Low-temperature annealing of 2D Ti₃C₂T_x MXene films using electron wind force in ambient conditions

Two-dimensional transition metal carbides and nitrides, known as MXenes, are layered materials with unique functionalities which make them suitable for applications such as energy storage devices, supercapacitors, electromagnetic interference shielding, and wireless communications. Since they are wet-processed, MXenes need annealing to improve their electrical conductivity. The extent of annealing highly depends on temperature; however, higher temperatures can also impact the resulting phases and structure. In this study, we present a non-thermal annealing process utilizing an electron wind force (EWF) method in ambient conditions. This process is demonstrated on freestanding Ti₃C₂T_x films, where we show up to 70% decrease in resistivity at temperatures below 120 °C compared to conventional thermal annealing methods. MXene structures before and after annealing are analyzed using Raman spectroscopy and ex situ and in situ X-ray diffraction. Surface terminations and intra-flake defects modification in Ti₃C₂T_x layers after EWF annealing impart better electrical conductivity to MXene film than the non-annealed films. Graphic abstract: [Figure not available: see fulltext.]