In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were charac...In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.展开更多
Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstra...Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstrate a compelling approach by surface modifying Pd2S nanocrystals with PPhz ligands,resulting in a catalyst with excellent catalytic activity and durable selectivity for the semi-hydrogenation of terminal alkynes.Experimental and theoretical investigations reveal that the presence of S sites on the Pd surface directs PPh_(3) ligands to preferentially form covalent bonds with S,creating distinctive surface S=PPh_(3) motifs.This configuration induces a partial positive charge on Pd,facilitating hydrogen transfer and thus promoting catalytic activity.Furthermore,the covalent bond between the ligand and catalyst surface forms a robust network,ensuring ligand stability and increasing the hydrogenation energy barrier of olefins.Consequently,the Pd_(4)S@PPhz catalyst exhibits an improved catalytic selectivity with durability in terminal alkyne semi-hydrogenation.This study introduces an effective strategy for designing selective hydrogenation catalysts with an enhanced performance.展开更多
We develop a unique ternary Pd-Ni-P nanocatalyst for the sensitive enzyme- free electrooxidation detection of glucose under alkaline conditions. By reducing the distance between the Pd and Ni active sites in the Pd-Ni...We develop a unique ternary Pd-Ni-P nanocatalyst for the sensitive enzyme- free electrooxidation detection of glucose under alkaline conditions. By reducing the distance between the Pd and Ni active sites in the Pd-Ni-P nanoparticles （NPs） via atom engineering, the catalyst structure is transformed from Pd@Ni-P dumbbells into spherical NPs, greatly enhancing the catalyst sensitivity. The glassy carbon electrode modified with Pd-Ni-P ternary NPs, which behaves as an efficient nonenzymatic glucose sensor, offers excellent electrocatalytic performance with a high sensitivity of 1,136 μA·mM^-1·cm^-2, a short response time of 2 s, a wide linear range of 0.5 μM to 10.24 mM, a low limit of detection of 0.15 μM （signal-to-noise ratio = 3）, and good selectivity and reproducibility. Moreover, owing to its superior catalytic performance, the Pd-Ni-P modified electrode has excellent reliability for glucose detection in real samples of human serum. Our study provides a promising alternative strategy for designing and constructing high-performance multicomponent nanocatalyst-based sensors.展开更多
Heterogeneous Pd nanocatalysts are efficient catalysts for the Heck reaction but require multi-step,sophisticated procedures and harsh reaction conditions.In this work,a green and facile strategy has been developed to...Heterogeneous Pd nanocatalysts are efficient catalysts for the Heck reaction but require multi-step,sophisticated procedures and harsh reaction conditions.In this work,a green and facile strategy has been developed to decorate Pd nanoparticles on polydopamine(PDA)-coated multi-walled carbon nanotubes(Pd/CNTs-PDA)via a one-pot method.The obtained nanoparticles were characterized by various techniques including transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy,which proved that Pd NPs are well-dispersed on the PDA and between the surfaces of the PDA and CNTs.The resultant Pd/CNTs-PDA catalysts exhibit excellent catalytic reactivity toward the Heck reaction at low temperatures.Moreover,by DFT simulation,we found that during the PDA polymerization process,a large number of unsaturated—N=and C=O species are more active than the groups on the PDA end product to anchor Pd NPs.The results provide evidence that the catalyst synthesized by the onepot method exhibited good activity because sufficient active sites could be created to effectively promote Pd NPs dispersion during the dopamine polymerization process.Additionally,the Pd/CNTs-PDA catalyst was successfully employed in Heck cross-coupling reactions with various functionalized substrates.This method opens a window for the fabrication of high-performance nanocomposite catalysts under mild conditions using simple methods and has several potential applications.展开更多
文摘In the present study,CNFs,ZnO and Al2O3 were deposited on the SMFs panels to investigate the deactivation mechanism of Pd-based catalysts in selective acetylene hydrogenation reaction.The examined supports were characterized by SEM,NH3-TPD and N2adsorption-desorption isotherms to indicate their intrinsic characteristics.Furthermore,in order to understand the mechanism of deactivation,the resulted green oil was characterized using FTIR and SIM DIS.FTIR results confirmed the presence of more unsaturated constituents and then,more branched hydrocarbons formed upon the reaction over alumina-supported catalyst in comparison with the ones supported on CNFs and ZnO,which in turn,could block the pores mouths.Besides the limited hydrogen transfer,N2 adsorption-desorption isotherms results supported that the lowest pore diameters of Al2O3/SMFs close to the surface led to fast deactivation,compared with the other catalysts,especially at higher temperatures.
