Targeting stable desalination via harnessing in situ oxygen reduction reaction in capacitive deionization

Capacitive deionization (CDI) offers a cost-effective and low-energy method for water desalination. However, the applicability of capacitive deionization (CDI) is often hindered by electrode instability caused by unwanted oxygen reduction reactions (ORR). To overcome it, we propose an innovative capacitive deionization-electro-oxidation (E X -CDI) hybrid system that harnesses ORR for in situ H 2 O 2 generation and micropollutant degradation. Through systematic investigation of the rational operating parameters, this study establishes a quantitative criterion for balancing the competition between capacitive electrosorption and Faradaic degradation, demonstrating that a charge allocation C d /C c ratio of 46.33%–72.59% is critical for sustaining stable desalination. Assisted by Machine Learning (ML), we decoupled the complex influencing factors and identified radical content and H 2 O 2 generation as the dominant governors of stability. The practical efficacy was confirmed through the successful treatment of aquaculture wastewater. Our findings offer a novel pathway for stabilizing CDI via the synergy of Faradaic and non-Faradaic processes, significantly diversifying its potential in advanced water treatment.