Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for ...Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.展开更多
The potential accumulation of platinum group elements(PGE)in the environment from automobile catalysts is high in urban areas,with the major sinks being roadside soils.Therefore,this investigation presented the detail...The potential accumulation of platinum group elements(PGE)in the environment from automobile catalysts is high in urban areas,with the major sinks being roadside soils.Therefore,this investigation presented the detailed study on characterized concentrations of Pt and Pd and their enrichment ratios in urban roadside soils in Xuzhou,China in March 2003.Data from 21 roadside topsoil samples analyzed by inductively coupled plasmamass spectrometer(ICP-MS)illustrated that the medians of concentrations of Pt and Pd were 2.9 and 2.8 ng/g,respectively.Hierarchical clustering analysis indicated that Pt and Pd were mainly from traffic emissions.Compared to unpolluted soils,computation of Pt and Pd enrichment ratios suggested that the Xuzhou roadside soils had average enrichment factors of 3.53 for Pt(in range of 1.22–5.73)and of 3.37 for Pd(in range of 1.35–4.46).Lower Pt/Pd ratios(in range of 0.35–2.86)in relation to similar studies in other countries were observed,which might be due to the different Pt/Pd ratios in Chinese automobile catalytic converters.Moreover,fine fraction(,250 mm)contained higher concentrations of Pt and Pd compared to the coarse fraction(250–500 mm).展开更多
A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sen...A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sensors. An enhancement on the electrocatalytic activity of the palladium nanoparticles toward H2O2 reduction was observed, which was related to the coverage of the carbon nanoparticles. With one monolayer of carbon nanoparticles, the H2O2 detection sensitivity reached the maximum, which was more than twice of that of the pure Pd nanoparticles.展开更多
Ay one of the most common transition metal catalysts,mononuclear palladium catalysts have been develped systematcally and a widely recognizedcatalytic mechanism featured with a pd/Pd catalytic cycle for a palladium ce...Ay one of the most common transition metal catalysts,mononuclear palladium catalysts have been develped systematcally and a widely recognizedcatalytic mechanism featured with a pd/Pd catalytic cycle for a palladium center has been proposed.However,recent research works have revealed thatpalladium clusters may also be catalysts or catalyti intermediates involved in the catalytic processes.This major discovery brings new perspectives for adeep and comprehensive understanding of the PRd-catalyzed reaction mechanisms.Combining with the latest advances in the field of organometllicchemistry,we here highlight the synthesis,structures,and catalytic reactivities of palladium custer compounds.This reviw discusses severalwel-defined syntheticstrategies and diversepalladum cluster-based catalytic systems in detail,to provide insights into the rational design of promisingpalladium cluster catalysts and the effective search for appropriate synthetic methods.展开更多
Infrared spectra of mass-selected homoleptic dinuclear palladium carbonyl cluster cations Pd2（CO）n （n=5 8） are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The ...Infrared spectra of mass-selected homoleptic dinuclear palladium carbonyl cluster cations Pd2（CO）n （n=5 8） are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The structures are established by comparison of the experimental spectra with simulated spectra derived from density functional calculations. The Pd2（CO）＋ cation is characterized to have two weakly semibridging CO groups with C2 symmetry. The Pd2（CO）6＋ and Pd2（CO）7＋ cations are determined to involve one weakly semibridging CO group. The Pd2（CO）8＋ cation is a CO coordination saturated cluster, which is determined to have a D2d structure with all of the carbonyl groups terminally bonded. Bonding analysis indicates that these cluster cations each has a Pd--Pd half bond. The Pd--Pd distance increases with the number of CO ligands.展开更多
基金supported by the National Natural Science Foundation of China (90922022)the Foundation of State Key Laboratory of Coal Combustion of Huazhong University of Science and Technology (FSKLCC1110)the Natural Science Foundation of Fujian Province,China (2012J01032,2012J01041)
文摘Oxide-supported transition metal systems have been the subject of enormous interest due to the improvement of catalytic properties relative to the separate metal.Thus in this paper,we embark on a systematic study for Pd n （n=1-5） clusters adsorbed on TiO2 （110） surface based on DFT-GGA calculations utilizing periodic supercell models.A single Pd adatom on the defect-free surface prefers to adsorb at a hollow site bridging a protruded oxygen and a five-fold titanium atom along the [110] direction,while Pd dimer is located on the channels with the Pd-Pd bond parallel to the surface.According to the transition states （TSs） search,the adsorbed Pd trimer tends to triangular growth mode,rather than linear mode,while the Pd4 and Pd5 clusters prefer three-dimensional （3D） models.However,the oxygen vacancy has almost no influence on the promotion of Pd n cluster nucleation.Additionally,of particular significance is that the Pd-TiO2 interaction is the main driving force at the beginning of Pd nucleation,whereas the Pd-Pd interaction gets down to control the growth process of Pd cluster as the cluster gets larger.It is hoped that our theoretical study would shed light on further designing high-performance TiO2 supported Pd-based catalysts.
