Charge storage improvement in uniformly grown TiO2 on Ti3C2Tx MXene surface

The energy storage capacity of MXenes can be significantly augmented by increasing their specific surface area, which can additionally amplify the number of active sites available for electrochemical reactions. Herein, we have presented a method to enhance the energy storage capacity of Ti3C2Tx MXenes by growing the TiO2 nanogrooves on the surface of Ti3C2Tx (termed as Ti3C2Tx-NG) without drying the exfoliated MXene layers using hydrothermal treatment. The Ti3C2Tx MXene flakes dimensions ranged from 500 to 1000 nm, whereas the decorated TiO2 nanogrooves have a size of ∼10 nm. The Ti3C2Tx MXene demonstrates a specific surface area (SSA) of ∼ 11 m2/g, while the Ti3C2Tx-NG exhibits an enhanced SSA of ∼40 m2/g. The Ti3C2Tx-NG utilized in the fabrication of symmetric supercapacitors exhibited a significantly higher specific capacitance (∼81 F/g) compared to Ti3C2Tx MXene (∼62 F/s) at a scan rate of 100 mV/s. Reversible oxidation and reduction reactions between TiO2 and Ti3C2Tx, accompanied by the adsorption or release of hydroxide ions (OH-) contribute to charge transport in the supercapacitors. Additionally, due to the layered structure of Ti3C2Tx MXene, a smaller number of ions can exist between two adjacent MXene layers due to the small spacing, whereas more ions can exist between two adjacent Ti3C2Tx-NG layers as interlayer spacing between adjacent layers is relatively broader due to the nanosized TiO2 nanogrooves, facilitating in the higher charge storage.