N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalyst...N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalysts, Pt/BaO/Al2O3, Pt/Pd mechanical mixing catalyst （Pt/BaO/Al203 ＋ Pd/Al2O3） and Pt-Pd co-impregnation catalyst （Pt-Pd/BaO/Al2O3） were prepared by incipient wetness imoreenation method. These catalysts were first evaluated in NSR activity tests using H2/CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H2-TPR techniques. In addition, temperature programmed reactions of NO with H2/CO were conducted to obtain further information about NzO formation mechanism. Compared with Pt/BaO/Al2O3 （Pt/BaO/Al2O3 ＋ Pd/Al2O3） produced less N2O and more NH3 during NOx storage and reduction process, while an opposite trend was found over （Pt-Pd/BaO/Al2O3 ＋ Al2O3）. Temperature programmed reactions of NO with H2/CO results showed that Pd/Al2O3 component in （Pt/BaO/Al2O3 ＋ Pd/Al2O3） played an important role in NO reduction to NH3, and the formed NH3 could reduce NOx to N2 leading to a decrease in N2O formation. Most of N2O formed over （Pt-Pd/BaO/Al2O3 ＋ Al2O3） was originated from Pd/BaO/Al2O3 component. H2-TPR results indicated Pd-Ba interaction resulted in more difficult- to-reduce PdOx species over Pd/BaO/Al2O3, which inhibits the NO dissociation and thus drives the selectivity to N2O in NO reduction.展开更多
Pd-based catalysts are extensively employed to catalyze CO oxidative coupling to generate DMO,while the expensive price and high usage of Pd hinder its massive application in industrial production.Designing Pd-based c...Pd-based catalysts are extensively employed to catalyze CO oxidative coupling to generate DMO,while the expensive price and high usage of Pd hinder its massive application in industrial production.Designing Pd-based catalysts with high efficiency and low Pd usage as well as expounding the catalytic mechanisms are significant for the reaction.In this study,we theoretically predict that Pd stripe doping Co(111)surface exhibits excellent performance than pure Pd(111),Pd monolayer supporting on Co(111)and Pd single atom doping Co(111)surface,and clearly expound the catalytic mechanisms through the density functional theory(DFT)calculation and micro-reaction kinetic model analysis.It is obtained that the favorable reaction pathway is COOCH_(3)-COOCH_(3)coupling pathway over these four catalysts,while the rate-controlling step is COOCH_(3)+CO+OCH_(3)→2COOCH_(3)on Pd stripe doping Co(111)surface,which is different from the case(2COOCH_(3)→DMO)on pure Pd(111),Pd monolayer supporting on Co(111)and Pd single atom doping Co(111)surface.This study can contribute a certain reference value for developing Pd-based catalysts with high efficiency and low Pd usage for CO oxidative coupling to DMO.展开更多
LaFe（1-x-y）CoxPdyO3 [（x, y） =（0, 0）,（0.40, 0）,（0.38, 0.05）] nanoparticles were synthesized via a co-precipitation route using ammonium hydroxide, sodium hydroxide and ammonium carbonate as the precipitant an...LaFe（1-x-y）CoxPdyO3 [（x, y） =（0, 0）,（0.40, 0）,（0.38, 0.05）] nanoparticles were synthesized via a co-precipitation route using ammonium hydroxide, sodium hydroxide and ammonium carbonate as the precipitant and calcination at different temperatures to study the compositional driven structural changes in lanthanum ferrites.Analysis of X-ray diffraction（XRD） patterns confirms the formation of single-phase perovskite structure and existence of orthorhombic Pnma symmetry for calcined powders. Field emission scanning electron microscope（FESEM） observations show that Pd-doped powders yield finer particles along with narrower particle size distribution compared with LaFeO3 and LaFe（0.6）Co（0.4）O3. Moreover,using ammonia as the precipitant leads to a smaller mean particle size of powders compared to NaOH, as well as significant difference in morphology of the particles.Raman analysis reveals that both Co and Pd atoms substitute Fe site in perovskite structure with shifting of phonon modes. Comparing Raman spectra demonstrates the presence of more oxygen vacancies in Pd-doped perovskites. It can be concluded from the results that Pd is successfully incorporated into the perovskite structure by co-precipitation method.展开更多
The chlorine evolution reaction(CER)serves as the cornerstone and crucial step in the conversion of chloride ions to chlorine gas,while accompanied by the occurrence of the oxygen evolution reaction(OER)in practical p...The chlorine evolution reaction(CER)serves as the cornerstone and crucial step in the conversion of chloride ions to chlorine gas,while accompanied by the occurrence of the oxygen evolution reaction(OER)in practical processes that lead to difficulty in achieving the purity requirements of the product Cl_(2)for industrial applications.Pd-doped Co_(3)O_(4) nanoneedles(Pd-Co_(3)O_(4)NNs)were synthesized via hydrothermal-calcination methods.Pd sites induce electron delocalization,creating asymmetric active Co sites in Co_(3)O_(4),enhancing CER performance.The unique nanoneedle arrays of the designed catalysts increase the number of exposed active sites,facilitating electron transfer and endowing the Pd-Co_(3)O_(4)NNs with a tip catalytic effect,further optimizing the catalytic reaction kinetics of CER with an overpotential of 118 mV at 100 mA cm^(-2)and a Tafel slope of 53.93 mV dec^(-1).The density functional theory(DFT)calculations reveal that Pd incorporation at octahedral sites triggers charge redistribution and d-band center downshift,weakening intermediate adsorption and sustaining catalytic activity.This work offers new insights into noble-metal-doped spinel oxides,highlighting their potential for industrial applications.展开更多
