A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the ...A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine. Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction. The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.展开更多
Palladium nanoparticles generated in situ for Suzuki coupling reactions and aerobic alcohol oxidation in water were recovered completely using linear polystyrene. The resultant polystyrene-stabilized palladium nanopar...Palladium nanoparticles generated in situ for Suzuki coupling reactions and aerobic alcohol oxidation in water were recovered completely using linear polystyrene. The resultant polystyrene-stabilized palladium nanoparticles were shown to be reusable without any loss of activity.展开更多
Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles (NPs) in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered...Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles (NPs) in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered the development of efficient catalysts for CO2 electroreduction. Herein, we report the systematic engineering of active phases of Pd NPs, which are exploited to select reaction pathways for CO2 electroreduction. In situ X-ray absorption spectroscopy, in situ attenuated total reflection-infrared spectroscopy, and density functional theory calculations suggest that the formation of a hydrogen-adsorbed Pd surface on a mixture of the α- and β-phases of a palladium-hydride core (α+β PdHx@PdHx) above -0.2 V (vs. a reversible hydrogen electrode) facilitates formate production via the HCOO intermediate, whereas the formation of a metallic Pd surface on the β-phase Pd hydride core (β PdHx@Pd) below -0.5 V promotes CO production via the COOH" intermediate. The main product, which is either formate or CO, can be selectively produced with high Faradaic efficiencies (〉90%) and mass activities in the potential window of 0.05 to -0.9 V with scalable application demonstration.展开更多
Fabrication of superior catalytic performance palladium-based catalysts with affordable cost is the key to develop direct ethanol fuel cell.Herein,Pd-decorated three-dimensional(3D)porous constructed from graphene oxi...Fabrication of superior catalytic performance palladium-based catalysts with affordable cost is the key to develop direct ethanol fuel cell.Herein,Pd-decorated three-dimensional(3D)porous constructed from graphene oxide(GO)and MXene combining with polystyrene(PS)particles as sacrificial templates(Pd/GO-MXene-PS)to elevate the catalytic performance for ethanol oxidation was proposed.The 3D porous interconnected structure of Pd/GO-MXene-PS was characterized by scanning electron microscope(SEM),transmission electron microscope(TEM)and Brunner−Emmet−Teller(BET).By optimizing the doping ratio of MXene to GO,the mass activity of Pd/GO_(5)-MXene_(5)-PS(2944.0 mA·mg^(−1))was 3.0 times higher than that of commercial Pd/C(950.4 mA·mg^(−1))toward ethanol oxidation in base solution.Meanwhile,the rotating disk electrode(RDE)results demonstrated that Pd/GO5-MXene5-PS had a faster kinetics of ethanol oxidation.The enhanced ethanol oxidation over Pd/GO5-MXene5-PS could attribute to the excellent 3D interconnected porous structure,large surface area,good conductivity and homogeneous Pd distribution.This work provided a new idea for creating 3D porous MXene composite materials in electrocatalysis.展开更多
Lipid microtubules with wound ribbon features were fabricated by self-assembling method, and the deposition patterns of colloidal Pd particles on tubular template were investigated. The result indicates that colloidal...Lipid microtubules with wound ribbon features were fabricated by self-assembling method, and the deposition patterns of colloidal Pd particles on tubular template were investigated. The result indicates that colloidal Pd nanoparticles are preferentially decorated on the helical markings in the interior and on the exterior of preformed tubule and to the edge of loosely helical ribbons to obtain helical deposition features. The multi-bilayer microstruc-ture of tubules can be marked by fine Pd nanoparticles deposited at the edge of helical ribbon. There are the site-specific interactions between lipid tubular template and colloidal Pd particles at the helical edge. A new route was illustrated that colloidal Pd particles firstly attach at the edge of thin flat membranes, and then thin membranes roll up and reassemble into tubule together with particles to form helical deposition patterns. The site-specific depo-sition of Pd is unbeneficial to obtain the homogeneous metal film on tubules, but it can be utilized to reveal the dif-ferent chemical nature of lipid molecular assembly.展开更多
Product selectivity adjustment is a much-studied topic in mesoscience that is critical for industrial processes and strongly related to reaction intermediates formed by interactions between catalytic active sites and ...Product selectivity adjustment is a much-studied topic in mesoscience that is critical for industrial processes and strongly related to reaction intermediates formed by interactions between catalytic active sites and reactants.Herein,we report efficient adjustment of the product selectivity in the hydrogenation of substituted nitroarenes via rational reaction intermediates achieved using controllable Pd nanoparticles.Pd nanoparticles fixed within zeolite Beta crystals(Pd@Beta)afforded rational Pd-NO2 interactions,in which the Pd nanoparticle-adsorbed substituted nitroarenes,such as nitrobenzaldehyde,were reasonably hydrogenated into the corresponding aminobenzaldehyde.However,for Pd nanoparticles supported on the external surfaces of zeolite beta crystals,various side products were obtained owing to the coexistence of Pd-NO2 and Pd-C=O interactions.When Pd nanoparticles were artificially controlled in various positions in a fixed-bed reactor,the product selectivity was significantly affected.These results demonstrate the importance of molecular adsorption and diffusion processes in adjusting product selectivity in catalytic reactions.展开更多
Pd nanoparticles less than 8 nm were photoinduced by a near-IR femtosecond laser. The sign of the refraction nonlinearity is negative for the Pd nanoparticles with TiO2, while it is positive for those without TiO2.
