Capacitance breakthroughs in free-standing electrodes through MXene functionalization

The discovery of the large group of 2D materials called MXenes has gathered much attention due to their potential applications in various fields as well as the evergrowing discoveries about their nature. One of the most interesting applications is energy storage devices. Herein, we demonstrated the impact of the functionalization with two different silanes on the electrochemical and structural properties of \mathrm{Ti_3}\mathrm{C_2}\mathrm{T_x} MXene. Materials are prepared and characterized as free-standing films obtained by a simple vacuum filtration method. The structure of the modified MXene electrodes was confirmed via SEM, FTIR, and XPS analysis. At the same time, the electrochemical properties were determined by cyclic voltammetry and galvanostatic charge-discharge in a two-electrode setup in aqueous electrolyte. Capacitance values at lower scanning speeds revealed the benefits of PEG silane functionalization (25.38 F/g), showing higher values compared to pure MXene (23.95 F/g) and MEMO silane (23.37 F/g). Capacitance retention decreased with the addition of silanes, but there was a significant increase in capacitance in the first 100 cycles. This study clarifies the benefits of adding different silanes to the structural and electrochemical properties of MXene for energy storage applications.