High capacitance of surface-modified 2D titanium carbide in acidic electrolyte

The electrochemical behavior of Ti3C2, a two-dimensional titanium carbide from the MXene family, in H2SO4 electrolyte is reported. To demonstrate the effect of surface chemistry on capacitive performance, Ti3C2 was modified by delamination or intercalation treatments. Electrochemical testing revealed an increase in capacitance, which was attributed to oxygen-containing functional groups. An extraordinary high intercalation capacitance of 415F·cm−3 at 5A·g−1 was obtained from electrodes with a specific surface area of just 98m2·g−1. Values up to 520F·cm−3 were recorded for delaminated MXene films at 2mV·s−1. This study highlights that the behavior of materials from the large family of two-dimensional MXene can be tuned by suitable modification of their surface chemistry. •Surface chemistry of two-dimensional Ti3C2 has been modified.•XPS analysis confirms replacement of terminal F-groups by oxygenated groups.•We demonstrate the contribution of pseudocapacitance mechanism.•We report excellent volumetric capacitance of 520F·cm−3.