Iron Oxide Pillared Graphite.pdf

Iron Oxide Pillared Graphite Kunimitsu Morishige* and Takanobu Hamada Department of Chemistry, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan Received February 28, 2005. In Final Form: May 17, 2005 We show that R-Fe2O3- and Fe3O4-pillared graphites can be prepared by pillaring graphite oxide with trinuclear iron acetato complex ion and calcining it in air and in vacuo, respectively. A pillared graphite structure is confirmed by transmission electron microscopy observations. The adsorption isotherms of water indicate that the mesopores of Fe3O4-pillared graphite constitute a hydrophobic nanospace. I. Introduction Certain layered metal oxides including clay minerals canbepillaredwith inorganic compoundsandtheresulting composites give a new type of porous materials, with pore sizes controllable in the micropore to mesopore ranges.1-3 The materials can be used as catalysts, catalytic supports, or adsorbents, and the preparation methods have been extensively examined. The pillaring process is realized due to ion-exchange reaction of the interlayer cations with bulky inorganic cations1 or delamination of the layered host materials and subsequent restacking of the exfoliated layers in the presence of bulky cations.3 Graphite oxide (GO) exhibits one-dimensional swelling and cation-exchange ability in a dilute alkaline solution,4 similarly to clay minerals. GO is prepared by oxidizing graphite in a liquid phase and contains aromatic regions with unoxidized benzene rings and regions with aliphatic six-membered rings.5 Although the various structural models of GO have been proposed over the years,5-7 its precise structure is still uncertain, because of the nearly amorphous nature of GO. The thermal decomposition of GO occurs around 523 K and results in the formation of defective graphene sheets.8 As a result, it is expected that metal oxide pillared graphite can be prepared by pillaring GO with bulky inorganic cations or positively charged colloidal nano