Confinement-Induced Donnan Potential Enables Sealed Hydrovoltaic Power From Microliter Water

Area of Science:

• Materials Science
• Energy Harvesting
• Nanotechnology

Background:

• Existing hydrovoltaic systems often depend on evaporation or humidity, limiting their application in sealed devices.
• Compact and encapsulated sustainable energy solutions are needed for portable electronics.

Purpose of the Study:

• To develop a sealed hydrovoltaic power generation system.
• To enable energy harvesting from minimal water input using a novel mechanism.

Main Methods:

• Engineered asymmetric nanochannel confinement using MXene/cellulose nanofiber (CNF) composites.
• Utilized confinement-induced ion selectivity and Donnan potential for capacitive charge accumulation.
• Leveraged slow capillary migration to sustain ion gradients and DC output.

Main Results:

• Achieved stable direct current (DC) output for up to 45 hours from a 3 µL water droplet.
• Demonstrated robust operation under varying airflow and humidity conditions (17%-90%).
• Showcased functionality with diverse electrolytes including tap water, seawater, and sweat.

Conclusions:

• The confinement-governed hydrovoltaic framework enables sealed energy generation independent of evaporation or ambient humidity.
• This technology offers a scalable platform for powering wearable and distributed electronics.
• The study expands the understanding of water-enabled energy generation mechanisms.