Ti O2-supported Pd Au bimetallic nanoparticles(NPs) with small size and good dispersity were prepared by the room-temperature ionic liquid-assisted bimetal sputtering, which is simple, environmentally friendly, and fr...Ti O2-supported Pd Au bimetallic nanoparticles(NPs) with small size and good dispersity were prepared by the room-temperature ionic liquid-assisted bimetal sputtering, which is simple, environmentally friendly, and free of additives and byproducts. Pd/Au atomic ratio can be tuned by controlling the sputtering conditions simply. High catalytic activity was found in Pd Au–NPs–Ti O2 hybrids for solvent-free selective oxidation of 1-phenylethanol using O2 as the oxidant at the low temperature of 50 °C and low pressure of 1 atm. It was found that Pd/Au ratio strongly affected the catalytical activity, and the highest conversion of about 35 % and turnover frequency of about 421 h-1were achieved at 1:1 of Pd/Au atomic ratio. The synergistic effect in Pd Au NPs was also discussed based on the comprehensive characterization results.The present approach may offer an alternative platform for future development of green-chemistry compatible bimetallic nanocatalysts.展开更多
Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent...Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent and the support substrate of Pd-NPs.Effect of various surfactants on the in situ deposition of PdNPs on MWCNTs was investigated.When MWCNTs were modified with a cationic surfactant(hexadecyl trimethyl ammonium bromide,CTAB),the amount of the Pd-NPs(Pd-NP/CTAB-MWCNT)generated by such an in situ deposition method gets a notable increase,and the size of the as-synthesized Pd-NPs becomes smaller,compared with those in the absence of any surfactant(Pd-NP/MWCNT)or in the presence of an anionic surfactant SDS(Pd-NP/SDS-MWCNT)and a neutral surfactant OP(PdNP/OP-MWCNT).Results show that the MWCNTs modified with CTAB are propitious to the in situ reduction of Pd2?.Among the prepared catalysts,Pd-NP/CTABMWCNT displays the highest electroactivity for ethanol oxidation in alkaline media.展开更多
Electrocatalysts for ethanol oxidation reaction(EOR)are generally limited by their poor durability because of the catalyst poisoning induced by the reaction intermediate carbon monoxide(CO).Therefore,the rapid oxidati...Electrocatalysts for ethanol oxidation reaction(EOR)are generally limited by their poor durability because of the catalyst poisoning induced by the reaction intermediate carbon monoxide(CO).Therefore,the rapid oxidation removal of CO intermediates is crucial to the durability of EOR-based catalysts.Herein,in order to effectively avoiding the catalyst CO poisoning and improve the durability,the graphene-nickel nitride hybrids(AG-Ni_(3)N)were designed for supporting palladium nanoparticles(Pd/AG-Ni_(3)N)and then used for ethanol electrooxidation.The density functional theory(DFT)calculations demonstrated the introduction of AG-Ni_(3)N depresses the CO absorption and simultaneously promotes the adsorption of OH species for CO oxidation removal.The fabricated Pd/AG-Ni_(3)N catalyst distinctively exhibits excellent electroactivity with the mass catalytic activity of 3499.5 m A mg^(-1) on EOR in alkaline media,which is around 5.24 times higher than Pd/C(commercial catalyst).Notably,the Pd/AG-Ni_(3)N hybrids display excellent stability and durability after chronoamperometric measurements with a total operation time of 150,000 s.展开更多
Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways:(i) reduct...Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways:(i) reduction with N2H4 in an ultrasonic bath and(ii) by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H2 in mild(100 ℃) conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H2O2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction(to water) induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment.This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.展开更多
A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crysta...A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles (PdNPs) with a narrow particle size distribution (3-5 nm) are uni- formly deposited onto the surface of Co304 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst (448 mA/mg Pd). The dependency of log/against logv reveals that MEO on Pd-CO304 electrode is under a diffusion control. Electrochemical impedance spectroscopy (EIS) measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-CO304 is observed at -0.05 V, which coincides with the potential of MEO peak.展开更多
