Surface Functional Modification for Boosting Power Density of Hydrovoltaic Devices

Abstract Generating electricity based on the interaction between water and materials is a new green energy harvesting technology. However, the performance based on streaming potential generation is not sufficient to drive microelectronic devices with high power supply demands. In this work, an asymmetric sandwich structure is designed with adjustable performance of hydrovoltaic devices as a power system for micro‐electronic devices. The flexible hydrovoltaic device structure that only consumes renewable energy is low‐cost, non‐polluting, and highly sustainable, achieving a satisfied output power density exceeding 124.5 µW·cm⁻² (2075 µW·cm⁻³). Both experimental results and theoretical calculations reveal that the working principle of the device depends on the evaporation potential rather than the streaming potential. In addition, the integration of multiple devices makes it easy to drive electronic devices for correct operation and energy storage. For the first time, this integrated hydroelectric photovoltaic device has demonstrated the ability to charge commercial button‐type lithium batteries with great success. The current work combines asymmetric structure and tunable performance, providing an alternative method for high‐efficiency hydrovoltaic devices with high power density.