Wide Range Of Visible Light Research Articles

Plasmon-enhanced dye-sensitized solar cells using SiO2 spheres decorated with tightly assembled silver nanoparticles

SiO2 spheres decorated with tightly assembled silver nanoparticles were incorporated into the photoanode of a dye-sensitized solar cell. Localized surface plasmon resonance from the assembled Ag nanoparticles increased the light absorption throughout the wide visible light range. This plasmon-enhanced light absorption resulted in a significant improvement in the device performance.

Synthesis and optical absorption of Ag/CdS core/shell plasmonic nanostructure

The Ag/CdS core/shell nanoparticles are synthesized by a facile method. The synthesis steps are simple and easy to be manipulated. The core/shell nanostructures are characterized by the transmission electron microscopy (TEM), X-ray diffraction (XRD), and UV–vis spectrometry techniques. Compared with bare Ag and CdS nanoparticles, the optical absorption of Ag/CdS composite nanostructures is greatly enhanced in a wide range of visible light. It can also be demonstrated in the simulations based on DDA method. The enhanced absorption of light is mainly due to the localized surface plasmon resonance (LSPR) effect excited on silver core. The optical response of such core/shell nanostructures is extended to longer wavelengths.

ChemInform Abstract: Fabrication of an Efficient BaTaO2N Photoanode Harvesting a Wide Range of Visible Light for Water Splitting.

AbstractBaTaO2N photoanodes that harvest visible light up to 660 nm are prepared on Ti substrates.

Fabrication of an Efficient BaTaO2N Photoanode Harvesting a Wide Range of Visible Light for Water Splitting

Photoanodes made from BaTaO2N that can harvest visible light up to 660 nm wavelength were fabricated on Ti substrates for achieving efficient water splitting. Both pre-treatment of BaTaO2N particles with an H2 stream and post-necking treatment with TaCl5 effectively increased the photocurrent due to the decreased electrical resistance in the porous BaTaO2N photoanode. A combination of pre-loading of CoO(x) on the BaTaO2N particles and post-loading of RhO(x) significantly improved both the photocurrent and stability under visible light irradiation, along with an obvious negative shift (ca. 300 mV) of the onset potential for water oxidation, while sole loading resulted in a lower photocurrent or insufficient stability. The IPCE value was estimated to be ca. 10% at 1.2 V vs RHE under 600 nm, which is the highest among photoanode materials that can harvest light beyond 600 nm for water oxidation. Photoelectrochemical water splitting into H2 and O2 under visible light was demonstrated using RhO(x)/CoO(x)/BaTaO2N/Ti photoanodes under an externally applied bias larger than 0.7 V to a Pt counter electrode.

(Oxy)nitrides with d0-electronic configuration as photocatalysts and photoanodes that operate under a wide range of visible light for overall water splitting

Water splitting to form H2 and O2 using semiconductor photocatalysts under sunlight is a possible means of clean energy production from renewable resources. (Oxy)nitrides are regarded as suitable candidates for the application, because of their suitable band edge positions, small band gaps (<3 eV), and stability under irradiation. Since early reports published in 2002 by Domen et al., it has been demonstrated that several (oxy)nitrides are active photocatalysts capable of reducing and oxidizing water in the presence of suitable electron donors and acceptors, respectively, under visible light (λ > 400 nm). Some have achieved direct water splitting into H2 and O2 with good reproducibility. (Oxy)nitrides are also attractive as water-splitting photoelectrodes, and highly efficient photoelectrochemical water splitting has been accomplished using tantalum-based (oxy)nitrides under visible light with good stability. However, there still remain a lot of challenges that have to be addressed in this research field. This perspective highlights recent progress in the development of (oxy)nitride materials for application in photocatalytic and photoelectrochemical water splitting made by the author and his colleagues, especially in the last 5 years.

