Active Magnetic Field Modulation in Metal−Organic Frameworks for Enhanced Hydrovoltaic Power Generation

While hydrovoltaic power generation is attracting increasing attention as a sustainable strategy for harvesting continuous clean energy, device performance is often limited by a directional mismatch between evaporation-driven proton transport and current collection at the electrodes. Herein, a nanoporous and magnetically responsive NM88B−NiCo 3 composite is constructed to enable active magnetic field modulation for enhanced proton transport in hydrovoltaic systems. The incorporation of ferromagnetic NiCo 3 nanosheets followed by directional magnetization establishes an internal magnetic field within the composite, which induces a directional bias during evaporation-driven proton transport toward more favorable pathways for charge collection at the electrodes. This enhances the hydrovoltaic output, increasing the output voltage by approximately 720% and improving the output current by more than one order of magnitude compared to the pristine NM88B-based device. Under optimal magnetization conditions, the NM88B−NiCo 3 device delivers a stable direct-current (DC) output with a maximum power density of 0.16 μW·cm −2 . Notably, the magnetic field-responsive output behavior of the NM88B−NiCo 3 device enables reversible and directional modulation of hydrovoltaic performance via external magnetic stimuli. This study demonstrates the distinctive advantages of utilizing a magnetic field as an additional physical dimension to regulate proton transport for the first time, providing a strategy for designing magnetically responsive hydrovoltaic devices and self-powered micro-energy systems.