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.

Modulating low-frequency tribocatalytic performance through defects in uni-doped and bi-doped SrTiO_(3)

Triboelectrification,a process that transforms mechanical energy into electrical energy through friction,holds promise for eco-friendly wastewater treatment.This study delves into the enhancement of tribocatalytic dye degradation using SrTiO_(3),a material notable for its non-piezoelectric and centrosymmetric properties.The synthesis of uni-and bi-doped SrTiOs particles,achieved through a solid-state reaction at 100℃,results in a high-purity cubic perovskite structure.Doping with rhodium(Rh)and carbon(C)causes crystal lattice contraction,internal stress,and significant oxygen vacancies.These changes notably improve tribocatalytic efficiency under solar irradiation,with Rh-doped SrTiO_(3) demonstrating an impressive degradation rate of approximately 88% for Rhodamine B(RhB),along with reaction rate constants near 0.9 h^(-1) at 554 nm and a noticeable blueshift.This study highlights that defects introduced by doping are integral to this process,boosting catalytic activity through energy state modification and enhancing surface redox radical production.Additionally,these defects are instrumental in generating a flexoelectric field,which markedly influences the separation of electron-hole pairs under solar irradiation.Our findings illuminate the complex interplay between material composition,defect states,and environmental conditions,paving the way for advanced strategies in environmental remediation through optimized tribocatalytic activity.

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.

Special Issue on Applications of Ferroelectric Materials in Environment and Energy Fields

Since the discovery of the Rochelle salt one century ago,ferroelectric materials have aroused extensive attention due to their strong response to various external fields such as electricity,force,heat,magnetism and light.1,2 Because of ferroelectric materials’excellent dielectric,piezoelectric and pyroelectric properties,modern ferroelectric devices are not only widely used in the field of information,but also blooming in the fields of environmental protection(electric card refrigeration,photocatalysis,piezoelectric catalysis,pyroelectric catalysis,etc.)and energy(solar cells,high-power energy storage,abnormal photovoltaic,etc.)in recent years.

Boosting tribo-catalytic conversion of H_(2)O and CO_(2)by Co_(3)O_(4)nanoparticles through metallic coatings in reactors

In recent years,more and more metal oxides have been finding critical tribo-catalytic applications.Presently,we have explored the tribo-catalytic conversion of H_(2)O and CO_(2)using Co_(3)O_(4)nanoparticles and obtained some surprising results.In an as-received 150 mL glass reactor enclosed with 10 mL of H_(2)O,0.10 g of Co_(3)O_(4)nanoparticles,1 atm of CO_(2),and a Teflon magnetic rotary disk,we observed the production of as much as 57.41μmol/L of H_(2),0.15μmol/L of CH_(4),and 0.21μmol/L of CO after 5 h of magnetic stirring.Metallic coatings of Cu,Ni,SUS316,Ti,Nb,Mo,and W were further introduced on reactor bottoms separately.For those coatings of Ni,SUS316,Ti,and Nb,the reduction of CO_(2)was dramatically enhanced,and C_(2+)products of C_(2)H_(6)and C_(2)H_(4)were observed.Especially for the Ti coating,the amounts of H_(2)and CH_(4)were increased by 2 and 26 times from those for the glass bottom,respectively,and the amounts of C_(2)H_(6)and C_(2)H_(4)were very impressive.The Co_(3)O_(4)nanoparticles were proven chemically stable under magnetic stirring in water,and hydroxyl radicals and superoxide radicals have been detected for the Co_(3)O_(4)nanoparticles under magnetic stirring through fluorescence spectroscopy and electron paramagnetic resonance spectroscopy analyses.These findings not only reveal outstanding capability of Co_(3)O_(4)to generate multicarbon products from H_(2)O and CO_(2)through tribo-catalysis but also highlight a promising potential of tribo-catalysis as a whole to harness mechanical energy for addressing energy shortages and environmental pollution.

Enhanced pyrocatalysis of the pyroelectric BiFeO_(3)/g-C_(3)N_(4) heterostructure for dye decomposition driven by cold–hot temperature alternation

The BiFeO_(3)/g-C_(3)N_(4) heterostructure,which is fabricated via a simple mixing–calcining method,benefits the significant enhancement of the pyrocatalytic performance.With the growth of g-C_(3)N_(4) content in the heterostructure pyrocatalysts from 0 to 25%,the decomposition ratio of Rhodamine B(RhB)dye after 18 cold-hot temperature fluctuation(25-65℃)cycles increases at first and then decreases,reaching a maximum value of~94.2%at 10%while that of the pure BiFeO_(3) is~67.7%.The enhanced dye decomposition may be due to the generation of the internal electric field which strengthens the separation of the positive and negative carriers and further accelerates their migrations.The intermediate products in the pyrocatalytic reaction also have been detected and confirmed,which proves the key role of the pyroelectric effect in realizing the dye decomposition using BiFeO_(3)/g-C_(3)N_(4) heterostructure catalyst.The pyroelectric BiFeO_(3)/g-C_(3)N_(4) heterostructure shows the potential application in pyrocatalytically degrading dye wastewater.

