Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch ...Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch procedure and continuous-flow procedure) were used to study the variations of reaction processing. The heterogeneous catalysts presented excellent reactivity and recyclability for iodobenzene and bromobenzene substrates in batch mode, which can be attributed to stabilization of Pd nanoparticles by the thiol and amino groups on the AC supports. However, significant dehalogenation in the reaction mixture and Pd leaching from the heterogeneous catalysts were observed in continuous-flow mode.This unique phenomenon in continuous-flow mode resulted in a dramatic decline in reaction selectivity and durability of heterogeneous catalysts comparing with that of batch mode. In addition, the heterogeneous Pd catalysts with thiol-and amino-modified AC supports exhibited different reactivity and durability in batch and continuous-flow mode owing to the difference of interaction between Pd species and AC supports.展开更多
Covalent organic frameworks(COFs)have emerged as a class of promising supports for electrocatalysis because of their advantages including good crystallinity,highly ordered pores,and structural diversity.However,their ...Covalent organic frameworks(COFs)have emerged as a class of promising supports for electrocatalysis because of their advantages including good crystallinity,highly ordered pores,and structural diversity.However,their poor conductivity represents the main obstruction to their practical application.Here,we reported a novel synthesis strategy for synergistically endowing a triphenylamine-based COFs with improved electrical conductivity and excellent catalytic activity for oxygen reduction,via the in-situ redox deposition and confined growth of palladium nanoparticles inside the porous structure of COFs using reductive triphenylamine frameworks as reducing agent;meanwhile,the triphenylamine unit was oxidized to radical cation structure and affords radical cation COFs with conductivity as high as3.2*10^(-1) S m^(-1).Such a uniform confine palladium nanoparticle on highly conductive COFs makes it an efficient electrocatalyst for four-electron oxygen reduction reaction(4e-ORR),showing excellent activities and fast kinetics with a remarkable half-wave potential(E_(1/2))of 0.865 V and an ultralow Tafel slope of 39.7 mV dec^(-1) in alkaline media even in the absence of extra commercial conductive fillers.The generality of this strategy was proved by preparing the different metal and metal alloy nanoparticles supported on COFs(Au@COF,Pt@COF,AuPd@COF,AgPd@COF,and PtPd@COF)using reductive triphenylamine frameworks as reducing agent.This work not only provides a facile strategy for the fabrication of highly conductive COF supported ORR electrocatalysts,but also sheds new light on the practical application of Zn-air battery.展开更多
An important area of research in nanotechnology deals with the synthesis of nanoparticles of different chemical compositions,sizes and controlled monodispersity.Currently,there is a growing need to develop environment...An important area of research in nanotechnology deals with the synthesis of nanoparticles of different chemical compositions,sizes and controlled monodispersity.Currently,there is a growing need to develop environmentally benign nanoparticle synthesis in which no toxic chemicals are used in the synthesis protocol.Palladium nanoparticles(Pd Np) are of interest because of their catalytic properties and affinity for hydrogen.Our protocol for the phyto-synthesis of Pd Np under moderate p H and room temperature offers a new means to develop environmentally benign nanoparticles.Solanum trilobatum is enlightened in our present study as it is enriched with phytochemicals to reduce palladium chloride ions.Poly MVA a dietary supplement based on the nontoxic chemotherapeutic lipoic acid-palladium complex(LA-Pd) is been hypothesized as the new paradigm of cancer therapy.Hence forth we successfully conjugated lipoic acid(S-Pd Np-LA) and vitamins(S-Pd Np-Vitamin-LA) to palladium nanoparticles synthesised from Solanum trilobatum leaf extract.These nanoparticles(S-Pd Np,S-Pd Np-LA,S-Pd Np-Vitamin-LA) were characterized with UV-Vis Spectroscopy,SEM and FTIR analysis,which revealed that S-Pd Np are polydisperse and of different morphologies ranging from 60?70 nm(S-Pd Np),65?80 nm(S-Pd Np-LA) and 75?100 nm(S-Pd Np-Vitamin-LA) in size.展开更多
Acrylonitrile reacts with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound arsine palladium(0) complex to afford stereoselectively (E)-cinnamo- nitriles in high yields.
Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen...Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen permeation, type of alloys and the fabrication methods. At last, the progress and achievements on palladium alloy membranes by Northwest Institute for Non-Ferrous Metal Research are emphasized.展开更多
Allylic alcohols react with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound bidentate sulfur palladium (0) complex to form 3-arylaldehydes or ketones in good yields.
