Ion Concentration Gradient Induced Efficient Ion Migration in Hydrogen‐Bonded Organic Frameworks for High‐Performance, Self‐Powered Humidity Sensing

As one of the driving forces of ion migration, ion concentration gradients have large untapped potential to improve the performance of humidity sensors. A self-powered flexible humidity sensor based on hydrogen-bonded organic framework electrolytes wherein Na⁺ concentration gradients induce efficient ion migration is presented that can be attributed to the reversible effect of ambient water molecules on the migration barrier of Na⁺. The sensor exhibits superior flexibility, rapid responsiveness, high sensitivity (0.17 µA/% relative humidity), rapid response time (1.06 s), and outstanding stability (>200 cycles). The humidity-responsive device based on the Na⁺ concentration gradient exhibited excellent self-powering capability, eliminating the need for an external power unit and demonstrating impressive humidity power generation potential, which achieves a high current density of up to 164 mA m^-2 and power density of 5.625 mW m^-2. This research presents a new paradigm for developing self-powered humidity sensors and demonstrates their exceptional performance in noncontact sensing applications.