Efficient chemicalwarfare agents(CWAs)detection is required to protect people from the cWAs in war and terrorism.In this work,a Pd-doped SnO_(2)nanoparticles-based gas sensor was developed to detect a nerve agent simu...Efficient chemicalwarfare agents(CWAs)detection is required to protect people from the cWAs in war and terrorism.In this work,a Pd-doped SnO_(2)nanoparticles-based gas sensor was developed to detect a nerve agent simulant named methyl salicylate.The sensing measurements of methyl salicylate under different Pd doping amounts found that the 0.5 at.%Pd-doped SnO_(2)exhibited a significant improvement in the detection of methyl salicylate at the ppb(1ppb=10-9)level,and the response value to 160 ppb methyl salicylate is 0.72 at 250℃.Compared with the pure SnO_(2),the response value is increased by 4.5 times,which could be attributed to the influence of the noble metal Pd on the oxygen state and its catalytic effect.In addition,the 0.5at.%Pd-doped SnO_(2)sensor still has an obvious response to 16ppb methyl salicylate with a response value of 0.13,indicating the lower detection limit of the sensor.展开更多
基金Acknowledgements This work was financially supported by the National Key Research and Development Program （No. 2017YFC0211002） and the National Natural Science Foundation of China （Grant No. 21476170）.
文摘N2O is a powerful greenhouse gas and plays an important role in destructing the ozone layer. This present work investigated the effects of Pd doping on N2O formation over Pt/BaO/Al2O3 catalyst. Three types of catalysts, Pt/BaO/Al2O3, Pt/Pd mechanical mixing catalyst （Pt/BaO/Al203 ＋ Pd/Al2O3） and Pt-Pd co-impregnation catalyst （Pt-Pd/BaO/Al2O3） were prepared by incipient wetness imoreenation method. These catalysts were first evaluated in NSR activity tests using H2/CO as reductants and then carefully characterized by BET, CO chemisorption, CO-DRIFTs and H2-TPR techniques. In addition, temperature programmed reactions of NO with H2/CO were conducted to obtain further information about NzO formation mechanism. Compared with Pt/BaO/Al2O3 （Pt/BaO/Al2O3 ＋ Pd/Al2O3） produced less N2O and more NH3 during NOx storage and reduction process, while an opposite trend was found over （Pt-Pd/BaO/Al2O3 ＋ Al2O3）. Temperature programmed reactions of NO with H2/CO results showed that Pd/Al2O3 component in （Pt/BaO/Al2O3 ＋ Pd/Al2O3） played an important role in NO reduction to NH3, and the formed NH3 could reduce NOx to N2 leading to a decrease in N2O formation. Most of N2O formed over （Pt-Pd/BaO/Al2O3 ＋ Al2O3） was originated from Pd/BaO/Al2O3 component. H2-TPR results indicated Pd-Ba interaction resulted in more difficult- to-reduce PdOx species over Pd/BaO/Al2O3, which inhibits the NO dissociation and thus drives the selectivity to N2O in NO reduction.
基金financially supported by the National Key Research and Development Program of China(2021YFA1502804)the Regional Innovation and Development Joint Fund of the National Natural Science Foundation of China(U22A20430)+3 种基金the Shanxi-Zheda Institute of Advanced Materials and Chemical Engineering(2022SX-FR001)the Natural Science Foundation of Shanxi Province(202203021212201)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxithe Foundation of Taiyuan University of Technology(2022QN138)
文摘Pd-based catalysts are extensively employed to catalyze CO oxidative coupling to generate DMO,while the expensive price and high usage of Pd hinder its massive application in industrial production.Designing Pd-based catalysts with high efficiency and low Pd usage as well as expounding the catalytic mechanisms are significant for the reaction.In this study,we theoretically predict that Pd stripe doping Co(111)surface exhibits excellent performance than pure Pd(111),Pd monolayer supporting on Co(111)and Pd single atom doping Co(111)surface,and clearly expound the catalytic mechanisms through the density functional theory(DFT)calculation and micro-reaction kinetic model analysis.It is obtained that the favorable reaction pathway is COOCH_(3)-COOCH_(3)coupling pathway over these four catalysts,while the rate-controlling step is COOCH_(3)+CO+OCH_(3)→2COOCH_(3)on Pd stripe doping Co(111)surface,which is different from the case(2COOCH_(3)→DMO)on pure Pd(111),Pd monolayer supporting on Co(111)and Pd single atom doping Co(111)surface.This study can contribute a certain reference value for developing Pd-based catalysts with high efficiency and low Pd usage for CO oxidative coupling to DMO.