The negative effects of hydrogen embrittlement on metallic systems have been investigated through determination of the mechanical properties of two metallic systems that were exposed to hydrogen. An assessment of the ...The negative effects of hydrogen embrittlement on metallic systems have been investigated through determination of the mechanical properties of two metallic systems that were exposed to hydrogen. An assessment of the effects of hydrogen absorption/desorption cycling on the tensile strength, ductility, and microhardness of pure palladium and the alloy palladium-silver (25 weight% silver) has been undertaken. The variables that are the focus of the study are the amount of hydrogen absorbed by the metal, deuterium isotope effect, number of hydrogen absorption/desorption cycles, and the hydrogen exposure temperature. Under all conditions studied, the mechanical properties of pure palladium were significantly altered as a result of hydrogen exposure, with significant hydrogen embrittlement occurring. In contrast, the mechanical properties of the palladium-silver alloy showed little alteration as a result of hydrogen exposure, including virtually no occurrence of hydrogen embrittlement.展开更多
Novel in-situ reduction approach was applied for the synthesis of palladium nanoparticles in the pores of mesoporous silica materials with grafted siliconhydride groups. Matrices possessing different structural proper...Novel in-situ reduction approach was applied for the synthesis of palladium nanoparticles in the pores of mesoporous silica materials with grafted siliconhydride groups. Matrices possessing different structural properties (MCM-41, SBA-15 and Silochrom) were used. Samples were studied by nitrogen adsorption-desorption method, low-angle X-ray diffraction, transmission electron microscopy (TEM) and FT-IR/PAS spectroscopy. The temperature-programmed oxidation (TPO) and reduction (TPR) methods were applied to examine reducibility of palladium species. Palladium containing catalysts were tested in methane oxidation reaction. It was demonstrated that relatively large pores in SBA-15 type silica facilitated formation of well-dispersed palladium nanoparticles confined in the pores channels. In the case of MCM-41 support, metallic palladium nanoparticles were formed on the external surface. The obtained materials showed high catalytic activity. Lower activity of the samples containing small crystallites located in the pore volume at high temperatures was related to worse accessibility of active sites to the reation mixture.展开更多
Dislocation structures in polycrystalline Ni 3Al alloy doped with palladium deformed at room temperature have been investigated by transmission electron microscopy. The structure consists mainly of dislocations dissoc...Dislocation structures in polycrystalline Ni 3Al alloy doped with palladium deformed at room temperature have been investigated by transmission electron microscopy. The structure consists mainly of dislocations dissociated into a /2〈011〉 super partials bounding an anti phase boundary (APB). Dislocations dissociated into a /3〈112〉 super Shockley partials bounding a superlattice intrinsic stacking fault (SISF) are also common debris. The majority of the SISFs are truncated loops, i.e. the partials bounding the SISF are of similar Burgers vector. These faulted loops are generated from APB coupled dislocations, according to a mechanism for formation of SISFs proposed by Suzuki et al , and recently modified by Chiba et al . The APB energies for {111} and {010} slip planes are measured to be 144±20 mJ/m 2 and 102±11 mJ/m 2 respectively, and the SISF energy has been estimated to be 12 mJ/m 2 in this alloy. It is concluded that the dislocation structure in Ni 74.5 Pd 2Al 23.5 alloy deformed at room temperature is similar to that in binary Ni 3Al, and the difference in fault energies between these two alloys is small. Thus, it seems unlikely that the enhancement of ductility of Ni 74.5 Pd 2Al 23.5 results from only such a small decrease of the ordering energy of the alloy. SISF bounding dislocations also have no apparent influence on the ductilization of Ni 74.5 Pd 2Al 23.5 alloy.展开更多
The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface ...The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface of porous ceramic tube. The experimental results shows that the addition of rare earths increases palladium deposition rates and the binary mixtures are superior to the single rare earths and the mixture of ytterbium-lanthanum is the most efficient. Adding the mixture of ytterbium-lanthanum can also reduce the plating temperature by 10~20 ℃, shrink the metal crystal size and improve the film densification compared to those by traditional electroless plating. A thin palladium film with 5 μm was prepared and the film made a highly pure hydrogen with a molar fraction of more than 99.97% from a H2-N2 gas mixture. More attentions were paid to analyze the physical and chemical behaviors of the rare earths in palladium film preparation.展开更多
Pd/YZ-Al2O3 (Y and Zr modified Al2O3, and hereafter, labelled as A1) catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy (XPS), NO-temperature progra...Pd/YZ-Al2O3 (Y and Zr modified Al2O3, and hereafter, labelled as A1) catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy (XPS), NO-temperature programmed desorption (NO-TPD), Nz-adsorption/desorption (Branauer-Emmet-Teller BET method), X-ray diffraction (XRD) and CO-chemisorption. Catalytic activities for CH4, CO and NO conversion were tested in a gas mixture simulated the emissions from natural gas vehicles (NGVs) operated under stoichiometric conditions. The results indicated that all catalysts exhibited excellent catalytic performances for CH4 and CO oxidation and the promoting effect of CeO2 or La2O3 was significant for NO conversion. XPS results showed that the electron density around Pd was increased by CeO2 and/or La2O3, the binding energy of Pd 3d decreased as the order: Pd/Al 〉 Pd/Ce/Al 〉 Pd/La/Al 〉 Pd/CeLa/Al. The electron-rich Pd showed Rh-like catalytic properties which exhibited good activity for the reduction of NO. NO-TPD results showed that the addition of CeO2 and/or La2O3 increased NO adsorption on surface, and promoted the conversion of NO.展开更多
