Amorphous titanium dioxide with synergistic effect of nitrogen doping and oxygen vacancies by photoexcited sol-gel preparation for enhanced photodegradation of tetracycline

Abstract

In this paper, a novel N-doped amorphous titanium dioxide (N₂₀AT-hν) photocatalyst was prepared by the sol–gel route in which the sol added with salicylaldehyde hydrazone undergoes gel after photoexcitation. Based on a systematic exploration of as-prepared catalysts, it is known that N₂₀AT-hν sample has a particle size of 50–60 nm, a specific surface area of 294.699 m² g⁻¹, and which is doped with nitrogen elements and forms abundant oxygen vacancies (OVs). The photocatalytic degradation rate of N₂₀AT-hν for 20 mg L⁻¹ tetracycline solution reached 92.23 % after 60 min, and the rate exhibited a slight decrease of 8.68 % after five cycles. Reactive species trapping experiments and electron spin resonance techniques indicate that superoxide radicals and holes are instrumental in photocatalytic degradation. Possible mechanism of forming the active species through OVs mediated traps and electron transfer pathways has been proposed. Furthermore, the predictive evaluations suggest that the degradation of tetracycline solutions by N₂₀AT-hν sample results in less harmful decomposition product. Benefiting from the environmental friendliness of preparation method and the superiority of elemental doping, N₂₀AT-hν material with synergistic effects has great potential for environmental applications.