Fig. 2: Performance of the self-powered chemoelectric humidity (CEH) sensors.

a The current change rate (CCR) of the CEH sensor under different relative humidity (RH). b The CCR (blue) of the sensor to switch RH (black) between 0 and 43.2%. c The CCR of the humidity sensor to cyclic RH changes between 11.3–57.6%, showing high reliability. d The response and recovery time to 0–100% RH switch. e Comparison of the response time and recovery time of our CEH sensor with previously reported humidity sensors, showing an excellent response, and recovery performance of our sensor (Resistive: MXene⁶¹, Paper⁹, MXene⁶², MXene/Ag⁶³, Graphene¹⁰, Graphene Fiber⁶⁴, GO⁴⁶, Graphene/Silk¹², PEDOT:PSS⁶⁵, Cellulose;⁴⁹ Capacitive: GO⁶⁶, Graphene⁶⁷, Al/PI⁶, Perovskite⁶⁸, Cu Fiber;⁶⁹ Self-powered: TiO₂²⁹, MXene/Cellulose⁷⁰, SnS₂/rGO²⁸, GO⁷¹, and TiO₂⁷²). GO graphene oxide, PEDOT:PSS poly (3,4-ethylenedioxythiophene):poly (styrenesulfonate), PI polyimide, rGO reduced graphene oxide. f Schematic illustration showing the response of the structure of the CEH sensors to humidity based on metal-air redox reaction.