Formation mechanism of Ti4O7 phase prepared by carbothermal reduction reaction

Abstract

AbstractThe unique structure of Ti4O7 endows it with excellent properties such as outstanding electrical conductivity and corrosion resistance, which makes it one of the most promising electrode materials in the electrochemical field. Carbothermal reduction reaction (CRR) is widely used to synthesize Ti4O7, while thermodynamics, kinetics, and reaction mechanism are still limited. Besides, the purity of Ti4O7 powders prepared by CRR is also relatively low. It's necessary to study the reaction mechanism of CRR and synthesize single‐phase Ti4O7. In this work, the unknown thermodynamic data were firstly assessed by the rule of oxygen potential increasing with oxygen mole fraction in oxides. In addition, the isothermal thermal analysis suggested that the reduction process was composed of interfacial and diffusion‐controlled reactions. The activation energy of the two stages was 272.0 and 325.4 kJ mol−1 respectively. Based on this, single‐phase Ti4O7 was successfully synthesized, and a core‐shell model of the reaction mechanism was proposed and well verified by the TEM results. This study provided an in‐depth and systematic analysis of the CRR process, and it is significant to realize the preparation of single‐phase Ti4O7.