Ti³⁺ self-doped and nitrogen-annealed TiO₂ nanocone arrays photoanode for efficient visible-LED-light-driven photoelectrocatalytic degradation of sulfamethazine

Developing efficient, durable and visible-light-driven photoanode with excellent environmental adaptability is of great significance for photoelectrocatalytic (PEC) degradation of organic pollutants. In this work, a novel Ti³⁺ self-doped and nitrogen-annealed TiO₂ nanocone arrays (Ti³⁺-TiO₂NCs(N₂)) photoanode was prepared for efficiently photoelectrocatalytic degradation of sulfamethazine (SMT) under visible light emitting diode (LED) irradiation, which obtained 98.68% removal for initial SMT concentration of 10 mg/L within 60 min. The visible light harvesting and charge transfer of TiO₂NCs were significantly improved after nitrogen annealing treatment. Additionally, the introduction of moderate Ti³⁺ sites further lowered charge transport resistance and introduced a new impurity energy level, which efficiently accelerated the transmission of photogenerated carriers and then generated more h⁺ and active species to degrade pollutants. After 15 recycling degradation experiments, Ti³⁺-TiO₂NCs(N₂) still obtained more than 97% SMT removal, demonstrating highly durable. Also, it exhibited promising application prospect for treatment of real wastewaters (secondary effluent, pharmaceutical wastewater and mariculture wastewater).