In spite of the numerous advances in the development of H_(2)and O_(2)evolutions upon water splitting,the separation of H_(2)from O_(2)still remains a severe challenge.Herein,the novel dual-functional nanocatalysts Pd...In spite of the numerous advances in the development of H_(2)and O_(2)evolutions upon water splitting,the separation of H_(2)from O_(2)still remains a severe challenge.Herein,the novel dual-functional nanocatalysts Pd/carbon nanosphere(CNS),obtained via immobilization of ultrafine Pd nanoparticles onto CNS,are developed and employed for both selective H_(2)generation from HCOOH dehydrogenation and O_(2)evolution from H_(2)O_(2)decomposition.In these reactions,the highest activities for Pd/CNS-800(i.e.,calcinated at 800℃)are 2478 h−1 and 993 min^(−1)for H_(2)and O_(2)evolution,respectively.The highly efficient and selective“on-off”switch for selective H_(2)generation from HCOOH is successfully realized by pH adjustment.This novel and highly efficient nanocatalyst Pd/CNS-800 not only provides new approaches for the promising application of HCOOH and H_(2)O_(2)as economic and safe H_(2)and O_(2)carriers,respectively,for fuel cells,but also promotes the development of“on-off”switch for on-demand H_(2)evolution.展开更多
In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react wit...In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react with formaldehyde to form novel reducing groups(-NH-CH_(2)OH),which can in situ auto-reduce the encapsulated Pd^(2+)ions to metallic Pd clusters/nanoparticles.As no additional reductants are required,the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd^(2+)precursor.When applied as catalysts in the hydrogenation of phenol in the aqueous phase,the obtained Pd(1.5)/MIL-125-NH-CH_(2)OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100%of phenol conversion and 100%of cyclohexanone selectivity at 70℃ after 5 h,as well as remarkable reusability for at least five cycles due to the large MOF surface area,the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH_(2)OH framework.展开更多
Using a liquid-solid phase inversion method, a hybrid matrix poly(vinylidene fluoride)(PVDF) membrane was prepared with alumina(Al2O3) nanoparticle addition. Pd/Fe nanoparticles(NPs) were successfully immobili...Using a liquid-solid phase inversion method, a hybrid matrix poly(vinylidene fluoride)(PVDF) membrane was prepared with alumina(Al2O3) nanoparticle addition. Pd/Fe nanoparticles(NPs) were successfully immobilized on the Al2O3/PVDF membrane, which was characterized by Scanning Electron Microscopy(SEM) and Transmission Electron Microscopy(TEM). The micrographs showed that the Pd/Fe NPs were dispersed homogeneously. Several important experimental parameters were optimized, including the mechanical properties, contact angle and surface area of Al2O3/PVDF composite membranes with different Al2O3 contents. At the same time, the ferrous ion concentration and the effect of hydrophilization were studied. The results showed that the modified Al2O3/PVDF membrane functioned well as a support. The Al2O3/PVDF membrane with immobilized Pd/Fe NPs exhibited high efficiency in terms of dichloroacetic acid(DCAA) dechlorination. Additionally, a reaction pathway for DCAA dechlorination by Pd/Fe NPs immobilized on the Al2O3/PVDF membrane system was proposed.展开更多
Graphene has been successfully modified with palladium nanoparticles in a facile manner by reducing palladium acetate [Pd(OAc)2] in the present of sodium dodecyl sulfate (SDS), which is used as both surfactant and the...Graphene has been successfully modified with palladium nanoparticles in a facile manner by reducing palladium acetate [Pd(OAc)2] in the present of sodium dodecyl sulfate (SDS), which is used as both surfactant and the reducing agent. The palladium nanoparticle-graphene hybrids (Pd-graphene hybrids) are characterized by high- resolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy. We demonstrate that the Pd-graphene hybrids can act as an efficient catalyst for the Suzuki reaction under aqueous and aerobic conditions, with the reaction reaching completion in as little as 5 min. The influence of the preparation conditions on the catalytic activities of the hybrids is also investigated.展开更多
Construction of metal-organic-frame works-based composite photocatalysts has attracted much attention for the reasonable band gap and high surface areas to improve the photocatalytic activity.In this study,the ternary...Construction of metal-organic-frame works-based composite photocatalysts has attracted much attention for the reasonable band gap and high surface areas to improve the photocatalytic activity.In this study,the ternary heterojunction Pd@UiO-66-NH_(2)@ZnIn_(2)S_(4)nanocomposites were facilely prepared for the first time by a two-step method.The visible-light-promoted hydrogen production rate of 0.3%Pd@UiO-66-NH_(2)@ZnIn_(2)S_(4)reaches up to 5.26 mmol g^(-1)h^(-1),which is evidently much higher than pure UiO-66-NH_(2),ZnIn_(2)S_(4)and binary UiO-66-NH_(2)/ZnIn_(2)S_(4)composites.Such a huge improvement in the photocatalytic performance is mainly attributed to the matched band gap of ZnIn_(2)S_(4)and UiO-66-NH_(2),and the introduction of Pd NPs into photocatalysts that broaden spectral response range and promote the photon induced charge carrier separation.This work may provide a feasible approach for the design and construction of metal-organic-frameworks-based photocatalytic materials.展开更多
