocrystalline Ti02 films coated with a monolayer of 1 harvest visible light very efficiently, their absorption threshold being around 800 nm. Conversion of incident photons into electric current is nearly quantitative over a large spectral range. These films were incorporated in a thin-layer regenerative solar cell equipped with a light-reflecting counter electrode. Short-circuit photocurrents exceeding 17 mA/cmZ were obtained in simulated AM 1.5 sunlight using lithium iodide/triiodide in acetonitrile or acetonitrile/ 3-methyl-2-oxazolidinone mixtures as redox electrolyte. The open-circuit photovoltage was 0.38 V and increased to 0.72 V by treating the dye-covered film with 4-terr-butylpyridine. A solar-to-electric energy conversion efficiency of 10% was attained with this system. The effect of temperature on the power output and long-term stability of the dye was also investigated. For the first time, a device based on a simple molecular light absorber attains a conversion efficiency commensurate with that of conventional silicon-based photovoltaic cells. a broad spectral range in the~isible.~ A subsequent time-resolved luminescence study by Eichberger and Willig3m showed this effect to be due to ultrafast (7 < 7 ps) electron injection from the excited state of the complex into the conduction band of the oxide occurring with a quantum yield near 100%. These important observations warrant further studies of the behavior of the relatively unexplored class of bis(2,2'-bipyridyl)ruthenium(II)- type redox sensitizers. Apart from their chemical stability and ease of interfacial charge exchange with semiconducting solids, the attractive feature of these complexes is their large visible light harvesting capacity which is superior to that of the widely studied tris(bipyridy1) Ru(I1) analogues, making them a judicious choice for solar energy conversion devices.
TL;DR: In this article, the optimum temperature at which C 2 -product yields were maximum was found when the promoter was changed from Li to Cs through group IA alkali metal chlorides.
Abstract: Oxidative dimerization of CH 4 has been studied using Co 3 O 4 catalysts promoted with chlorides of Li, Na, K and Cs. Chemical modification of Co 3 O 4 - LiCl catalyst at the reaction conditions was evidenced by ESR spectroscopy. A decrease in the optimum temperature, at which C 2 - product yields were maximum, was noticed when the promoter was changed from Li to Cs through group IA alkali metal chlorides.
Patent•
12 Mar 1993
TL;DR: In this paper, a cellule photoelectrochimique regeneratrice (PE-GEM) is defined, which comprenant un premier substrate (1), transparent comportant une premiere electrode (6), transparente, un second substrate (4), transparentcomportant a second electrode (8) transparente sur laquelle est deposede une premiere couche (10), d'un oxyde semiconducteur photoelectroneme (10) d'oxyde semiconductor) actif realisee sous forme d'une nan
Abstract: L'invention concerne une cellule photoelectrochimique regeneratrice (1) comprenant un premier substrat (2) transparent comportant une premiere electrode (6) transparente, un second substrat (4) transparent comportant une seconde electrode (8) transparente sur laquelle est deposee une premiere couche (10) d'un oxyde semiconducteur photoelectrochimiquement actif realisee sous forme d'une nanostructure poreuse formee de particules (12) colloidales frittees, les substrats (2, 4) etant arranges entre eux pour definir un espace rempli d'un electrolyte (16), ledit electrolyte (16) impregnant ladite structure poreuse de sorte qu'il est en contact d'une part avec l'electrode (6) portee par le premier substrat (2) et d'autre part avec l'electrode (8) portee par le second substrat (4), caracterisee en ce que le second substrat comporte en outre une seconde couche (20) continue et dense d'un oxyde semiconducteur s'etendant entre la seconde electrode (8) et la premiere couche (10) d'oxyde semiconducteur.