Preparation of carbon-coated blue TiO2 reactive membrane electrodes for efficient electrochemical degradation of organic pollutants.

The blue TiO2 anode exhibits excellent electrocatalytic activity in degrading various organic pollutants in wastewater. However, its limited operational lifespan severely hinders its practical applications. This study designed a carbon-coated blue TiO2 nanotube array reactive electrochemical membrane (TF/BTNA-C) synergizing dual engineering strategies: (1) carbon coating via hydrothermal deposition to enhance conductivity, stabilize Ti3+ species and mitigate electrode corrosion, and (2) a flow-through membrane reactor configuration leveraging confinement effects for intensified reaction kinetics to overcome traditional flow-by mass transfer limitations. The carbon overlayer enhanced interfacial electron transfer efficiency while shielding the electrocatalytic substrate, resulting in a 2.4-fold prolonged service life compared to uncoated counterparts. Crucially, the flow-through operation's spatial confinement effect enforced forced convection through membrane pores, creating locally concentrated •OH gradients at reactive interfaces. The confinement architecture synergistically couples Ti foam's 3D macroporous channels with TiO2 nanotube arrays, extended the residence time of pollutants, achieving a 104.7% increase in tetracycline hydrochloride (TCH) degradation compared to conventional flow-by systems under an ultralow current density (2 mA cm-2). The confinement-enhanced mass transfer amplifies apparent reaction kinetics by 3.96-fold. Radical quenching experiments identified hydroxyl radicals (·OH) as the predominant reactive oxygen species (ROS), accounting for 84.26% of TCH oxidation. Accelerated lifetime testing coupled with cycle durability assessments revealed that the carbon-modified anode demonstrating robust electrochemical stability. These findings demonstrate that the TF/BTNA-C exhibits compelling potential for energy-efficient remediation of recalcitrant organic contaminants in continuous-flow wastewater treatment systems.