Laser-assisted rapid synthesis of anatase/rutile TiO2 heterojunction with Function-specified micro-zones for the effective photo-oxidation of sulfamethoxazole

Abstract

A solid-state laser scanning treatment (SLST) was adopted to synthesize anatase/rutile TiO2 heterojunction with effective charge carrier separation and high surface adsorption performances for the photodegradation of sulfamethoxazole (SMX). The 1064 nm pulsed fiber laser could in-situ generate rutile zones on the pristine sheet-like anatase crystal enclosed by (001) facets, which could form the well-defined anatase/rutile interface to promote the formation of dominating active species (h+ and ∙OH) on the anatase zones. X-ray absorption fine structure (XAFS) measurements, low temperature electron paramagnetic resonance (LT-EPR) as well as the density functional theory (DFT) simulation proved that the oxygen vacancies (VO) could both introduce defective energy states to promote the light absorption and enhance the SMX adsorption on anatase zones. Based on the delicately designed micro-zones, the photodegradation efficiency of the optimized catalyst could reach 99.3 %, which demonstrated ∼7 times higher performance than that of pristine TiO2 and exhibited robust stability under environmental conditions. Gaussian and Vienna Ab Initio Package (VASP) programs were used to provide detailed degradation pathways and mechanism for SMX. This SLST could be potentially employed to create function-specified zones on various catalysts for different applicational aims.