Experimental research on optimized synthesis of Bi2Fe4O9 nanoplates and its piezo-catalytic performance
[Objective]Piezocatalysis is a catalytic effect driven by the stress-induced electricity of piezoelectric crystallites.Utilizing the piezoelectric effect,piezoelectric catalysis technology can induce the generation of piezoelectric potential in piezoelectric materials through mechanical energy to drive redox reactions,offering promising applications in alleviating energy crises and managing environmental pollution.Despite significant progress in piezoelectric catalysis with piezoelectric materials,suboptimal piezoelectric catalytic performance remains an issue owing to factors such as low separation efficiency of charge carriers and the limited active sites available for surface reactions.To further enhance the piezoelectric catalytic performance,this study employs an optimized approach to fabricate Bi2Fe4O9nanosheets.The catalytic degradation performance of these nanosheets was investigated using rhodamine B simulated wastewater in an ultrasound-induced Bi2Fe4O9 nanosheet piezoelectric catalysis system.[Methods]Bi2Fe4O9 nanosheets were synthesized using a hydrothermal method optimized with bismuth nitrate pentahydrate(Bi(NO3)3.5H2O)and iron nitrate pentahydrate(Fe(NO3)3·9H2O)as raw materials.X-ray diffraction(XRD)analysis using Cu Kα radiation(λ=1.5406 A)was used to characterize the crystal structure of the Bi2Fe4O9 sample.The morphology and composition were characterized using field emission transmission electron microscopy.The elemental composition and chemical states of the catalysts were analyzed using X-ray photoelectron spectroscopy with data obtained processed through XPSPEAK software.The piezoelectric properties of the Bi2Fe4O9 nanosheets were evaluated through force-phase microscopy and transient current measurements conducted at an electrochemical workstation.The piezocatalytic performance of Bi2Fe4O9 nanosheets was evaluated by ultrasonic activation of Bi2Fe4O9 nanosheets to catalyze persulfate(US/Bi2Fe4O9/S2O82-)for rhodamine B(RhB)degradation.Additionally,control experiments(US/S2O82-and Bi2Fe4O9/S2O8-)were also conducted under the same reaction conditions.[Results]SEM results indicated that the Bi2Fe4O9 samples prepared by the optimized hydrothermal method had a smooth surface,single dispersion,and an average size of 910 x 82 nm in thin flake-like structures.The high peak height of the(001)crystal plane diffraction suggested that the optimized hydrothermal method promotes exposure of the(001)crystal plane,facilitating electron and hole transfer to the crystal surface and preventing their recombination.Elemental mapping confirmed the uniform distribution of Bi,Fe,and O within the Bi2Fe4O9 nanosheets.Transient current measurements showed a significant increase when the ultrasonic device was activated,which instantaneously decreased once the ultrasonic device was turned off.The ultrasound-cavitation-induced Bi2Fe4O9 nanosheets piezoelectric catalysis S2O8-system(US/Bi2Fe4O9/S2O82-)achieved a RhB removal rate of 97.8％,while the ultrasound-activated S2O82-system(US/S2O82-)and the Bi2Fe4O9-activated S2O8-system(Bi2Fe4O9/S2O82-)achieved an RhB removal rate of 32.5％and 72.3％,respectively.This demonstrates a significant synergistic promotion effect of the multi-field coupling system combining ultrasound activation piezoelectric and piezoelectric catalysis.[Conclusions]Bi2Fe4O9 nanosheets prepared using the optimized hydrothermal method exhibited enhanced piezoelectric properties.The optimized hydrothermal method fabricates Bi2Fe4O9 nanosheets of high purity,uniform size,and good dispersibility.Besides,elements of Bi,Fe and O are uniformly distributed across the Bi2Fe4O9 nanosheets.Piezoelectric property analysis shows that Bi2Fe4O9 nanosheets demonstrate significant piezoelectric properties,while the piezoelectric potential induced by ultrasonic cavitation triggers redox reactions.Compared with US/S2O82-orBi2Fe4O9/S2O8-,the multi-field coupling system of ultrasonic activation piezoelectricity and piezoelectric catalysis(US/Bi2Fe4O9/S2O82-)has a significant synergistic enhancement effect.The findings provide new insights into the development of piezocatalysts and the mechanism of piezocatalytic degradation.
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