  MXenes are a family of two-dimensional (2D) carbides and nitrides that
display extraordinary electrical, optical, chemical, and electrochemical
properties. There is a perception that MXenes are unstable and degrade quickly,
limiting potential applications and requiring specific storage conditions to
last for a long time. This was true for delaminated MXenes flakes in dilute
dispersions prepared from defective precursors when MXene research was in its
infancy. Since then, significant developments in MXene synthesis, processing,
and understanding of its chemistry led to dramatic increases in environmental
stability. Herein, we analyze Ti$_3$C$_2$T$_x$ free-standing films aged from 4
to 9 years through structural and morphological characterization along with
electrical conductivity measurements to reveal the effect, or lack thereof, of
prolonged storage under ambient conditions. Further, we show that the decrease
in electronic conductivity over time is largely caused by the uptake of water
by the hydrophilic surface chemistry of MXenes, which can be easily removed and
its effect reversed by vacuum annealing.
