Dual-interfacial gating unlocks bidirectional ionic flux for high-efficiency hydrovoltaic energy harvesting

Abstract

Hydrovoltaic devices, capable of harvesting energy from water of moisture, hold great potential for decentralized and sustainable electricity generation. However, their current density remains limited by unidirectional, single-ion transport, leaving nearly half of available charge carriers unused. Here, we propose a dual-interfacial gating (DIG) strategy that spatially separates cation and anion pathways, enabling simultaneous and bidirectional ion migration to fully exploit the ionic flux. This configuration significantly enhances current density, achieving a record value of 1.48 mA cm⁻³—one order of magnitude higher than those of typical hydrovoltaic systems (0.01–0.1 mA cm⁻³) and surpassing previously reported state-of-the-art results. Mechanistic insights from finite-element analysis and charge-injection experiments reveal that spatially segregated ion pathways effectively enhance ionic transport through simultaneous counter-directional ion migration. The scalable DIG architecture allows practical large-area integration; a 468 cm² module generates 353 mA of short-circuit current, powering miniature fans continuously for over 3 hours and driving wearable sweat-based biosensors. These advances address the long-standing bottleneck of single-ion transport and establish a practical pathway toward high-performance, scalable moisture-driven power sources for sustainable energy, IoT and healthcare applications.