The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the...The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the complex has been stUdied from the TG-DTGcurves by means of the Achar et al. and Coats-Redfern methods,the most probab1e kinetic equation canbe expressed as dofdtrAe -E / RT * l /(2Q).The corresponding kinetic compensation effect expressions arefound to be lnuA=0. 1794E+0. 1689.The non-isothermal thermal decomposition process of the complex isone-dimensional diffusion.But electrochemical studies of the complex(Cu2L'2)from cyclic voltamrnetriccurves by means of powder microelectrodes technique'',shows one two-electron irreversible process.展开更多
Some monosubstituted Keggin or Dawson anions nave been reporten by Hill to be "remarkably effective" catalysts for the epoxidation of alkenes, Hill, Finke and Neumann reported respectively that the transitio...Some monosubstituted Keggin or Dawson anions nave been reporten by Hill to be "remarkably effective" catalysts for the epoxidation of alkenes, Hill, Finke and Neumann reported respectively that the transition metal monosubstituted heteropolyanions [PW;O;M（H;O）]";, [P;W;O;M（L）]"- and [SiW;O;Ru（H;O）];have an ability to catalyze the epoxidation of alkenes. And the undecatungstotitanates with one kind of transition metal have展开更多
The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that t...The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.展开更多
Biochar,derived from the waste pyrolysis process,is a promising class of functional materials for environmental remediation owing to its large surface area,abundant surface functionalities and redox properties.This re...Biochar,derived from the waste pyrolysis process,is a promising class of functional materials for environmental remediation owing to its large surface area,abundant surface functionalities and redox properties.This review focuses on the compositions,structures and electron transfer abilities of biochar and their roles in pollutant transformation in environmental remediation.First,the redox properties of biochar are systemically introduced,and the influencing factors are thoroughly discussed.Furthermore,biochar-involved redox reactions for pollutant reduction are distinctly classified on the basis of the different oxidants and reaction conditions.The reactive species in each system are comprehensively introduced,while the roles of biochar are adequately analyzed.This review aims to address the growing need for a comprehensive understanding of the role of biochar in pollutant transformation.Moreover,it also seeks to guide future research and the design of biochar materials for advanced water purification,highlighting the need for precise control of redox properties to achieve improved environmental outcomes.展开更多
Cyclic voltammetric studies of clusters(C_6H_5-C_2C_6 H_4-R-p)Co_2(CO)_(6-n) L_n[n=0,2; L=PPh_3,P(OEt)_3] and(RCH_2C)_2Co_2(CO_4)(PPh_3)_2 on Pt electrode are described. The primary reduction(0/-1)and oxidation (+1/0)...Cyclic voltammetric studies of clusters(C_6H_5-C_2C_6 H_4-R-p)Co_2(CO)_(6-n) L_n[n=0,2; L=PPh_3,P(OEt)_3] and(RCH_2C)_2Co_2(CO_4)(PPh_3)_2 on Pt electrode are described. The primary reduction(0/-1)and oxidation (+1/0) steps are considered as a mono-electron process for all clusters. For the clusters (C_6H_5C_2C_6H_4-R-P)Co_2(CO)_6, a good linear relation between reduction poten- tial EF_p^(red) and Hammett constant σp of R in the clusters is found. For the clusters(RC_2R′)Co_2(CO)_4L_2, their radical anions are extremely unstable at room temperature and fragment into a series of mono- nuclear species, one of which is(RC-3R′)Co(CO)_2PPh_3. The reaction of radical anions of (RC_2R’)- Co_2(CO)_(6-n) (PPh_3)_n(n=0,2) with PPh_3 also produces mononuclear species (RC_2R’)Co(CO)_2PPh_3 which has been detected by means of cyclic voltammetry and ESR. The influence of R on redox pro- perties of clusters is discussed.展开更多
Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox proces...Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox processes remain largely unknown.Herein,multiple spectroscopic and electrochemical approaches in concert with wet-chemistry analyses were employed to characterize the redox properties of weathered microplastics.The spectroscopic results indicated that weathering of phenol-formaldehyde resins(PFs)by hydrogen peroxide(H2O2)led to a slight decrease in the content of phenol functional groups,accompanied by an increase in semiquinone radicals,quinone,and carboxylic groups.Electrochemical and wet-chemistry quantifications,coupled with microbial-chemical characterizations,demonstrated that the PFs exhibited appreciable electron-donating capacity(0.264-1.15 mmol e-g^(-1))and electron-accepting capacity(0.120-0.300 mmol e-g^(-1)).Specifically,the phenol groups and semiquinone radicals were responsible for the electron-donating capacity,whereas the quinone groups dominated the electron-accepting capacity.The reversible redox peaks in the cyclic voltammograms and the enhanced electron-donating capacity after accepting electrons from microbial reduction demonstrated the reversibility of the electron-donating and-accepting reactions.More importantly,the electron-donating phenol groups and weathering-induced semiquinone radicals were found to mediate the production of H2O2 from oxygen for arsenite oxidation.In addition to the H2O2-weathered PFs,the ozone-aged PF and polystyrene were also found to have electron-donating and arsenite-oxidation capacity.This study reports important redox properties of microplastics and their effect in mediating contaminant transformation.These findings will help to better understand the fate,transformation,and biogeochemical roles of microplastics on element cycling and contaminant fate.展开更多
Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.30x samples synthesized by sol-gel method were tested for redox properties through the dynamic oxygen storage measurement and characterized using X-ray diffraction, BET, electron paramag...Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.30x samples synthesized by sol-gel method were tested for redox properties through the dynamic oxygen storage measurement and characterized using X-ray diffraction, BET, electron paramagnetic resonance, and X-ray photoelectron spectroscopy. The results showed that redox performances of ceria-based materials could be enhanced by synergetic effects between Mn-O and Ce-O. Fresh and aged samples were characterized with the fluorite-type cubic structure similar to CeO2, and furthermore, the thermal stability of Mn0.1Ce0.9Ox materials was improved by the introduction of some Zr atoms. From XPS, it could be concluded that Mn^2＋/Mn^3＋ redox couples existed on the surface of Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.3Ox samples. Electron paramagnetic resonance researches revealed that there were three types of Mn^2＋ species： isolated Mn^2＋ substituting for Ce^4＋ ions in the lattice with a cubic symmetry, ones in defect with a noncubic symmetry, and at the surface of samples.展开更多
Excellent catalysts with low-temperature activity and relatively wide temperature window for selective catalytic reduction of NO with ammonia(NH_(3)-SCR) are highly demanded in view of the practical treatment of NO.He...Excellent catalysts with low-temperature activity and relatively wide temperature window for selective catalytic reduction of NO with ammonia(NH_(3)-SCR) are highly demanded in view of the practical treatment of NO.Herein,we have designed a highly active VOx-MnOx/CeO_(2) material based on the intrinsic requirement of SCR reaction for catalyst,namely redox sites and surface acid sites.The vanadium oxide and manganese oxide are highly dispersed over the ceria mesosphere via simple incipient wetness impregnation.The loading of manganese could introduce acid sites and enhance the redox property remarkably,while the loading of vanadium increases acid sites and weakens redox property.Through tentatively controlling the appropriate loading ratio of the two components,the optimal catalyst achieves a balance between redox property and surface acidity.The work shed light on the development of new SCR catalyst with superior low temperature activity,wide work temperature window and good hydrothermal stability.展开更多
Three La-doped CeO2-ZrO2-Al2O3(CZA)composite oxide samples,namely,CZA-I,CZA-II and CZA-III,were prepared following a co-precipitation method in the presence of La2O3,La(NO3)3-6H2O and H[La(EDTA)]-16H2O precursors,resp...Three La-doped CeO2-ZrO2-Al2O3(CZA)composite oxide samples,namely,CZA-I,CZA-II and CZA-III,were prepared following a co-precipitation method in the presence of La2O3,La(NO3)3-6H2O and H[La(EDTA)]-16H2O precursors,respectively.When the precursor samples are sintered at 1000°C,the as-prepared composite oxides mainly exhibit the CeO2-ZrO2 cubic fluorite phase,while theγ-Al2O3 andδ-Al2O3 phases appear when the precursor samples are subjected to sintering at 1100 and 1200°C.CZA-III exhibits improved redox properties after high-temperature treatment compared with CZA-I and CZA-II.CZA-III presents the largest surface area of 97.46 m2/g among the three CZAs when the CZA-III precursor sample is sintered at 1000°C.Furthermore,the corresponding oxygen storage capacity(OSC)is the largest with value of 400.27μmol/g when CZA-III precursor sample is sintered at 1000°C.Additionally,CZA-III exhibits the best thermal stability and the highest reduction temperature.However,by increasing the sintering temperature to 1200°C,there is a dramatic decline in the properties of surface area and OSC.And a decrease for CZA-III in surface area by 58.94%and a decrease of the OSC value by 74.56%are observed.展开更多
Density functional theory is used to investigate the complexes structures and properties of poly(vinyl ethylene carbonate)(PVEC/LiTFSI)and poly(vinylene carbonate)(PVCA/LiDFOB)electrolytes containing five-membered rin...Density functional theory is used to investigate the complexes structures and properties of poly(vinyl ethylene carbonate)(PVEC/LiTFSI)and poly(vinylene carbonate)(PVCA/LiDFOB)electrolytes containing five-membered ring carbonate groups under the polymer/Li^(+)model and the polymer/lithium salt model.In addition,the calculated and experimental values of the oxidation potentials of the two electrolytes were compared,and the reasons for the differences in the oxidation potentials of the two electrolytes are elucidated.The calculation results show that the PVEC/LiTFSI has more free ion structures and diverse coordination structures compared to PVCA/LiDFOB electrolyte.This provides a reasonable theoretical explanation for its higher ionic conductivity and lower cation mobility number.The PVEC/LiTFSI electrolyte has a lower oxidation potential compared to the PVCA/LiDFOB electrolyte,which is attributed to the proton transfer that occurs during its oxidation.展开更多
