Photocatalytic activity and mechanism of nano-cubic barium titanate prepared by a hydrothermal method

This paper presents a study on the efficiency and mechanisms underlying the photo-catalytic degradation of crystal violet (CV) using nano-cubic barium titanate (BaTiO3). This study used P25-TiO2 as a starting material for the synthesis of BaTiO3, due to of its low cost, stability, and nontoxicity, compared with titanium alkoxide. The BaTiO3 was first synthesized using the autoclave hydrothermal method under alkaline condition with P25-TiO2 and Ba(OH)2·8H2O as starting materials, using various NaOH concentrations, reaction durations, and reaction temperatures. The characterization of the resulting BaTiO3 was confirmed by SEM-EDS, powder XRD, HR-XPS, FT-IR, DR-UV, and BET. The band gap of nanocubic BaTiO3 is estimated to be 2.93–3.05 eV and the lower band gap has a positive effect on photocatalytic activity. The photo-degradation efficiency of CV dye by BaTiO3 was measured under UV light irradiation with various pH reaction media in dark room conditions for comparison. Degradation intermediates were separated using HPLC-PDA-ESI/MS to identify the possible mechanism involved in photo-degradation according to variations in the concentration ratio of intermediates during the course of the reaction.