Tuneable work function of titanium carbide (Ti3C2Tx) by modification in surface termination groups

Titanium carbide (Ti3C2Tx) has been synthesized using varied percentages of etching agent (HF, from 5% to 50%) and it is demonstrated that this leads to a substantial change in the surface termination groups of Ti3C2Tx. Data shows hexagonal structure and evolution of accordion-like structure due to systematic removal of Al-layers, as a function of HF percentage, resulting in increased surface area. The EDAX and spectroscopy data reveal an increase in –F and –OH groups on the surface. Electrostatic field microscopy (EFM) shows lowest negative charge in 50% etched sample and highest negative charge in 30% etched sample. This is attributed to the interplay between the aggressive etching (which is a function of HF percentage) and charge-distribution capacity (owing to the stability sought by the system through the changes in surface area) of the system. The work function varies in the range of 3.78 eV–4.01 eV. Specific capacitance measurements reveal 50% etched sample with lowest specific capacitance (4.8 F/g); while 30% etched showed highest (11.9 F/g). A simple chemical approach is hence projected to achieve tuning in work function of MXene through manipulation of surface area and surface termination groups.