Cerium dioxide(CeO_(2))photocatalysts are used in treating environmental pollution and addressing the energy crisis due to their excellent oxygen storage capacities and abundant oxygen vacancies.In this paper,CeO_(2)p...Cerium dioxide(CeO_(2))photocatalysts are used in treating environmental pollution and addressing the energy crisis due to their excellent oxygen storage capacities and abundant oxygen vacancies.In this paper,CeO_(2)precursors were synthesized with different water-alcohol ratios via a solvothermal method,and CeO_(2)photocatalysts with different Ce^(3+)/Ce^(4+)ratios were obtained by changing the precursor calcination atmospheres(air,Ar)as well as the calcination time.The effects of CeO_(2)with different Ce^(3+)/Ce^(4+)ratios in photocatalytic degradations of methylene blue under visible light were investigated.X-ray photoelectron spectroscopy results showed that the surfaces of the samples calcined under Ar had higher Ce^(3+)/Ce^(4+)ratios and oxygen vacancy concentrations,which reduced the band gaps of the catalysts and improved their utilization of visible light.In addition,the many Ce^(3+)/Ce^(4+)redox centers and oxygen vacancies on the sample surfaces improved the separation and transfer efficiencies of the photogenerated carriers.The sample C2-Ar calcined under Ar showed a high adsorption capacity and excellent photocatalytic activity by removing 96%of the methylene blue within 120 min,which was more than twice the degradation rate of the sample(C2-air)prepared via calcination under air.Trapping experiments showed that photogenerated holes played a key role in the photocatalytic process.In addition,a synergistic photocatalytic mechanism for the Ce^(3+)/Ce^(4+)redox centers and oxygen vacancies was elucidated in detail,and the sensitization of cerium dioxide by dyes aided the degradation of methylene blue.展开更多
Photocatalytic oxidative desulfurization(PODS)over efficient earth-abundant catalysts to obtain clean fuel oil is of great importance for the environmental protection.In this work,a series of Ce-doped MIL-125-NH_(2)ph...Photocatalytic oxidative desulfurization(PODS)over efficient earth-abundant catalysts to obtain clean fuel oil is of great importance for the environmental protection.In this work,a series of Ce-doped MIL-125-NH_(2)photocatalysts were successfully prepared via a simple in-situ doping method and exhibited superior PODS performance of dibenzothiophene(DBT)under mild reaction conditions.The 1.0 mol%Ce/MIL-125-NH_(2)catalyst achieved 100%sulfur removal within 22 min at 30℃ under visible light illumination,which is mainly attributed to the high surface area and the formation of Ce-Ti-oxo clusters due to electronic coupling.The valence transformation of Ce^(4+)/Ce^(3+)and Ti^(4+)/Ti^(3+)redox mediators could not only expose abundant Lewis acid sites,but also promote the separation and transfer of photogenerated charges.In addition,increasing the reaction temperature has been demonstrated to be effective in promoting the PODS performance.Additionally,a thermo-enhanced PODS mechanism was proposed over Ce/MIL-125-NH_(2),demonstrating the great potential of thermal energy to promote the desulfurization activity.展开更多
Lithium cobalt oxide(LiCoO_(2))is proverbially employed as cathode materials of lithium-ion batteries attributed to the high theoretical capacity,and currently,it is developing towards higher cut-off voltages in the p...Lithium cobalt oxide(LiCoO_(2))is proverbially employed as cathode materials of lithium-ion batteries attributed to the high theoretical capacity,and currently,it is developing towards higher cut-off voltages in the pursuit of higher energy density.However,it suffers from serious structural degradation and surface side reactions,in particular,at the voltage above 4.60 V,leading to rapid decay of the battery life.Taking into account the desirable oxygen buffering property and the fast ion mobility characteristic of cerium oxide fluoride,in this work,we prepared Ce&F co-modified LiCoO_(2)by using the precursors of Ce(NO_(3))_(3)·6H_(2)O and NH_(4)F,and evaluated the electrochemical performance under voltages exceeding 4.60 V.The results indicated that the modified samples have multiphase heterostructure of surface CeO_(2-x)and unique Ce-O-F solid