Wood Hydrogel for Efficient Moisture-Electric Generation

Moisture-induced electricity generation is an emerging sustainable technology for alleviating the ever-growing energy crisis. Wood is a promising biobased hydrovoltaic material due to its natural porosity and hydrophilicity. In this work, we developed an efficient wood hydrogel-based moist-electric generator (WHMEG) by combining a wood porous structure and ionic hydrogels. The ionically conductive wood hydrogel was fabricated by infiltrating poly(vinyl alcohol) (PVA)/poly(acrylic acid) (PAA) hydrogels into the porous structure of delignified wood. The balsa wood exposed more hydrophilic cellulose and porous channels after delignification (DL), creating favorable conditions for the filling and cross-linking of the hydrogel networks. The filling of PAA/PVA ionic hydrogels significantly improved the ionic conductivity of wood, from 3.78 × 10–4 S/cm in raw wood to 5.39 × 10–4 S/cm in the wood hydrogel with an 8 h delignification (longitudinal direction), which created favorable conditions for ion diffusion and migration. When exposed to atmospheric moisture, driven by the synergistic effect of asymmetric moisture adsorption and ion migration, a single WHMEG device (DL for 8 h) with dimensions of 1 cm × 1 cm could generate an open-circuit voltage of ∼525 mV and a short-circuit current of ∼1.85 μA in the ambient environment (∼25 °C and 65 ± 5% relative humidity). Our findings contribute to the development of energy-harvesting systems from sustainable wood materials.