Professor Nicholas Kotov of the University of Michigan Ann Arbor is supported by the Chemical Catalysis program of the Division of Chemistry to develop photocatalytic nanospiked particles as a new type of heterogeneous nanocatalysts. These particles are made of zinc oxide (ZnO) needles, a highly active material, used to speed up (catalyze) reactions when exposed to light. The needles are grown around a spherical core that have the ability to form suspensions in both water-loving and water-hating liquids. The main advantage of particles with a surface of nanospikes is their ability to disperse and conduct reactions in water-hating solvents while retaining their water-loving surface states. In most cases, nanoscale photocatalysts improve efficiency and selectivity, reduce energy costs and simplify manufacturing operations for many important industrial processes. Many nanoscale photocatalysts work only in water and other polar solvents important starting materials and reaction products are only compatible with nonpolar (water-hating) solvents. The ability of nanospiked particles to perform photocatalysis may improve the efficiency of plastics manufacturing. These materials may also open up new reaction pathways and improve the chemical and pharmaceutical production. During the course this research, graduate and undergraduate students are trained in advanced research methods in nanoscience and catalysis. A collaborative program with science and art teachers in the Ypsalanti, Michigan area school district is established to devise new teaching and learning projects that combine art and science to help promote interest in nanoscience and technology.
The omnipdispersive nanospiked particles are synthesized by growing ZnO nanorods on silica, alumina and titania microscale cores. The utility of these catalytic particles in organic solvents with respect to conversion rate and selectivity are tested for the photooxidation of cyclohexane to cyclohexanol and cyclohexanone, which are the key precursors for the large scale production of many common polymers. The reaction mechanism and kinetics are investigated. In addition, detailed experimental and theoretical modelling studies are conducted to arrive at a basic understanding of the catalytic activity of nanospiked particles and to develop an engineering foundation of inorganic, colloidal, heterogeneous photocatalysts.
