Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in exce...Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and H2 chemisorption results confirmed that Pd-Cu singleatom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.展开更多
A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,...A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.展开更多
Surface strain engineering is considered as an effective strategy to promote the electrocatalytic properties of noble metal nanocrystals.Herein,we construct a dual-phase palladium-copper(DP-PdCu)bimetallic electrocata...Surface strain engineering is considered as an effective strategy to promote the electrocatalytic properties of noble metal nanocrystals.Herein,we construct a dual-phase palladium-copper(DP-PdCu)bimetallic electrocatalyst with remarkable biaxial strain via a one-pot wet-chemical approach for formic acid oxidation.The biaxial strain originates from the lattice mismatch between the disordered face-centered cubic(FCC)phase and ordered body-centered cubic(BCC)phase in each of DP-PdCu:nanoparticles.The proportion of FCC and BCC phases and size of PdCu nanoparticles are dependent on the addition amount of:capping agent,cetyltrimethylammonium bromide(CTAB).Density functional theory calculations reveal the downshift of d-band:center of Pd atoms due to the interfacial strain,which weakens the adsorption strength of undesired intermediates.These merit the,DP-PdCu catalyst with superior mass activity of 0.55 A·mg_(pd)^(-1) and specific activity of 1.91 mA·cm_(pd)^(-2) toward formic acid oxidation,outperforming the single FCC/EICC PdCu and commercial Pd/C catalysts.This will provide new insights into the structure design of high-performance electrocatalysts via strain engineering.展开更多
Nano-particle Pd/?-Al2O3 monometallic and Pd-Cu/?-Al2O3 bimetall ic catalysts were prepared by solvated metal atom impregnation (SMAI) method. Th e results of XRD measurement indicated that Pd- Cu alloy was formed in ...Nano-particle Pd/?-Al2O3 monometallic and Pd-Cu/?-Al2O3 bimetall ic catalysts were prepared by solvated metal atom impregnation (SMAI) method. Th e results of XRD measurement indicated that Pd- Cu alloy was formed in the bim etallic catalysts and the crystalline particle size of the alloy increased as Cu contents increased with average diameters < 6.0nm for all the samples. XPS and Auger spectra showed that Pd was in zero- valent state, Cu existed mainly in z ero- valent state and partially in monovalent state Cu+. The Pd/?-Al2O3 and Pd-Cu/?-Al2O3 catalysts exhibited higher activity for CO oxidation at low temperature. The activity of Pd-Cu/?-Al2O3 bimetallic catalyst was hig her than that of Pd/?-Al2O3 monometallic catalyst. The Pd-Cu/?-Al2O3 c atalyst with Pd/Cu atomic ratio of 1∶1 showed the highest activity.展开更多
The development of advanced electrocatalysts for efficient catalyzing ethanol oxidation reaction(EOR)and oxygen reduction reaction(ORR) is significant for direct ethanol fuel cells(DEFCs).However,in many previous stud...The development of advanced electrocatalysts for efficient catalyzing ethanol oxidation reaction(EOR)and oxygen reduction reaction(ORR) is significant for direct ethanol fuel cells(DEFCs).However,in many previous studies,the major difficulties including lower utilization efficiency and weaker anti-CO-poison ability of Pt hamper the practical testing of such DEFCs,Herein,ternary Pt22Pd27C51 ultrathin(~5 nm)NWs are fabricated via a facile surfactant-free strategy.The surface and electronic structures of Pt22Pd27Cu51 NWs are further tailored via acid-etching treatment.The resulted PtPdCu NWs with an optimal atomic Pt/Pd/Cu ratio of 36:41:23 display excellent specific activities towards EOR(4.38 mA/cm^(2))and ORR(1.16 mA/cm^(2)),which are 19.8-and 5.7-folds larger than that of Pt/C,respectively.A singlecell was fabricated using Pt36Pd41Cu23 NWs as electrocatalyst in both anode and cathode with Pt loading of 1.2 mgpt/cm^(2).The power density measured at 80 ℃ is 21.7 mW/cm^(2),which is ~3.9 folds enhancement relative to that fabricated by using Pt/C(2 mgPt/cm^(2)).The enhanced catalytic performance of Pt36Pd41Cu23NWs could be attributed to that synergistic effect between Pt,Pd and Cu enhances CO anti-poisoning ability and promotes the C-C bond cleavage.This work provides a promising strategy for developing efficient electrocatalysts for DEFCs.展开更多
