Gradient Oxidation Enhanced Wood Harvester for Hydrovoltaic Energy

Natural woods, as the promising candidate for energy harvester are plagued by inefficient water molecule transportation and low electron density because of weakened solid–liquid interface interaction. Here, a hydrovoltaic wood device is created with a hierarchical structure and gradient distribution of interfacial C/O ratio after mild and environmentally benign oxygen plasma modification. Attributed to the synergistic enhancement of solid–liquid interfacial polarization and water molecular transportation, the oxygen plasma modified wood device demonstrates superior hydrovoltaic performance, with multi-fold enhancements in voltage (0.25 V), current (2.25 µA), and power density (0.14 µW cm⁻²). Distinct from previous studies that relied on compositing or external electrolytes, the approach achieves these improvements solely through intrinsic structural and interfacial regulation of wood via oxygen plasma etching, establishing a dual innovation of enhanced interfacial polarization and hierarchical pore engineering. Multiscale numerical simulations cooperatively reveal that gradient oxygen plasma treatment offers a stronger drag force to promote rapid water molecular migration and ion transportation, resulting in a 71% increase in charge transfer and nearly doubled hydrogen bonding between water molecules and cellulose. This study paves a promising pathway to optimize interfacial transport mechanism of wood device for further development of highly efficient energy harvesting devices from natural resources.