A novel method for the determination of nickel and palladium in environmental samples by low temperature ETV-ICP-OES with dimethylglyoxime(DMG) as both the extractant and chemical modifier has been developed. In thi...A novel method for the determination of nickel and palladium in environmental samples by low temperature ETV-ICP-OES with dimethylglyoxime(DMG) as both the extractant and chemical modifier has been developed. In this study, it was found that nickel and palladium can form complexes with dimethylglyoxime(0. 05%, mass fraction) at pH 6.0 and can be extracted into chloroform quantitatively. The complexes can be evaporated into plasma at a suita-ble temperature( 1400℃) for ICP-OES detection. Under the optimized conditions, the detection limits of nickel and palladium are 0.48 and 0. 40 ng/mL, respectively, while the RSD values are separately 5.0% and 3.1% (p = 50 ng/mL, n = 7). The proposed method was applied to the determination of the target analytes in environmental sam-ples with satisfactory results.展开更多
The Fengshan porphyry-skarn copper-molybdenum (Cu-Mo) deposit is located in the south-eastern Hubei Province in east China. Cu-Mo mineralization is hosted in the Fengshan granodiorite porphyry stock that intruded th...The Fengshan porphyry-skarn copper-molybdenum (Cu-Mo) deposit is located in the south-eastern Hubei Province in east China. Cu-Mo mineralization is hosted in the Fengshan granodiorite porphyry stock that intruded the Triassic Daye Formation carbonate rocks in the early Cretaceous (-140 Ma), as well as the contact zone between granodiorite porphyry stock and carbonate rocks, forming the porphyry-type and skaru-type association. The Fengshan granodiorite stock and the immediate country rocks are strongly fractured and intensely altered by hydrothermal fluids. In addition to intense skarn alteration, the prominent alteration types are potassic, phyllic, and propylitic, whereas argiilation is less common. Mineralization occurs as veins, stock works, and disseminations, and the main ore minerals are chalcopyrite, pyrite, molybdenite, bornite, and magnetite. The contents of palladium, platinum and gold (Pd, Pt and Au) are determined in nine samples from fresh and mineralized granodiorite and different types of altered rocks. The results show that the Pd content is systematically higher than Pt, which is typical for porphyry ore deposits worldwide. The Pt content ranges from 0.037 tol.765 ppb, and the Pd content ranges between 0.165 and 17.979 ppb. Pd and Pt are more concentrated in porphyry mineralization than skarn mineralization, and have negative correlations with Au. The reconnaissance study presented here confirms the existence of Pd and Pt in the Fengshan porphyry-skarn Cu-Mo deposit. When compared with intracontinent and island arc geotectonic settings, the Pd, Pt, and Au contents in the Fengshan porphyry Cu-Mo deposit in the intracontinent is lower than the continental margin types and island are types. A combination of available data indicates that Pd and Pt were derived from oxidized alkaline magmas generated by the partial melting of an enriched mantle source.展开更多
A series of solvent-stabilized palladium colloidal nanoparticles were prepared via thermal decomposition of palladium acetate methylisobutylketone (MIBK) solution in the presence of alkali and alcohol with microwave i...A series of solvent-stabilized palladium colloidal nanoparticles were prepared via thermal decomposition of palladium acetate methylisobutylketone (MIBK) solution in the presence of alkali and alcohol with microwave irradiation. The colloidal nanoparticles were characterized with TEM, XPS and XRD. The average diameters of nanoparticles increase from 30 to 40 nm with the increase in concentration of palladium acetate. TEM and XRD observation demonstrated that the palladium colloidal nanoparticles were clusters agglomerated from hundreds of smaller palladium crystallines with size of 3-4 nm. The influence of the concentrations of alkali and alcohol to the particle size was also discussed.展开更多
We report a nanocarbon material with nanodiamond(ND) core and graphene shell(ND@G) as a support for Pd nanocatalysts. The designed catalyst performed good selectivity of styrene(85.2%) at full conversion of phenylacet...We report a nanocarbon material with nanodiamond(ND) core and graphene shell(ND@G) as a support for Pd nanocatalysts. The designed catalyst performed good selectivity of styrene(85.2%) at full conversion of phenylacetylene and superior stability under mild conditions. Supported Pd catalysts are characterized by means of high resolution transmission electron microscopy(HRTEM), Raman, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and H2 temperature-programmed reduction(H2-TPR).The results clearly show that formation of the strong metal-support interaction(SMSI) between Pd nanoclusters and the defective graphene shell helpfully modifies the selectivity and stability of the Pd-based catalysts.展开更多
