Progress in the research on organic piezoelectric catalysts for dye decomposition

Organic contaminants have posed a direct and substantial risk to human wellness and the environment.In recent years,piezo-electric catalysis has evolved as a novel and effective method for decomposing these contaminants.Although piezoelectric materials offer a wide range of options,most related studies thus far have focused on inorganic materials and have paid little attention to organic materi-als.Organic materials have advantages,such as being lightweight,inexpensive,and easy to process,over inorganic materials.Therefore,this paper provides a comprehensive review of the progress made in the research on piezoelectric catalysis using organic materials,high-lighting their catalytic efficiency in addressing various pollutants.In addition,the applications of organic materials in piezoelectric cata-lysis for water decomposition to produce hydrogen,disinfect bacteria,treat tumors,and reduce carbon dioxide are presented.Finally,fu-ture developmental trends regarding the piezoelectric catalytic potential of organic materials are explored.

Ferroelectric BaTiO_(3) /Pr_(2)O_(3) heterojunction harvesting roomtemperature cold–hot alternation energy for efficiently pyrocatalytic dye decomposition

The strong pyrocatalytic dye decomposition of the BaTiO_(3)/Pr_(2)O_(3) heterojunction catalyst under cold–hot alternation conditions has been demonstrated in this work.For pure BaTiO_(3) nanofibers,~54%rhodamine B(RhB)dye is decomposed under the cold–hot alternation of 29–57℃.With the loading content of Pr_(2)O_(3) increases from 0 to 4 wt%,the pyrocatalytic decomposition ratio of RhB solution increases first and then decreases,eventually achieving a maximum of 91%at 3 wt%.The enhanced pyrocatalytic performance after loading Pr_(2)O_(3) can be attributed to an internal electric field of the heterojunction,which effectively separates positive and negative charges.The strongly pyrocatalytic performance of BaTiO_(3)/Pr_(2)O_(3) makes it hopeful for applications in the dye wastewater treatment through harvesting the environmental cold–hot temperature alternation thermal energy in future.

Visible light photocatalytic dye decomposition behaviour of solid state reaction grown Zn_2TiO_4 nanoparticles

In this investigation, visible photocatalytic dye decomposition is carried out with compound semiconductor nanoparticles of zinc orthotitanate(Zn2TiO4). These nanoparticles were grown by the solid state reaction method and characterized by field emission scanning electron microscopy, transmission electron microscopy, Xray diffraction,diffuse reflectance spectroscopy,photoluminescence study, and Brunauer-Emmett-Teller(BET)study. The BET surface area of the Zn2TiO4nanoparticles was found to be 8.78 m2/g. The photocatalytic activity is carried out by using a 500 W halogen light source having a spectrum in the range of 450 to 860 nm and the reaction kinetics was found to be the pseudo first order. The reaction rate constant was found to be 0.069 min-1. Discussion is given on the possible mechanism of the observed visible photocatalytic dye decomposition activity. The cost of the material used is very low, so it could be very useful for visible photocatalytic dye decomposition.

Enhancement of photocatalytic activity by femtosecond-laser induced periodic surface structures of Si

Laser induced periodic surface structures(LIPSS)represent a kind of top down approach to produce highly reproducible nano/microstructures without going for any sophisticated process of lithography.This method is much simpler and cost effective.In this work,LIPSS on Si surfaces were generated using femtosecond laser pulses of 800 nm wavelength.Photocatalytic substrates were prepared by depositing TiO2 thin films on top of the structured and unstructured Si wafer.The coatings were produced by sputtering from a Ti target in two different types of oxygen atmospheres.In first case,the oxygen pressure within the sputtering chamber was chosen to be high(3×10^–2 mbar)whereas it was one order of magnitude lower in second case(2.1×10^–3 mbar).In photocatalytic dye decomposition study of Methylene blue dye it was found that in the presence of LIPSS the activity can be enhanced by 2.1 and 3.3 times with high pressure and low pressure grown TiO2 thin films,respectively.The increase in photocatalytic activity is attributed to the enlargement of effective surface area.In comparative study,the dye decomposition rates of TiO2 thin films grown on LIPSS are found to be much higher than the value for standard reference thin film material Pilkington Activ^TM.

Piezocatalytic performance of Fe_(2)O_(3)−Bi_(2)MoO_(6) catalyst for dye degradation

A Fe_(2)O_(3)−Bi_(2)MoO_(6) heterojunction was synthesized via a hydrothermal method.Scanning electron microscopy,transmission electron microscopy,energy-dispersive X-ray,powder X-ray diffraction,Fourier transform infrared spectroscopy and ultra-violet−visible near-infrared spectrometry were performed to measure the structures,morphologies and optical properties of the as-prepared samples.The various factors that affected the piezocatalytic property of composite catalyst were studied.The highest rhodamine B degradation rate of 96.6%was attained on the 3% Fe_(2)O_(3)−Bi_(2)MoO_(6) composite catalyst under 60 min of ultrasonic vibration.The good piezocatalytic activity was ascribed to the formation of a hierarchical flower-shaped microsphere structure and the heterostructure between Fe_(2)O_(3) and Bi_(2)MoO_(6),which effectively separated the ultrasound-induced electron–hole pairs and suppressed their recombination.Furthermore,a potential piezoelectric catalytic dye degradation mechanism of the Fe_(2)O_(3)−Bi_(2)MoO_(6) catalyst was proposed based on the band potential and quenching effect of radical scavengers.The results demonstrated the potential of using Fe_(2)O_(3)−Bi_(2)MoO_(6) nanocomposites in piezocatalytic applications.