Remarkably enhanced catalytic performance in CoOx/Bi4Ti3O12 heterostructures for methyl orange degradation via piezocatalysis and piezo-photocatalysis

• Published in: Ultrasonics sonochemistry 2023-11, Vol.100, p.106616-106616, Article 106616
• Main Authors: Wang, Kaiqi, Guan, Ziying, Liang, Xiaoya, Song, Shuyue, Lu, Pengyu, Zhao, Chunran, Yue, Lin, Zeng, Zhihao, Wu, Ying, He, Yiming
• Format: Article
• Language: English
• Subjects: Bi4Ti3O12; CoOx; Original; Piezo-photocatalysis; piezocatalytic MO degradation
• ISSN: 1350-4177; 1873-2828
• DOI: 10.1016/j.ultsonch.2023.106616

[Display omitted] •CoOx nanoparticles were photodeposited on Bi4Ti3O12 nanosheets to form a novel piezocatalyst.•CoOx/Bi4Ti3O12 realized piezocatalytic organic degradation by harvesting ultrasonic vibration energy.•CoOx acts as hole trappers to improve the charge separation of Bi4Ti3O12.•CoOx/Bi4Ti3O12 showed superior piezo and piezo-photocatalytic performance than Bi4Ti3O12. A novel heterojunction composite of CoOx/Bi4Ti3O12 was synthesized through a combination of molten salt and photodeposition methods. The optimal sample exhibited superior performance in the piezocatalytic degradation of methyl orange (MO) dye with a degradation rate of 1.09 h−1, which was 2.4 times higher than that of pristine Bi4Ti3O12. Various characterizations were conducted to reveal the fundamental nature accountable for the outstanding piezocatalytic performance of CoOx/Bi4Ti3O12. The investigation of the band structure indicated that the CoOx/Bi4Ti3O12 composite formed a type-I p-n heterojunction structure, with CoOx acting as a hole trapper to effectively separate and transfer piezogenerated carriers. Significantly, the MO degradation rate of the best CoOx/Bi4Ti3O12 sample further increased to 2.96 h−1 under combined ultrasonic vibration and simulated sunlight. The synergy between piezocatalysis and photocatalysis can be ascribed to the following factors. The photoexcitation process ensures the sufficient generation of charge carriers in the CoOx/Bi4Ti3O12, while the piezoelectric field within Bi4Ti3O12 promotes the separation of electron-hole pairs in the bulk phase. Furthermore, the heterojunction structure between Bi4Ti3O12 and CoOx significantly facilitates the surface separation of charge carriers. This increased involvement of free electrons and holes in the reaction leads to a remarkable enhancement in catalytic MO degradation. This work contributes to the understanding of the coupling mechanism between the piezoelectric effect and photocatalysis, and also provides a promising strategy for the development of efficient catalysts for wastewater treatment.