Moisture electric generators with Ti3C2Tx–gelatin nanocomposites driven by the hydrovoltaic effect for self-powered flexible humidity sensors

Abstract

Moisture electric generators (MEGs) self-powered by the hydrovoltaic effect were developed from gelatin-incorporated Ti3C2Tx nanosheets as flexible humidity sensors. Ti3C2Tx provides hydrophilicity, directional nanochannels, and abundant active functional groups to the Ti3C2Tx–gelatin nanocomposite, enabling versatile modification and endowing the material with high electrical conductivity. Gelatin, with its triple-stranded helix-like structure, offers abundant water-absorbing functional groups and oxidation resistance to the nanocomposite. The proposed material design induces an ion gradient and charge transfer, which are beneficial for self-powered humidity sensing via the hydrovoltaic effect. Optimization of the Ti3C2Tx–gelatin ratio led to a high open-circuit voltage of 0.55 V and short-circuit current of 0.24 mA at a relative humidity of 90%. The flexible humidity sensor demonstrated long-term operational stability and reliability over 18 h as well as feasibility as a moisture-controlled energy-generating switch by powering light-emitting diodes. We believe that our findings will promote the use of MEGs in self-powered flexible sensor applications based on engineered nanocomposites.