Copper-cerium oxide (Cu-CeO2) nanoparticles engineered with a high defect density for redox catalysis

This technology presents a low-temperature synthesis of copper doped cerium oxide nanoparticles with a controllable and high dopant density. These nanoparticles act as catalysts in oxidation-reduction ("redox") chemical processes. For example, the water-gas shift reaction is a redox process that produces hydrogen and carbon monoxide, which can be converted in additional steps into usable forms of energy. Low catalytic efficiency of undoped metal nanoparticles is a major problem in this reaction. The incorporation of dopants, such as copper, into this material greatly increases their effectiveness as a catalyst. Doping CeO2 with Cu in particular allows for catalytic activity at significantly lower temperatures than undoped CeO2 nanoparticles. This technology can be used as a catalyst for not only the water-gas shift reaction, but for other redox processes as well.

Copper-cerium oxide nanoparticles can be engineered at low temperatures and with high control over their chemical composition

This synthesis of Cu-CeO2 nanoparticles is completed at low temperatures (40 degrees C) and yields doped nanoparticles with a high amount of incorporated Cu. In addition, the amount of copper dopant can be controlled directly from the amount of copper precursor added to the reaction, allowing for tuning of the dopant density in the final product. The low temperatures reduce the cost of production compared to high temperature syntheses. Furthermore, because the reaction is run in aqueous solution, the costs involved with purchasing and disposing of organic solvents are avoided. While other low temperature, aqueous based syntheses have been developed for Cu-CeO2, the dopant densities in their final nanoparticles were too low to have an effect on its properties. This technology has a synthesis whose final product has a sufficiently dopant density to increase its catalytic activity.

The synthesized nanoparticles were characterized by high-resolution transmission electron microscopy, x-ray diffraction, and Raman spectroscopy techniques to show both their high uniformity as well as their high copper incorporation.

Lead Inventor:

Siu-Wai Chan, Sc.D.

Applications:

• Can be used as effective catalyst in water gas shift reaction for generating hydrogen in fuel cells
• The nanoparticles are a potential catalyst for other redox reactions
• This catalyst can be used in eliminating nitrogen oxide emissions from diesel exhaust
• It also has usage in cold starting of automobile engines/lasers/hydrocarbon conversion reactors
• Material in air filters for conversion of CO and/or indoor volatile organic compounds/smoking articles
• The technique can be a cost effective method to prepare nanoparticles with significant extended defects
• The technique can be used as an excellent substitute of current expensive processes producing uniform generation of defects in nanoparticles

Advantages:

• This technique presents a straightforward method to produce nanoparticle catalysts with a high defect density
• This technique uses a totally aqueous procedure, thus it can save costs in purchasing and disposing of organic solvents and reagents
• This technique uses low temperature process (40 degrees C), thus it does not require a large energy input
• The average yield is high
• The nanoparticles are uniform in size

Patent information:

Patent Pending WO/2010/045484

Tech Ventures Reference: IR M09-024

Related Publications:

• R. Si, J. Raitano, N. Yi, L. Zhang, S.-W. Chan, M. Flytzani-Stephanopoulos. "Structure sensitivity of the low-temperature water-gas shift reaction on Cu-CeO2 catalysts." Catalysis Today. 2012 Jan 17;180(1):68-80.

• F. Zhang, S.-W. Chan, J. E. Spanier, E. Apak, Q. Jin, R. D. Robinson, I. P. Herman. "Cerium oxide nanoparticles: Size-selective formation and structure analysis." Applied Physics Letters. 2002 Jan 7;80(1):127-129.