One-step hydrothermal synthesis of porous Ti₃C₂T_<i>z</i> MXene/rGO gels for supercapacitor applications

Abstract

Titanium carbide/reduced graphene oxide (Ti₃C₂T_<i>z</i>/rGO) gels were prepared by a one-step hydrothermal process. The gels show a highly porous structure with a surface area of ∼224 m² g^-1 and average pore diameter of ∼3.6 nm. The content of GO and Ti₃C₂T_<i>z</i> nanosheets in the reaction precursor was varied to yield different microstructures. The supercapacitor performance of Ti₃C₂T_<i>z</i>/rGO gels varied significantly with composition. Specific capacitance initially increased with increasing Ti₃C₂T_<i>z</i> content, but at high Ti₃C₂T_<i>z</i> content gels cannot be formed. Also, the retention of capacitance decreased with increasing Ti₃C₂T_<i>z</i> content. Ti₃C₂T_<i>z</i>/rGO gel electrodes exhibit enhanced supercapacitor properties with high potential window (1.5 V) and large specific capacitance (920 F g^-1) in comparison to pure rGO and Ti₃C₂T_<i>z</i>. The synergistic effect of EDLC from rGO and redox capacitance from Ti₃C₂T_<i>z</i> was the reason for the enhanced supercapacitor performance. A symmetric two-electrode supercapacitor cell was constructed with Ti₃C₂T_<i>z</i>/rGO, which showed very high areal capacitance (158 mF cm^-2), large energy density (∼31.5 μW h cm^-2 corresponding to a power density of ∼370 μW cm^-2), and long stability (∼93% retention) after 10 000 cycles.