Pyroelectric Catalysis And Piezoelectric Catalysis Of Ferroelectric Barium Titanate Nanomaterials

The printing and dyeing wastewater is usually rich in color,high in chroma,and contains a variety of dyes and chemical residues,which makes the treatment of the dye wastewater become an internationally recognized problem.Nowadays,the widely investigated photocatalysis is considered as one green and promising treatment method of dye wastewater.However,there are some drawbacks such as low utilization of solar energy and low light-permeation in deep colored dye,which limits the practical application of photocatalysis.It is therefore necessary to develop novel catalytic method to decompose the dye wastewater.In this work,we have synthesized barium titanate?Ba Ti O₃?nanomaterials through using a hydrothermal method.We propose pyroelectric catalysis and piezoelectric catalysis for dye decomposition on basis of the pyroelectric effect and piezoelectric effect of Ba Ti O₃,which can use the energy of cold-hot temperature variation and vibration,respectively.Furthermore,we have improved the catalytic activity in three ways:1)modification of Ba Ti O₃ through noble metals;2)adding a small amount of carbon to promote carrier migration;3)trying to harvest multiple energies at the same time.The main research contents are as follows:1.Pyroelectric catalysis of Ba Ti O₃ nanofibers loaded with noble metalsThe pyroelectric catalysis performance for Rh B dye decomposition is studied through the hydrothermally-synthesized Ba Ti O₃ nanofibers loaded with noble metal Ag or Pd?Ba Ti O₃@Ag,Ba Ti O₃@Pd?.After 72 cold-hot?30-52°C?cycles,Ba Ti O₃,Ba Ti O₃@Ag?2.0wt%?and Ba Ti O₃@Pd?2.0wt%?decompose 48%,92%,and 95%of Rh B dyes,respectively.The study shows that the noble metal loading can significantly improve the pyroelectric catalysis performance of Ba Ti O₃.The possible physical mechanism of this enhancement may be due to that the noble metal loading can help trap and transfer the pyroelectrically-induced negative charges on the Ba Ti O₃nanofibers surface,thus promoting the charge separation.2.Piezoelectric catalysis of Ba Ti O₃ nanofibers mixed with carbonThe piezoelectric catalysis performance for Rh B dye decomposition is studied through the hydrothermally-synthesized Ba Ti O₃ nanofibers mixed with carbon?Ba Ti O₃/C?.After 40 min of vibration,the Rh B decomposition ratio of Ba Ti O₃ and Ba Ti O₃+2 wt%C are respectively 48.4%and 75.5%,while their rate constants are respectively 0.01942 min^-1 and 0.04901 min^-1.The study shows that the mixing carbon can significantly improve the piezoelectric catalysis performance.The possible physical mechanism is that the role of carbon is to help capture and transfer the negative charges generated by Ba Ti O₃ nanofibers and then promotes charge separation.3.Photo-Piezoelectric synergetic catalysis of Ba Ti O₃ nanofibersBesides the pyroelectric catalysis and piezoelectric catalysis,Ba Ti O₃ can also exhibit excellent photocatalysis performance.The Photo-Piezoelectric synergetic catalysis performance for Rh B dye decomposition is studied through the hydrothermally-synthesized Ba Ti O₃ nanofibers.With the simultaneous exertion of light and vibration,the rate constant of Photo-Piezoelectric synergetic catalysis is as high as0.10307 min^-1,which is larger than that of the photocatalysis of 0.00641 min^-1 or that of the piezoelectric catalysis of 0.01859 min^-1.The enhanced catalytic activity is correlated with the piezoelectric potential formed in the Ba Ti O₃ under external vibration,which is helpful to effectively facilitate the separation of photogenerated electrons and holes.Furthermore,Ba Ti O₃ exhibits good recyclable performance.