Monolithic ion-electron coupling interfaces enable low-impedance moisture-electric generators.

Abstract

Moisture-electric generators (MEGs) offer a promising route for harvesting ubiquitous atmospheric energy, yet their performance is fundamentally constrained by inefficient ion-electron coupling at the electrode-electrolyte interface. Existing strategies primarily focus on optimizing hygroscopic materials or ionic transport, while overlooking the critical role of interfacial impedance arising from structurally discontinuous contacts. Here we show a monolithic silicon nanowires (SiNWs)/ionic hydrogel architecture that establishes continuous ion-electron coupling pathways through conformal integration of the electrode and active layer. The monolithic interface reduces the charge transfer resistance by over one order of magnitude compared to conventional stacked configurations. The resulting device delivers an open-circuit voltage of 1.35 V and a short-circuit current density of 27.5 µA cm-2 at 25  °C and 60% relative humidity, outperforming benchmark devices by ∼60%. Impedance spectroscopy combined with distribution of relaxation time analysis reveals suppressed interfacial polarization and accelerated ion-electron conversion kinetics. This work establishes a general interface engineering strategy for low-impedance hydrovoltaic systems and highlights the central role of ion-electron coupling in moisture-enabled energy conversion.