A novel three-component reaction of o-bromobenzaldehyde, terminal alkynes and tert-butyl amine has been established, which proceeded smoothly to give 3-substituted isoquinolines in good yields in the presence of palla...A novel three-component reaction of o-bromobenzaldehyde, terminal alkynes and tert-butyl amine has been established, which proceeded smoothly to give 3-substituted isoquinolines in good yields in the presence of palladium/copper catalysts under microwave irradiation.展开更多
近年来,具有丰富活性中心的二维合金高效电催化剂的合成引起人们极大关注.本工作以十六烷基三甲基溴化铵和六羰基钼为结构导向剂合成出三金属钯-银-铜纳米片组装体.用高角度环形暗场扫描透射电子显微镜、透射电子显微镜和X射线衍射仪对...近年来,具有丰富活性中心的二维合金高效电催化剂的合成引起人们极大关注.本工作以十六烷基三甲基溴化铵和六羰基钼为结构导向剂合成出三金属钯-银-铜纳米片组装体.用高角度环形暗场扫描透射电子显微镜、透射电子显微镜和X射线衍射仪对三金属PdAgCu纳米片组装体的形貌和结构进行了表征.结果表明三金属Pd6Ag3Cu2纳米片组装体电催化性能优异,且对乙二醇氧化反应(5696 mA mgPd^(-1))和乙醇氧化反应(4374 mA mgPd^(-1))具有良好的催化稳定性.电催化活性的增强可归因于应变效应、配体效应及双功能效应的协同作用.本文系统研究了三金属电催化剂对C2醇的电催化机理,发现较高的羟基和C2醇浓度有利于乙二醇氧化反应和乙醇氧化反应.展开更多
文摘Galvanic replacement, co-impregnation and sequential impregnation have been employed to prepare Pd-Cu bimetallic catalysts with less than 1 wt-% Cu and ca. 0.03 wt-% Pd for selective hydrogenation of acetylene in excess ethylene. High angle annular dark field-scanning transmission electron microscopy （HAADF-STEM） and H2 chemisorption results confirmed that Pd-Cu singleatom alloy structures were constructed in all three bimetallic catalysts. Catalytic tests indicated that when the conversion of acetylene was above 99%, the selectivity of ethylene of these three single atom alloy catalysts was still more than 73%. Furthermore, the single atom alloy catalyst prepared by sequential incipient wetness impregnation was found to have the best stability among the three procedures used.
基金financial support from the National Natural Science Foundation of China(No.22171215)the Excellent Youth Foundation of Hubei Scientific Committee(No.2022CFA092)the GuangDong Basic and Applied Basic Research Foundation(No.2022A1515110113).
文摘A cooperative Pd/Cu-catalyzed three-component cross-coupling reaction of alkynes,B_(2)Pin_(2) and alkene-tethered aryl halides is reported.This reaction proceeds under mild conditions and shows broad sub-strate scope,providing a variety of heterocycles containing tetrasubstituted alkenylboronate moieties in synthetically useful yields with excellent chemoselectivity and regioselectivity.This transformation fea-tures the catalytic generation ofβ-borylalkenylcopper intermediates and their use in Pd-catalyzed Heck cyclization/cross-couplings.An enantioselective cascade cyclization/cross-coupling process has also been developed for the synthesis of enantiomerically enriched oxindole bearing a tetrasubstituted alkenyl-boronate moiety.
基金supported by the National Key Research and Development Program of China(No.2016YFB0101201)the National Natural Science Foundation of China(Nos.21822506 and 51761165025)the 111 project of B12015.
文摘Surface strain engineering is considered as an effective strategy to promote the electrocatalytic properties of noble metal nanocrystals.Herein,we construct a dual-phase palladium-copper(DP-PdCu)bimetallic electrocatalyst with remarkable biaxial strain via a one-pot wet-chemical approach for formic acid oxidation.The biaxial strain originates from the lattice mismatch between the disordered face-centered cubic(FCC)phase and ordered body-centered cubic(BCC)phase in each of DP-PdCu:nanoparticles.The proportion of FCC and BCC phases and size of PdCu nanoparticles are dependent on the addition amount of:capping agent,cetyltrimethylammonium bromide(CTAB).Density functional theory calculations reveal the downshift of d-band:center of Pd atoms due to the interfacial strain,which weakens the adsorption strength of undesired intermediates.These merit the,DP-PdCu catalyst with superior mass activity of 0.55 A·mg_(pd)^(-1) and specific activity of 1.91 mA·cm_(pd)^(-2) toward formic acid oxidation,outperforming the single FCC/EICC PdCu and commercial Pd/C catalysts.This will provide new insights into the structure design of high-performance electrocatalysts via strain engineering.