Engineering the morphology of nanomaterials and modifying their electronic structure are effective ways to improve their performance in electrocatalysis. Through combining the co-reduction of Pd2+ and Cu2+ precursors ...Engineering the morphology of nanomaterials and modifying their electronic structure are effective ways to improve their performance in electrocatalysis. Through combining the co-reduction of Pd2+ and Cu2+ precursors with a digestive ripening process in oleylamine, we report the synthesis of copper-palladium(Cu-Pd) alloy multicubes with rough surfaces. Benefiting from their alloy and unique rough-surfaced structure,which provides ample edge/corner and step atoms as well as the electronic coupling between Cu and Pd leading to the lower of d-band center, the rough-surfaced Cu-Pd alloy multicubes show much better electrocatalytic performance not only for formic acid oxidation but also for oxygen reduction in comparison with those of spherical Cu-Pd alloy nanoparticles and commercial Pd/C catalyst. In contrast, we confirm that the rough-surfaced Cu-Pd alloy multicubes only exhibit very low Faradaic efficiency(34.3%) for electrocatalytic conversion of carbon dioxide(CO2) to carbon monoxide(CO) due to the presence of strong competing hydrogen evolution reaction, which results in their very poor selectivity for the reduction of CO2 to CO. The findings in this study not only offer a promising strategy to produce highly effective electrocatalysts for direct formic acid fuel cells, but also enlighten the ideas to design efficient electrocatalysts for CO2 reduction.展开更多
The rapid development of two-dimensional(2D)transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties.In particular,palladium diselenide(PdSe_(2))with a novel penta...The rapid development of two-dimensional(2D)transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties.In particular,palladium diselenide(PdSe_(2))with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research inter-est.Consequently,tremendous research progress has been achieved regarding the physics,chemistry,and electronics of PdSe_(2).Accordingly,in this review,we recapitulate and summarize the most recent research on PdSe_(2),including its structure,properties,synthesis,and appli-cations.First,a mechanical exfoliation method to obtain PdSe_(2) nanosheets is introduced,and large-area synthesis strate-gies are explained with respect to chemical vapor deposition and metal selenization.Next,the electronic and optoelectronic properties of PdSe_(2) and related hetero-structures,such as field-effect transistors,photodetectors,sensors,and thermoelec-tric devices,are discussed.Subsequently,the integration of systems into infrared image sensors on the basis of PdSe_(2) van der Waals heterostructures is explored.Finally,future opportunities are highlighted to serve as a general guide for physicists,chemists,materials scientists,and engineers.Therefore,this com-prehensive review may shed light on the research conducted by the 2D material community.展开更多
Supported palladium catalysts, which were used in the oxidative esterification of methacrolein to methyl methacrylate, have been prepared with different carriers and Pd precursors. Experimental results revealed that P...Supported palladium catalysts, which were used in the oxidative esterification of methacrolein to methyl methacrylate, have been prepared with different carriers and Pd precursors. Experimental results revealed that Pd catalysts with r-Al2O3 support and Na2PdC14 precursor showed good performance. Pd catalyst modified with Pb and Mg indicated that Pd-Mg bimetallic catalyst exhibited considerably higher activity and Pd-Pb exhibited both higher activity and selectivity. 92.27% methacrolein conversion and 90.57% methyl methacrylate selectivity were obtained on Pd-Pb-Mg catalyst.展开更多
The activity and thermal stability of Pd/Al2O3 and Pd/(Al2O3+MOx) (M=Ca, La, Ce) palladium catalysts in the reaction of complete oxidation of methane are presented in this study. The catalyst supports were prepar...The activity and thermal stability of Pd/Al2O3 and Pd/(Al2O3+MOx) (M=Ca, La, Ce) palladium catalysts in the reaction of complete oxidation of methane are presented in this study. The catalyst supports were prepared by sol-gel method and they were dried either conventionally or with supercritical carbon dioxide. Then they were impregnated with palladium nitrate solution. The catalysts with unmodified alumina had a high surface area. The activity and thermal stability of the aluminasupported catalyst was also very high. The introduction of calcium, lanthanum, or cerium oxide into alumina support caused a decrease of the surface area in the way dependent on the support precursor drying method. These modifiers decreased the activity of palladium catalysts, and they required higher temperatures for the complete oxidation of methane than unmodified Pd/Al2O3. The improvement of the palladium activity by lanthanum and cerium support modifier was observed only at low temperatures of the reaction.展开更多
基金the support of the National Natural Science Foundation of China (20222809, 21978146)TsinghuaFoshan Innovation Special Fund (2021THFS0214)。
文摘Suzuki-Miyaura reaction of aryl halides with phenylboronic acid using a heterogeneous palladium catalyst based on activated carbons(AC) was systematically investigated in this work. Two different reaction modes(batch procedure and continuous-flow procedure) were used to study the variations of reaction processing. The heterogeneous catalysts presented excellent reactivity and recyclability for iodobenzene and bromobenzene substrates in batch mode, which can be attributed to stabilization of Pd nanoparticles by the thiol and amino groups on the AC supports. However, significant dehalogenation in the reaction mixture and Pd leaching from the heterogeneous catalysts were observed in continuous-flow mode.This unique phenomenon in continuous-flow mode resulted in a dramatic decline in reaction selectivity and durability of heterogeneous catalysts comparing with that of batch mode. In addition, the heterogeneous Pd catalysts with thiol-and amino-modified AC supports exhibited different reactivity and durability in batch and continuous-flow mode owing to the difference of interaction between Pd species and AC supports.