The structure,the morphology and the thermal,optical and the surface properties of nanocrystalline CeO_2 doped with Mn have been studied by X-ray diffraction（XRD）,field-emission transmission electron microscopy（FE-...The structure,the morphology and the thermal,optical and the surface properties of nanocrystalline CeO_2 doped with Mn have been studied by X-ray diffraction（XRD）,field-emission transmission electron microscopy（FE-TEM）,energy-dispersive X-ray analysis,thermogravimetric analysis,UV–Vis absorption spectroscopy and Fourier transform infrared spectroscopy.The XRD results confirmed the successful incorporation of Mn into the CeO_2 lattice through the formation of nanoscale face-centered cubic solid solution.The FE-TEM observations supported the nanocrystalline nature of the solid solutions.The presence of structural defects and their role on the band gap have been discussed on the basis of absorption spectral studies.The structural differences correlate with results from temperature-programmed reaction（TPR）experiments with H_2 consumption.The TPR measurements showed an enhanced bulk reduction at much lower temperatures,indicating increased oxygen mobility in the samples,which enable to enhanced oxygen diffusion at lower temperatures.展开更多
A novel mononuclear copper（Ⅱ） complex [Cu（bbmc）Cl_2]·DMF,where bbmc is 1,1-bis（1H-benzoimidazol-2-ylmethyl）cyclohexane,was synthesized and characterized by X-ray single-crystal structure analysis.The compl...A novel mononuclear copper（Ⅱ） complex [Cu（bbmc）Cl_2]·DMF,where bbmc is 1,1-bis（1H-benzoimidazol-2-ylmethyl）cyclohexane,was synthesized and characterized by X-ray single-crystal structure analysis.The complex crystallizes in triclinic,space group P1 with a = 9.1088（5）,b = 11.0075（4）,c = 14.2326（6）A,α = 97.188（3）,β = 96.394（4）,γ = 111.430（4）°,V = 1298.73（10） A^3,Z = 2,D_c = 1.409 g/cm^3,μ（Mo Kα） = 1.074 mm^-1,F（000） = 572,S = 1.078,R = 0.0381 and w R = 0.0876 for 5593 observed reflections with I 〉 2σ（I）.The central Cu（Ⅱ） ion adopts a distorted tetrahedral geometry coordinated by two nitrogen atoms of the ligand and two chloride ions.The complex showed its thermal decomposition temperature up to 226 ℃ and exhibited an irreversible one-electron transfer process involving Cu^Ⅱ/Cu^I couple.展开更多
Refractory organic pollutants in water threaten human health and environmental safety,and advanced oxidation processes (AOPs) are effective for the degradation of these pollutants.Catalysts play vital role in AOPs,and...Refractory organic pollutants in water threaten human health and environmental safety,and advanced oxidation processes (AOPs) are effective for the degradation of these pollutants.Catalysts play vital role in AOPs,and Ce-based catalysts have exhibited excellent performance.Recently,the development and application of Ce-based catalysts in various AOPs have been reported.Our study conducts the first review in this rapid growing field.This paper clarifies the variety and properties of Ce-based catalysts.Their applications in different AOP systems (catalytic ozonation,photodegradation,Fenton-like reactions,sulfate radicalbased AOPs,and catalytic sonochemistry) are discussed.Different Ce-based catalysts suit different reaction systems and produce different active radicals.Finally,future research directions of Ce-based catalysts in AOP systems are suggested.展开更多
Modification and performance of Li induced silica phase transition of （Mn＋W）/SiO2 catalyst, under reaction conditions of oxidative coupling of methane （OCM）, have been investigated employing textural characteriza...Modification and performance of Li induced silica phase transition of （Mn＋W）/SiO2 catalyst, under reaction conditions of oxidative coupling of methane （OCM）, have been investigated employing textural characterizations and redox studies. Stability and precrystalline form of fresh Li induced silica phase transition catalyst depend on the Li loading. A catalyst, with high lithium loading, destabilizes on OCM stream. This destabilization is not due to Li evaporation at OCM reaction conditions, α-cristobalite is proposed to be an intermediate in the crystallization of amorphous silica into quartz in the Li-induced silica phase transition process. However, the type of crystalline structure was found to be unimportant with regard to the formation of a selective catalyst. Metal-metal interactions of Li-Mn, Li-W and Mn-W, which are affected during silica phase crystallization, are found to be critical parameters of the trimetallic catalyst and were studied by TPR. Role of lithium in Li doped （Mn＋W）/SiO2 catalyst is described as a moderator of the Mn-W interaction by involving W in silica phase transition. These interactions help in the improvement of transition metal redox properties, especially that of Mn, in favor of OCM selectivity.展开更多
Atomic layer deposition(ALD)attracts great attention nowadays due to its ability for designing and modifying catalytic systems at the molecular level.There are several reported review papers published recently discuss...Atomic layer deposition(ALD)attracts great attention nowadays due to its ability for designing and modifying catalytic systems at the molecular level.There are several reported review papers published recently discussing this technique in catalysis.However,the mechanism on how the deposited materials improve the catalyst stability and tune the reaction selectivity is still unclear.Herein,catalytic systems created via ALD on stepwise preparation and/or modification under self-limiting reaction conditions are summarized.The effects of deposited materials in terms of electronic/geometry modification over the catalytic nanoparticles(NPs)are discussed.These effects explain the mechanism of the catalytic stability improvement and the selectivity modification.The unique properties of ALD for designing new catalytic systems are further investigated for building up photocatalytic reaction nanobowls,tandem catalyst and bi-active-component metallic catalytic systems.展开更多
