An estuarine-inspired dual-gradient hydrogel for stable and scalable moisture energy harvesting up to a single-module 100 mA output

A dual-layer hydrogel device with asymmetric water–salt gradients achieves 96.4 µA cm −2 current density and stable moisture energy harvesting for over 500 hours, alongside scalability to 1000 cm 2 , enabling a single-module output exceeding 100 mA.