基金financially supported by the National Natural Science Foundation of China(21674068,52173133,52161145402)the Sichuan Science and Technology Department(2021YFH0180)。
文摘Covalent organic frameworks(COFs)have emerged as a class of promising supports for electrocatalysis because of their advantages including good crystallinity,highly ordered pores,and structural diversity.However,their poor conductivity represents the main obstruction to their practical application.Here,we reported a novel synthesis strategy for synergistically endowing a triphenylamine-based COFs with improved electrical conductivity and excellent catalytic activity for oxygen reduction,via the in-situ redox deposition and confined growth of palladium nanoparticles inside the porous structure of COFs using reductive triphenylamine frameworks as reducing agent;meanwhile,the triphenylamine unit was oxidized to radical cation structure and affords radical cation COFs with conductivity as high as3.2*10^(-1) S m^(-1).Such a uniform confine palladium nanoparticle on highly conductive COFs makes it an efficient electrocatalyst for four-electron oxygen reduction reaction(4e-ORR),showing excellent activities and fast kinetics with a remarkable half-wave potential(E_(1/2))of 0.865 V and an ultralow Tafel slope of 39.7 mV dec^(-1) in alkaline media even in the absence of extra commercial conductive fillers.The generality of this strategy was proved by preparing the different metal and metal alloy nanoparticles supported on COFs(Au@COF,Pt@COF,AuPd@COF,AgPd@COF,and PtPd@COF)using reductive triphenylamine frameworks as reducing agent.This work not only provides a facile strategy for the fabrication of highly conductive COF supported ORR electrocatalysts,but also sheds new light on the practical application of Zn-air battery.
文摘An important area of research in nanotechnology deals with the synthesis of nanoparticles of different chemical compositions,sizes and controlled monodispersity.Currently,there is a growing need to develop environmentally benign nanoparticle synthesis in which no toxic chemicals are used in the synthesis protocol.Palladium nanoparticles(Pd Np) are of interest because of their catalytic properties and affinity for hydrogen.Our protocol for the phyto-synthesis of Pd Np under moderate p H and room temperature offers a new means to develop environmentally benign nanoparticles.Solanum trilobatum is enlightened in our present study as it is enriched with phytochemicals to reduce palladium chloride ions.Poly MVA a dietary supplement based on the nontoxic chemotherapeutic lipoic acid-palladium complex(LA-Pd) is been hypothesized as the new paradigm of cancer therapy.Hence forth we successfully conjugated lipoic acid(S-Pd Np-LA) and vitamins(S-Pd Np-Vitamin-LA) to palladium nanoparticles synthesised from Solanum trilobatum leaf extract.These nanoparticles(S-Pd Np,S-Pd Np-LA,S-Pd Np-Vitamin-LA) were characterized with UV-Vis Spectroscopy,SEM and FTIR analysis,which revealed that S-Pd Np are polydisperse and of different morphologies ranging from 60?70 nm(S-Pd Np),65?80 nm(S-Pd Np-LA) and 75?100 nm(S-Pd Np-Vitamin-LA) in size.
文摘Acrylonitrile reacts with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound arsine palladium(0) complex to afford stereoselectively (E)-cinnamo- nitriles in high yields.
文摘Palladium and palladium alloy membranes have attracted wide attention in hydrogen permeation areas for their excellent permeability, perm -selectivity and thermal stability. This paper review the principle of hydrogen permeation, type of alloys and the fabrication methods. At last, the progress and achievements on palladium alloy membranes by Northwest Institute for Non-Ferrous Metal Research are emphasized.
文摘Allylic alcohols react with aryl iodides in the presence of tri-n-butylamine and a catalytic amount of a silica-bound bidentate sulfur palladium (0) complex to form 3-arylaldehydes or ketones in good yields.
文摘The negative effects of hydrogen embrittlement on metallic systems have been investigated through determination of the mechanical properties of two metallic systems that were exposed to hydrogen. An assessment of the effects of hydrogen absorption/desorption cycling on the tensile strength, ductility, and microhardness of pure palladium and the alloy palladium-silver (25 weight% silver) has been undertaken. The variables that are the focus of the study are the amount of hydrogen absorbed by the metal, deuterium isotope effect, number of hydrogen absorption/desorption cycles, and the hydrogen exposure temperature. Under all conditions studied, the mechanical properties of pure palladium were significantly altered as a result of hydrogen exposure, with significant hydrogen embrittlement occurring. In contrast, the mechanical properties of the palladium-silver alloy showed little alteration as a result of hydrogen exposure, including virtually no occurrence of hydrogen embrittlement.
