Ti_nO_2n-1 is a series of substoichiometric oxides of titanium with many excellent properties such as high electronic conductivity, strong visible light absorption, outstanding electrochemistry stability and environmental compatibility. Ti₄O₇ exhibits a single crystal conductivity of 1500 S ·cm^-1, comparable to that of graphite. These materials have been studied for many years and their properties of structure, magnetics and electrics have been widely investigated. A lot of preparation methods have been developed for the purpose of property research and application development. The most commonly used preparation method is reduction of TiO₂ or its precursor at a high temperature, and some interesting morphologies have been obtained, like nanosphere, nanorod and nanowire. In recent years, their wonderful properties arouse peoples interest for their applications in noble electrodes, catalyst carriers, lithium batteries, thermoelectric and photoelectric materials, photocatalysis materials and so on. For example, Ti₄O₇ has been commoditized and utilized in many fields. However, a lot of work is remained to do for the full use of these titanic oxides, such as exploration of new feature and strategies to improve the specific surface area of these materials.According to the work of the predecessors, this paper introduces the structure features, physicochemical properties of Ti_nO_2n-1, and makes a summary of some typical preparation methods and applications, with the purpose of providing some reference for the research and development of Ti_nO_2n-1 series compounds.

Contents
1 Introduction
2 Structural properties of Ti_nO_2n-1
3 Physicochemical properties of Ti_nO_2n-1
4 Preparation methods of Ti_nO_2n-1
4.1 High temperature sintering
4.2 Laser ablation
4.3 Sol-gel sintering
5 Application of Ti_nO_2n-1
5.1 Application of Ti_nO_2n-1 in noble electrodes
5.2 Application of Ti_nO_2n-1 in fuel cells
5.3 Application of Ti_nO_2n-1 in batteries
5.4 Application of Ti_nO_2n-1 in thermoelectric and photoelectric materials
5.5 Application of Ti_nO_2n-1 in photocatalytic degradation
[JP] 6 Conclusion and outlook