ZrO2-based mixed metal oxide catalysts for the industrially important dehydrogenation process of ethylbenzene to styrene monomer have been explored by our group for the past 20 years.These efforts were subjected to th...ZrO2-based mixed metal oxide catalysts for the industrially important dehydrogenation process of ethylbenzene to styrene monomer have been explored by our group for the past 20 years.These efforts were subjected to the activation of CO2 over mixed metal oxide catalysts and resulted in several promising benefits to the dehydrogenation processes,such as stabilized conversion and selectivity,suppressed coke formation and commercially-acceptable longevity.In this review,we summarize the most recent developments on ZrO2-based mixed metal oxide catalysts,including the further optimization of sol-gel process in the synthesis of catalysts,rationalizing acid-base properties by doping,co-operative properties between redox and acid-base active sites and additional promoters towards the effective improvement of the longevity of catalysts.展开更多
Copper–ceria(Cu O–CeO2) catalysts have been known to be very effective for the oxidation of CO, and their chemical behavior has been extensively studied during the last decades. However, the effect of different CeO2...Copper–ceria(Cu O–CeO2) catalysts have been known to be very effective for the oxidation of CO, and their chemical behavior has been extensively studied during the last decades. However, the effect of different CeO2 crystal surfaces on the catalytic activity of Cu O–CeO2 for the oxidation of CO is still unclear and should be further elucidated. In this study, we deposited 1 wt% Cu on mostly {100}-exposed CeO2 nanocubes(1 Cu Ce NC) and mostly {110}-exposed CeO2 nanorods(1 Cu Ce NR), respectively. Both 1 Cu Ce NC and 1 Cu Ce NR have been used as catalysts for the oxidation of CO and achieved 100% and 50% CO conversion at 130 ℃, respectively. The differences in the catalytic activity of 1 Cu Ce NC and 1 Cu Ce NR were analyzed using temperature-programmed reduction of H2 and temperature-programmed desorption of CO techniques. The results confirmed the excellent reducibility of the 1 Cu Ce NC catalyst, which was attributed to the weak interactions between Cu and the CeO2 support. Moreover, in situ diffuse reflectance infrared Fourier-transform spectroscopy studies indicated that the {100} planes of 1 Cu Ce NC facilitated the generation of active Cu(I) sites, which resulted in the formation of highly reactive Cu(I)-CO species during the oxidation of CO. Both the excellent redox properties and effective CO adsorption capacity of the 1 Cu Ce NC catalyst increased its catalytic reactivity.展开更多
A series of supported CeO2/TiO2 catalysts were prepared to explore the influence of CeO2 loading on these catalysts for the selective catalytic reduction of NO3 by NH3(NH3-SCR).The catalysts were investigated in detai...A series of supported CeO2/TiO2 catalysts were prepared to explore the influence of CeO2 loading on these catalysts for the selective catalytic reduction of NO3 by NH3(NH3-SCR).The catalysts were investigated in detail by means of XRD,Raman,H2-TPR,NH3-TPD,XPS,in situ DRIFTS,and NH3-SCR reaction.The activity of the catalyst is closely related to the content of CeO2.When the loading of CeO2 is near the dispersion capacity(1.16 mmol Ce4+/100 m^2 TiO2),the catalytic activity is better.This may be because that the dispersed CeO2 is the active species and the catalyst has appropriate redox property,along with the larger amounts of surface Ce content and surface adsorbed oxygen species.Finally,a possible reaction mechanism via the Langmuir-Hinshelwood(L-H)mechanism is tentatively proposed to further understand the NH3-SCR reaction.展开更多
Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption,...Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The Pd-only three-way catalysts （Pd-TWC） supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3＋ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.展开更多
The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollu...The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollutants of three car fleet were investigated at every 100,000 km miles. The results showed that HC, NOx, and CO emission values could meet Euro Ⅳ regulation limits at every point. The redox properties of TWC and CCC were measured by CO reduction during each isothermal. It was obvious that both aged TWC and aged CCC behaved a good redox property at 673 and 773 K. Based on XRD and BET measurement results, TWC and CCC washcoat were characterized with good thermal stability.展开更多
文摘The paper reports the synthetic procedure and character of Copper(II) binuclearcoordination compound of 1,4-bis-(1'-phenyl-3'-methyl-5'-pyrazolone Thenon-isothermal kinetics of thermal decomposition of the complex has been stUdied from the TG-DTGcurves by means of the Achar et al. and Coats-Redfern methods,the most probab1e kinetic equation canbe expressed as dofdtrAe -E / RT * l /(2Q).The corresponding kinetic compensation effect expressions arefound to be lnuA=0. 1794E+0. 1689.The non-isothermal thermal decomposition process of the complex isone-dimensional diffusion.But electrochemical studies of the complex(Cu2L'2)from cyclic voltamrnetriccurves by means of powder microelectrodes technique'',shows one two-electron irreversible process.