solution phase.At 3.0–4.60 V and 25℃,the preferred sample LCO-0.5Ce-0.3F has a high initial discharge specific capacity of 221.9 mA h g^(-1)at 0.1 C,with the retention of 80.3%and 89.6%after 300 cycles at 1 and 5 C,comparing with the pristine LCO(56.4%and 22.6%).And at 3.0–4.65 V,its retention is 64.0%after 300 cycles at 1 C,versus 8.5%of the pristine LCO.Through structural characterizations and DFT calculations,it suggests that Ce^(4+)&F^(-)co-doping suppresses the H3 to H1/3 irreversible phase transition,stabilizes the lattice structure,and reduces the redox activity of the lattice oxygen by modulating the Co 3d–O 2p energy band,consequently improving the electrochemical performance of LiCoO_(2)at high voltages.展开更多
BACKGROUND This is the first documentation of a spontaneous and nonspecific chemical reaction of an iodinated contrast media with ammonium persulfate used in As3+-Ce4+catalytic spectrophotometry for urine iodine conce...BACKGROUND This is the first documentation of a spontaneous and nonspecific chemical reaction of an iodinated contrast media with ammonium persulfate used in As3+-Ce4+catalytic spectrophotometry for urine iodine concentration(UIC)detection.CASE SUMMARY We herein report an incidental case who had a dual source computed tomography examination for papillary thyroid carcinoma diagnosis.Serial spot urine specimens were collected during her hospitalization and were measured by As3+-Ce4+catalytic spectrophotometry on a Beckman Coulter AU5800.The reacted solutions were“brownish”,and the results showed extremely high iodine concentrations despite serial dilutions.The patient claimed no dietary habit of iodized salt or iodine-containing medical history,which strongly pointed to iodinated contrast media(ICM)via intravenous injection.Even with 0.01%ICM,its interruption is still profound on the desired urine iodine reaction with ammonium persulfate,leading to inaccurate UIC and possibly inappropriate treatment.CONCLUSION The following laboratory suggestions should be considered:(1)As3+-Ce4+catalytic spectrophotometry is only suitable for UIC measurement after confirmed ICM renal clearance;(2)A mass spectrometry-based method can be applied as an alternative during the ICM clearance period;and(3)The UIC baseline can be confirmed after ICM injection by consecutive detection for at least 2 mo.展开更多
It is found through experiments that metallic chromium coating with fine grained and compact crystal structure and high lustre degree can be obtained at near room temperatures by addition of 1.2g.L-1 Ce4+ ion in a cli...It is found through experiments that metallic chromium coating with fine grained and compact crystal structure and high lustre degree can be obtained at near room temperatures by addition of 1.2g.L-1 Ce4+ ion in a clirondum plating bath containing 200g.L-1 CrO3 and 2g.L-1 H2SO4. As compared with the traditional chromium plating technology, the new technology can decrease the CrO3 concentration in the plating bath by one-fifth, and decrease the operating temperature by about 30 degrees. The results of X-ray diffeaction experiments reveal that the electrocrystallization of metallic chromium in the coating is orientated along the (200) crystal plane. Hence, the coating eAnbits high degree of lustre. The results of cathodic polarization curve and differential capactiance curve mesearements show that Ce4+ ion can be adsorbed specifically on the cathode surface. This increases the cathodic polarization value and thus malles the rate of nucleation much faster than that of crystal growth, leading to the formation of fine grained chromium coating. Consequently, the lustre degree of the chromium coating is increased.展开更多
Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and a...Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and atmospheric pressure. The adsorbents were characterized by XRD, XRF and pyridine infrared spectrum （IR）. The adsorption experiments show that the desulfurization performance of Ce（IV）Y is much better than that of NaY. The sulfur removal over both NaY and Ce（IV）Y decreases with the increase of toluene concentration in MG, however, the decline tendency on Ce（IV）Y is smooth, and it is steep on NaY. FT-IR spectra of thiophene adsorption indicate that thiophene molecules are mainly adsorbed on NaY via π electron interaction, but on Ce（IV）Y, in addition to the π electron interaction, both Ce^4＋-S direct interaction and protonation of thiophene also play important roles. Toluene molecules are adsorbed on NaY also via π electron interaction. Although the amount of Bronsted acid sites is increased due to the introduction of Ce^4＋ ions into NaY zeolite, it is not found to influence the adsorption mode of toluene over Ce（IV）Y. Compared with NaY zeolite, the improved desulfurization performance over Ce（IV）Y for removing organic sulfur compounds from MG solution, especially those containing large amount of aromatics, may be ascribed to the direct Ce（IV）-S interaction, which is much resistant to the influence resulted from toluene adsorption.展开更多
The purpose of this work is to explore the effects of the introduction methods of Ce^4+and Zr^4+on the physicochemical properties,activity,and K tolerance of V2 O5-WO3/TiO2 catalyst for the selective catalytic reducti...The purpose of this work is to explore the effects of the introduction methods of Ce^4+and Zr^4+on the physicochemical properties,activity,and K tolerance of V2 O5-WO3/TiO2 catalyst for the selective catalytic reduction of NOx by NH3.Four different methods,namely pre-impregnation,post-impregnation,coimpregnation,and co-precipitation,were used to synthesize a series of V2 O5-WO3-TiO2-CeO2-ZrO2 catalysts.The catalysts were characterized by XRD,BET,NH3-TPD,XPS,and H2-TPR techniques.Moreover,the activity and anti-K poisoning performance were tested by an NH3-SCR model reaction.The results show that the introduction of Ce^4+and Zr^4+can improve the catalytic performance of V2O5-WO3/TiO2 catalyst,but the impregnation method cannot enhance the anti-K poisoning performance.Ce^4+and Zr^4+introduced by co-precipitation method can effectively improve the tolerance of K,which is mainly due to the incorporation of Ce^4+and Zr^4+into TiO2 lattice to form a uniform TiO2-CeO2-ZrO2 solid solution,resulting in the optimal surface acidity and redox performance,and reducing the decreases caused by Kpoisoning.Furthermore,based on the best introduction method,we further optimized the molar ratio of Ce^4+/Zr^4+,It is found that the catalyst exhibits the best anti-K poisoning performance when the molar ratio of Ce^4+/Zr^4+is 2:1.展开更多
基金supported by National Natural Science Foundation of China(Grant No.51974168)Science and Technology Major Project Inner Mongolia Autonomous Region in China(Grant Nos.2019ZD023 and 2021ZD0028)State Key Laboratory of Silicate Materials for Architectures(Wuhan University of Technology)(Grant No.SYSJJ2020-08).
文摘Cerium dioxide(CeO_(2))photocatalysts are used in treating environmental pollution and addressing the energy crisis due to their excellent oxygen storage capacities and abundant oxygen vacancies.In this paper,CeO_(2)precursors were synthesized with different water-alcohol ratios via a solvothermal method,and CeO_(2)photocatalysts with different Ce^(3+)/Ce^(4+)ratios were obtained by changing the precursor calcination atmospheres(air,Ar)as well as the calcination time.The effects of CeO_(2)with different Ce^(3+)/Ce^(4+)ratios in photocatalytic degradations of methylene blue under visible light were investigated.X-ray photoelectron spectroscopy results showed that the surfaces of the samples calcined under Ar had higher Ce^(3+)/Ce^(4+)ratios and oxygen vacancy concentrations,which reduced the band gaps of the catalysts and improved their utilization of visible light.In addition,the many Ce^(3+)/Ce^(4+)redox centers and oxygen vacancies on the sample surfaces improved the separation and transfer efficiencies of the photogenerated carriers.The sample C2-Ar calcined under Ar showed a high adsorption capacity and excellent photocatalytic activity by removing 96%of the methylene blue within 120 min,which was more than twice the degradation rate of the sample(C2-air)prepared via calcination under air.Trapping experiments showed that photogenerated holes played a key role in the photocatalytic process.In addition,a synergistic photocatalytic mechanism for the Ce^(3+)/Ce^(4+)redox centers and oxygen vacancies was elucidated in detail,and the sensitization of cerium dioxide by dyes aided the degradation of methylene blue.