基金National Natural Science Foundation of China(grant no.92261207,and NSFC Center for Single-Atom Catalysis under grant no.22388102)New Cornerstone Science Foundation.R.Q.acknowledges support from National Key R&D Program of China(2022YFA1504500)+2 种基金Young Scientists Fund of the National Natural Science Foundation of China(22202164)Natural Science Foundation of Fujian Province(2023J05006)Fundamental Research Funds for the Central Universities(20720230002).
文摘Surface modification of metallic nanocatalysts with organic ligands has emerged as an effective strategy to enhance catalytic selectivity,although offten at the expense of catalytic activity.In this study,we demonstrate a compelling approach by surface modifying Pd2S nanocrystals with PPhz ligands,resulting in a catalyst with excellent catalytic activity and durable selectivity for the semi-hydrogenation of terminal alkynes.Experimental and theoretical investigations reveal that the presence of S sites on the Pd surface directs PPh_(3) ligands to preferentially form covalent bonds with S,creating distinctive surface S=PPh_(3) motifs.This configuration induces a partial positive charge on Pd,facilitating hydrogen transfer and thus promoting catalytic activity.Furthermore,the covalent bond between the ligand and catalyst surface forms a robust network,ensuring ligand stability and increasing the hydrogenation energy barrier of olefins.Consequently,the Pd_(4)S@PPhz catalyst exhibits an improved catalytic selectivity with durability in terminal alkyne semi-hydrogenation.This study introduces an effective strategy for designing selective hydrogenation catalysts with an enhanced performance.
基金This work was supported by the National Natural Science Foundation of China （Nos. 21475007, 21675009, and 21275015）. We also thank the support from the ＂Public Hatching Platform for Recruited Talents of Beijing University of Chemical Technology＂.
文摘We develop a unique ternary Pd-Ni-P nanocatalyst for the sensitive enzyme- free electrooxidation detection of glucose under alkaline conditions. By reducing the distance between the Pd and Ni active sites in the Pd-Ni-P nanoparticles （NPs） via atom engineering, the catalyst structure is transformed from Pd@Ni-P dumbbells into spherical NPs, greatly enhancing the catalyst sensitivity. The glassy carbon electrode modified with Pd-Ni-P ternary NPs, which behaves as an efficient nonenzymatic glucose sensor, offers excellent electrocatalytic performance with a high sensitivity of 1,136 μA·mM^-1·cm^-2, a short response time of 2 s, a wide linear range of 0.5 μM to 10.24 mM, a low limit of detection of 0.15 μM （signal-to-noise ratio = 3）, and good selectivity and reproducibility. Moreover, owing to its superior catalytic performance, the Pd-Ni-P modified electrode has excellent reliability for glucose detection in real samples of human serum. Our study provides a promising alternative strategy for designing and constructing high-performance multicomponent nanocatalyst-based sensors.
基金supported by the National Natural Science Foundation of China(Nos.21506174,21406039)the Fundamental Research Funds for the Central Universities,Southwest Minzu University(2020NYBPY04)+1 种基金the China Scholarship Council Program(201908510082)Guangdong Natural Science Foundation(2017A030307038)。
文摘Heterogeneous Pd nanocatalysts are efficient catalysts for the Heck reaction but require multi-step,sophisticated procedures and harsh reaction conditions.In this work,a green and facile strategy has been developed to decorate Pd nanoparticles on polydopamine(PDA)-coated multi-walled carbon nanotubes(Pd/CNTs-PDA)via a one-pot method.The obtained nanoparticles were characterized by various techniques including transmission electron microscopy,X-ray diffraction,and X-ray photoelectron spectroscopy,which proved that Pd NPs are well-dispersed on the PDA and between the surfaces of the PDA and CNTs.The resultant Pd/CNTs-PDA catalysts exhibit excellent catalytic reactivity toward the Heck reaction at low temperatures.Moreover,by DFT simulation,we found that during the PDA polymerization process,a large number of unsaturated—N=and C=O species are more active than the groups on the PDA end product to anchor Pd NPs.The results provide evidence that the catalyst synthesized by the onepot method exhibited good activity because sufficient active sites could be created to effectively promote Pd NPs dispersion during the dopamine polymerization process.Additionally,the Pd/CNTs-PDA catalyst was successfully employed in Heck cross-coupling reactions with various functionalized substrates.This method opens a window for the fabrication of high-performance nanocomposite catalysts under mild conditions using simple methods and has several potential applications.
