A technique to enhance the piezo-photocatalytic performance of nanosheets is reported in a study published in the journal Nano Energy.
Study: Excellent piezo-photocatalytic performance of Bi4Ti3O12 nanoplates synthesized by molten-salt method. Image Credit: Sooa/Shutterstock.com
Advances in Photocatalytic Technologies
Bi4Ti3O12 (BiTO) is an Aurivillius-type stacked perovskite oxide with ferroelectric characteristics that has piqued the interest among researchers owing to its use in the degradation of organic compounds, carbon emission control, and NOx elimination. Specific techniques, such as doping, noble metal alteration, semiconductor nanostructure building and oxygen vacancy injection, can be utilized to improve the photocatalytic efficiency of BiTO to a reasonable value. However, any further improvement in efficiency is still a challenge. Furthermore, the preparation processes for BiTO nanoparticles are often complicated. It is hoped that an easy and successful technique may be applied to improve the PC efficiency of BiTO.
Recently, the piezo-phototronic phenomenon was applied to improve the photocatalytic efficiency of piezoelectric elements. The piezoelectric potential generated by physical loading may efficiently segregate the free carriers inside the piezoelectric element, considerably improving catalytic efficacy.
Limitations of Previous Studies
Some traditional ferroelectric perovskite minerals, including BiFeO3, BaTiO3, and PbZrxTi1-xO3, as well as non-ferroelectric elements, including ZnO and MoS2, have already been intensively researched for piezo-photocatalysis. Unfortunately, research into the piezo-photocatalysis of BiTO is still in its early stages.
Despite significant advances in prior studies on BiTO, the piezo-photocatalytic efficiency of BiTO is insufficient. It can be demonstrated that the PC efficiency of BiTO nanoparticles generated using various synthesis techniques varies greatly. Even though hydrothermal BiTO has a high specific surface area, the lesser synthesis temperature, which is lower than 200°C most of the time, may result in inadequate crystallinity of BiTO, which compromises the piezoelectric effect.
The solid-state reaction method enables the elevated synthesis of BiTO. However, the bigger grain size and lower surface area restrict catalytic effectiveness. The nano-threads produced by electro-spinning have a non-compact architecture that can be seriously harmed by extended vibrations. The MS approach produces a saline solution, which partially dissolves the reactants and so facilitates efficient ion transportation and chemical interactions between the reactants. It offers many benefits, including dependability, scalability, universal applicability, and easy aggregation of nanostructures with clean surfaces, among others.
Important Findings of the Study
In this study, the team reported that the single-step MS approach can be used to create well-defined, monodisperse, and substantially crystalline Bi4Ti3O12 nanostructures. The experiments performed by the team showed MS-BiTO nanostructures had higher piezo-photocatalytic performance than Bi4Ti3O12 nanostructures produced by solid-state reaction technique and hydrothermal process owing to a favorable combination of geometry, crystalline nature, specific surface area and size.
The study showed that MS-BiTO nanostructures photo-catalytically degrade RhB at a rate that is 3.4 times faster than SSR-BiTO and two times faster than HY-BTiO. The piezo-photocatalytic performance achieves k values which are 5.6 times the piezo-catalytic k value and 2.1 times the PC k value, when light and ultrasound are coactivated.
The team argued that the significantly increased piezo-photocatalytic performance is due to the efficient segregation of carriers induced by the breakdown of the screening effect on ferroelectric polarization charges. Additionally, it was deduced that the MS-BiTO nanostructures had a relatively high piezo-photocatalytic performance rate of degradation for MO and TC. The team finally concluded that the MS-BiTO nanostructures manufactured using the MS approach have a great potential for piezo-photocatalysis
A Way Forward
For the very first time, the piezo-photocatalytic performance efficiency of MS-produced BiTO nanostructures was thoroughly examined. The efficient segregation of carriers generated by the lamellar architecture and significant ferroelectric polarization results in an elevated photocatalytic reaction rate for the deterioration of rhodamine B (RhB) under light irradiation. Additionally, the PPT phenomenon was used to considerably boost the PC performance of BiTO nanoparticles.
The depletion efficacy of RhB solution reaches 95 percent in less than half an hour when sunlight and ultrasound are co-excited, resulting in a high response rate. The rate is much higher than the rate of piezo-photocatalysis of BiTO nanoparticles generated using solid-state reaction or hydrothermal technique. The research is projected to initialize the development of a novel technique for synthesizing additional effective piezo-photocatalysts..
Xie, Z., Tang, X., Shi, J., Wang, Y., Yuan, G., & Liu, J. (2022). Excellent piezo-photocatalytic performance of Bi4Ti3O12 nanoplates synthesized by molten-salt method. Nano Energy. Available at: https://doi.org/10.1016/j.nanoen.2022.107247