Self-powered flexible Janus-like metal-organic framework membrane for sustainable moisture-enabled electrokinetic...

Amid growing demand for clean, affordable, and sustainable energy, leveraging naturally available resources such as atmospheric moisture has become increasingly attractive. In this work, we introduce MOFs@FP-CB, a flexible Janus-like asymmetric membrane developed through a straightforward dip-coating process and engineered for efficient electrokinetic energy harvesting from controlled humidity. A carbon-black-modified filter paper substrate is coated with two functional layers of the membrane, comprising a hydrophilic, hygroscopic, negatively charged SO₄-MOF-808 layer on one side and a hydrophobic, positively charged ZIF-8 layer on the other side, arranged laterally. By creating a steady lateral moisture gradient, this asymmetric arrangement facilitates directed and selective ion transport via nanoconfined MOF channels. The device produces a voltage of 0.20 V and a current of 20.6 μA at controlled conditions (25 °C and 65% relative humidity (RH)). Electrical output can be easily scaled owing to its modular design, reaching up to 129.7 μA and 1.49 V through basic parallel and series connections, respectively, and we further showed that the system is capable of powering a red LED when 20 membranes are connected in series. The membrane provides exceptional mechanical flexibility and operational durability while maintaining its performance under a wide range of environmental conditions, regardless of temperature and RH. These characteristics position MOFs@FP-CB as a viable and affordable platform for next-generation wearable, self-powered moisture energy harvesting systems.