A promising electrochemical sensor was fabricated by electrodeposition of Pd nanoparticles (PdNPs) on poly(thiophene-3-acetic acid) (PTAA)-modified glassy carbon electrode (GCE), forming a PdNPs/PTAA composite...A promising electrochemical sensor was fabricated by electrodeposition of Pd nanoparticles (PdNPs) on poly(thiophene-3-acetic acid) (PTAA)-modified glassy carbon electrode (GCE), forming a PdNPs/PTAA composites-modified GCE (PdNPs/PTAA/GCE). Scanning electron microscope (SEM) and electrochemical techniques were used for the characterization of these composites. It was found that the PdNPs/PTAA layer was very uniform. ]Electrochemical experiments showed that this proposed PdNPs/PTAA composites-modified electrode exhibited excellent electrocatalytic activity towards the oxidation of hydrazine. Under the optimum conditions, the proposed sensor can be applied to the quantification of hydrazine with a wide linear range from 8.0 × 10-9 mol/L to 1.0 × 10-5 mol/L with a low detection limit of 2.67 × 10-9 mol/L. The experiment results also showed that the sensor exhibited good reproducibility and long-term stability, as well as high selectivity with no interference from other potential competing species.展开更多
Pd/CeO2 catalysts with flower-like morphology were fabricated via an ultrasonic-assisted membrane reduction (UAMR) and hydrothermal methods. The catalysts were physically characterized and evaluated for three-way ca...Pd/CeO2 catalysts with flower-like morphology were fabricated via an ultrasonic-assisted membrane reduction (UAMR) and hydrothermal methods. The catalysts were physically characterized and evaluated for three-way catalytic activities versus tradi- tional Pd/CeO2 catalysts. Flower-like Pd/CeO2 catalysts exhibited a higher catalytic performance and better thermal stability than the Pd/CeO2 prepared by conventional impregnation. The flower-like Pd/CeO2 catalysts were constructed from 20-50 nm thick nanosheet petals. These petals were in turn constructed from 10 nm CeO2 nanoparticles that self-assembled into the flower-like morphology re- sulting in abundant pores in all directions. The Pd nanoparticles were anchored and dispersed on both the interior and surface of the pores and had minimal sintering. When these catalysts were aged, the structure and morphology of the catalysts remained unchanged with important industrial implications for this new type of material including improved catalytic performance and high thermal stabil- ity. Regardless of the Pd loading, both the fresh and aged Pd/CeO2 catalysts prepared by the UAMR-hydrothermal method exhibited better performance than the corresponding samples prepared by conventional impregnation means.展开更多
Nanotechnology plays a key role in the development of innovative scaffolds for bone tissue engineering(BTE)allowing the incorporation of nanomaterials able to improve cell proliferation and differentiation.In this stu...Nanotechnology plays a key role in the development of innovative scaffolds for bone tissue engineering(BTE)allowing the incorporation of nanomaterials able to improve cell proliferation and differentiation.In this study,Mg-HA-Coll type I scaffolds(Mg-HA-based scaffolds)were nanofunctionalized with gold nanorods(Au NRs),palladium nanoparticles(Pd NPs)and maghemite nanoparticles(MAG NPs).Nanofunctionalized Mg-HA-based scaffolds(NF-HA-Ss)were tested for their ability to promote both the proliferation and the differentiation of adipose-derived mesenchymal stem cells(hADSCs).Results clearly highlight that MAG nanofunctionalization substantially improves cell proliferation up to 70% compared with the control(Mg-HA-based scaffold),whereas both Au NRs and Pd NPs nanofunctionalization induce a cell growth inhibition of 94% and 89%,respectively.Similar evidences were found for the osteoinductive properties showing relevant calcium deposits(25% higher than the control)for MAG nanofunctionalization,while a decreasing of cell differentiation(20% lower than the control)for both Au NRs and Pd NPs derivatization.These results are in agreement with previous studies that found cytotoxic effects for both Pd NPs and Au NRs.The excellent improvement of both osteoconductivity and osteoinductivity of the MAG NF-HA-S could be attributed to the high intrinsic magnetic field of superparamagnetic MAG NPs.These findings may pave the way for the development of innovative nanostructured scaffolds for BTE.展开更多
基金supported by the National Basic Research Program of China(Grant No.2007CB209700)the Graduate Student Innovation Foundation of Jiangsu Province,China(Grant No.CX09B_075Z)the Research Funding of Nanjing University of Aeronautics and Astronautics,China(Grant No.NS2010165)
文摘A novel electrode material based on chemically modified graphene (CMG) with aminophenyl groups is covalently functionalized by a nucleophilic ring-opening reaction between the epoxy groups of graphene oxide and the aminophenyl groups of p-phenylenediamine. Palladium nanoparticles with an average diameter of 4.2 nm are deposited on the CMG by a liquid-phase borohydride reduction. The electrocatalytic activity and stability of the Pd/CMG composite towards formic acid oxidation are found to be higher than those of reduced graphene oxide and commercial carbon materials such as Vulcan XC-72 supported Pd electrocatalysts.