基金supported by the National Key Research and Development Program of China(No.2021YFB3500700)the National Natural Science Foundation of China(No.21976054)Fundamental Research Funds for the Central Universities(No.FRFTP-20-005A3)。
文摘Photocatalytic oxidative desulfurization(PODS)over efficient earth-abundant catalysts to obtain clean fuel oil is of great importance for the environmental protection.In this work,a series of Ce-doped MIL-125-NH_(2)photocatalysts were successfully prepared via a simple in-situ doping method and exhibited superior PODS performance of dibenzothiophene(DBT)under mild reaction conditions.The 1.0 mol%Ce/MIL-125-NH_(2)catalyst achieved 100%sulfur removal within 22 min at 30℃ under visible light illumination,which is mainly attributed to the high surface area and the formation of Ce-Ti-oxo clusters due to electronic coupling.The valence transformation of Ce^(4+)/Ce^(3+)and Ti^(4+)/Ti^(3+)redox mediators could not only expose abundant Lewis acid sites,but also promote the separation and transfer of photogenerated charges.In addition,increasing the reaction temperature has been demonstrated to be effective in promoting the PODS performance.Additionally,a thermo-enhanced PODS mechanism was proposed over Ce/MIL-125-NH_(2),demonstrating the great potential of thermal energy to promote the desulfurization activity.
基金partially supported by the Major Program of the National Natural Science Foundation of China(No.22090034)the Haihe Laboratory of Sustainable Chemical Transformations for financial support。
文摘Lithium cobalt oxide(LiCoO_(2))is proverbially employed as cathode materials of lithium-ion batteries attributed to the high theoretical capacity,and currently,it is developing towards higher cut-off voltages in the pursuit of higher energy density.However,it suffers from serious structural degradation and surface side reactions,in particular,at the voltage above 4.60 V,leading to rapid decay of the battery life.Taking into account the desirable oxygen buffering property and the fast ion mobility characteristic of cerium oxide fluoride,in this work,we prepared Ce&F co-modified LiCoO_(2)by using the precursors of Ce(NO_(3))_(3)·6H_(2)O and NH_(4)F,and evaluated the electrochemical performance under voltages exceeding 4.60 V.The results indicated that the modified samples have multiphase heterostructure of surface CeO_(2-x)and unique Ce-O-F solid solution phase.At 3.0–4.60 V and 25℃,the preferred sample LCO-0.5Ce-0.3F has a high initial discharge specific capacity of 221.9 mA h g^(-1)at 0.1 C,with the retention of 80.3%and 89.6%after 300 cycles at 1 and 5 C,comparing with the pristine LCO(56.4%and 22.6%).And at 3.0–4.65 V,its retention is 64.0%after 300 cycles at 1 C,versus 8.5%of the pristine LCO.Through structural characterizations and DFT calculations,it suggests that Ce^(4+)&F^(-)co-doping suppresses the H3 to H1/3 irreversible phase transition,stabilizes the lattice structure,and reduces the redox activity of the lattice oxygen by modulating the Co 3d–O 2p energy band,consequently improving the electrochemical performance of LiCoO_(2)at high voltages.
基金Supported by the“The Six Top Talent Project”of Jiangsu Province,No.WSW-004the Key Laboratory for Laboratory Medicine of Jiangsu Province of China,No.ZDXKB2016005。
文摘BACKGROUND This is the first documentation of a spontaneous and nonspecific chemical reaction of an iodinated contrast media with ammonium persulfate used in As3+-Ce4+catalytic spectrophotometry for urine iodine concentration(UIC)detection.CASE SUMMARY We herein report an incidental case who had a dual source computed tomography examination for papillary thyroid carcinoma diagnosis.Serial spot urine specimens were collected during her hospitalization and were measured by As3+-Ce4+catalytic spectrophotometry on a Beckman Coulter AU5800.The reacted solutions were“brownish”,and the results showed extremely high iodine concentrations despite serial dilutions.The patient claimed no dietary habit of iodized salt or iodine-containing medical history,which strongly pointed to iodinated contrast media(ICM)via intravenous injection.Even with 0.01%ICM,its interruption is still profound on the desired urine iodine reaction with ammonium persulfate,leading to inaccurate UIC and possibly inappropriate treatment.CONCLUSION The following laboratory suggestions should be considered:(1)As3+-Ce4+catalytic spectrophotometry is only suitable for UIC measurement after confirmed ICM renal clearance;(2)A mass spectrometry-based method can be applied as an alternative during the ICM clearance period;and(3)The UIC baseline can be confirmed after ICM injection by consecutive detection for at least 2 mo.