基金This work was supported by the Natural Science Foundation of Jiangsu Educational Bureau(No.07KJB610005)the China Postdoctoral Science Foundation(No.20070411029).
文摘The potential accumulation of platinum group elements(PGE)in the environment from automobile catalysts is high in urban areas,with the major sinks being roadside soils.Therefore,this investigation presented the detailed study on characterized concentrations of Pt and Pd and their enrichment ratios in urban roadside soils in Xuzhou,China in March 2003.Data from 21 roadside topsoil samples analyzed by inductively coupled plasmamass spectrometer(ICP-MS)illustrated that the medians of concentrations of Pt and Pd were 2.9 and 2.8 ng/g,respectively.Hierarchical clustering analysis indicated that Pt and Pd were mainly from traffic emissions.Compared to unpolluted soils,computation of Pt and Pd enrichment ratios suggested that the Xuzhou roadside soils had average enrichment factors of 3.53 for Pt(in range of 1.22–5.73)and of 3.37 for Pd(in range of 1.35–4.46).Lower Pt/Pd ratios(in range of 0.35–2.86)in relation to similar studies in other countries were observed,which might be due to the different Pt/Pd ratios in Chinese automobile catalytic converters.Moreover,fine fraction(,250 mm)contained higher concentrations of Pt and Pd compared to the coarse fraction(250–500 mm).
基金supported by the National Natural Science Foundation of China(No.11627806 and No.61301015)supported by a Project funded by the Priority Academic Programme Development of Jiangsu Higher Education Institutions
文摘A nanocomposite electrocatalyst was prepared with the method of cluster beam deposition of palladium nanoparticle thin lms on carbon nanoparticle supporting layers and used as sensitive nonenzyme hydrogen peroxide sensors. An enhancement on the electrocatalytic activity of the palladium nanoparticles toward H2O2 reduction was observed, which was related to the coverage of the carbon nanoparticles. With one monolayer of carbon nanoparticles, the H2O2 detection sensitivity reached the maximum, which was more than twice of that of the pure Pd nanoparticles.
基金National Natural Science Foundation of China (Nos.21772111,21821001,91956125 and 21661132006)the Top-Notch YoungTalents Program of China are gratefully acknowledged.
文摘Ay one of the most common transition metal catalysts,mononuclear palladium catalysts have been develped systematcally and a widely recognizedcatalytic mechanism featured with a pd/Pd catalytic cycle for a palladium center has been proposed.However,recent research works have revealed thatpalladium clusters may also be catalysts or catalyti intermediates involved in the catalytic processes.This major discovery brings new perspectives for adeep and comprehensive understanding of the PRd-catalyzed reaction mechanisms.Combining with the latest advances in the field of organometllicchemistry,we here highlight the synthesis,structures,and catalytic reactivities of palladium custer compounds.This reviw discusses severalwel-defined syntheticstrategies and diversepalladum cluster-based catalytic systems in detail,to provide insights into the rational design of promisingpalladium cluster catalysts and the effective search for appropriate synthetic methods.
文摘Infrared spectra of mass-selected homoleptic dinuclear palladium carbonyl cluster cations Pd2（CO）n （n=5 8） are measured via infrared photodissociation spectroscopy in the carbonyl stretching frequency region. The structures are established by comparison of the experimental spectra with simulated spectra derived from density functional calculations. The Pd2（CO）＋ cation is characterized to have two weakly semibridging CO groups with C2 symmetry. The Pd2（CO）6＋ and Pd2（CO）7＋ cations are determined to involve one weakly semibridging CO group. The Pd2（CO）8＋ cation is a CO coordination saturated cluster, which is determined to have a D2d structure with all of the carbonyl groups terminally bonded. Bonding analysis indicates that these cluster cations each has a Pd--Pd half bond. The Pd--Pd distance increases with the number of CO ligands.
基金We thank the financial supports by the National Natural Science Foundation of China (Nos.21221062 and 21521091) and the National Basic Research Program of China (973 program,No.2013CB932800).