基金Supported by the National Natural Science Foundation of ChinaLaboratory of Apphed spectroscopy
文摘Some monosubstituted Keggin or Dawson anions nave been reporten by Hill to be "remarkably effective" catalysts for the epoxidation of alkenes, Hill, Finke and Neumann reported respectively that the transition metal monosubstituted heteropolyanions [PW;O;M（H;O）]";, [P;W;O;M（L）]"- and [SiW;O;Ru（H;O）];have an ability to catalyze the epoxidation of alkenes. And the undecatungstotitanates with one kind of transition metal have
基金Supported by the foundation of laboratory of rare earth chemistry and physics
文摘The redox properties of K17[Ln(As2W17O61)2](Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Tm or Yb) in solution were investigated using polarographic and cyclic voltammographic methods. Experimental results indicate that the heteropolyanions underwent three-step-two-electron-tungsten-reduction processes, and each reduction process was accompanied by adding two protons.
基金supported by the Natural Science Foundation of China(No.52306280)the Research Funds of the Institute of Zhejiang University-Quzhou(Nos.IZQRCZX023 and IZQ2023KJ1001)the Zhejiang Province“Pioneer”and“Lingyan”Research and Development Project(No.2024C03232).
文摘Biochar,derived from the waste pyrolysis process,is a promising class of functional materials for environmental remediation owing to its large surface area,abundant surface functionalities and redox properties.This review focuses on the compositions,structures and electron transfer abilities of biochar and their roles in pollutant transformation in environmental remediation.First,the redox properties of biochar are systemically introduced,and the influencing factors are thoroughly discussed.Furthermore,biochar-involved redox reactions for pollutant reduction are distinctly classified on the basis of the different oxidants and reaction conditions.The reactive species in each system are comprehensively introduced,while the roles of biochar are adequately analyzed.This review aims to address the growing need for a comprehensive understanding of the role of biochar in pollutant transformation.Moreover,it also seeks to guide future research and the design of biochar materials for advanced water purification,highlighting the need for precise control of redox properties to achieve improved environmental outcomes.
基金This project was supported by the National Natural Science Foundation of China as an item of major project.
文摘Cyclic voltammetric studies of clusters(C_6H_5-C_2C_6 H_4-R-p)Co_2(CO)_(6-n) L_n[n=0,2; L=PPh_3,P(OEt)_3] and(RCH_2C)_2Co_2(CO_4)(PPh_3)_2 on Pt electrode are described. The primary reduction(0/-1)and oxidation (+1/0) steps are considered as a mono-electron process for all clusters. For the clusters (C_6H_5C_2C_6H_4-R-P)Co_2(CO)_6, a good linear relation between reduction poten- tial EF_p^(red) and Hammett constant σp of R in the clusters is found. For the clusters(RC_2R′)Co_2(CO)_4L_2, their radical anions are extremely unstable at room temperature and fragment into a series of mono- nuclear species, one of which is(RC-3R′)Co(CO)_2PPh_3. The reaction of radical anions of (RC_2R’)- Co_2(CO)_(6-n) (PPh_3)_n(n=0,2) with PPh_3 also produces mononuclear species (RC_2R’)Co(CO)_2PPh_3 which has been detected by means of cyclic voltammetry and ESR. The influence of R on redox pro- perties of clusters is discussed.
基金the National Natural Science Foundation of China(4197310)the Alabama Agricultural Experiment Station,and the Hatch Program of the National Institute of Food and Agriculture,U.S.Department of Agriculture(ALA016-1-19123).
文摘Microplastics have attracted global concern.The environmental-weathering processes control their fate,transport,transformation,and toxicity to wildlife and human health,but their impacts on biogeochemical redox processes remain largely unknown.Herein,multiple spectroscopic and electrochemical approaches in concert with wet-chemistry analyses were employed to characterize the redox properties of weathered microplastics.The spectroscopic results indicated that weathering of phenol-formaldehyde resins(PFs)by hydrogen peroxide(H2O2)led to a slight decrease in the content of phenol functional groups,accompanied by an increase in semiquinone radicals,quinone,and carboxylic groups.Electrochemical and wet-chemistry quantifications,coupled with microbial-chemical characterizations,demonstrated that the PFs exhibited appreciable electron-donating capacity(0.264-1.15 mmol e-g^(-1))and electron-accepting capacity(0.120-0.300 mmol e-g^(-1)).Specifically,the phenol groups and semiquinone radicals were responsible for the electron-donating capacity,whereas the quinone groups dominated the electron-accepting capacity.The reversible redox peaks in the cyclic voltammograms and the enhanced electron-donating capacity after accepting electrons from microbial reduction demonstrated the reversibility of the electron-donating and-accepting reactions.More importantly,the electron-donating phenol groups and weathering-induced semiquinone radicals were found to mediate the production of H2O2 from oxygen for arsenite oxidation.In addition to the H2O2-weathered PFs,the ozone-aged PF and polystyrene were also found to have electron-donating and arsenite-oxidation capacity.This study reports important redox properties of microplastics and their effect in mediating contaminant transformation.These findings will help to better understand the fate,transformation,and biogeochemical roles of microplastics on element cycling and contaminant fate.