基金This work was supported by European Community,seventh Framework Programm(FP/2007-2013)Marie Curie International Research Staff Exchange Scheme(grant no.230790)project MEC 06 MAT2006 01997.
文摘Novel in-situ reduction approach was applied for the synthesis of palladium nanoparticles in the pores of mesoporous silica materials with grafted siliconhydride groups. Matrices possessing different structural properties (MCM-41, SBA-15 and Silochrom) were used. Samples were studied by nitrogen adsorption-desorption method, low-angle X-ray diffraction, transmission electron microscopy (TEM) and FT-IR/PAS spectroscopy. The temperature-programmed oxidation (TPO) and reduction (TPR) methods were applied to examine reducibility of palladium species. Palladium containing catalysts were tested in methane oxidation reaction. It was demonstrated that relatively large pores in SBA-15 type silica facilitated formation of well-dispersed palladium nanoparticles confined in the pores channels. In the case of MCM-41 support, metallic palladium nanoparticles were formed on the external surface. The obtained materials showed high catalytic activity. Lower activity of the samples containing small crystallites located in the pore volume at high temperatures was related to worse accessibility of active sites to the reation mixture.
文摘Dislocation structures in polycrystalline Ni 3Al alloy doped with palladium deformed at room temperature have been investigated by transmission electron microscopy. The structure consists mainly of dislocations dissociated into a /2〈011〉 super partials bounding an anti phase boundary (APB). Dislocations dissociated into a /3〈112〉 super Shockley partials bounding a superlattice intrinsic stacking fault (SISF) are also common debris. The majority of the SISFs are truncated loops, i.e. the partials bounding the SISF are of similar Burgers vector. These faulted loops are generated from APB coupled dislocations, according to a mechanism for formation of SISFs proposed by Suzuki et al , and recently modified by Chiba et al . The APB energies for {111} and {010} slip planes are measured to be 144±20 mJ/m 2 and 102±11 mJ/m 2 respectively, and the SISF energy has been estimated to be 12 mJ/m 2 in this alloy. It is concluded that the dislocation structure in Ni 74.5 Pd 2Al 23.5 alloy deformed at room temperature is similar to that in binary Ni 3Al, and the difference in fault energies between these two alloys is small. Thus, it seems unlikely that the enhancement of ductility of Ni 74.5 Pd 2Al 23.5 results from only such a small decrease of the ordering energy of the alloy. SISF bounding dislocations also have no apparent influence on the ductilization of Ni 74.5 Pd 2Al 23.5 alloy.
基金Project supported by Science and Technology Committee of Jiangxi Province
文摘The rare earths of ytterbium, lanthanum, praseodymium, neodymium and their binary mixtures were respectively added into the traditional electroless plating solution to prepare thin palladium film on the inner surface of porous ceramic tube. The experimental results shows that the addition of rare earths increases palladium deposition rates and the binary mixtures are superior to the single rare earths and the mixture of ytterbium-lanthanum is the most efficient. Adding the mixture of ytterbium-lanthanum can also reduce the plating temperature by 10~20 ℃, shrink the metal crystal size and improve the film densification compared to those by traditional electroless plating. A thin palladium film with 5 μm was prepared and the film made a highly pure hydrogen with a molar fraction of more than 99.97% from a H2-N2 gas mixture. More attentions were paid to analyze the physical and chemical behaviors of the rare earths in palladium film preparation.
基金supported by the Key Program of National Natural Science Foundation of China (20333030)the National High Technology Research and Development Program of China (863 Program, No. 2006AA06Z347)the National Natural Science Foundation of China (No. 20773090)
文摘Pd/YZ-Al2O3 (Y and Zr modified Al2O3, and hereafter, labelled as A1) catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy (XPS), NO-temperature programmed desorption (NO-TPD), Nz-adsorption/desorption (Branauer-Emmet-Teller BET method), X-ray diffraction (XRD) and CO-chemisorption. Catalytic activities for CH4, CO and NO conversion were tested in a gas mixture simulated the emissions from natural gas vehicles (NGVs) operated under stoichiometric conditions. The results indicated that all catalysts exhibited excellent catalytic performances for CH4 and CO oxidation and the promoting effect of CeO2 or La2O3 was significant for NO conversion. XPS results showed that the electron density around Pd was increased by CeO2 and/or La2O3, the binding energy of Pd 3d decreased as the order: Pd/Al 〉 Pd/Ce/Al 〉 Pd/La/Al 〉 Pd/CeLa/Al. The electron-rich Pd showed Rh-like catalytic properties which exhibited good activity for the reduction of NO. NO-TPD results showed that the addition of CeO2 and/or La2O3 increased NO adsorption on surface, and promoted the conversion of NO.
基金Supported by the National Natural Science Foundation of China(No.20575048).
