Free-standing and film-type moisture-driven
energy generators (MEGs)
that harness the preferential interaction of ionized moisture with
hydrophilic materials are interesting because of their wearability
and portability without needing a water container. However, most such
MEGs work in limited humidity conditions, which provide a substantial
moisture gradient. Herein, we present a high-performance MEG with
sustainable power-production capability in a wide range of environments.
The bilayer-based device comprises a negatively surface-charged, hydrophilic
MXene (Ti3C2T
x
)
aerogel and polyacrylamide (PAM) ionic hydrogel. The preferential
selection on the MXene aerogel of positive charges supplied from the
salts and water in the hydrogel is predicted by the first-principle
simulation, which results in a high electric output in a wide relative
humidity range from 20% to 95%. Furthermore, by replacing the hydrogel
with an organohydrogel of PAM that has excellent water retention and
structural stability, a device with long-term electricity generation
is realized for more than 15 days in a broad temperature range (from
−20 to 80 °C). Our MXene aerogel MEGs connected in series
supply sufficient power for commercial electronic components in various
outdoor environments. Moreover, an MXene aerogel MEG works as a self-powered
sensor for recognizing finger bending and facial expression.