Development of highly efficient supramolecular CO2reduction photocatalysts with high turnover frequency and durability

New Ru(II)-Re(I) supramolecular photocatalysts with a rhenium(I) biscarbonyl complex as a catalyst unit were synthesized. They photocatalyzed CO2 reduction to CO using a wide-range of visible light, and their photocatalytic abilities were strongly affected by the phosphorus ligands on the Re site. Especially, Ru-Re(FPh), with two P(p-FPh)3 ligands, exhibited tremendous photocatalytic properties, i.e. TN(CO) = 207 and phi(CO) = 0.15, and, in addition, this is one of the fastest-operating photocatalysts for CO2 reduction to CO, with TF(CO) = 281 h(-1). We also clarified a balance of transferred electrons in this photocatalytic reaction and found that the two electrons necessary for CO formation were provided by two sequential reductive quenching processes of the excited Ru photosensitizer unit by the reductant BNAH.

Single-Crystalline Rutile TiO2 Hollow Spheres: Room-Temperature Synthesis, Tailored Visible-Light-Extinction, and Effective Scattering Layer for Quantum Dot-Sensitized Solar Cells

A general synthesis of inorganic single-crystalline hollow spheres has been achieved through a mechanism analogous to the Kirkendall effect, based on a simple one-step laser process performed at room temperature. Taking TiO(2) as an example, we describe the laser process by investigating the influence of experimental parameters, for example, laser wavelength, laser fluence/irradiation time, liquid medium, and concentration of starting materials, on the formation of hollow spheres. It was found that the size-tailored TiO(2) hollow spheres demonstrate tunable light scattering over a wide visible-light range. Inspired by the effect of light scattering, we introduced the TiO(2) hollow sphere's scattering layer in quantum dot-sensitized solar cells and achieved a current notable 10% improvement of solar-to-electric conversion efficiency, indicating that TiO(2) hollow spheres are potential candidates in optical and optoelectronic devices.

Novel Stannite-type Complex Sulfide Photocatalysts AI2-Zn-AIV-S4 (AI = Cu and Ag; AIV = Sn and Ge) for Hydrogen Evolution under Visible-Light Irradiation

Photophysical properties and photocatalytic activities for H2 evolution of the series of stannite-type complex sulfides AI2-Zn-AIV-S4 (AI = Cu and Ag; AIV = Sn and Ge) were studied. Diffuse reflection spectra and the plane-wave-based density functional theory (DFT) calculation suggested that the conduction bands were made up of Ge4s4p or Sn5s5p with S3p orbitals, while the valence bands consisted of Cu3d and Ag4d with S3p orbitals. The constituting elements of AI and AIV affected the photophysical and photocatalytic properties. Ru cocatalyst-loaded Cu2ZnGeS4, Ag2ZnGeS4, and Ag2ZnSnS4 showed high activities for photocatalytic H2 evolution from an aqueous Na2S+K2SO3 solution under visible-light irradiation. Combination of Cu and Ag made it possible that the CuAgZnSnS4 photocatalyst with a narrow band gap (1.4 eV) utilized a wide range of visible light for the H2 evolution.

Photoinduced degradation of organic dye over LiBiO3 under illumination of white fluorescent light

We report dye-degradation effects of a semiconductor LiBiO3 revealed under illumination of a conventionally used white fluorescent light. Optical absorbance spectra of LiBiO3 were broadened so smoothly, with the absorption edge penetrated to around 730 nm, that the material was able to absorb a wide range of visible light. Results showed that solution of a standard dye, methylene blue, was degraded completely after 4 h illumination. Furthermore, the value of total organic carbon decreased 70% in the decolorized solution, suggesting that the molecular form of the original methylene blue was mineralized effectively to nonorganic fragments by the photoinduced oxidization effect. Moreover, the wavelength dependence of apparent photonic efficiency was evaluated using a standard Xe lamp coupled with monochromatic filters. These results were interpreted from the viewpoint of this material’s electronic structure.

金属錯体を光触媒として用いた二酸化炭素の高効率還元

Highly efficient photocatalytic CO2 reduction using metal complexes, particularly rhenium(I) bipyridine complexes, is reviewed. Importance about development of such CO2 reduction photocatalysts is explained from the points of both problems with global warming and shortage of fossil fuels. Recent progress in photocatalysts for CO2 reduction has been achieved using the following systems and methods: (1) introduction of a phosphine ligand to rhenium(I) mononuclear complexes, (2) a mixed system of two rhenium(I) complexes, of which quantum yield for CO2 reduction reaches up to 59%, (3) introduction of interligand weak (π-π and CH-π) interaction into rhenium(I) complexes, and (4) supramolecular photocatalysts constructed with both Ru(II) and Re(I) complexes, which can efficiently use a wide range of visible light.

