Surface Modifications of Layered Perovskite Oxysulfide Photocatalyst YTiOS to Enhance Visible-Light-Driven Water Splitting.

Increasing the efficiency of visible-light-driven water splitting systems will require improvements in the charge separation characteristics and redox reaction kinetics associated with narrow-bandgap photocatalysts. Although the traditional approach of loading a single cocatalyst on selective facets provides reaction sites and reduces the reaction overpotential, pronounced surface charge carrier recombination still results in limited efficiency increases. The present study demonstrates a significant improvement in the hydrogen evolution activity of the layered single-crystal photocatalyst YTiOS.

PdPt/SrTiO:Al-catalysed redox-selective photoreduction of unsaturated carboxylic acids using minimal electron-donor and water.

We developed a semiconductor photocatalyst, Pd-Pt alloy nanoparticle-loaded, Al-doped SrTiO (PdPt/STO:Al), for photoreduction of unsaturated carboxylic acids. Due to the cooperative STO:Al surface and Pd-Pt alloy nanoparticles, the catalyst dispersed in water provided highly redox-selective photoreduction against oxidative degradation of starting materials/products and against reductive evolution of H, where minimal glycolic acid worked as an efficient electron-donating fuel.

Nanoparticulate TiN Loading to Promote Z-Scheme Water Splitting Using a Narrow-Bandgap Nonoxide-Based Photocatalyst Sheet.

Some oxide-based particulate photocatalyst sheets exhibit excellent activity during the water-splitting reaction. The replacement of oxide photocatalysts with narrow-bandgap photocatalysts based on nonoxides could provide the higher solar-to-hydrogen energy conversion efficiencies that are required for practical implementation. Unfortunately, the activity of nonoxide-based photocatalyst sheets is low in many cases, indicating the need for strategies to improve the quality of nonoxide photocatalysts and the charge transfer process.

Synergistic Effect of Hydrochloric Acid and Phytic Acid Doping on Polyaniline-Coupled g-CN Nanosheets for Photocatalytic Cr(VI) Reduction and Dye Degradation.

In this study, graphitic carbon nitride (g-CN) nanosheets (CNns) were modified using polyaniline (PANI) codoped with an inorganic (hydrochloric acid, HCl) and an organic (phytic acid, PA) acid. Our results revealed that these samples exhibited extended visible-light absorption and a three-dimensional (3D) hierarchical structure with a large specific surface area. They also inhibited photoluminescence emission, reduced electrical resistance, and provided abundant free radicals, resulting in high photocatalytic performance.

Photocatalytic overall water splitting on Pt nanocluster-intercalated, restacked KCaNbO nanosheets: the promotional effect of co-existing ions.

Promotional effects of co-existing ions on overall water splitting into H and O have been studied in bulk-type semiconductor photocatalysts (, TiO), but such an effect remains unexplored in two-dimensional nanosheet photocatalysts. Here we examined the effect of co-existing ions on the photocatalytic water splitting activity of Pt nanocluster-intercalated KCaNbO nanosheets. Interestingly, not only anions, as usually observed in bulk-type photocatalysts, but also cations had a significant influence on the photocatalytic performance.

Graphitic carbon nitride prepared from urea as a photocatalyst for visible-light carbon dioxide reduction with the aid of a mononuclear ruthenium(II) complex.

Graphitic carbon nitride (g-CN) was synthesized by heating urea at different temperatures (773-923 K) in air, and was examined as a photocatalyst for CO reduction. With increasing synthesis temperature, the conversion of urea into g-CN was facilitated, as confirmed by X-ray diffraction, FTIR spectroscopy and elemental analysis. The as-synthesized g-CN samples, further modified with Ag nanoparticles, were capable of reducing CO into formate under visible light (λ > 400 nm) in the presence of triethanolamine as an electron donor, with the aid of a molecular Ru(II) cocatalyst (RuP).

Undoped Layered Perovskite Oxynitride Li LaTa O N for Photocatalytic CO Reduction with Visible Light.