基金973 Program (2004CB719503)863 Program (2006AA060305)China Postdoctoral Science Foundation (20070410196)
文摘Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.30x samples synthesized by sol-gel method were tested for redox properties through the dynamic oxygen storage measurement and characterized using X-ray diffraction, BET, electron paramagnetic resonance, and X-ray photoelectron spectroscopy. The results showed that redox performances of ceria-based materials could be enhanced by synergetic effects between Mn-O and Ce-O. Fresh and aged samples were characterized with the fluorite-type cubic structure similar to CeO2, and furthermore, the thermal stability of Mn0.1Ce0.9Ox materials was improved by the introduction of some Zr atoms. From XPS, it could be concluded that Mn^2＋/Mn^3＋ redox couples existed on the surface of Mn0.1Ce0.9Ox and Mn0.1Ce0.6Zr0.3Ox samples. Electron paramagnetic resonance researches revealed that there were three types of Mn^2＋ species： isolated Mn^2＋ substituting for Ce^4＋ ions in the lattice with a cubic symmetry, ones in defect with a noncubic symmetry, and at the surface of samples.
基金Project supported by the National Natural Science Foundation of China (21576054)Science and Technology Planning of Guangdong Province (2016B020241003)+1 种基金Natural Science Foundation of Guangdong Province(2018A030310563)Foundation of Higher Education of Guangdong Province(2018KZDXM031)。
文摘Excellent catalysts with low-temperature activity and relatively wide temperature window for selective catalytic reduction of NO with ammonia(NH_(3)-SCR) are highly demanded in view of the practical treatment of NO.Herein,we have designed a highly active VOx-MnOx/CeO_(2) material based on the intrinsic requirement of SCR reaction for catalyst,namely redox sites and surface acid sites.The vanadium oxide and manganese oxide are highly dispersed over the ceria mesosphere via simple incipient wetness impregnation.The loading of manganese could introduce acid sites and enhance the redox property remarkably,while the loading of vanadium increases acid sites and weakens redox property.Through tentatively controlling the appropriate loading ratio of the two components,the optimal catalyst achieves a balance between redox property and surface acidity.The work shed light on the development of new SCR catalyst with superior low temperature activity,wide work temperature window and good hydrothermal stability.
基金Project(14JJ4043)supported by the Natural Science Foundation of Hunan Province,China
文摘Three La-doped CeO2-ZrO2-Al2O3(CZA)composite oxide samples,namely,CZA-I,CZA-II and CZA-III,were prepared following a co-precipitation method in the presence of La2O3,La(NO3)3-6H2O and H[La(EDTA)]-16H2O precursors,respectively.When the precursor samples are sintered at 1000°C,the as-prepared composite oxides mainly exhibit the CeO2-ZrO2 cubic fluorite phase,while theγ-Al2O3 andδ-Al2O3 phases appear when the precursor samples are subjected to sintering at 1100 and 1200°C.CZA-III exhibits improved redox properties after high-temperature treatment compared with CZA-I and CZA-II.CZA-III presents the largest surface area of 97.46 m2/g among the three CZAs when the CZA-III precursor sample is sintered at 1000°C.Furthermore,the corresponding oxygen storage capacity(OSC)is the largest with value of 400.27μmol/g when CZA-III precursor sample is sintered at 1000°C.Additionally,CZA-III exhibits the best thermal stability and the highest reduction temperature.However,by increasing the sintering temperature to 1200°C,there is a dramatic decline in the properties of surface area and OSC.And a decrease for CZA-III in surface area by 58.94%and a decrease of the OSC value by 74.56%are observed.
文摘Density functional theory is used to investigate the complexes structures and properties of poly(vinyl ethylene carbonate)(PVEC/LiTFSI)and poly(vinylene carbonate)(PVCA/LiDFOB)electrolytes containing five-membered ring carbonate groups under the polymer/Li^(+)model and the polymer/lithium salt model.In addition,the calculated and experimental values of the oxidation potentials of the two electrolytes were compared,and the reasons for the differences in the oxidation potentials of the two electrolytes are elucidated.The calculation results show that the PVEC/LiTFSI has more free ion structures and diverse coordination structures compared to PVCA/LiDFOB electrolyte.This provides a reasonable theoretical explanation for its higher ionic conductivity and lower cation mobility number.The PVEC/LiTFSI electrolyte has a lower oxidation potential compared to the PVCA/LiDFOB electrolyte,which is attributed to the proton transfer that occurs during its oxidation.
基金the Deanship of Scientific Research at King Saud University for its funding this Prolific Research Group(PRG-1436-26)
文摘The structure,the morphology and the thermal,optical and the surface properties of nanocrystalline CeO_2 doped with Mn have been studied by X-ray diffraction（XRD）,field-emission transmission electron microscopy（FE-TEM）,energy-dispersive X-ray analysis,thermogravimetric analysis,UV–Vis absorption spectroscopy and Fourier transform infrared spectroscopy.The XRD results confirmed the successful incorporation of Mn into the CeO_2 lattice through the formation of nanoscale face-centered cubic solid solution.The FE-TEM observations supported the nanocrystalline nature of the solid solutions.The presence of structural defects and their role on the band gap have been discussed on the basis of absorption spectral studies.The structural differences correlate with results from temperature-programmed reaction（TPR）experiments with H_2 consumption.The TPR measurements showed an enhanced bulk reduction at much lower temperatures,indicating increased oxygen mobility in the samples,which enable to enhanced oxygen diffusion at lower temperatures.
