Publications

Self-assembly of photo-reduced graphene-titania films

Washburn, Cody M.; Bell, Nelson S.; McKenzie, Bonnie B.; Brumbach, Michael T.

In an aim to develop photo-responsive composites, the UV photo-reduction of aqueous titanium oxide nanoparticle-graphene oxide (TiO{sub 2}-GO) dispersions (Lambert et al. J Phys. Chem. 2010 113 (46), 19812-19823) was undertaken. Photo-reduction led to the formation of a black precipitate as well as a soluble portion, comprised of titanium oxide nanoparticle-reduced graphene oxide (TiO{sub 2}-RGO). When allowed to slowly evaporate, self assembled titanium oxide nanoparticle-graphene oxide (SA-TiO{sub 2}-RGO) films formed at the air-liquid interface of the solution. The thickness of SARGO-TiO{sub 2} films range from {approx}30-100 nm when deposited on substrates, and appear to be comprised of a mosaic assembly of graphene nanosheets and TiO{sub 2}, as observed by scanning electron microscopy. Raman spectroscopy and X-ray photoelectron spectroscopy indicate that the graphene oxide is only partially reduced in the SA-TiO{sub 2}-RGO material. These films were also deposited onto inter-digitated electrodes and their photo-responsive behavior was examined. UV-exposure lead to a {approx} 200 kOhm decrease in resistance across the device, resulting in a cathodically biased film. The cathodic bias of the films was utilized for the subsequent reduction of Ag(NO{sub 3}) into silver (Ag) nanoparticles, forming a ternary Ag-(SA-RGO-TiO{sub 2}) composite. Various aspects of the self assembled films, their photoconductive properties as well as potential applications will be presented.