The development of novel materials is a fundamental focal point of chemical research; and this interest is mandated by advancements in all areas of industry and technology. A good example of the synergism between scientific discovery and technological development is the electronics industry, where discoveries of new semiconducting materials resulted in the evolution from vacuum tubes to diodes and transistors, and eventually to miniature chips. The progression of this technology led to the development * To whom correspondence should be addressed. B.L.C.: (504) 2801385 (phone); (504) 280-3185 (fax); bcushing@uno.edu (e-mail). C.J.O.: (504)280-6846(phone);(504)280-3185(fax);coconnor@uno.edu (e-mail). 3893 Chem. Rev. 2004, 104, 3893−3946

http://depa.fquim.unam.mx/amyd//archivero/FidelmarLechugaSanabria_4940.pdf

Recent advances in the liquid-phase syntheses of inorganic nanoparticles.

Single-crystalline and uniform nanopolyhedra, nanorods, and nanocubes of cubic CeO2 were selectively prepared by a hydrothermal method at temperatures in the range of 100-180 degrees C under different NaOH concentrations, using Ce(NO3)3 as the cerium source. According to high-resolution transmission electron microscopy, they have different exposed crystal planes: {111} and {100} for polyhedra, {110} and {100} for rods, and {100} for cubes. During the synthesis, the formation of hexagonal Ce(OH)3 intermediate species and their transformation into CeO2 at elevated temperature, together with the base concentration, have been demonstrated as the key factors responsible for the shape evolution. Oxygen storage capacity (OSC) measurements at 400 degrees C revealed that the oxygen storage takes place both at the surface and in the bulk for the as-obtained CeO2 nanorods and nanocubes, but is restricted at the surface for the nanopolyhedra just like the bulk one, because the {100}/{110}-dominated surface structures are more reactive for CO oxidation than the {111}-dominated one. This result suggests that high OSC materials might be designed and obtained by shape-selective synthetic strategy.

Shape-selective synthesis and oxygen storage behavior of ceria nanopolyhedra, nanorods, and nanocubes.

It is well known that urbanization and industrialization have resulted in the rapidly increasing emissions of volatile organic compounds (VOCs), which are a major contributor to the formation of secondary pollutants (e.g., tropospheric ozone, PAN (peroxyacetyl nitrate), and secondary organic aerosols) and photochemical smog. The emission of these pollutants has led to a large decline in air quality in numerous regions around the world, which has ultimately led to concerns regarding their impact on human health and general well-being. Catalytic oxidation is regarded as one of the most promising strategies for VOC removal from industrial waste streams. This Review systematically documents the progresses and developments made in the understanding and design of heterogeneous catalysts for VOC oxidation over the past two decades. It addresses in detail how catalytic performance is often drastically affected by the pollutant sources and reaction conditions. It also highlights the primary routes for catalyst deactivation and discusses protocols for their subsequent reactivation. Kinetic models and proposed oxidation mechanisms for representative VOCs are also provided. Typical catalytic reactors and oxidizers for industrial VOC destruction are further discussed. We believe that this Review will provide a great foundation and reference point for future design and development in this field.

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Recent Advances in the Catalytic Oxidation of Volatile Organic Compounds: A Review Based on Pollutant Sorts and Sources.

Methods, systems, compositions include biocompatible polymer coated nanoceria that function as aqueous redox catalyst with enhanced activity at an acidic to moderately alkaline pH value between 1 and 8. The compositions are used as oxidizing agents for decomposition, decontamination or inactivation of organic contaminants, such as, pesticides and chemical warfare agents. Another use includes nanoceria as targetable nanocatalyst prepared by conjugating various targeting ligands to the nanoparticle coating to form a colorimetric or fluorescent probe in immunoassays and other molecule binding assays that involve the use of a molecule in solution that changes the color of the solution or emits a fluorescent signal, where localization of nanoceria to organs or tissue is assessed by treatment with an oxidation sensitive dye or other detection devices. Versatility and uses of the nanoceria compositions are controlled by pH value, choice of dye substrate and thickness of the polymer coating on the ceria nanoparticles.

/pdf/oxidase-activity-of-polymeric-coated-cerium-oxide-4shmqnmx1r.pdf

Oxidase activity of polymeric coated cerium oxide nanoparticles

Catalytic oxidation of volatile organic compounds (VOCs) – A review

Cerium(IV) oxide ultrafine particles were prepared using a reaction within reversed micelles, which was known as a microemulsion method. The ultrafine particles, which were obtained by mixing the water-in-oil microemulsions containing cerium nitrate solution with those of ammonium hydroxide, were characterized by high-resolution electron microscope (HREM) observations. HREM micrographs revealed that nanometer-sized CeO2 particles were formed, and their shapes were uniform. Selected-area electron diffraction patterns of the particles were completely indexed as those of cerium(IV) oxide with the cubic fluorite structure, and the lattice constant calculated from radii of Debye−Sherrer rings was 0.541 nm. Most of the particles were distributed between 2 and 6 nm, and the mean particle size obtained in this method was between 2.6 and 4.1 nm. The size of 2.6 nm is the smallest among the values ever reported for CeO2 particles. Both direct and indirect optical energy gaps of the particles were independent of the...

Characterization of Cerium(IV) Oxide Ultrafine Particles Prepared Using Reversed Micelles

https://link.springer.com/content/pdf/10.1023/A:1015342925372.pdf

Synthesis of cerium oxide nanoparticles by hydrothermal crystallization with citric acid

A new UV-blocking material consisting of cerium oxide (ceria) and turbostratic boron nitride (t-BN) has been synthesized. The surface of the ceria powders was coated with a t-BN layer by means of reaction between boric acid and urea on the surface of ceria. The thickness of the t-BN layer estimated by high resolution transmission electron microscopy was ca. 10 nm. The BN-coating was very effective in reducing the catalytic activity of the ceria and the resulting matrial showed good light scattering and absorption of UV light. BN-coated ceria particles included in an organic thin film showed higher transparency and blocked UV light more effectively than conventional micronized titanium dioxide or zinc oxide particles, two inorganic materials in common use in cosmetics and in many other applications as UV blocking materials.

Synthesis of BN-coated CeO2 fine powder as a new UV blocking material

Preparation of ceria–zirconia sub-catalysts for automotive exhaust cleaning

Direct decomposition of nitrogen oxides (NOx), which are the main air pollutants responsible for photochemical smog and acid rain, into N2 and O2 (2NO → N2 + O2) offers the most ideal route for NOx removal by catalysis. Direct decomposition of NOx is versatile and economic because no reductants are required. However, the catalytic activities of conventional catalysts are insufficient, particularly in the presence of other gases such as O2 and CO2. In recent years, however, investigation of different catalyst structures and compositions has led to enhanced catalytic activity. In particular, significant advances have been made in improving the tolerance of the catalyst to coexisting gases. These direct NO decomposition catalysts have been designed with a view to maximizing the cavity space and number of oxide anion vacancies in the crystal lattice. In this review article, recent advances in the direct NO decomposition catalysts are summarized.

https://www.tpbin.com/Uploads/Subjects/54cb0dae-2951-4b8d-ae98-9dc4ac04bcc9.pdf

Toshiyuki Masui

Papers

Characterization of Cerium(IV) Oxide Ultrafine Particles Prepared Using Reversed Micelles

Synthesis of cerium oxide nanoparticles by hydrothermal crystallization with citric acid

Synthesis of BN-coated CeO2 fine powder as a new UV blocking material

Preparation of ceria–zirconia sub-catalysts for automotive exhaust cleaning

Advances in direct NOx decomposition catalysts