Preparation of indium-tin oxide (ITO) nano-aciculae by a simple precipitation near boiling point and post-calcination method

ITO nano-aciculae (needle-like nanometer crystals) were prepared by post-calcination of ITO precursor nano-aciculae, which were synthesized by a simple precipitation near boiling point method. Transparent conductive film formed of ITO nano-aciculae was prepared by a simple coating process. ITO precursor nano-aciculae, ITO nano-aciculae and films were characterized with morphology, phase structure, optical and electrical properties, etc. The cross-sectional diameters of most of ITO nano-aciculae were mainly in the range of 20 to 60 nm, and the aspect ratios were mostly in the range of 4 to 12. Moreover, the ITO nano-aciculae had smaller cross-sectional diameters and bigger aspect ratios in comparison with the ITO precursor nano-aciculae on the whole. ITO precursor nano-aciculae were composed of very subtle nano-wires of 3 to 4 nm in cross-sectional diameter, and the nano-wires were regularly arranged to be parallel to the axial direction of ITO precursor nano-aciculae. However, ITO nano-aciculae were composed of caky subunits (flaky grain) whose flat surfaces were perpendicular to the axial direction. ITO precursor nano-aciculae were composed of In(OH) 3 and Sn 3O 2(OH) 2, and growth of nano-wires in ITO precursor nano-aciculae was along the [1 0 0] direction of In(OH) 3. ITO nano-aciculae were ITO solid solution being not well-crystallized. ITO nano-aciculae were interlaced with each other and formed an alveolate meshwork (meshed texture). The average transmittance of the film was about 85% in a wide visible light range of 400 to 1000 nm, and the sheet resistance of the film was 4.3 kΩ/□. The ITO nano-aciculae film was used as low and middle-grade transparent conductive film.

P‐121: Optical Anisotropic Compensator by Polymer Stabilization Technique

AbstractPolymer stabilization technique was applied for making optical anisotropic compensators for the purpose of controlling the wave length dispersion characteristic. Quarter wave compensators with hybrid aligned structure were prepared by this technique using liquid crystals (LCs) with different optical birefringence (Δn). The wavelength dispersion of the resulting compensators depended on the Δn of the LC used. The compensator using LC with the smallest Δn was found to give almost same retardation value over the wide range of visible light. Hybrid compensators were combined with hybrid aligned liquid crystal cells for reflective‐ LCD application. The hybrid compensator with very low wavelength dispersion gave the reversed dispersion characteristics very close to the ideal one at black state.

Single-step Photo fabrication of Kinoforms in use of Azobenzene-containing Polymer Films

ABSTRACTWe propose a new method of optically fabricating kinoforms using polyester containing cyanoazobenzene units in the side chain. This method utilizes the surface relief structures induced optically on the azopolymer films. Using a gray-tone amplitude mask with black and white lines as a spatial light modulator, we constructed the surface relief structures on the azopolymer films with an argon-ion laser beam (488nm). The relief depths constructed were deep enough to provide a wide range of visible light with a phase difference of 2π. In addition, irradiation on the azopolymer film with a spatially modulated light that had multilevel intensities inscribed the multilevel relief structure reflecting the intensity modulation. This property is applicable to the fabrication of diffractive optical elements, especially kinoforms, because the multilevel relief structure provides an incident light with phase modulation. We designed a phase pattern for a kinoform by computation and expressed it as a gray-tone amplitude mask. Irradiation on the film through the gray-tone mask with the pump beam inscribed a multilevel relief structure that diffracted an incident light to produce a desired image. The desired image appeared without the effect of the internal refractive index modulation of the film. We, therefore, confirmed a possibility of fabricating a kinoform with a multilevel relief structure on the azopolymer film. Since our fabrication method for kinoforms requires only exposure, it has a significant advantage over other techniques that require additional processes such as developing and etching.