基金the Nanomaterials and Micro-devices Research Center(NMRC)of OIT for financial and instrumental supportssupported by the Joint Studies Program(2010)of the Institute for Mo-lecular Science.
文摘Palladium nanoparticles generated in situ for Suzuki coupling reactions and aerobic alcohol oxidation in water were recovered completely using linear polystyrene. The resultant polystyrene-stabilized palladium nanoparticles were shown to be reusable without any loss of activity.
文摘Active-phase engineering is regularly utilized to tune the selectivity of metal nanoparticles (NPs) in heterogeneous catalysis. However, the lack of understanding of the active phase in electrocatalysis has hampered the development of efficient catalysts for CO2 electroreduction. Herein, we report the systematic engineering of active phases of Pd NPs, which are exploited to select reaction pathways for CO2 electroreduction. In situ X-ray absorption spectroscopy, in situ attenuated total reflection-infrared spectroscopy, and density functional theory calculations suggest that the formation of a hydrogen-adsorbed Pd surface on a mixture of the α- and β-phases of a palladium-hydride core (α+β PdHx@PdHx) above -0.2 V (vs. a reversible hydrogen electrode) facilitates formate production via the HCOO intermediate, whereas the formation of a metallic Pd surface on the β-phase Pd hydride core (β PdHx@Pd) below -0.5 V promotes CO production via the COOH" intermediate. The main product, which is either formate or CO, can be selectively produced with high Faradaic efficiencies (〉90%) and mass activities in the potential window of 0.05 to -0.9 V with scalable application demonstration.
基金financially supported by the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning(No.A30B191410)the Sailing Project from Science and Technology Commission of Shanghai Municipality(No.17YF1406600)+6 种基金Chenguang Project Supported by Shanghai Municipal Education Commission(No.18CG68)Gaoyuan Discipline of Shanghai-Materials Science and Engineering(No.A30NH221903)the Open Project of Jiangsu Key Laboratory for Carbon-Based Functional Materials&Devices(Soochow University)(No.KS2022)Collaborative Innovation Center of Suzhou Nano Science&Technologythe 111 ProjectJoint International Research Laboratory of Carbon-Based Functional Materials and Devicesthe Project of Guangdong Provincial Education(No.2020KTSCX131)。
文摘Fabrication of superior catalytic performance palladium-based catalysts with affordable cost is the key to develop direct ethanol fuel cell.Herein,Pd-decorated three-dimensional(3D)porous constructed from graphene oxide(GO)and MXene combining with polystyrene(PS)particles as sacrificial templates(Pd/GO-MXene-PS)to elevate the catalytic performance for ethanol oxidation was proposed.The 3D porous interconnected structure of Pd/GO-MXene-PS was characterized by scanning electron microscope(SEM),transmission electron microscope(TEM)and Brunner−Emmet−Teller(BET).By optimizing the doping ratio of MXene to GO,the mass activity of Pd/GO_(5)-MXene_(5)-PS(2944.0 mA·mg^(−1))was 3.0 times higher than that of commercial Pd/C(950.4 mA·mg^(−1))toward ethanol oxidation in base solution.Meanwhile,the rotating disk electrode(RDE)results demonstrated that Pd/GO5-MXene5-PS had a faster kinetics of ethanol oxidation.The enhanced ethanol oxidation over Pd/GO5-MXene5-PS could attribute to the excellent 3D interconnected porous structure,large surface area,good conductivity and homogeneous Pd distribution.This work provided a new idea for creating 3D porous MXene composite materials in electrocatalysis.