Oxynitrides are promising visible-light-responsive photocatalysts, but their structures are almost confined with three-dimensional (3D) structures such as perovskites. A phase-pure Li LaTa O N with a layered perovskite structure was successfully prepared by thermal ammonolysis of a lithium-rich oxide precursor. Li LaTa O N exhibited high crystallinity and visible-light absorption up to 500 nm.

A Stable, Narrow-Gap Oxyfluoride Photocatalyst for Visible-Light Hydrogen Evolution and Carbon Dioxide Reduction.

Mixed anion compounds such as oxynitrides and oxychalcogenides are recognized as potential candidates of visible-light-driven photocatalysts since, as compared with oxygen 2p orbitals, p orbitals of less electronegative anion (e.g., N, S) can form a valence band that has more negative potential.

Effects of the SrTiO support on visible-light water oxidation with CoO nanoparticles.

The photocatalytic activity of SrTiO modified with CoO nanoparticles for water oxidation under visible light (λ > 480 nm) was investigated with respect to the physicochemical properties of the SrTiO support. SrTiO was synthesized by a polymerized complex method or a hydrothermal method, followed by calcination in air at different temperatures in order to obtain SrTiO particles having different sizes. CoO nanoparticles, which provide both visible light absorption and water oxidation centers, were loaded on the as-prepared SrTiO by an impregnation method using Co(NO) as the precursor, followed by heating at 423 K in air.

Robust Binding between Carbon Nitride Nanosheets and a Binuclear Ruthenium(II) Complex Enabling Durable, Selective CO Reduction under Visible Light in Aqueous Solution.

Carbon nitride nanosheets (NS-C N ) were found to undergo robust binding with a binuclear ruthenium(II) complex (RuRu') even in basic aqueous solution. A hybrid material consisting of NS-C N (further modified with nanoparticulate Ag) and RuRu' promoted the photocatalytic reduction of CO to formate in aqueous media, in conjunction with high selectivity (approximately 98 %) and a good turnover number (>2000 with respect to the loaded Ru complex). These represent the highest values yet reported for a powder-based photocatalytic system during CO reduction under visible light in an aqueous environment.

Cobalt Oxide Nanoclusters on Rutile Titania as Bifunctional Units for Water Oxidation Catalysis and Visible Light Absorption: Understanding the Structure-Activity Relationship.

The structure of cobalt oxide (CoO) nanoparticles dispersed on rutile TiO (R-TiO) was characterized by X-ray diffraction, UV-vis-NIR diffuse reflectance spectroscopy, high-resolution transmission electron microscopy, X-ray absorption fine-structure spectroscopy, and X-ray photoelectron spectroscopy. The CoO nanoparticles were loaded onto R-TiO by an impregnation method from an aqueous solution containing Co(NO)·6HO followed by heating in air. Modification of the R-TiO with 2.

Modification of Wide-Band-Gap Oxide Semiconductors with Cobalt Hydroxide Nanoclusters for Visible-Light Water Oxidation.

Cobalt-based compounds, such as cobalt(II) hydroxide, are known to be good catalysts for water oxidation. Herein, we report that such cobalt species can also activate wide-band-gap semiconductors towards visible-light water oxidation. Rutile TiO2 powder, a well-known wide-band-gap semiconductor, was capable of harvesting visible light with wavelengths of up to 850 nm, and thus catalyzed water oxidation to produce molecular oxygen, when decorated with cobalt(II) hydroxide nanoclusters.

Intercalation of highly dispersed metal nanoclusters into a layered metal oxide for photocatalytic overall water splitting.

Metal nanoclusters (involving metals such as platinum) with a diameter smaller than 1 nm were deposited on the interlayer nanospace of KCa2 Nb3 O10 using the electrostatic attraction between a cationic metal complex (e.g., [Pt(NH3 )4 ]Cl2 ) and a negatively charged two-dimensional Ca2 Nb3 O10 (-) sheet, without the aid of any additional reagent.

Systematical investigation on characteristics of a photocatalyst: tantalum oxynitrides.