文摘It is found through experiments that metallic chromium coating with fine grained and compact crystal structure and high lustre degree can be obtained at near room temperatures by addition of 1.2g.L-1 Ce4+ ion in a clirondum plating bath containing 200g.L-1 CrO3 and 2g.L-1 H2SO4. As compared with the traditional chromium plating technology, the new technology can decrease the CrO3 concentration in the plating bath by one-fifth, and decrease the operating temperature by about 30 degrees. The results of X-ray diffeaction experiments reveal that the electrocrystallization of metallic chromium in the coating is orientated along the (200) crystal plane. Hence, the coating eAnbits high degree of lustre. The results of cathodic polarization curve and differential capactiance curve mesearements show that Ce4+ ion can be adsorbed specifically on the cathode surface. This increases the cathodic polarization value and thus malles the rate of nucleation much faster than that of crystal growth, leading to the formation of fine grained chromium coating. Consequently, the lustre degree of the chromium coating is increased.
基金supported by the Fundamental Research Funds for the Key Universities (Grant No. DUT10LK25)the National Natural Science Foundation of China (Grant No. 21106014)
文摘Zeolites NaY and Ce（IV）Y were employed as adsorbents to remove organic sulfur compounds from model gasoline （MG） solutions with and without toluene in static adsorption experiments at room temperature （RT） and atmospheric pressure. The adsorbents were characterized by XRD, XRF and pyridine infrared spectrum （IR）. The adsorption experiments show that the desulfurization performance of Ce（IV）Y is much better than that of NaY. The sulfur removal over both NaY and Ce（IV）Y decreases with the increase of toluene concentration in MG, however, the decline tendency on Ce（IV）Y is smooth, and it is steep on NaY. FT-IR spectra of thiophene adsorption indicate that thiophene molecules are mainly adsorbed on NaY via π electron interaction, but on Ce（IV）Y, in addition to the π electron interaction, both Ce^4＋-S direct interaction and protonation of thiophene also play important roles. Toluene molecules are adsorbed on NaY also via π electron interaction. Although the amount of Bronsted acid sites is increased due to the introduction of Ce^4＋ ions into NaY zeolite, it is not found to influence the adsorption mode of toluene over Ce（IV）Y. Compared with NaY zeolite, the improved desulfurization performance over Ce（IV）Y for removing organic sulfur compounds from MG solution, especially those containing large amount of aromatics, may be ascribed to the direct Ce（IV）-S interaction, which is much resistant to the influence resulted from toluene adsorption.
基金Project supported by the National Natural Science Foundation of China(21876168)the Key Projects for Common Key Technology Innovation in Key Industries in Chongqing(cstc2016zdcy-ztzx0020-01)+1 种基金Youth Innovation Promotion Association CAS(2019376)the Graduate Innovation Project of Chongqing Technology and Business University(yjscxx201803-028-22)。
文摘The purpose of this work is to explore the effects of the introduction methods of Ce^4+and Zr^4+on the physicochemical properties,activity,and K tolerance of V2 O5-WO3/TiO2 catalyst for the selective catalytic reduction of NOx by NH3.Four different methods,namely pre-impregnation,post-impregnation,coimpregnation,and co-precipitation,were used to synthesize a series of V2 O5-WO3-TiO2-CeO2-ZrO2 catalysts.The catalysts were characterized by XRD,BET,NH3-TPD,XPS,and H2-TPR techniques.Moreover,the activity and anti-K poisoning performance were tested by an NH3-SCR model reaction.The results show that the introduction of Ce^4+and Zr^4+can improve the catalytic performance of V2O5-WO3/TiO2 catalyst,but the impregnation method cannot enhance the anti-K poisoning performance.Ce^4+and Zr^4+introduced by co-precipitation method can effectively improve the tolerance of K,which is mainly due to the incorporation of Ce^4+and Zr^4+into TiO2 lattice to form a uniform TiO2-CeO2-ZrO2 solid solution,resulting in the optimal surface acidity and redox performance,and reducing the decreases caused by Kpoisoning.Furthermore,based on the best introduction method,we further optimized the molar ratio of Ce^4+/Zr^4+,It is found that the catalyst exhibits the best anti-K poisoning performance when the molar ratio of Ce^4+/Zr^4+is 2:1.