文摘Lipid microtubules with wound ribbon features were fabricated by self-assembling method, and the deposition patterns of colloidal Pd particles on tubular template were investigated. The result indicates that colloidal Pd nanoparticles are preferentially decorated on the helical markings in the interior and on the exterior of preformed tubule and to the edge of loosely helical ribbons to obtain helical deposition features. The multi-bilayer microstruc-ture of tubules can be marked by fine Pd nanoparticles deposited at the edge of helical ribbon. There are the site-specific interactions between lipid tubular template and colloidal Pd particles at the helical edge. A new route was illustrated that colloidal Pd particles firstly attach at the edge of thin flat membranes, and then thin membranes roll up and reassemble into tubule together with particles to form helical deposition patterns. The site-specific depo-sition of Pd is unbeneficial to obtain the homogeneous metal film on tubules, but it can be utilized to reveal the dif-ferent chemical nature of lipid molecular assembly.
基金This work is supported by the National Natural Science Foundation of China(91634201,21403192 and 91645105)the China Postdoctoral Science Foundation(2018M630662)。
文摘Product selectivity adjustment is a much-studied topic in mesoscience that is critical for industrial processes and strongly related to reaction intermediates formed by interactions between catalytic active sites and reactants.Herein,we report efficient adjustment of the product selectivity in the hydrogenation of substituted nitroarenes via rational reaction intermediates achieved using controllable Pd nanoparticles.Pd nanoparticles fixed within zeolite Beta crystals(Pd@Beta)afforded rational Pd-NO2 interactions,in which the Pd nanoparticle-adsorbed substituted nitroarenes,such as nitrobenzaldehyde,were reasonably hydrogenated into the corresponding aminobenzaldehyde.However,for Pd nanoparticles supported on the external surfaces of zeolite beta crystals,various side products were obtained owing to the coexistence of Pd-NO2 and Pd-C=O interactions.When Pd nanoparticles were artificially controlled in various positions in a fixed-bed reactor,the product selectivity was significantly affected.These results demonstrate the importance of molecular adsorption and diffusion processes in adjusting product selectivity in catalytic reactions.
文摘Pd nanoparticles less than 8 nm were photoinduced by a near-IR femtosecond laser. The sign of the refraction nonlinearity is negative for the Pd nanoparticles with TiO2, while it is positive for those without TiO2.
基金supported by the National Natural Science Foundation of China(No.61274019)the Collaborative Innovation Center of Suzhou Nano Science & Technologythe Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘Ti O2-supported Pd Au bimetallic nanoparticles(NPs) with small size and good dispersity were prepared by the room-temperature ionic liquid-assisted bimetal sputtering, which is simple, environmentally friendly, and free of additives and byproducts. Pd/Au atomic ratio can be tuned by controlling the sputtering conditions simply. High catalytic activity was found in Pd Au–NPs–Ti O2 hybrids for solvent-free selective oxidation of 1-phenylethanol using O2 as the oxidant at the low temperature of 50 °C and low pressure of 1 atm. It was found that Pd/Au ratio strongly affected the catalytical activity, and the highest conversion of about 35 % and turnover frequency of about 421 h-1were achieved at 1:1 of Pd/Au atomic ratio. The synergistic effect in Pd Au NPs was also discussed based on the comprehensive characterization results.The present approach may offer an alternative platform for future development of green-chemistry compatible bimetallic nanocatalysts.
基金supported by the National Natural Science Foundation of China (Nos. 21376070 and 20876038)Scientific Research Fund of Hunan Provincial Edu- cation Department (No. 11K023)Hunan Provincial Natural Science Foundation of China (14JJ2096)
文摘Pd nanoparticles(Pd-NPs)were prepared and directly anchored on the surface of multi-walled carbon nanotubes(MWCNTs)in the absence of chemical reduction agent,where MWCNTs were used as both the chemical reduction agent and the support substrate of Pd-NPs.Effect of various surfactants on the in situ deposition of PdNPs on MWCNTs was investigated.When MWCNTs were modified with a cationic surfactant(hexadecyl trimethyl ammonium bromide,CTAB),the amount of the Pd-NPs(Pd-NP/CTAB-MWCNT)generated by such an in situ deposition method gets a notable increase,and the size of the as-synthesized Pd-NPs becomes smaller,compared with those in the absence of any surfactant(Pd-NP/MWCNT)or in the presence of an anionic surfactant SDS(Pd-NP/SDS-MWCNT)and a neutral surfactant OP(PdNP/OP-MWCNT).Results show that the MWCNTs modified with CTAB are propitious to the in situ reduction of Pd2?.Among the prepared catalysts,Pd-NP/CTABMWCNT displays the highest electroactivity for ethanol oxidation in alkaline media.