基金financially supported by University of Tehran(No.810729920/6/02)Iran Nanotechnology Initiative Council
文摘LaFe（1-x-y）CoxPdyO3 [（x, y） =（0, 0）,（0.40, 0）,（0.38, 0.05）] nanoparticles were synthesized via a co-precipitation route using ammonium hydroxide, sodium hydroxide and ammonium carbonate as the precipitant and calcination at different temperatures to study the compositional driven structural changes in lanthanum ferrites.Analysis of X-ray diffraction（XRD） patterns confirms the formation of single-phase perovskite structure and existence of orthorhombic Pnma symmetry for calcined powders. Field emission scanning electron microscope（FESEM） observations show that Pd-doped powders yield finer particles along with narrower particle size distribution compared with LaFeO3 and LaFe（0.6）Co（0.4）O3. Moreover,using ammonia as the precipitant leads to a smaller mean particle size of powders compared to NaOH, as well as significant difference in morphology of the particles.Raman analysis reveals that both Co and Pd atoms substitute Fe site in perovskite structure with shifting of phonon modes. Comparing Raman spectra demonstrates the presence of more oxygen vacancies in Pd-doped perovskites. It can be concluded from the results that Pd is successfully incorporated into the perovskite structure by co-precipitation method.
基金supported by the National Natural Science Foundation of China(Grant Nos.52402273,52272222,52072197)Youth Innovation Team Development Program of Shandong Higher Education Institutions(Grant No.2022KJ155)Taishan Scholar Young Talent Program(Grant No.tsqn201909114)。
文摘The chlorine evolution reaction(CER)serves as the cornerstone and crucial step in the conversion of chloride ions to chlorine gas,while accompanied by the occurrence of the oxygen evolution reaction(OER)in practical processes that lead to difficulty in achieving the purity requirements of the product Cl_(2)for industrial applications.Pd-doped Co_(3)O_(4) nanoneedles(Pd-Co_(3)O_(4)NNs)were synthesized via hydrothermal-calcination methods.Pd sites induce electron delocalization,creating asymmetric active Co sites in Co_(3)O_(4),enhancing CER performance.The unique nanoneedle arrays of the designed catalysts increase the number of exposed active sites,facilitating electron transfer and endowing the Pd-Co_(3)O_(4)NNs with a tip catalytic effect,further optimizing the catalytic reaction kinetics of CER with an overpotential of 118 mV at 100 mA cm^(-2)and a Tafel slope of 53.93 mV dec^(-1).The density functional theory(DFT)calculations reveal that Pd incorporation at octahedral sites triggers charge redistribution and d-band center downshift,weakening intermediate adsorption and sustaining catalytic activity.This work offers new insights into noble-metal-doped spinel oxides,highlighting their potential for industrial applications.
基金supported by the Science and Technology on Aerospace Chemical Power Laboratory,Hubei Institute of Aerospace Chemical Technology(U20B2018)the Open Research Fund Program of Science and Technology on Aerospace Chemical Power Laboratory(STACPL320201B02 and STACPL320181B03-1)the National Natural Science Foundation of China(Nos.61971204 and 51902114).
文摘Efficient chemicalwarfare agents(CWAs)detection is required to protect people from the cWAs in war and terrorism.In this work,a Pd-doped SnO_(2)nanoparticles-based gas sensor was developed to detect a nerve agent simulant named methyl salicylate.The sensing measurements of methyl salicylate under different Pd doping amounts found that the 0.5 at.%Pd-doped SnO_(2)exhibited a significant improvement in the detection of methyl salicylate at the ppb(1ppb=10-9)level,and the response value to 160 ppb methyl salicylate is 0.72 at 250℃.Compared with the pure SnO_(2),the response value is increased by 4.5 times,which could be attributed to the influence of the noble metal Pd on the oxygen state and its catalytic effect.In addition,the 0.5at.%Pd-doped SnO_(2)sensor still has an obvious response to 16ppb methyl salicylate with a response value of 0.13,indicating the lower detection limit of the sensor.