基金Financially supported from National Natural Science Foundation of China(No.21403191)Natural Science Foundation of Guangdong Province(Nos.2014A030307010 and 2015A0303010406)+2 种基金Special funds for public welfare research and capacity building in Guangdong Province(No.2015A010105031)Zhanjiang Science Technology Project(No.2013B01054)Lingnan Normal University Science Research Foundation(Nos.L1301 and LZL1504)
文摘A novel mononuclear copper（Ⅱ） complex [Cu（bbmc）Cl_2]·DMF,where bbmc is 1,1-bis（1H-benzoimidazol-2-ylmethyl）cyclohexane,was synthesized and characterized by X-ray single-crystal structure analysis.The complex crystallizes in triclinic,space group P1 with a = 9.1088（5）,b = 11.0075（4）,c = 14.2326（6）A,α = 97.188（3）,β = 96.394（4）,γ = 111.430（4）°,V = 1298.73（10） A^3,Z = 2,D_c = 1.409 g/cm^3,μ（Mo Kα） = 1.074 mm^-1,F（000） = 572,S = 1.078,R = 0.0381 and w R = 0.0876 for 5593 observed reflections with I 〉 2σ（I）.The central Cu（Ⅱ） ion adopts a distorted tetrahedral geometry coordinated by two nitrogen atoms of the ligand and two chloride ions.The complex showed its thermal decomposition temperature up to 226 ℃ and exhibited an irreversible one-electron transfer process involving Cu^Ⅱ/Cu^I couple.
基金supported by National Water Pollution Control and Treatment Science and Technology Major Project (No.2018ZX07110003)the National Natural Science Foundation of China (No.51779068)。
文摘Refractory organic pollutants in water threaten human health and environmental safety,and advanced oxidation processes (AOPs) are effective for the degradation of these pollutants.Catalysts play vital role in AOPs,and Ce-based catalysts have exhibited excellent performance.Recently,the development and application of Ce-based catalysts in various AOPs have been reported.Our study conducts the first review in this rapid growing field.This paper clarifies the variety and properties of Ce-based catalysts.Their applications in different AOP systems (catalytic ozonation,photodegradation,Fenton-like reactions,sulfate radicalbased AOPs,and catalytic sonochemistry) are discussed.Different Ce-based catalysts suit different reaction systems and produce different active radicals.Finally,future research directions of Ce-based catalysts in AOP systems are suggested.
文摘Modification and performance of Li induced silica phase transition of （Mn＋W）/SiO2 catalyst, under reaction conditions of oxidative coupling of methane （OCM）, have been investigated employing textural characterizations and redox studies. Stability and precrystalline form of fresh Li induced silica phase transition catalyst depend on the Li loading. A catalyst, with high lithium loading, destabilizes on OCM stream. This destabilization is not due to Li evaporation at OCM reaction conditions, α-cristobalite is proposed to be an intermediate in the crystallization of amorphous silica into quartz in the Li-induced silica phase transition process. However, the type of crystalline structure was found to be unimportant with regard to the formation of a selective catalyst. Metal-metal interactions of Li-Mn, Li-W and Mn-W, which are affected during silica phase crystallization, are found to be critical parameters of the trimetallic catalyst and were studied by TPR. Role of lithium in Li doped （Mn＋W）/SiO2 catalyst is described as a moderator of the Mn-W interaction by involving W in silica phase transition. These interactions help in the improvement of transition metal redox properties, especially that of Mn, in favor of OCM selectivity.
基金supported by the U.S. Department of Energy, Office of Science, and Office of the Basic Energy Sciences, under Contract DE-AC-02-06CH11357~~
文摘Atomic layer deposition(ALD)attracts great attention nowadays due to its ability for designing and modifying catalytic systems at the molecular level.There are several reported review papers published recently discussing this technique in catalysis.However,the mechanism on how the deposited materials improve the catalyst stability and tune the reaction selectivity is still unclear.Herein,catalytic systems created via ALD on stepwise preparation and/or modification under self-limiting reaction conditions are summarized.The effects of deposited materials in terms of electronic/geometry modification over the catalytic nanoparticles(NPs)are discussed.These effects explain the mechanism of the catalytic stability improvement and the selectivity modification.The unique properties of ALD for designing new catalytic systems are further investigated for building up photocatalytic reaction nanobowls,tandem catalyst and bi-active-component metallic catalytic systems.