基金funded by the National Natural Science Foundation of China(No.91745112)sponsored by Shanghai Rising-Star Program(No.19QA1404100)+1 种基金Financial support from the Science and Technology Commission of Shanghai Municipality(Nos.19DZ2271100 and 18020500800)the support from the Opening Project of PCOSS,Xiamen University,201910。
文摘Electrocatalysts for ethanol oxidation reaction(EOR)are generally limited by their poor durability because of the catalyst poisoning induced by the reaction intermediate carbon monoxide(CO).Therefore,the rapid oxidation removal of CO intermediates is crucial to the durability of EOR-based catalysts.Herein,in order to effectively avoiding the catalyst CO poisoning and improve the durability,the graphene-nickel nitride hybrids(AG-Ni_(3)N)were designed for supporting palladium nanoparticles(Pd/AG-Ni_(3)N)and then used for ethanol electrooxidation.The density functional theory(DFT)calculations demonstrated the introduction of AG-Ni_(3)N depresses the CO absorption and simultaneously promotes the adsorption of OH species for CO oxidation removal.The fabricated Pd/AG-Ni_(3)N catalyst distinctively exhibits excellent electroactivity with the mass catalytic activity of 3499.5 m A mg^(-1) on EOR in alkaline media,which is around 5.24 times higher than Pd/C(commercial catalyst).Notably,the Pd/AG-Ni_(3)N hybrids display excellent stability and durability after chronoamperometric measurements with a total operation time of 150,000 s.
文摘Two families of catalysts, based on Pd nanoparticles supported on ceramic asymmetric tubular alumina membranes, are studies in the direct synthesis of H2O2. They are prepared by depositing Pd in two ways:(i) reduction with N2H4 in an ultrasonic bath and(ii) by impregnation-deposition. The first preparation leads to larger particles, with average size of around 11 nm, while the second preparation leads to smaller particles, with average size around 4 nm. The catalytic membranes were tested as prepared, after thermal treatment in air and after further pre-reduction with H2 in mild(100 ℃) conditions. Samples were characterized by TEM, CO-chemisorption monitored by DRIFTS method and TPR, while catalytic tests have been performed in a semi-batch recirculation membrane reactor. Experimental catalytic results were analysed using two kinetics models to derive the reaction constants for the parallel and consecutive reactions of the kinetic network. Smaller particles of Pd show lower selectivity due to the higher rate of parallel combustion, even if the better dispersion of Pd and thus higher metal surface area in the sample lead to a productivity in H2O2 similar or even higher than the sample with the larger Pd particles. Independently on the presence of smaller or larger Pd nanoparticles, an oxidation treatment leads to a significant enhancement in the productivity, although the catalyst progressively reduces during the catalytic process. The inhibition of the parallel combustion reaction(to water) induced from the calcination treatment remains after the in-situ reduction of the oxidized Pd species formed during the pre-treatment.This is likely due to the elimination of defect sites which dissociatively activate oxygen, and tentatively attributed to Pd sites able to give three- and four-fold coordination of CO.
基金supported by the National Basic Research Program of China(2013CB934001)the Natural Science Foundation of Beijing(2051001)the Natural Science Foundation of China(51074011)
文摘A CO3O4 nanorod supported Pd electro-catalyst for the methanol electro-oxidation (MEO) has been fabricated by the combination of hydrother- mal synthesis and microwave-assisted polyol reduction processes. The crystallographic property and microstructure have been characterized using XRD, SEM and TEM. The results demonstrate that Pd nanoparticles (PdNPs) with a narrow particle size distribution (3-5 nm) are uni- formly deposited onto the surface of Co304 nanorods. Electrochemical measurements show that this catalyst having a larger electrochemically active surface area and a more negative onset-potential exhibits enhanced catalytic activity of 504 mA/mg Pd for MEO comparing with the Pd/C catalyst (448 mA/mg Pd). The dependency of log/against logv reveals that MEO on Pd-CO304 electrode is under a diffusion control. Electrochemical impedance spectroscopy (EIS) measurement agrees well with the CV results. The minimum charge transfer resistance of MEO on Pd-CO304 is observed at -0.05 V, which coincides with the potential of MEO peak.
基金National Natural Science Foundation of China,Grant/Award Number:21805166111 Project of China,Grant/Award Number:D20015+1 种基金Ministryof Education,Hubei province,China,Grant/Award Number:T2020004Foundation of Science and Technology Bureau of Yichang City,Grant/Award Number:A21‐3‐012。
文摘In spite of the numerous advances in the development of H_(2)and O_(2)evolutions upon water splitting,the separation of H_(2)from O_(2)still remains a severe challenge.Herein,the novel dual-functional nanocatalysts Pd/carbon nanosphere(CNS),obtained via immobilization of ultrafine Pd nanoparticles onto CNS,are developed and employed for both selective H_(2)generation from HCOOH dehydrogenation and O_(2)evolution from H_(2)O_(2)decomposition.In these reactions,the highest activities for Pd/CNS-800(i.e.,calcinated at 800℃)are 2478 h−1 and 993 min^(−1)for H_(2)and O_(2)evolution,respectively.The highly efficient and selective“on-off”switch for selective H_(2)generation from HCOOH is successfully realized by pH adjustment.This novel and highly efficient nanocatalyst Pd/CNS-800 not only provides new approaches for the promising application of HCOOH and H_(2)O_(2)as economic and safe H_(2)and O_(2)carriers,respectively,for fuel cells,but also promotes the development of“on-off”switch for on-demand H_(2)evolution.
