Oxygen plasma treatment of carbon black-coated fabric for enhanced evaporation-driven electrokinetic power generation

Background: Evaporation-based energy harvesting offers a low-cost and sustainable method for generating electricity from natural water sources. However, existing systems often rely on complex nanomaterials and face scalability challenges. Particularly, evaporation-driven electrokinetic power generators require surface engineering to improve ion transport. This study presents a simple and scalable strategy to boost performance by introducing oxygen-containing surface functional groups onto carbon black-coated non-woven fabric (CB/NWF) strips through oxygen plasma treatment. Methods: CB/NWF strips were treated with low-pressure oxygen plasma at 200 W for 3 min under a pressure of 0.3 mbar. This process enriched the carbon black surface with hydroxyl and carboxyl groups, strengthened the interfacial electrical double layer (EDL) within the CB/NWF capillaries, thereby facilitating ion transport and enhancing power generation performance. Significant Findings: A single oxygen plasma-treated CB/NWF strip exhibited over 300 % and 250 % increases in short-circuit current and open-circuit voltage, respectively, achieving a maximum current of 11.8 µA and a voltage of 230 mV in seawater. A generator composed of 16 CB/NWF strips produced an output current of 11 µA and an output voltage of 1.6 V. These findings demonstrate the potential of oxygen plasma-treated CB/NWF for realizing scalable and sustainable energy-harvesting devices from natural water sources.