Defect Chemistry of a Zinc-Doped Lepidocrocite Titanate CsxTi2-x/2Znx/2O4 (x=0.7) and its Protonic Form

A zinc-doped layered titanate CsxTi2-x/2Znx/2O4 (x = 0.7) with lepidocrocite (gamma-FeOOH)-type layered structure was prepared via solid-state calcination. A complete extraction of both lattice Zn atoms and interlayer Cs ions was observed upon acid exchange, producing a protonic form H2xTi2-x/2 square O-x/2(4)center dot H2O that inherited the original lepidocrocite-type layered structure. This new phase was distinguished from its isomorphous related compounds in terms of high proton content, high charge density, and high defect content as a consequence of extractable Zn atoms located in the host framework. The protonic titanate H2xTi2-x/2 square O-x/2(4)center dot H2O readily underwent delamination to produce its molecular single sheets Ti1-delta square O-delta(2)4 delta- (delta = 0.175) with distinctive two-dimensional morphology and small thickness (similar to 1 nm), suggesting promising applications in the assembly of functional nanostructures.