Effect of Sb-site nonstoichiometry on the structure and microwave dielectric properties of Li_(3)Mg_(2)Sb_(1-x)O_(6) ceramics

The non-stoichiometric Li_(3)Mg_(2)Sb_(1-x)O_(6)(0.05≤x≤0.125)compounds have been prepared via the mixed oxide method.The influences of Sb nonstoichiometry on the sintering behavior,microstructure,phase composition along with microwave dielectric performances for Li_(3)Mg_(2)Sb_(1-x)O_(6) ceramics were studied.Combined with X-ray diffraction(XRD)and Raman spectra,it was confirmed that phase composition could not be affected by the Sb nonstoichiometry and almost pure phase Li_(3)Mg_(2)SbO_(6) was formed in all compositions.Appropriate Sb-deficiency in Li_(3)Mg_(2)SbO_(6) not only lowered its sintering temperature but also remarkably improved its Q×f value.In particular,non-stoichiometric Li_(3)Mg_(2)Sb_(0.9)O_(6) ceramics sintered at 1250℃/5 h owned seldom low dielectric constant ε_(r)=10.8,near-zero resonant frequency temperature coefficient τ_(f)=-8.0 ppm/℃,and high quality factor Q×f=86,300 GHz(at 10.4 GHz).This study provides an alternative approach to ameliorate its dielectric performances for Li_(3)Mg_(2)SbO_(6)-based compounds through defect-engineering.

Toward artificial intelligent self-cooling electronic skins:Large electrocaloric effect in all-inorganic flexible thin films at room temperature

Intelligent robots have assisted mankind in achieving and operating thousands of functions,especially with the arrival of the artificial intelligent.However,heat dissipation and thermal management in the intelligent robots remain big challenges,which limit their miniaturization and performance.Electrocaloric(EC)materials,which exhibit temperature change in response to the application or withdrawal of an electric field,open a new strategy for cooling technology and have gained a flurry of research interest in recent years.Toward artificial intelligent self-cooling electronic skins,large-scale flexible materials with high EC effect near room temperature are in demand.Here,we report a large room temperature EC effect in flexible Pb_(0.82)Ba_(0.08)La_(0.1)Zr0.9Ti_(0.1)O_(3)(PBLZT)inorganic thin films via a transfer-free cost-effective sol-gel process,assisted by unique two-dimensional mica substrates.The maximum adiabatic temperature change and isothermal entropy change of the flexible PBLZT thin films reach to 22.5 K and 25.9 J K^(-1) kg^(-1) at room temperature.In particular,the flexible PBLZT thin films exhibit a stable EC effect both under bending state and after bending for 20000 times.Our flexible EC materials offer an alternative strategy to the development of cooling technologies for both artificial intelligent robots and personal wearable cooling devices.

High efficiently harvesting visible light and vibration energy in(1−x)AgNbO_(3)-xLiTaO_(3) solid solution around antiferroelectric-ferroelectric phase boundary for dye degradation

Simultaneously employing light and vibration energy by piezoelectric material to realize environmental remediation is an advanced oxidation method.Silver niobate(AgNbO_(3))is a visible light driven photocatalyst for the removal of organic pollutants.However,the high recombination rate of photo-generated electrons and holes suppresses its photocatalytic activity.Piezoelectric potential excited by vibration can facilitate the separation of light induced charges.Unfortunately,AgNbO_(3) is an antiferroelectric.In this work,distinct photo-/vibration-bi-catalysis has been achieved in ferroelectric(1−x)AgNbO_(3)-xLiTaO_(3) solid solution.The results show that ~96% Rhodamine B(RhB)can be decomposed under the bi-excitation of ultrasound and visible light within 120 min with 0.95AgNbO_(3)-0.05LiTaO_(3) catalyst.The synergy effect from efficient visible light excitation and enhanced separation of the photo-induced charges from the electric field by the mechanical strain results in the distinct decomposition performance of catalysts.

Flammable gases produced by TiO_(2) nanoparticles under magnetic stirring in water

The friction between nanomaterials and Teflon magnetic stirring rods has recently drawn much attention for its role in dye degradation by magnetic stirring in dark.Presently the friction between TiO_(2) nanoparticles and magnetic stirring rods in water has been deliberately enhanced and explored.As much as 1.00 g TiO_(2) nanoparticles were dispersed in 50 mL water in 100 mL quartz glass reactor,which got gas-closed with about 50 mL air and a Teflon magnetic stirring rod in it.The suspension in the reactor was magnetically stirred in dark.Flammable gases of 22.00 ppm CO,2.45 ppm CH_(4),and 0.75 ppm H_(2) were surprisingly observed after 50 h of magnetic stirring.For reference,only 1.78 ppm CO,2.17 ppm CH_(4),and 0.33 ppm H_(2) were obtained after the same time of magnetic stirring without TiO_(2) nanoparticles.Four magnetic stirring rods were simultaneously employed to further enhance the stirring,and as much as 30.04 ppm CO,2.61 ppm CH_(4),and 8.98 ppm H_(2) were produced after 50 h of magnetic stirring.A mechanism for the catalytic role of TiO_(2) nanoparticles in producing the flammable gases is established,in which mechanical energy is absorbed through friction by TiO_(2) nanoparticles and converted into chemical energy for the reduction of CO_(2) and H_(2)O.This finding clearly demonstrates a great potential for nanostructured semiconductors to utilize mechanical energy through friction for the production of flammable gases.