46656-G5
Catalytically Active Low Density Porous Copper (II) Monoliths
Accomplishments: In the first year of this grant being in place we have published one paper in the Journal of Materials Chemistry. This article described the synthesis of a highly porous monolithic copper (II) chloride hydroxide aerogel. This paper showed that annealing the copper (II) chloride hydroxide aerogel at 400oC in static air resulted in a phase change to the desired Copper (II) oxide. It was observed during this study that the annealing rate and dwell time have a significant impact on the copper (II) oxides surface area and porosity. In addition the annealed materials were fragile and were not able to retain their monolithic shape.
We have been investigating the effect of modifying reactions condition such as reaction solvent, overall concentration and counter ion present in the reaction system to determine the affect on particle morphology and the resultant gels surface area and pore structure. We have been exploring methods to improve structural integrity of the monolithic materials to do this we have been incorporating either an inert support oxide such as aluminum oxide or a active metal oxide such as nickel (II) oxide. In doing this we have been able to form composite oxides which are able to retain their monolithic structure when annealed at 500oC. We continue to study the resultant affect on morphology due to changing the ratio of the two metals in the composite oxides.
Challenges: The copper aerogels produced using the epoxide sol-gel approach have been identified to be in a copper (II) chloride hydroxide phase and not the desired copper (II) oxide phase. This material while monolithic and highly porous is very fragile. Therefore one of the primary challenges that we have had to address is the stability of the aerogels materials upon annealing. To address this issue without incorporating a secondary metal oxide to form a composite material we have been looking to improve structural integrity by using metal salts in which the counter ion is fully dissociated from the copper, such as nitrates. Alternative methods are also being investigated which look to increase the degree of cross-linking in the material by using alternative epoxides and changing the initial pH of the reaction.
Students: The main students attached to this project are Charlotte Sisk and Andrew Shobe. Charlotte joined my group in the summer of 2005 prior to notification of this award and Andrew joined in fall 2007 after notification of this award. Both are on track to graduate in 2009/10 with a PhD and Masters respectively. Preston Brown and Simerjeet Gill worked part time on this project.
Future: We expect that we will be able to improve the structural integrity of our materials in the next 3 months for the simple copper oxides. Once we have fully characterized the materials and ensured that we have nanocrystalline copper (II)oxide as the primary phase, we plan on investigating their catalytic performance for the oxidation of carbon monoxide. We also believe nickel-copper oxide composites we will show enhance cooperative activity from the presence of the second transition metal.
