Structure, Properties, Preparation, and Application of Layered Titanates

As a typical cation-exchangeable layered compound, layered titanate has a unique open layered structure. Its excellent physical and chemical properties allow its wide use in the energy, environmental protection, electronics, biology, and other fields. This paper reviews the recent progress in the research on the structure, synthesis, properties, and application of layered titanates. Various reactivities, as well as the advantages and disadvantages, of different synthetic methods are discussed. The reaction mechanism and influencing factors of the ion exchange reaction, intercalation reaction, and exfoliation reaction are analyzed. The latest research progress on layered titanates and their modified products in the fields of photocatalysis, adsorption, electrochemistry, and other applications is summarized. Finally, the future development of layered titanate and its exfoliated product two-dimensional nanosheets is proposed.

Topochemical synthesis of Mn2O3/TiO2 and MnTiO3/TiO2 nanocomposites as lithium-ion battery anodes with fast Li+ migration and giant pseudocapacitance via the mesocrystalline effect

Transition metal compounds are a promising substitute for graphite as lithium-ion battery (LIB) anodes. In this study, mesocrystalline Mn₂O₃/TiO₂ and MnTiO₃/TiO₂ nanocomposites were synthesized using a layered titanic acid H_1.07Ti_1.73O₄ (HTO) precursor. The β-MnOOH layer is intercalated into the interlayer of HTO by Mn²⁺-exchange treatment of H₂O₂-intercalated HTO, which includes ion-exchange of Mn²⁺ with H⁺ in the interlayer and oxidation of Mn²⁺ to the β-MnOOH layer by H₂O₂ in the interlayer space. Mesocrystalline Mn₂O₃/TiO₂ and MnTiO₃/TiO₂ nanocomposites with a platelike morphology were obtained by heat treatment of a sandwich layered HTO/β-MnOOH under air and H₂/Ar atmospheres, respectively. The electrochemical results suggest that the mesocrystalline Mn₂O₃/TiO₂ and MnTiO₃/TiO₂ nanocomposites show a synergistic effect for enhanced cycling stability and a mesocrystalline effect for enhanced discharge-charge specific capacity by improving the Li⁺ mobility and enhancing the pseudocapacitance of the mesocrystalline nanocomposites as LIB anode materials. The discharge-charge specific capacity of the mesocrystalline Mn₂O₃/TiO₂ nanocomposite is twice as high as that of the polycrystalline one caused by the mesocrystalline effect. Furthermore, the synergistic and mesocrystalline effects led to a stable large discharge-charge specific capacity of 710 mA h g^-1 for the mesocrystalline Mn₂O₃/TiO₂ nanocomposite. This work proposes a new concept to enhance the performance of anode materials for LIBs using mesocrystalline materials.

Completely suppressed high-voltage phase transition of P2/O3-Na0.7Li0.1Ni0.1Fe0.2Mn0.6O2via Li/Ni co-doping for sodium storage

A novel P2/O3-Na0.7Li0.1Ni0.1Fe0.2Mn0.6O2 cathode is prepared via Li/Ni co-doping, and delivers attractive cycling and rate performances due to the high Na+ diffusion coefficient and the complete suppression of the high-voltage P2–Z phase transition.