Improved piezo-photocatalysis for aquatic multi-pollutant removal via BiOBr/BaTiO3 heterojunction construction

Piezo-catalysis is a green and effective method for degrading rich and obstinate molecules in wastewater. Yet, the piezo-catalytic performance of frequently-used barium titanate (BTO) is still limited for practical applications, thus it is crucial to construct high-efficiency BTO-based catalysts. Herein, BiOBr/BTO heterojunction-based piezo-photocatalysts were successfully prepared using the chemical precipitation method, and an internal electric field was established via ultrasound to promote the separation of photogenerated electron-hole pairs through the synergistic effect of piezocatalysis and photocatalysis. Transmission electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy were utilized to characterize the heterojunction. The degradation performance of Rhodamine B (RhB) by BiOBr/BTO is the best among various pollutants, giving a reaction rate constant up to 20.839 × 10−2 min−1, exceeding numerous previously reported catalysts. In addition, the piezo-photocatalytic reaction rate of BiOBr/BTO for Methyl Orange was 9.298 × 10−2 min−1, ≈ 3.3 times than those of pure BTO (2.806 × 10−2 min−1), and also ≈ 15.9 times and 3.3 times than those of single photocatalysis (0.585 × 10−2 min−1) or piezocatalysis (2.848 × 10−2 min−1). Importantly, the BiOBr/BTO heterojunction demonstrates excellent catalytic degradation performance for a broad range of pollutants (e.g., dyes and antibiotics) and their mixtures, as well as favorable cycling stability and repeatability with changed environmental conditions, displaying applicability in actual wastewater treatment. The possible degradation pathways of RhB were analyzed by liquid chromatography-mass spectrometry. The present work supplies a feasible strategy for the preparation of high-efficiency piezo-photocatalytic BTO-based heterojunctions, which can guide other composites for environmental remediation.