(200a) Magnetically Recoverable Tio2 Photocatalyst Particles by Means of Atomic Layer Deposition

King, D. M., University of Colorado, Boulder
Buechler, K. J., ALD NanoSolutions, Inc.
Weimer, A., University of Colorado, Boulder

Titania (TiO2) is a well-established general purpose UV-photocatalyst for decomposing biological and organic contaminants. Ultrafine TiO2 is a desirable candidate for a catalytically active additive to polluted water or air streams, although its drawbacks include non-recoverability. Atomic Layer Deposition (ALD) is a process by which conformal, pinhole-free oxide barrier coatings can be applied to a variety of substrate types (e.g. metals, metal oxides, and polymers) and geometries. Particle ALD offers the flexibility to augment bulk particle properties with desired surface properties by depositing controllable-thickness, functional oxide layers. ALD is employed here to deposit nano-thick films of TiO2 onto iron nanoparticles, thus creating recoverable, high surface area, magnetically separable photocatalyst particles. The effectiveness of a surface catalyst is directly tied to active substrate surface area and surface quality. It is known that the crystalline phase (amorphous, rutile and anatase) of TiO2 ALD films is temperature dependent; a phase-based activity dependence will also be presented and optimized for comparison to the photocatalytic activity of commercially available Degussa P25 TiO2 nanoparticles. Environmental restoration efforts can be greatly enhanced by the availability of a cost-effective, renewable photocatalyst such as an ultrafine TiO2 coated ferromagnetic nanoparticle.