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

Decontamination and disinfection of water by solar photocatalysis: Recent overview and trends

Two-photon excitation provides a means of activating chemical or physical processes with high spatial resolution in three dimensions and has made possible the development of three-dimensional fluorescence imaging, optical data storage, and lithographic microfabrication. These applications take advantage of the fact that the two-photon absorption probability depends quadratically on intensity, so under tight-focusing conditions, the absorption is confined at the focus to a volume of order λ3 (where λ is the laser wavelength). Any subsequent process, such as fluorescence or a photoinduced chemical reaction, is also localized in this small volume. Although three-dimensional data storage and microfabrication have been illustrated using two-photon-initiated polymerization of resins incorporating conventional ultraviolet-absorbing initiators, such photopolymer systems exhibit low photosensitivity as the initiators have small two-photon absorption cross-sections (δ). Consequently, this approach requires high laser power, and its widespread use remains impractical. Here we report on a class of π;-conjugated compounds that exhibit large δ (as high as 1, 250 × 10−50 cm4 s per photon) and enhanced two-photon sensitivity relative to ultraviolet initiators. Two-photon excitable resins based on these new initiators have been developed and used to demonstrate a scheme for three-dimensional data storage which permits fluorescent and refractive read-out, and the fabrication of three-dimensional micro-optical and micromechanical structures, including photonic-bandgap-type structures.

Two-photon polymerization initiators for three-dimensional optical data storage and microfabrication

Reports that promote persulfate-based advanced oxidation process (AOP) as a viable alternative to hydrogen peroxide-based processes have been rapidly accumulating in recent water treatment literature. Various strategies to activate peroxide bonds in persulfate precursors have been proposed and the capacity to degrade a wide range of organic pollutants has been demonstrated. Compared to traditional AOPs in which hydroxyl radical serves as the main oxidant, persulfate-based AOPs have been claimed to involve different in situ generated oxidants such as sulfate radical and singlet oxygen as well as nonradical oxidation pathways. However, there exist controversial observations and interpretations around some of these claims, challenging robust scientific progress of this technology toward practical use. This Critical Review comparatively examines the activation mechanisms of peroxymonosulfate and peroxydisulfate and the formation pathways of oxidizing species. Properties of the main oxidizing species are scrutinized and the role of singlet oxygen is debated. In addition, the impacts of water parameters and constituents such as pH, background organic matter, halide, phosphate, and carbonate on persulfate-driven chemistry are discussed. The opportunity for niche applications is also presented, emphasizing the need for parallel efforts to remove currently prevalent knowledge roadblocks.

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Persulfate-Based Advanced Oxidation: Critical Assessment of Opportunities and Roadblocks.

Chemistry of persulfates in water and wastewater treatment: A review

Accelerated bleaching, photobleaching and mineralization of the non-biodegradable azo-dye, Orange II, was obsd. with oxone in solns. with Co2+-ions. The bleaching rate of Orange II in the dark was found to follow a first-order kinetics with respect to [Co2+] with a rate const. of 20 M-1 s-1. Fitting of the Orange II photobleaching exptl. points in the presence of the Co2+/oxone reagent was carried out and followed the trend known for reactions presenting a chain radical branched mechanism. The photobleaching trace could be fitted by a single math. expression with an error <5% with respect to the exptl. data. The bleaching trace obsd. for the Orange II soln. in the dark followed zero-order decay kinetics. In a typical run, Orange II (0.20 mM or TOC 30 mg C/L) in the presence of oxone and Co2+ was bleached under visible light within .apprx.15 s. The Co2+-ion concns. necessary to catalyze the Orange II mineralization by oxone was obsd. to be .apprx.100 times lower than the oxone concn. A 100% TOC decrease, under visible light irradn., was attained for an Orange II (0.2 mM) soln. in the presence of Co2+-ions (0.06 mM) and oxone (20 mM) within times .apprx.70 min for solns. purged with oxygen. Under visible light irradn., Orange II mineralization in the presence of O2 involves the photo-dissocn. of reaction intermediates leading to org. peroxides in the second step of the mineralization process. [on SciFinder (R)]

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Bleaching and photobleaching of Orange II within seconds by the oxone/Co2+ reagent in Fenton-like processes

Photocatalytic degradation of Acid Red 88 using Au–TiO2 nanoparticles in aqueous solutions

Transparent conducting Li (0-5 wt%) doped NiO thin films with preferential growth along the (111) plane were deposited onto glass substrates by pyrolytic decomposition of nickel nitrate and lithium chloride precursors at 500 °C in air. The effect of Li concentration on the structural, optical and transport properties of NiO thin films was studied by x-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), spectral transmittance, photoluminescence and linear four-probe resistivity. Activation energies as a function of Li concentration were deduced from the temperature dependent resistivity data measured in the range 300-448 K. The figure of merit was deduced by combining the spectral transmittance and sheet resistance values. The variation in properties of NiO thin film due to Li doping are discussed based on the above results. A dye-sensitized solar cell has also been fabricated for the optimized Li doped NiO thin film and the results are presented.

http://iopscience.iop.org/article/10.1088/0957-4484/19/48/485707/pdf

Spray deposition and characterization of nanostructured Li doped NiO thin films for application in dye-sensitized solar cells.

Transparent conducting Li (0–5 wt%) doped NiO thin films with preferential growth along the
(111) plane were deposited onto glass substrates by pyrolytic decomposition of nickel nitrate
and lithium chloride precursors at 500 ◦C in air. The effect of Li concentration on the structural,
optical and transport properties of NiO thin films was studied by x-ray diffraction (XRD),
scanning electron microscopy (SEM), atomic force microscopy (AFM), spectral transmittance,
photoluminescence and linear four-probe resistivity. Activation energies as a function of Li
concentration were deduced from the temperature dependent resistivity data measured in the
range 300–448 K. The figure of merit was deduced by combining the spectral transmittance and
sheet resistance values. The variation in properties of NiO thin film due to Li doping are
discussed based on the above results. A dye-sensitized solar cell has also been fabricated for the
optimized Li doped NiO thin film and the results are presented.

Pichai Maruthamuthu

Papers

Bleaching and photobleaching of Orange II within seconds by the oxone/Co2+ reagent in Fenton-like processes

Photocatalytic degradation of Acid Red 88 using Au–TiO2 nanoparticles in aqueous solutions

Spray deposition and characterization of nanostructured Li doped NiO thin films for application in dye-sensitized solar cells.

Spray deposition and characterization of nanostructured Li doped NiO thin films for application in dye-sensitized solar cells

Performance of a new polymer electrolyte incorporated with diphenylamine in nanocrystalline dye-sensitized solar cell