Influence of nitrogen sources on N-doped reduced TiO2 prepared using atmospheric plasma spraying for photocatalytic tetracycline and ciprofloxacin degradation

Abstract

N-doped reduced TiO2 porous photocatalyst coatings are prepared by atmospheric plasma spraying (APS) technology combined with the geomimetic concept. Unlike traditional photocatalyst preparation methods, this method can be manufactured on a large scale and considerably shortens the preparation time by only 15 min. In this study, acetamide and urea, with one or two nitrogen atoms in the structure, were used as dopants to prepare N-doped TiO2 (T1N and T2N) for photocatalytic antibiotic degradation. Tetracycline (TC, 20 ppm/100 mL) and ciprofloxacin (CIP, 20 ppm/100 mL) were photodegraded under AM1.5G solar simulator illumination. The T1N obtained a higher lattice-nitrogen ratio than T2N, which gave T1N better photocatalytic activity. The rate constants of photodegradation of TC and CIP under simulated solar irradiation are 1.70 and 1.42 (×10−2 min−1), which are more than twice that of T2N and nearly 20 times higher than that of pristine TiO2. Moreover, after 10 rounds of recycling tests, the photocatalyst showed good performance and structural stability. The scavenger test suggested that ̇O2− is the most important reactive species in TC degradation, while ̇OH and h+ play an important role in CIP degradation. The degradation pathways of TC and CIP were proposed. This photocatalyst coating preparation method is suitable for large-scale production and is a time-saving, sustainable, diversified, and future-looking technology.