Bioinspired gradient-structured wood interfaces achieving efficient ion diffusion to generate electricity from natural evaporation

Abstract

The silent yet ubiquitous natural evaporation of water stores immense energy, and electrical double layers from the hydrolysis of oxygen-containing functional groups are the key to power generation at the solid–liquid interface of evaporation. However, slow ion diffusion in evaporation-driven water transport limits efficient energy harvesting for electricity generation. In contrast to the typical homogeneous interfacial oxygen-containing functional groups (OCGs), we present a high-performance wood-based interfacial evaporation-driven nanogenerator (W-IENG) with significantly distributed OCG gradients, which is constructed through a rational process design using bioinspired self-assembled multilayer nanofiber membranes. Based on the abundance of reactive OCGs contained in wood derivatives, our design is simply constructed by gradient reduction in the number of hydrolysis sites of OCGs using different materials. In particular, this porous interface exhibits lower charge transfer resistance and higher ionic conductivity. As a result, the power density of our device is approximately 7.5 times higher than the average value of previously reported W-IENGs. These findings provide novel insights into the optimization of efficient evaporative power generation systems through the functional coupling of evaporation interfaces using the OCG gradient and facilitate the effective utilization of energy in the natural environment.