Author
Prashant V. Kamat
Other affiliations: Indian Institute of Technology Kanpur, Council of Scientific and Industrial Research, Université du Québec à Trois-Rivières ...read more
Bio: Prashant V. Kamat is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Racism & Excited state. The author has an hindex of 140, co-authored 725 publications receiving 79259 citations. Previous affiliations of Prashant V. Kamat include Indian Institute of Technology Kanpur & Council of Scientific and Industrial Research.
Topics: Racism, Excited state, Electron transfer, Quantum dot, Flash photolysis
Papers published on a yearly basis
Papers
More filters
••
TL;DR: In this article, free base porphyrin molecules form well-defined and ordered nanoclusters in mixed solvents with absorption characteristics that significantly differ from those of the monomer form.
Abstract: Free base porphyrin molecules form well-defined and ordered nanoclusters in mixed solvents with absorption characteristics that significantly differ from those of the monomer form. These self-assembled crystallites in acetonitrile/toluene (9 ∶ 1, v/v) can be deposited as thin films on a nanostructured TiO2 electrode using an electrophoretic technique. This porphyrin cluster assembly is highly photoactive and capable of undergoing charge separation under visible light excitation. Photoexcitation of the porphyrin film electrode assembly in a photoelectrochemical cell with visible light produces relatively high photocurrent generation. A maximum photocurrent of 0.15 mA cm−2 and a photovoltage of 250 mV were attained using the I3−/I− redox couple. The electron flow to the TiO2 electrode can be facilitated by application of a positive potential. An incident photon-to-photocurrent generation efficiency (IPCE) of 2.0% has been achieved at an applied bias potential of 0.2 V vs. SCE. The broad photoresponse of these crystallites throughout the visible range as well as the ease of assembling them on the electrode surface opens up new avenues for harvesting a wide wavelength range of solar light.
66 citations
••
TL;DR: In this article, it has been demonstrated that with the aid of the laser flash photolysis, one can carry out both the oxidation of SCN/sup -/ and the reduction of oxazine dye on the semiconductor particles simultaneously.
Abstract: Association of SCN/sup -/ with TiO/sub 2/ colloids in acetonitrile resulted in the appearance of an absorption band with a maximum around 285 nm. The apparent association constant as measured by a Benesi-Hildebrand plot was 350 M/sup -1/. Generation of (SCN)/sub 2//sup -/. was observed within the pulse duration (<8 ns) when the thiocyanate complex of TiO/sub 2/ in acetonitrile to 337-nm laser pulse excitation. The quantum yield for the production of (SCN/sub 2//sup -/. was determined to be 0.04. With the aid of the laser flash photolysis, it has been demonstrated that one can carry out both the oxidation of SCN/sup -/ and the reduction of oxazine dye on the semiconductor particles simultaneously. Effective capture of the holes and electrons enhanced the efficiency of the photoelectrochemical oxidation and reduction processes at these microelectrodes. 22 references, 6 figures, 1 table.
65 citations
••
TL;DR: In this paper, the absorption and emission properties of rose bengal have been characterized on the surfaces of SiO{sub 2, AlOsub 2 O{sub 3, and TiO{ sub 2} particles.
Abstract: The absorption and emission properties of rose bengal have been characterized on the surfaces of SiO{sub 2}, Al{sub 2}O{sub 3}, and TiO{sub 2} particles. The intrinsic properties of these oxide supports play an important role in effecting and controlling the photochemistry of the adsorbed dye. On the Al{sub 2}O surface, a biphotonic photoionization process leads to the production of semioxidized dye. However, a charge injection from the excited dye into the conduction band dominates on the TiO{sub 2} particles. Steady-state photolysis indicates a rapid photodegradation of the dye only on the surface of TiO{sub 2}. The diffuse reflectance laser flash photolysis experiments which elucidate the mechanism of photochemical processes on these oxide supports are described.
65 citations
••
TL;DR: In this paper, the design of chromophore-functionalized metal nanoparticles and the detailed investigation of the ground and excited-state interactions between the metal particles and the photoactive molecules are reported.
Abstract: We report in this Account the design of chromophore-functionalized metal nanoparticles and the detailed investigation of the ground- and excited-state interactions between the metal nanoparticles and the photoactive molecules. The methodologies adopted for organizing chromophore-functionalized gold nanoparticles on two-dimensional surfaces and the mechanistic details of various deactivation channels of the photoexcited chromophores, such as energy and electron transfer to the metal nanoparticle, are presented. The possible applications of such chromophore-functionalized gold nanoparticles in photovoltaics, light-mediated binding and release of biologically important molecules such as amino acid derivatives, and fluorescent display devices are described.
