Sustainable and Clean Energy Harvesting Device Using Reversible Redox Reactions Driven Alternately by Light and...

In nature, moisture and solar irradiation serve as abundant clean energy sources for advancing next-generation power generators. However, the irregular spatial-temporal distribution and alternating occurrence patterns of the dual stimuli in real-world conditions present substantial challenges to the research and development of relevant technologies. Moreover, the existing moisture-driven power generators still suffer from the problem of short power generation duration. Herein, a sustainable energy generator alternately powered by moisture and light (MLG) is demonstrated, enabled by an asymmetric design of [Fe(CN)₆]^{3 -}/[Fe(CN)₆]^{4 -} redox couple introduced into the hygroscopic hydrogel. The alternating states include two types: moisture-only effects and combined light-moisture effects with photothermal energy being dominant. The alternating moisture and light stimuli drive forward and reverse redox reactions respectively, generating a continuously alternating current output. Under pure moisture activation at 98% RH, the device exhibits peak outputs of 3.2 mA current and 0.23 V voltage. Notably, when the moisture-induced current decays to less than 100 nA after prolonged operation, a 20-min illumination at 1.5 sun intensity effectively restores the moisture-triggered current to 166 µA. The system demonstrates exceptional cycling stability under repeated light-moisture alternations, highlighting its considerable potential for sustainable energy harvesting through complementary environmental energy utilization.