  Highly stable ozone and hydrogen sensing elements were fabricated based on
well-crystalline rounded cube-shaped CsPbBr$_3$ submicron crystals, synthesized
by a facile solution process performed under ambient conditions. It is shown
that such elements demonstrate enhanced room temperature gas sensing ability
compared to the previously reported metal halide and oxide-based ones.
Electrical measurements performed on these sensing components revealed high
response to ultra-low ozone and hydrogen concentrations, namely 4 ppb and 5 ppm
respectively, as well as an impressive repeatability of the sensing behavior
even after a few months of storage in ambient conditions. Both ozone and
hydrogen detecting sensors were self-powered, i.e. they do not require the use
of UV or heating external stimuli, and exhibited fast detection and short
restoration times. These attractive properties along with the simple synthesis
conditions could provide an easy, efficient and low-cost potential technology
for the realization of future gas sensing devices.
