Hierarchically mesostructured doped CeO2 with potential for solar-cell use

Abstract

Many properties provided by supramolecular chemistry, nanotechnology and catalysis only appear in solids exhibiting large surface areas and regular porosity at the nanometre scale. In nanometre-sized particles, the ratio of the number of atoms in the surface to the number in the bulk is much larger than for micrometre-sized materials, and this can lead to novel properties. Here we report the preparation of a hierarchically structured mesoporous material from nanoparticles of CeO(2) of strictly uniform size. The synthesis involves self-assembly of these 5-nm CeO(2) pre-treated nanoparticles in the presence of a structure directing agent (poly(alkylene oxide) block polymer). The walls of this hexagonal structured CeO(2) material are formed from the primary nanoparticles. The material possesses large pore volumes, high surface areas, and marked thermal stability, allowing it to be easily doped after synthesis whilst maintaining textural and mechanical integrity. It also exhibits a photovoltaic response, which is directly derived from the nanometric particle size-normal CeO(2) does not show this response. We have constructed operational organic-dye-free solar cells using nanometric ceria particles (in both mesostructured or amorphous forms) as the active component, and find efficiencies that depend on the illuminating power.

Cerium oxide nanoparticle: a remarkably versatile rare earth nanomaterial for biological applications

“…When combined with oxygen in a nanoparticle formulation, cerium oxide adopts a fluorite crystalline structure that emerges as a fascinating material. 3 This cerium oxide nanoparticle (CeONP) has been used prolifically in various engineering and biological applications, such as solid-oxide fuel cells, 4 high-temperature oxidation protection materials, 5 catalytic materials, 6,7 solar cells 8 and potential pharmacological agents. 9 Although useful because of its various properties and applications, the main application of CeONPs is in the field of catalysis, and stems from their unique structure and atomic properties compared with other materials.…”

Cério: propriedades catalíticas, aplicações tecnológicas e ambientais

“…Além dessa função reguladora de oxigênio, a presença de CeO 2 também evita que os catalisadores CTV percam a eficiência em altas temperaturas, pois ela inibe/ desloca as transições de fase de outros materiais como, por ex., do suporte de alumina 16,19,22 . A adição de íons lantânio, zircônia, BaO e SiO 2 à estrutura do CeO 2 pode contribuir para aumentar a quantidade de defeitos na rede cristalina e proporcionar ao CeO 2 maior capacidade para armazenar oxigênio 22,[27][28][29][30][31][32][33]35,38,[42][43][44][45] , melhorando o desempenho dos catalisadores CTV. Atualmente, o uso de CeO 2 neste tipo de catalisador é uma das principais aplicações tecnológicas deste elemento e tem consumido a maior parte do cério produzido mundialmente 4,6 .…”

Erratum to: Sol–gel synthesis of mesoporous WO3–TiO2 composite thin films for photochromic devices

“…With higher surface areas and ordered pore structures, mesoporous metal oxides may demonstrate better performances than conventional metal oxides in applications such as energy conversion and storage, catalysis, sensing, adsorption,separation, etc. Utilization of highly crystalline mesoporous metal oxides (e.g., CeO 2 , TiO 2 ) in dye sensitized solar cells (DSSCs) has been reported recently [25][26][27][28][29][30]. Corma et al [25] found that ordered mesoporous CeO 2 prepared using CeO 2 nanoparticles (5 nm) as the building blocks showed a photovoltaic response, whereas conventional CeO 2 did not.…”

“…Utilization of highly crystalline mesoporous metal oxides (e.g., CeO 2 , TiO 2 ) in dye sensitized solar cells (DSSCs) has been reported recently [25][26][27][28][29][30]. Corma et al [25] found that ordered mesoporous CeO 2 prepared using CeO 2 nanoparticles (5 nm) as the building blocks showed a photovoltaic response, whereas conventional CeO 2 did not. The better photovoltaic behaviour of mesoporous nanocrystalline CeO 2 is probably due to its high surface/grain-boundary area that enhances the electronic transport properties of nanocrystalline CeO 2 .…”