Automotive catalytic converters: current status and some perspectives

Recent development in 2D materials beyond graphene

Nitrogen-doped titanium dioxide as visible-light-sensitive photocatalyst: designs, developments, and prospects.

Photocatalysis has been attracting much research interest because of its wide applications in renewable energy and environmental remediation. There are many materials that are found to show good photocatalytic activity in the presence of ultraviolet (UV) and visible light. However, the applications of these materials are limited to the UV portion of sunlight. α-Fe 2 O 3 has an advantage over the other conventional materials like TiO 2 , ZnO, etc . in using solar energy for photocatalytic applications due to its lower band gap ∼2.2 eV value. As a result of which Fe 2 O 3 is capable of absorbing a large portion of the visible solar spectrum (absorbance edge ∼600 nm). Also its good chemical stability in aqueous medium, low cost, abundance and nontoxic nature makes it a promising material for photocatalytic water treatment and water splitting applications. Except these advantages the usage of Fe 2 O 3 has been restricted by many anomalies such as higher e–h recombination effect, low diffusion length and VB positioning (VB is positive with respect to H + /H 2 potential). This article reviews the research that has been carried out to overcome these basic limitations and to enhance the photocatalytic activity of α-Fe 2 O 3 .

α-Fe2O3 as a photocatalytic material: A review

A review on silicene - New candidate for electronics

A thin, insulating layer with high electrical resistivity is vital to achieving high performance of powder magnetic cores. Using layer-by-layer deposition of silica nanosheets or colloidal silica over insulating layers composed of strontium phosphate and boron oxide, we succeeded in fabricating insulating layers with high electrical resistivity on iron powder particles, which were subsequently used to prepare toroidal cores. The compact density of these cores decreased after coating with colloidal silica due to the substantial increase in the volume, causing the magnetic flux density to deteriorate. Coating with silica nanosheets, on the other hand, resulted in a higher electrical resistivity and a good balance between high magnetic flux density and low iron loss due to the thinner silica layers. Transmission electron microscopy images showed that the thickness of the colloidal silica coating was about 700 nm, while that of the silica nanosheet coating was 30 nm. There was one drawback to using silica nanosheets, namely a deterioration in the core mechanical strength. Nevertheless, the silica nanosheet coating resulted in nanoscale-thick silica layers that are favorable for enhancing the electrical resistivity.

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Improving Powder Magnetic Core Properties via Application of Thin, Insulating Silica-Nanosheet Layers on Iron Powder Particles

Soft Synthesis of Single‐Crystal Silicon Monolayer Sheets

Reversible changes in the Pt oxidation state and nanostructure on a ceria-based supported Pt

The effect of periodic operation over Pt and Pt/Ba catalysts supported on γ-alumina under oxidizing conditions was investigated using simulated automotive exhaust gas from lean-burn combustion. The conversion of hydrocarbons and NOx was measured in cycled feedstream and steady feedstream under oxidizing conditions. The activities of the catalysts were improved in the cycled feedstream between oxidizing and reducing atmospheres under average oxidizing conditions. In particular, the NOx reduction on the Pt/Bt catalyst was higher than that on the Pt catalyst in the cycling operation. From the mass spectral analysis in streams of NO O2 C3H6 and NO O2 H2 (balance He) gas, it was found that NO was oxidized and stored on the Pt/Ba catalyst under oxidizing conditions, and that the stored NOx on the catalyst was subsequently reduced to N2 under reducing conditions.

Effect of periodic operation over Pt catalysts in simulated oxidizing exhaust gas

The purpose of this study is to test the concept of protecting vulnerable sites on cathode catalysts in polymer electrolyte fuel cells. Pt single-crystal surfaces were modified by depositing Au atoms selectively on (100) step sites and their electrocatalytic activities for oxygen reduction reaction (ORR) and stabilities against potential cycles were examined. The ORR activities were raised by 70% by the Au modifications, and this rise in the activity was ascribed to enhanced local ORR activities on Pt(111) terraces by the surface Au atoms. The Au modifications also stabilized the Pt surfaces against potential cycles by protecting the low-coordinated (100) step sites from surface reorganizations. Thus, the surface modification by selective Au depositions on vulnerable sites is a promising method to enhance both the ORR activity and durability of the catalysts.

Naoko Takahashi

Papers

Improving Powder Magnetic Core Properties via Application of Thin, Insulating Silica-Nanosheet Layers on Iron Powder Particles

Soft Synthesis of Single‐Crystal Silicon Monolayer Sheets

Reversible changes in the Pt oxidation state and nanostructure on a ceria-based supported Pt

Effect of periodic operation over Pt catalysts in simulated oxidizing exhaust gas

Activities and Stabilities of Au-Modified Stepped-Pt Single-Crystal Electrodes as Model Cathode Catalysts in Polymer Electrolyte Fuel Cells.