Three dimensions are not necessarily better than two. Not where ceria is concerned, in any case. Ceria is an important catalyst. Because of its outstanding ability to store oxygen and release it, ceria is primarily used in oxidation reactions.
Christopher B. Murray and a team at the University of Pennsylvania have now developed a simple synthetic technique to produce ceria in the form of nanoplates. As the researchers report in the journal Angewandte Chemie, these have proven to be better at storing oxygen than conventional three-dimensional nanoparticles.
In automotive catalytic converters, ceria helps to level out hydrocarbon spikes. It can also be used in the removal of soot from diesel exhaust and organic compounds from wastewater, for example. In fuel cells, ceria is used as a solid electrolyte. Cerium, a rare-earth metal, can easily switch between two different oxidation states (+IV and +III), so it undergoes a smooth transition between CeO2 and materials with a lower oxygen content. This makes ceria an ideal material for oxygen storage.
Ceria can be produced as a nanomaterial in various different forms. Almost all of the previously described forms were three-dimensional. Murray’s team has now developed a handy method for the synthesis of two-dimensional nanoplates. Their synthetic technique is based on the thermal decomposition of cerium acetate at 320 to 330 °C. Critical to their success is the presence of a mineralization agent, which speeds up the crystallization process and controls the morphology. Depending on the reaction conditions, the researchers obtained either roughly square plates with a thickness of 2 nm and edges about 12 nm in length, or elongated plates with dimensions of about 14 x 152 nm.
To test the oxygen storage capacities of the various forms of ceria, the researchers established a very simple thermogravimetric test: They alternately exposed the samples to oxygen and hydrogen and recorded the change in mass due to oxygen absorption/emission. The nanoplates proved to be superior to the conventional particulate systems and displayed an oxygen capacity three to four times as high as that of conventional three-dimensional nanoparticles. The plates do have a higher surface-to-volume ratio than the three-dimensional particles but the uptake of oxygen in the body of the nanoplates is required to explain this magnitude of enhancement. Furthermore, not all surfaces of a ceria crystal are equally good for the absorption and emission of oxygen. It turns out that the platelet surfaces were of the right type.Author: Christopher B. Murray, University of Pennsylvania, Philadelphia (USA), http://cbmurray.sas.upenn.edu/ie/index.html
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine