Laser-induced growth of metal oxide films on quartz tubes for photocatalytic water treatments

Abstract

A solid-state pulsed laser technique was developed to in situ grow arbitrary immobilized catalysts (Fe3O4, CeO2, WO3 etc.) on the inner surface of quartz tube with robust adhering strength. In a case study, anatase/rutile hetero-phase TiO2 film was deposited to serve as immobilized photocatalysts for the effective removal of antibiotics from aqueous environment. The X-ray absorption spectroscopy, low temperature electron paramagnetic resonance and the density functional theory simulation directly confirm a defect-assisted type-II band alignment was established to facilitate the charge transfer at the hereto-interphase. In addition, the oxygen vacancy enriched anatase phase with greater binding energy towards the dissolved oxygen facilitated the O2– generation. Meanwhile, the rutile phase enriched with Ti3+ could effectively activate the antibiotics to promote the direct h+ mediated oxidation. Such integration of unique atomic vacancies prevent defects from becoming electron-hole recombination centers and consequently extend the lifetime of the photoexcited charge carrier. The degradation mechanism of oxytetracycline was thoroughly examined by ultra-high resolution electrospray time-of-flight mass spectrometry and Fukui function, while the ecological structure–activity relationships program assessed the toxicity of contaminant to the environment. Milewhile, a continuous water treatment apparatus employing the catalytic tubes as reactors was established and demonstrated a ∼ 95 % OTC degradation under the natural sunlight adopting river water as the background. The experimental studies also claimed that ∼ 90 % of the initial activity could be retained after 100 cycles reuse, which permits their great potential for the applicational scenarios.