Solar Evaporation-Based Energy Harvesting Using a Leaf-Inspired Energy-Harvesting Foam

Sustainable and green energy techniques are in high demand as new energy sources. Over the decades, streaming potential/current has attracted attention as a hydrovoltaic energy technology. However, state-of-the-art technologies have bottlenecks in their practical application. Here, we propose a conductive polymer foam, called leaf-inspired energy-harvesting foam (LIEHF), containing polydimethylsiloxane with macro- and microporous structures homogeneously mixed with conductive carbon materials. The elastic and broadband light-absorbing LIEHF can enhance solar evaporation and generate electricity on the basis of the streaming potential/current used for efficient solar energy conversion with mechanical stability. As a result, a single LIEHF with a size of 15 × 15 × 10 mm³ can generate electrical outputs with an open-circuit voltage, a short-circuit current, and a power density of 254 mV, 42 μA, and 1 μW cm^–2, respectively, in a sustainable manner under ambient conditions with 1 sun irradiation. The proposed LIEHF outperforms previous carbon-based devices utilizing evaporation-driven streaming potential/current. By connecting to electronic components and microfluidic devices, the proposed LIEHF can be utilized for practical applications, such as in lighting, sensing, and pumping, and as a capacitor charger.