The effect of mild oxidation induced by heat treatment on the pseudocapacitance performance of Ti3C2Tx MXene

Abstract

MXene, as an emerging two-dimensional material, holds great potential in the field of supercapacitors due to its graphene-like layered structure and high conductivity. However, MXene also faces a series of challenges; including oxidation, self-aggregation, and re-stacking issues caused by van der Waals and hydrogen bond interactions within its two-dimensional layers. These challenges limit the exposure of surface-active sites, slow down electron transfer rates, and subsequently affect its electrochemical performance as an electrode material for supercapacitors. To overcome these issues and further optimize the electrochemical performance of MXene, this study focuses on exploring the effects of the low-temperature heat treatment process on the interlayer spacing, surface functional groups and electrochemical energy storage performance of Ti₃C₂T_x MXene. The results reveal that Ti₃C₂T_x MXene annealed at 300 °C for 3 h exhibits excellent pseudocapacitance performance. At a scan rate of 2 mV s⁻¹, its specific capacitance reaches up to 394.1 F g⁻¹, and the capacitance retention rate remains at a high level of 105.1 % after 9000 cycles. This work shows that the heat treatment and appropriate oxidation of MXene at low temperatures can promote the charge storage capacity of MXene, thereby fully unlocking their potential in supercapacitors.