Sequential H 2 O 2 Production and Activation via Dual-Cathode Flow-Through Electrocatalysis for Efficient and Sustainable Water Treatment

Conventional electrochemical water treatment typically focuses on anodic oxidation or cathodic reduction. In contrast, highly efficient anode–cathode synergy can achieve effects beyond the capability of either single electrode, enabling low-carbon and sustainable pollutant removal. Herein, we developed a reagent- and aeration-free system for continuous ·OH generation by integrating anodic O 2 evolution with cathodic H 2 O 2 production and activation cascades in a dual-cathode stacked flow-through electrochemical reactor. Low-cost graphite felt (GF) and stainless-steel mesh (SSM) cathodes selectively facilitated O 2 /H 2 O 2 and H 2 O 2 /·OH conversions. The stacked flow-through design established a self-sustaining ·OH production pathway, driving O 2 transport from the anode to the GF cathode for H 2 O 2 generation, followed by directional H 2 O 2 delivery to the SSM cathode for ·OH formation. Compared to a single-cathode system, the dual-cathode design maintained high Cr(VI) reduction (>95%) while enhancing Ni-EDTA decomplexation and total organic carbon (TOC) removal by up to 41% and 70%, respectively. Under optimized conditions (2.5 V, 2.5 mL/min), the dimensionally stable anode (DSA)/GF-SSM stacked flow-through system achieved 100% Cr(VI) detoxification, 99.9% Ni-EDTA decomplexation, and 50.8% TOC mineralization. Moreover, it demonstrated exceptional longevity and industrial scalability through continuous operation for 50 days. This study presents a feasible energy-efficient ·OH generation strategy, offering a practical, sustainable, and environmentally friendly solution for treating complex wastewater.