Tantalum oxynitrides with various nitrogen contents were synthesized from Ta2O5 powder by nitridation under a flow of ammonia at 1123 K for various durations. X-ray powder diffraction, transmission electron microscopy, Ultraviolet-visible spectroscopy, energy-dispersive spectroscopy, elemental analysis and photocatalytic reaction were performed to investigate these samples. Selected-area electron diffraction analysis of the mixed crystalline phases of powder samples revealed that each particle had only one crystalline phase.

Nano-sized TiN on carbon black as an efficient electrocatalyst for the oxygen reduction reaction prepared using an mpg-C3N4 template.

The direct synthesis of TiN nanoparticles on carbon black (CB) was achieved using an mpg-C(3)N(4)/CB composite as a template. The obtained TiN/CB composites ensured improved contact between TiN and CB, functioning as an efficient cathode catalyst for oxygen reduction reaction (ORR) in polymer electrolyte fuel cells (PEFCs). The preparation procedure developed in this study is applicable for the synthesis of a variety of supported nano-nitride catalysts.

Highly dispersed noble-metal/chromia (core/shell) nanoparticles as efficient hydrogen evolution promoters for photocatalytic overall water splitting under visible light.

Highly dispersed rhodium nanoparticles (1.7 +/- 0.3 nm) prepared by a liquid-phase reduction method were loaded on a solid solution of GaN and ZnO without forming aggregates, achieving improved activity for visible-light-driven overall water splitting when the nanoparticles are coated with a chromia shell.

Preparation of core-shell-structured nanoparticles (with a noble-metal or metal oxide core and a chromia shell) and their application in water splitting by means of visible light.

Core-shell-structured nanoparticles, consisting of a noble metal or metal oxide core and a chromia (Cr(2)O(3)) shell, were studied as promoters for photocatalytic water splitting under visible light. Core nanoparticles were loaded by impregnation, adsorption or photodeposition onto a solid solution of gallium nitride and zinc oxide (abbreviated GaN:ZnO), which is a particulate semiconductor photocatalyst with a band gap of approximately 2.7 eV, and a Cr(2)O(3) shell was formed by photodeposition using a K(2)CrO(4) precursor.

Modified Ta3N5 powder as a photocatalyst for O2 evolution in a two-step water splitting system with an iodate/iodide shuttle redox mediator under visible light.

Modification of tantalum nitride (Ta(3)N(5)), which has a band gap of 2.1 eV, with nanoparticulate iridium (Ir) and rutile titania (R-TiO(2)) achieved functionality as an O(2) evolution photocatalyst in a two-step water-splitting system with an IO(3)(-)/I(-) shuttle redox mediator under visible light (lambda > 420 nm) in combination with a Pt/ZrO(2)/TaON H(2) evolution photocatalyst. The loaded Ir nanoparticles acted as active sites to reduce IO(3)(-) to I(-), while the R-TiO(2) modifier suppressed the adsorption of I(-) on Ta(3)N(5), allowing Ta(3)N(5) to evolve O(2) in the two-step water-splitting system.

Efficient nonsacrificial water splitting through two-step photoexcitation by visible light using a modified oxynitride as a hydrogen evolution photocatalyst.

A two-step photocatalytic water splitting (Z-scheme) system consisting of a modified ZrO(2)/TaON species (H(2) evolution photocatalyst), an O(2) evolution photocatalyst, and a reversible donor/acceptor pair (i.e., redox mediator) was investigated.

The effects of starting materials in the synthesis of (Ga(1-x)Znx)(N(1-x)O(x)) solid solution on its photocatalytic activity for overall water splitting under visible light.

The influence of starting materials on the physicochemical and photocatalytic properties of (Ga(1-x)Zn(x))(N(1-x)O(x)) were investigated in an attempt to optimize the preparation conditions. The catalyst was successfully prepared by nitriding a starting mixture of ZnO and Ga2O3. A mixture of metallic zinc and GaN, however, did not afford the desired compound.