H2O2 assisted room temperature oxidation of Ti2C MXene for Li-ion battery anodes

Abstract

Herein we demonstrate that a prominent member of the MXene family, Ti₂C, undergoes surface oxidation at room temperature when treated with hydrogen peroxide (H₂O₂). The H₂O₂ treatment results in opening up of MXene sheets and formation of TiO₂ nanocrystals on their surface, which is evidenced by the high surface area of H₂O₂ treated MXene and X-ray diffraction (XRD) analysis. We show that the reaction time and the amount of hydrogen peroxide used are the limiting factors, which determine the morphology and composition of the final product. Furthermore, it is shown that the performance of H₂O₂ treated MXene as an anode material in Li ion batteries (LIBs) was significantly improved as compared to as-prepared MXenes. For instance, after 50 charge/discharge cycles, specific discharge capacities of 389 mA h g⁻¹, 337 mA h g⁻¹ and 297 mA h g⁻¹ were obtained for H₂O₂ treated MXene at current densities of 100 mA g⁻¹, 500 mA g⁻¹ and 1000 mA g⁻¹, respectively. In addition, when tested at a very high current density, such as 5000 mA g⁻¹, the H₂O₂ treated MXene showed a specific capacity of 150 mA h g⁻¹ and excellent rate capability. These results clearly demonstrate that H₂O₂ treatment of Ti₂C MXene improves MXene properties in energy storage applications, such as Li ion batteries or capacitors.