Dual-engineered cobalt doping in Ni-Sb-SnO2/enhanced TiO2 nanotube arrays (ETNA) anode: Electron shuttling-driven hydroxyl radical generation and long-term stability for low-concentration organic wastewater treatment

Electrochemical oxidation (EO) has emerged as a promising technology for eliminating recalcitrant organic pollutants from wastewater, yet its industrial implementation is constrained by the intrinsic limitations of conventional anodes, including sluggish charge transfer kinetics, rapid passivation, and excessive energy consumption. The simultaneous resolution of these drawbacks at low cost remains challenging. Herein, we engineered high-efficiency and stable CoNi-Sb-SnO 2 /enhanced TiO 2 nanotube arrays (ETNA) anode through a novel dual-strategy cobalt doping. Cobalt-triggered electron shuttling and ETNA interlayer optimization synergistically enhances the electrode’s electrocatalytic activity, conductivity, and stability. Experimental results reveal that Co dopants create electron-deficient centers to enrich charge density on adjacent Sn/Sb sites, synergizing with Ni-mediated O 3 production to enable ultrafast hydroxyl radical (·OH) yield (93.9 % tetracycline removal in 30 min) across a broad pH range. Crucially, the cobalt-bridged ETNA interlayer, with enriched oxygen vacancy and reconstructed anode surface, significantly reduces charge transfer resistance by 62.2 % and suppresses substrate corrosion, extending the anode lifespan to 15.7-fold while saving 54.8 % energy consumption. Density functional theory (DFT) calculations further corroborate that Co doping declines the d-band center, weakening oxygen intermediate adsorption and facilitating ·OH desorption. This work establishes a paradigm for achieving comprehensive electrode performance enhancement through targeted electronic structure engineering, enabling the development of cost-effective and durable anodes with direct applicability to low-concentration organic wastewater treatment.