One-step synthesizing Ti3C2Tx doped with slight amount of Ni2+ to enhance the electrochemical stability

Abstract

Two-dimensional layered material of Ti3C2Tx has attracted widespread attention due to its high conductivity, rich surface functional groups and excellent hydrophilicity. However, its practical application is hindered by the problems of re-stacking and the instability rooted from easy oxidation of low valent Ti. Here, a simple synthesis strategy that the surface of Ti3C2Tx is decorated by Ni2+ has been developed: a small amount of Ni2+ is added into the Ti3C2Tx dispersion to bind to the surface vacancies to obtain Ti3C2Tx-Ni during the ultrasonic stripping process. Therefore, the interlayer spacing of Ti3C2Tx-Ni-2 is expanded from 1.12 nm (for Ti3C2Tx) to 1.22 nm, meaning that the stacking and aggregation effect has been alleviated. Compared with the short storage time of Ti3C2Tx, the suspension of Ti3C2Tx-Ni-2 can keep stability for more than 270 days. The self-supporting Ti3C2Tx-Ni-2 film exhibits a specific capacitance of 208.0 F g−1 in 1.0 M H2SO4 and 82.8 F g−1 in 1.0 M Na2SO4 electrolyte at a scan rate of 2 mV s−1. Furthermore, it can still maintain 100 % of the initial capacitance after 10,000 cycles at a current density of 5 A g−1 in neutral electrolyte, while the Ti3C2Tx film can only retain 74.8 % of its initial capacitance.