Ruud van Ommen
Delft University of Technology
Manufacturing nanostructured particles by atomic layer deposition (ALD)
Location: EB1 Room 1011
Friday, November 14th 2014 - 11:00 am
Whereas most ALD research is aimed at depositing ultrathin films on wafers and other flat substrates, ALD can also be used to provide the surface of particles with either an ultrathin continuous coating or a decoration of nanoclusters. When carried out in a so-called fluidized bed, ALD is an attractive way of producing nanostructured particles with excellent scale-up potential. In such a system, the particles are suspended in an upward gas flow. We can do this both for nanoparticles and micron-sized particles. Nanoparticles - contrary to what is typically observed for larger particles - are fluidized as very dilute agglomerates with distinctive fluidization characteristics. I will discuss the challenges related to fluidization and coating of nanoparticles. Moreover, I will give a number of examples of the applications of nanostructured particles.
Like most conventional ALD reactors, fluidized-bed ALD reactors are typically operated in a temporal mode: the pulses of the different gaseous reactants are delivered subsequently in time. An alternative is to separate the administering of the reactants in space. We recently developed a spatial ALD reactor for particles. I will discuss spatial ALD of Pt on TiO2 nanoparticles that are pneumatically transported through the reactor with nitrogen at atmospheric pressure, and the use of this material as a photocatalyst. With the current setup, we are able to produce nanostructured particles via ALD at a production rate of about 1 g/min. However, the experience with pneumatic transport from other fields opens up promising scale-up prospects for continuous particle ALD.
Dr. J. Ruud van Ommen is working as an associate professor in the Chemical Engineering department of Delft University of Technology. He obtained his PhD at Delft University in 2001; he was appointed as assistant professor at Delft afterwards. In 2004-2005, he was a visiting researcher at Chalmers University of Technology, Sweden. In the summer of 2009, he was a visiting professor at the University of Colorado at Boulder, USA, working on fluidization and coating of nanoparticles. He is currently leading a team of seven PhD students, two post-docs, one technician, and several undergrad students in Delft.
Dr. van Ommen's research fields are solids processing and reactor engineering. His current research focuses on chemical engineering approaches to make nanostructured materials with high precision in a scalable manner, using methods such as atomic layer deposition, molecular layer deposition and electrospray deposition. In 2011, he was awarded a prestigious ERC starting grant; this was followed by an ERC proof-of-concept grant in 2013. Currently he is investigating applications of nanostructured particles in catalysis, energy conversion, energy storage, and health.