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
Bolstering fat cells offers potential new leukemia treatment
17.10.2017 | McMaster University
Ocean atmosphere rife with microbes
17.10.2017 | King Abdullah University of Science & Technology (KAUST)
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
17.10.2017 | Life Sciences
17.10.2017 | Life Sciences
17.10.2017 | Earth Sciences