65 citations
••
TL;DR: In this article, photoinduced electron transfer between C+{sub 60} (or C{sub 70}) and DMA in the PMMA film was carried out with 532-nm laser pulse excitation.
Abstract: The singlet and triplet excited states of C{sub 60} and C{sub 70} have been characterized in poly(methyl methacrylate) (PMMA) films by using picosecond and nanosecond laser flash photolysis techniques. The absorption properties and lifetimes of these excited states are very similar to those observed in solutions. When complexed with dimethylaniline (DMA) in the PMMA films, these fullerenes exhibit decreased lifetimes in their excited states. Photoinduced electron transfer between C+{sub 60} (or C{sub 70}) and DMA in the PMMA film was carried out with 532-nm laser pulse excitation. The polymeric environment facilitated the stabilization of electron-transfer products. 38 refs., 10 figs.
64 citations
Cited by
More filters
••
[...]
TL;DR: There is, I think, something ethereal about i —the square root of minus one, which seems an odd beast at that time—an intruder hovering on the edge of reality.
Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.
Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …
33,785 citations
••
TL;DR: Two organolead halide perovskite nanocrystals were found to efficiently sensitize TiO(2) for visible-light conversion in photoelectrochemical cells, which exhibit strong band-gap absorptions as semiconductors.
Abstract: Two organolead halide perovskite nanocrystals, CH3NH3PbBr3 and CH3NH3PbI3, were found to efficiently sensitize TiO2 for visible-light conversion in photoelectrochemical cells. When self-assembled on mesoporous TiO2 films, the nanocrystalline perovskites exhibit strong band-gap absorptions as semiconductors. The CH3NH3PbI3-based photocell with spectral sensitivity of up to 800 nm yielded a solar energy conversion efficiency of 3.8%. The CH3NH3PbBr3-based cell showed a high photovoltage of 0.96 V with an external quantum conversion efficiency of 65%.
16,634 citations
••
TL;DR: This work reviews the historical development of Transition metal dichalcogenides, methods for preparing atomically thin layers, their electronic and optical properties, and prospects for future advances in electronics and optoelectronics.
Abstract: Single-layer metal dichalcogenides are two-dimensional semiconductors that present strong potential for electronic and sensing applications complementary to that of graphene.
13,348 citations
••
TL;DR: A review of gold nanoparticles can be found in this article, where the most stable metal nanoparticles, called gold colloids (AuNPs), have been used for catalysis and biology applications.
Abstract: Although gold is the subject of one of the most ancient themes of investigation in science, its renaissance now leads to an exponentially increasing number of publications, especially in the context of emerging nanoscience and nanotechnology with nanoparticles and self-assembled monolayers (SAMs). We will limit the present review to gold nanoparticles (AuNPs), also called gold colloids. AuNPs are the most stable metal nanoparticles, and they present fascinating aspects such as their assembly of multiple types involving materials science, the behavior of the individual particles, size-related electronic, magnetic and optical properties (quantum size effect), and their applications to catalysis and biology. Their promises are in these fields as well as in the bottom-up approach of nanotechnology, and they will be key materials and building block in the 21st century. Whereas the extraction of gold started in the 5th millennium B.C. near Varna (Bulgaria) and reached 10 tons per year in Egypt around 1200-1300 B.C. when the marvelous statue of Touthankamon was constructed, it is probable that “soluble” gold appeared around the 5th or 4th century B.C. in Egypt and China. In antiquity, materials were used in an ecological sense for both aesthetic and curative purposes. Colloidal gold was used to make ruby glass 293 Chem. Rev. 2004, 104, 293−346
11,752 citations
••
TL;DR: Film and powders of TiO2-x Nx have revealed an improvement over titanium dioxide (TiO2) under visible light in optical absorption and photocatalytic activity such as photodegradations of methylene blue and gaseous acetaldehyde and hydrophilicity of the film surface.
Abstract: To use solar irradiation or interior lighting efficiently, we sought a photocatalyst with high reactivity under visible light. Films and powders of TiO 2- x N x have revealed an improvement over titanium dioxide (TiO 2 ) under visible light (wavelength 2 has proven to be indispensable for band-gap narrowing and photocatalytic activity, as assessed by first-principles calculations and x-ray photoemission spectroscopy.
11,402 citations