This critical review shows the basis of photocatalytic water splitting and experimental points, and surveys heterogeneous photocatalyst materials for water splitting into H2 and O2, and H2 or O2 evolution from an aqueous solution containing a sacrificial reagent Many oxides consisting of metal cations with d0 and d10 configurations, metal (oxy)sulfide and metal (oxy)nitride photocatalysts have been reported, especially during the latest decade The fruitful photocatalyst library gives important information on factors affecting photocatalytic performances and design of new materials Photocatalytic water splitting and H2 evolution using abundant compounds as electron donors are expected to contribute to construction of a clean and simple system for solar hydrogen production, and a solution of global energy and environmental issues in the future (361 references)

Heterogeneous photocatalyst materials for water splitting

Nanotubes from Carbon.

We demonstrate the efficient chemical vapor deposition synthesis of single-walled carbon nanotubes where the activity and lifetime of the catalysts are enhanced by water. Water-stimulated enhanced catalytic activity results in massive growth of superdense and vertically aligned nanotube forests with heights up to 2.5 millimeters that can be easily separated from the catalysts, providing nanotube material with carbon purity above 99.98%. Moreover, patterned, highly organized intrinsic nanotube structures were successfully fabricated. The water-assisted synthesis method addresses many critical problems that currently plague carbon nanotube synthesis.

http://science.sciencemag.org/content/sci/306/5700/1362.full.pdf

Water-Assisted Highly Efficient Synthesis of Impurity-Free Single-Walled Carbon Nanotubes

http://absimage.aps.org/image/MAR05/MWS_MAR05-2004-000692.pdf

Water-Assisted Highly Efficient Synthesis of Impurity-Free Single-Walled Carbon Nanotubes-``Super-Growth''

Polymer/carbon nanotube (CNT) composites are expected to have good processability characteristics of the polymer and excellent functional properties of the CNTs. The critical challenge, however, is how to enhance dispersion and alignment of CNTs in the matrix. Here, we review recent progress and advances that have been made on: (a) dispersion of CNTs in a polymer matrix, including optimum blending, in situ polymerization and chemical functionalization; and (b) alignment of CNTs in the matrix enhanced by ex situ techniques, force and magnetic fields, electrospinning and liquid crystalline phase-induced methods. In addition, discussions on mechanical, thermal, electrical, electrochemical, optical and super-hydrophobic properties; and applications of polymer/CNT composites are included. Enhanced dispersion and alignment of CNTs in the polymer matrix will promote and extend the applications and developments of polymer/CNT nanocomposites.

Dispersion and alignment of carbon nanotubes in polymer matrix: A review

Purifying single-walled nanotubes

A purification procedure for single-walled nanotubes is presented in this report. A novel purification method that incorporates the hydrothermal treatment along with other treatments such as extrac...

Purification procedure for single-walled nanotubes

Visible light sensitive and highly active Cu-doped ZnS hollow photocatalyst particles “Cu-ZnS-shell” were successfully developed. These particles could generate H2 through photocatalytic decomposition of HS− ion in Na2S solution. The photoactivity under xenon lamp irradiation was 6 and 130 times higher than that of copper-free “ZnS-shell” and coprecipitated ZnS particles, respectively. “Cu-ZnS-shell” particles were prepared by doping the “ZnS-shell” particles synthesized using zinc oxide as precursor with Cu, utilizing the difference in ionization tendency between zinc and copper. Though the photoactivity of “ZnS-shell” was higher than that of coprecipitated ZnS, their photoactivity under visible light conditions was low. However, the “Cu-ZnS-shell” was active to light of wavelengths higher than 440 nm and is preferred over CdS, which requires an expensive support metal catalyst such as platinum to decompose HS− ion.

Hideyuki Takahashi

Papers

Purifying single-walled nanotubes

Purification procedure for single-walled nanotubes

Cu-Doped ZnS Hollow Particle with High Activity for Hydrogen Generation from Alkaline Sulfide Solution under Visible Light

Chemical Synthesis of Sub-micrometer- to Nanometer-Sized Magnetic FeCo Dice

Designed synthesis of cobalt and its alloys by polyol process