La2Ti2O7 nanosheets synthesized under magnetic field for ofloxacin ferrophotocatalytic degradation

Abstract

Ferrophotocatalytic degradation is considered as a promising strategy for environmental remediation. In this work, layered perovskite La2Ti2O7 was synthesized by a hydrothermal method. The La2Ti2O7 powders obtained under magnetic fields exhibit rectangular nanosheets with about ten nanometers in thickness, 400 nanometers in width and several micrometers in length. The La2Ti2O7 nanosheets expose dominant {0 0 1} facets and other secondary {0 1 0} and {1 0 0} facets. The well-dispersed nanosheets enjoy narrower band gaps, better ferroelectricity and better photocatalytic ability toward ofloxacin pollutant in comparison with the powders prepared without a magnetic field. The La2Ti2O7 nanosheets require 20 min to photodegrade 90% of ofloxacin. Their photodegradation effect is enhanced after polarization, and further improved under an ultrasonic vibration within only 10 min to degrade above 90% ofloxacin pollutant, which is superior to the recent reports. The photogenerated electrons play a main role through •O2− and •OH radicals. The strong built-in electric field and fewer domain boundaries in the ferroelectric nanocrystallites after polarization effectively separate the photogenerated electron-hole pairs and promote their migration to surface for photodegradation reaction. This work is helpful to develop high-performance ferrocatalysts and promote the ferroelectric application in water remediation.