Mechanism and Kinetics of Oxidation Reaction of Aqueous Ti3C2Tx Suspensions at Different pHs and Temperatures

Abstract

Understanding the oxidation reaction of aqueous Ti 3 C 2 T x MXene suspensions is very important for fostering fundamental academic studies as well as widespread industrial applications. Herein, we investigated the mechanism and kinetics of the oxidation reaction of aqueous Ti 3 C 2 T x suspensions at various pH and temperature conditions. Through comprehensive analysis, the mechanism of the chemical oxidative degradation of aqueous Ti 3 C 2 T x colloids was established. Chemical oxidation produces solid products such as TiO 2 and amorphous carbon as well as various gaseous species including CH 4, CO, CO 2, and HF. Additionally, our comprehensive kinetic study proposes that aqueous Ti 3 C 2 T x dispersions are degraded via an acid-catalyzed oxidation reaction, where, under acidic conditions, the protonation of the hydroxyl terminal groups on the Ti 3 C 2 T x flakes induces electron localization on titanium atoms and accelerates their oxidation reaction. In contrast, under basic conditions, the electrostatically alkali-metalized hydroxyl intermediates forming a bulky solvent cage results in less electron localization on titanium atoms, and thus retards their oxidative degradation.