文摘Nano-particle Pd/?-Al2O3 monometallic and Pd-Cu/?-Al2O3 bimetall ic catalysts were prepared by solvated metal atom impregnation (SMAI) method. Th e results of XRD measurement indicated that Pd- Cu alloy was formed in the bim etallic catalysts and the crystalline particle size of the alloy increased as Cu contents increased with average diameters < 6.0nm for all the samples. XPS and Auger spectra showed that Pd was in zero- valent state, Cu existed mainly in z ero- valent state and partially in monovalent state Cu+. The Pd/?-Al2O3 and Pd-Cu/?-Al2O3 catalysts exhibited higher activity for CO oxidation at low temperature. The activity of Pd-Cu/?-Al2O3 bimetallic catalyst was hig her than that of Pd/?-Al2O3 monometallic catalyst. The Pd-Cu/?-Al2O3 c atalyst with Pd/Cu atomic ratio of 1∶1 showed the highest activity.
基金supported by the National Natural Science Foundation of China (No. 21902119)。
文摘The development of advanced electrocatalysts for efficient catalyzing ethanol oxidation reaction(EOR)and oxygen reduction reaction(ORR) is significant for direct ethanol fuel cells(DEFCs).However,in many previous studies,the major difficulties including lower utilization efficiency and weaker anti-CO-poison ability of Pt hamper the practical testing of such DEFCs,Herein,ternary Pt22Pd27C51 ultrathin(~5 nm)NWs are fabricated via a facile surfactant-free strategy.The surface and electronic structures of Pt22Pd27Cu51 NWs are further tailored via acid-etching treatment.The resulted PtPdCu NWs with an optimal atomic Pt/Pd/Cu ratio of 36:41:23 display excellent specific activities towards EOR(4.38 mA/cm^(2))and ORR(1.16 mA/cm^(2)),which are 19.8-and 5.7-folds larger than that of Pt/C,respectively.A singlecell was fabricated using Pt36Pd41Cu23 NWs as electrocatalyst in both anode and cathode with Pt loading of 1.2 mgpt/cm^(2).The power density measured at 80 ℃ is 21.7 mW/cm^(2),which is ~3.9 folds enhancement relative to that fabricated by using Pt/C(2 mgPt/cm^(2)).The enhanced catalytic performance of Pt36Pd41Cu23NWs could be attributed to that synergistic effect between Pt,Pd and Cu enhances CO anti-poisoning ability and promotes the C-C bond cleavage.This work provides a promising strategy for developing efficient electrocatalysts for DEFCs.
基金supported by the National Basic Research Program of China(973 Program,2011CB201400)the National Natural Science Foundation of China(21173008,21373019,21433001)~~
基金Acknowledgement This work was supported by the National Natural Science Foundation of China （No. 21002038） and the Self-determined Research Funds of CCNU from the Colleges＇ Basic Research and Operation of MOE （No. CCNU09A01014）.
文摘A novel three-component reaction of o-bromobenzaldehyde, terminal alkynes and tert-butyl amine has been established, which proceeded smoothly to give 3-substituted isoquinolines in good yields in the presence of palladium/copper catalysts under microwave irradiation.
基金supported by the National Natural Science Foundation of China(22172084 and 21773133)the World-Class Discipline Program of Shandong Province,China。
文摘近年来,具有丰富活性中心的二维合金高效电催化剂的合成引起人们极大关注.本工作以十六烷基三甲基溴化铵和六羰基钼为结构导向剂合成出三金属钯-银-铜纳米片组装体.用高角度环形暗场扫描透射电子显微镜、透射电子显微镜和X射线衍射仪对三金属PdAgCu纳米片组装体的形貌和结构进行了表征.结果表明三金属Pd6Ag3Cu2纳米片组装体电催化性能优异,且对乙二醇氧化反应(5696 mA mgPd^(-1))和乙醇氧化反应(4374 mA mgPd^(-1))具有良好的催化稳定性.电催化活性的增强可归因于应变效应、配体效应及双功能效应的协同作用.本文系统研究了三金属电催化剂对C2醇的电催化机理,发现较高的羟基和C2醇浓度有利于乙二醇氧化反应和乙醇氧化反应.
文摘以活性碳(Vulcan XC-72)为载体,用改良的化学还原法制备不同Pd:Cu比例的Pd_x-Cu/C催化剂,使用X-射线衍射(XRD)、透射电镜(TEM)、X-射线光电子能谱(XPS)和电化学方法对其进行了表征,研究了Cu对Pd/C催化剂催化性能的影响。结果表明:随着Pd与Cu原子比的提高Pd_x-Cu/C催化剂的催化活性先提高后降低,当Pd:Cu=8:1时Pd8-Cu/C催化剂粒子均匀分散在碳载体表面,其直径约为2.8 nm;在催化剂中掺入的少量Cu元素部分进入Pd晶格形成了合金。这种催化剂在混合水溶液中表现出最佳的催化活性和稳定性,对C_2H_5OH氧化的催化峰电流密度达到114 m A/cm^2,是Pd/C的2.5倍,是JM-Pd/C的3.6倍。
