posted on 2022-11-28, 06:05authored byLuyu Yang, Lei Zhang, Dongping Sun
Moisture-activated
electric generators (MEGs) that harvest clean
energy from atmospheric humidity offer exciting opportunities for
upgraded energy conversions. However, it is challenging to obtain
MEGs that are both easy to fabricate and of high output power, due
to the requirement for particular functional materials and the cumbersome
manufacturing process. Herein, a simple and general method is adopted
to prepare MEGs with chemically gradient structures. As a specific
example, a gradient distribution of citric acid was successfully constructed
inside an A4 printer paper by asymmetric drying, which can generate
a continuous voltage of tens of millivolts by ambient humidity, and
even to volts (275 mV and 7.6 μA cm–2) under
asymmetric humidity stimulation, and the maximum power density output
was 2.1 μW cm–2. The driving force behind
this energy conversion is a self-maintained ionic gradient created
within the paper by the asymmetric ionization of gradient organic
acids when exposed to gradient or nongradient humid air. This work
broadens the class of materials and possibilities for the rapid development
of MEGs, shedding new light on the revolution of generators that harvest
green and sustainable energy for power generation.