基金funded by Saudi Arabia Basic Industries Corporation(Kingdom of Saudi Arabia),the BK21 Plus Project in 2014
文摘ZrO2-based mixed metal oxide catalysts for the industrially important dehydrogenation process of ethylbenzene to styrene monomer have been explored by our group for the past 20 years.These efforts were subjected to the activation of CO2 over mixed metal oxide catalysts and resulted in several promising benefits to the dehydrogenation processes,such as stabilized conversion and selectivity,suppressed coke formation and commercially-acceptable longevity.In this review,we summarize the most recent developments on ZrO2-based mixed metal oxide catalysts,including the further optimization of sol-gel process in the synthesis of catalysts,rationalizing acid-base properties by doping,co-operative properties between redox and acid-base active sites and additional promoters towards the effective improvement of the longevity of catalysts.
文摘Copper–ceria(Cu O–CeO2) catalysts have been known to be very effective for the oxidation of CO, and their chemical behavior has been extensively studied during the last decades. However, the effect of different CeO2 crystal surfaces on the catalytic activity of Cu O–CeO2 for the oxidation of CO is still unclear and should be further elucidated. In this study, we deposited 1 wt% Cu on mostly {100}-exposed CeO2 nanocubes(1 Cu Ce NC) and mostly {110}-exposed CeO2 nanorods(1 Cu Ce NR), respectively. Both 1 Cu Ce NC and 1 Cu Ce NR have been used as catalysts for the oxidation of CO and achieved 100% and 50% CO conversion at 130 ℃, respectively. The differences in the catalytic activity of 1 Cu Ce NC and 1 Cu Ce NR were analyzed using temperature-programmed reduction of H2 and temperature-programmed desorption of CO techniques. The results confirmed the excellent reducibility of the 1 Cu Ce NC catalyst, which was attributed to the weak interactions between Cu and the CeO2 support. Moreover, in situ diffuse reflectance infrared Fourier-transform spectroscopy studies indicated that the {100} planes of 1 Cu Ce NC facilitated the generation of active Cu(I) sites, which resulted in the formation of highly reactive Cu(I)-CO species during the oxidation of CO. Both the excellent redox properties and effective CO adsorption capacity of the 1 Cu Ce NC catalyst increased its catalytic reactivity.
基金Project supported by the National Natural Science Foundation of China(21773106,21677069,51674002,21307001)the Open Project Program of Jiangsu Key Laboratory of Vehicle Emissions Control(OVEC037)。
文摘A series of supported CeO2/TiO2 catalysts were prepared to explore the influence of CeO2 loading on these catalysts for the selective catalytic reduction of NO3 by NH3(NH3-SCR).The catalysts were investigated in detail by means of XRD,Raman,H2-TPR,NH3-TPD,XPS,in situ DRIFTS,and NH3-SCR reaction.The activity of the catalyst is closely related to the content of CeO2.When the loading of CeO2 is near the dispersion capacity(1.16 mmol Ce4+/100 m^2 TiO2),the catalytic activity is better.This may be because that the dispersed CeO2 is the active species and the catalyst has appropriate redox property,along with the larger amounts of surface Ce content and surface adsorbed oxygen species.Finally,a possible reaction mechanism via the Langmuir-Hinshelwood(L-H)mechanism is tentatively proposed to further understand the NH3-SCR reaction.
基金Project supported by National Natural Science Foundation of China (20773090, 20803049)the Specialized Research Fund for the Doctoral Program of Higher Education (20070610026, 200806100009)
文摘Ce-Zr-Al-Nd2O3 （CZAN） support materials were prepared by co-precipitation and impregnation methods, respectively. They were characterized by X-ray diffTaction （XRD）, low temperature nitrogen adsorption-desorption, oxygen pulsing technique, H2-temperamre programmed reduction （H2-TPR） and X-ray photoelectron spectroscopy （XPS）. The Pd-only three-way catalysts （Pd-TWC） supported on these materials were prepared by incipient wetness method and studied by activity tests. The results demonstrated that the CZAN supports obtained by the two methods showed better structural, textural and redox properties than the CZA without Nd2O3, and the addition of Nd203 improved the catalytic activity of TWC. Especially, the CZAN-i support prepared by impregnation method had better thermal stability and redox property. Meanwhile, the Pd/CZAN-i catalyst exhibited the best catalytic performance. XPS measurements indicated that the Nd-modified samples possessed more Ce3＋ and oxygen vacancies on the surface of samples, which led to a better redox property. The excellent redox property of support materials helped to improve the catalytic activity of TWC.
基金supported by the 863 Program (2006AA060305)China Postdoctoral Science Foundation (20070410196)+1 种基金Jiangsu Province Planned Projects for Postdoctoral Research Funds (0702054C)Jiangsu Province Natural Science Fund (BK2008532)
文摘The durability of three-way catalyst （TWC） and corresponding close-coupled catalyst （CCC） for Euro Ⅳ stage regulation was investigated through Vehicle Road Running Mode tests, whereas emissions of regulated pollutants of three car fleet were investigated at every 100,000 km miles. The results showed that HC, NOx, and CO emission values could meet Euro Ⅳ regulation limits at every point. The redox properties of TWC and CCC were measured by CO reduction during each isothermal. It was obvious that both aged TWC and aged CCC behaved a good redox property at 673 and 773 K. Based on XRD and BET measurement results, TWC and CCC washcoat were characterized with good thermal stability.
