(145d) Bio-Inspired Energy Harvesting Via Hydrovoltaics: Transpiration through Cellulose-Carbon Micro/Nanochannel Composites

In nature, plants absorb and transport water and vital nutrients, including ions, from the ground through their vascular systems. Evaporation through stomata induces imbalances in vapor pressure and water content, resulting in a spontaneous and continuous water flow. Inspired by this ubiquitous mass transport process, hydrophilic micro/nanochannel structures have been developed to effectively channel water, particularly in applications related to sustainable energy harvesting.

Hydrovoltaics, which generates electrical power by channeling an ionic solution through hydrophilic micro/nanoporous platforms, has recently gained attention as a promising energy harvesting technology. The pressure-driven flow of an ionic solution through a charged capillary channel induces an electrical potential between the inlet and outlet—known as the streaming potential. Evaporation sustains the solution flow, enabling consistent electricity generation.

In this study, we mimic the principles of plant transpiration using a hydrophilic micro-nanochannel composite fabricated from cellulose membranes and carbon black nanoparticles which are both derivable from plant cell walls. By leveraging bio-inspired materials and transpiration, combined with electrokinetic mass transport phenomena, we successfully generated 0.4 V and 1 µA of electricity by channeling a 1 M NaCl aqueous solution. We also investigated the physicochemical properties of the cellulose-based channels, such as surface charge density and hydrophilicity. Furthermore, environmental factors including relative humidity and temperature that affect evaporation and solution flow rate through the channel were examined. This work demonstrates a pathway for adapting natural phenomena and materials for energy harvesting, contributing to sustainable solutions for the global energy crisis.