Asymmetric self-powered cellulose-based aerogel for moisture-electricity generation and humidity sensing

In view of the current problems of fossil consumption and environmental pollution, harvesting electricity from water to obtain renewable and clean energy has become a trend. Herein, an asymmetric self-powered cellulose-based aerogel generator (SMEG) was proposed by directional freeze-drying using quaternized cellulose nanofibril (Q-CNF), sodium carboxymethylcellulose (CMC) and single-walled carbon nanotube. When exposed to humid air, the prepared aerogel generated ionic ionization and directional flow, resulting in a potential difference. The single SMEG could separately produce a continuous voltage and current output of up to 668 mV and 6.4 μA, accompanied by a power density of 0.871 μW⋅cm−2 at high humidity (90 %). Meanwhile, connecting several SMEG devices could directly provide satisfied power for some commercial electronics including LED lights and calculators. More importantly, it was compatible for applications in contactless sensing and respiratory monitoring with high moisture sensitivity and good durability. This work provides a low-cost and environmentally friendly strategy for the optimal design of moisture-electricity generators and self-powered humidity sensors.