Defect Chemistry of a Zinc-Doped Lepidocrocite Titanate Cs_xTi_2−x/2Zn_x/2O₄ (x = 0.7) and its Protonic Form

A zinc-doped layered titanate Cs x Ti 2− x /2 Zn x /2 O 4 ( x = 0.7) with lepidocrocite (γ-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 H 2 x Ti 2− x /2 ◻ x /2 O 4 ·H 2 O 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 H 2 x Ti 2− x /2 ◻ x /2 O 4 ·H 2 O readily underwent delamination to produce its molecular single sheets Ti 1−δ ◻ δ O 2 4δ− (δ = 0.175) with distinctive two-dimensional morphology and small thickness (∼1 nm), suggesting promising applications in the assembly of functional nanostructures.