文摘A novel method for the determination of nickel and palladium in environmental samples by low temperature ETV-ICP-OES with dimethylglyoxime(DMG) as both the extractant and chemical modifier has been developed. In this study, it was found that nickel and palladium can form complexes with dimethylglyoxime(0. 05%, mass fraction) at pH 6.0 and can be extracted into chloroform quantitatively. The complexes can be evaporated into plasma at a suita-ble temperature( 1400℃) for ICP-OES detection. Under the optimized conditions, the detection limits of nickel and palladium are 0.48 and 0. 40 ng/mL, respectively, while the RSD values are separately 5.0% and 3.1% (p = 50 ng/mL, n = 7). The proposed method was applied to the determination of the target analytes in environmental sam-ples with satisfactory results.
基金supported by the National Natural Science Foundation of China(No. 40902026)Research Foundation for Outstanding Young Teachers,China University of Geosciences (Wuhan)(No.CUGQNL0735)
文摘The Fengshan porphyry-skarn copper-molybdenum (Cu-Mo) deposit is located in the south-eastern Hubei Province in east China. Cu-Mo mineralization is hosted in the Fengshan granodiorite porphyry stock that intruded the Triassic Daye Formation carbonate rocks in the early Cretaceous (-140 Ma), as well as the contact zone between granodiorite porphyry stock and carbonate rocks, forming the porphyry-type and skaru-type association. The Fengshan granodiorite stock and the immediate country rocks are strongly fractured and intensely altered by hydrothermal fluids. In addition to intense skarn alteration, the prominent alteration types are potassic, phyllic, and propylitic, whereas argiilation is less common. Mineralization occurs as veins, stock works, and disseminations, and the main ore minerals are chalcopyrite, pyrite, molybdenite, bornite, and magnetite. The contents of palladium, platinum and gold (Pd, Pt and Au) are determined in nine samples from fresh and mineralized granodiorite and different types of altered rocks. The results show that the Pd content is systematically higher than Pt, which is typical for porphyry ore deposits worldwide. The Pt content ranges from 0.037 tol.765 ppb, and the Pd content ranges between 0.165 and 17.979 ppb. Pd and Pt are more concentrated in porphyry mineralization than skarn mineralization, and have negative correlations with Au. The reconnaissance study presented here confirms the existence of Pd and Pt in the Fengshan porphyry-skarn Cu-Mo deposit. When compared with intracontinent and island arc geotectonic settings, the Pd, Pt, and Au contents in the Fengshan porphyry Cu-Mo deposit in the intracontinent is lower than the continental margin types and island are types. A combination of available data indicates that Pd and Pt were derived from oxidized alkaline magmas generated by the partial melting of an enriched mantle source.
基金The project is partially supported by the Natural Sci-ence Foundation of Hubei Province under contract No.2003ABA072.
文摘A series of solvent-stabilized palladium colloidal nanoparticles were prepared via thermal decomposition of palladium acetate methylisobutylketone (MIBK) solution in the presence of alkali and alcohol with microwave irradiation. The colloidal nanoparticles were characterized with TEM, XPS and XRD. The average diameters of nanoparticles increase from 30 to 40 nm with the increase in concentration of palladium acetate. TEM and XRD observation demonstrated that the palladium colloidal nanoparticles were clusters agglomerated from hundreds of smaller palladium crystallines with size of 3-4 nm. The influence of the concentrations of alkali and alcohol to the particle size was also discussed.
基金supported by the Ministry of Science and Technology (2016YFA0204100)the National Natural Science Foundation of China (21573254, 21703261 and 91545110)+2 种基金the Youth Innovation Promotion Association (CAS), and the Sinopec China and Strategic Priority Research Program of the Chinese Academy of Sciences (XDA09030103)the Chongqing Research Program of Basic Research and Frontier Technology (cstc2016jcyjA0432)Scientific and Technological Research Program of Chongqing Municipal Education Commission (KJ1600328)
文摘We report a nanocarbon material with nanodiamond(ND) core and graphene shell(ND@G) as a support for Pd nanocatalysts. The designed catalyst performed good selectivity of styrene(85.2%) at full conversion of phenylacetylene and superior stability under mild conditions. Supported Pd catalysts are characterized by means of high resolution transmission electron microscopy(HRTEM), Raman, X-ray diffraction(XRD), X-ray photoelectron spectroscopy(XPS) and H2 temperature-programmed reduction(H2-TPR).The results clearly show that formation of the strong metal-support interaction(SMSI) between Pd nanoclusters and the defective graphene shell helpfully modifies the selectivity and stability of the Pd-based catalysts.
基金Financial supports from the National Natural Science Foundation of China (Grant No.: 21506225, 21573240 and 21706265)Center for Mesoscience, Institute of Process Engineering, Chinese Academy of Sciences (Grant No.: COM2015A001 and MPCS-2017-A-02)
文摘Engineering the morphology of nanomaterials and modifying their electronic structure are effective ways to improve their performance in electrocatalysis. Through combining the co-reduction of Pd2+ and Cu2+ precursors with a digestive ripening process in oleylamine, we report the synthesis of copper-palladium(Cu-Pd) alloy multicubes with rough surfaces. Benefiting from their alloy and unique rough-surfaced structure,which provides ample edge/corner and step atoms as well as the electronic coupling between Cu and Pd leading to the lower of d-band center, the rough-surfaced Cu-Pd alloy multicubes show much better electrocatalytic performance not only for formic acid oxidation but also for oxygen reduction in comparison with those of spherical Cu-Pd alloy nanoparticles and commercial Pd/C catalyst. In contrast, we confirm that the rough-surfaced Cu-Pd alloy multicubes only exhibit very low Faradaic efficiency(34.3%) for electrocatalytic conversion of carbon dioxide(CO2) to carbon monoxide(CO) due to the presence of strong competing hydrogen evolution reaction, which results in their very poor selectivity for the reduction of CO2 to CO. The findings in this study not only offer a promising strategy to produce highly effective electrocatalysts for direct formic acid fuel cells, but also enlighten the ideas to design efficient electrocatalysts for CO2 reduction.
基金H.L.acknowledges the National Key Research and Development Program of China(2017YFB0405400)from the Ministry of Science and Technology(MOST)of Chinathe Natural Science Foundation for Distinguished Young Scientist of Shandong Province(Grant No.JQ201814)+6 种基金We thank the Project of“20 items of University”of Jinan(2018GXRC031)W.Z thanks Taishan Scholars Project Special Funds(tsqn201812083)and NSFC(No.52022037)The authors show their gratitude to the National Natural Science Foundation of China(NSFC grant No.51802113,51802116)the Natural Science Foundation of Shandong Province,China(grant No.ZR2019BEM040,ZR2018BEM015)M.H.R.thanks the National Science Foundation China(NSFC,Project 52071225)the National Science Center and the Czech Republic under the ERDF program“Institute of Environmental Technology-Excellent Research”(No.CZ.02.1.01/0.0/0.0/16_019/0000853)the Sino-German Research Institute for support(Project No.GZ 1400).
文摘The rapid development of two-dimensional(2D)transition-metal dichalcogenides has been possible owing to their special structures and remarkable properties.In particular,palladium diselenide(PdSe_(2))with a novel pentagonal structure and unique physical characteristics have recently attracted extensive research inter-est.Consequently,tremendous research progress has been achieved regarding the physics,chemistry,and electronics of PdSe_(2).Accordingly,in this review,we recapitulate and summarize the most recent research on PdSe_(2),including its structure,properties,synthesis,and appli-cations.First,a mechanical exfoliation method to obtain PdSe_(2) nanosheets is introduced,and large-area synthesis strate-gies are explained with respect to chemical vapor deposition and metal selenization.Next,the electronic and optoelectronic properties of PdSe_(2) and related hetero-structures,such as field-effect transistors,photodetectors,sensors,and thermoelec-tric devices,are discussed.Subsequently,the integration of systems into infrared image sensors on the basis of PdSe_(2) van der Waals heterostructures is explored.Finally,future opportunities are highlighted to serve as a general guide for physicists,chemists,materials scientists,and engineers.Therefore,this com-prehensive review may shed light on the research conducted by the 2D material community.
基金Financial supported by the National Natural Science Foundation of China (No.20436050)Foundation of Graduate University of the Chinese Academy of Sciences.
文摘Supported palladium catalysts, which were used in the oxidative esterification of methacrolein to methyl methacrylate, have been prepared with different carriers and Pd precursors. Experimental results revealed that Pd catalysts with r-Al2O3 support and Na2PdC14 precursor showed good performance. Pd catalyst modified with Pb and Mg indicated that Pd-Mg bimetallic catalyst exhibited considerably higher activity and Pd-Pb exhibited both higher activity and selectivity. 92.27% methacrolein conversion and 90.57% methyl methacrylate selectivity were obtained on Pd-Pb-Mg catalyst.
文摘The activity and thermal stability of Pd/Al2O3 and Pd/(Al2O3+MOx) (M=Ca, La, Ce) palladium catalysts in the reaction of complete oxidation of methane are presented in this study. The catalyst supports were prepared by sol-gel method and they were dried either conventionally or with supercritical carbon dioxide. Then they were impregnated with palladium nitrate solution. The catalysts with unmodified alumina had a high surface area. The activity and thermal stability of the aluminasupported catalyst was also very high. The introduction of calcium, lanthanum, or cerium oxide into alumina support caused a decrease of the surface area in the way dependent on the support precursor drying method. These modifiers decreased the activity of palladium catalysts, and they required higher temperatures for the complete oxidation of methane than unmodified Pd/Al2O3. The improvement of the palladium activity by lanthanum and cerium support modifier was observed only at low temperatures of the reaction.