基金financial support from the National Natural Science Foundation of China(Grant No.51802015)the Research Department Closed Carbon Cycle Economy(CCCE)at the Ruhr-University Bochum,Fundamental Research Funds for the Central Universities(No.FRF-TP-20-005A3)the Fundamental Research Funds for the Central Universities and the Youth Teacher International Exchange&Growth Program(Grant No.QNXM20210016)。
文摘In this work,a novel in situ auto-reduction strategy was developed to encapsulate uniformly dispersed Pd clusters/nanoparticles in MIL-125-NH_(2).It is demonstrated that the amino groups in MIL-125-NH_(2)can react with formaldehyde to form novel reducing groups(-NH-CH_(2)OH),which can in situ auto-reduce the encapsulated Pd^(2+)ions to metallic Pd clusters/nanoparticles.As no additional reductants are required,the strategy limits the aggregation and migration of Pd clusters and the formation of large Pd nanoparticles via controlling the amount of Pd^(2+)precursor.When applied as catalysts in the hydrogenation of phenol in the aqueous phase,the obtained Pd(1.5)/MIL-125-NH-CH_(2)OH catalyst with highly dispersed Pd clusters/nanoparticles with the size of around 2 nm exhibited 100%of phenol conversion and 100%of cyclohexanone selectivity at 70℃ after 5 h,as well as remarkable reusability for at least five cycles due to the large MOF surface area,the highly dispersed Pd clusters/nanoparticles and their excellent stability within the MIL-125-NH-CH_(2)OH framework.
基金supported by the Nature Science Foundation of Heilongjiang Province (No. B201410)the Postdoctoral Foundation Project of Heilongjiang Province (No. LBH-Z13128)+3 种基金the Science and Technology Research Program of Education Bureau of Heilongjiang Province (No. 12531206)the Special Scientific Research Projects of Harbin Normal University (12XQXG02)the National Nature Science Foundation of China (No. 41030743)the National Nature Science Foundation of China (No. 42171217)
文摘Using a liquid-solid phase inversion method, a hybrid matrix poly(vinylidene fluoride)(PVDF) membrane was prepared with alumina(Al2O3) nanoparticle addition. Pd/Fe nanoparticles(NPs) were successfully immobilized on the Al2O3/PVDF membrane, which was characterized by Scanning Electron Microscopy(SEM) and Transmission Electron Microscopy(TEM). The micrographs showed that the Pd/Fe NPs were dispersed homogeneously. Several important experimental parameters were optimized, including the mechanical properties, contact angle and surface area of Al2O3/PVDF composite membranes with different Al2O3 contents. At the same time, the ferrous ion concentration and the effect of hydrophilization were studied. The results showed that the modified Al2O3/PVDF membrane functioned well as a support. The Al2O3/PVDF membrane with immobilized Pd/Fe NPs exhibited high efficiency in terms of dichloroacetic acid(DCAA) dechlorination. Additionally, a reaction pathway for DCAA dechlorination by Pd/Fe NPs immobilized on the Al2O3/PVDF membrane system was proposed.
基金The authors would like to acknowledge the support of this work by the National Natural Science Foundation of China(20776095)and the Programme of Introducing Talents of Discipline to Universities(No.B06006).
文摘Graphene has been successfully modified with palladium nanoparticles in a facile manner by reducing palladium acetate [Pd(OAc)2] in the present of sodium dodecyl sulfate (SDS), which is used as both surfactant and the reducing agent. The palladium nanoparticle-graphene hybrids (Pd-graphene hybrids) are characterized by high- resolution transmission electron microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, and energy dispersive X-ray spectroscopy. We demonstrate that the Pd-graphene hybrids can act as an efficient catalyst for the Suzuki reaction under aqueous and aerobic conditions, with the reaction reaching completion in as little as 5 min. The influence of the preparation conditions on the catalytic activities of the hybrids is also investigated.
基金the Natural Science Foundation of Shanghai(No.19ZR1403500)the National Natural Science Foundation of China(No.21373054)the Natural Science Foundation of Shanghai Science and Technology Committee(No.19DZ2270100)。
文摘Construction of metal-organic-frame works-based composite photocatalysts has attracted much attention for the reasonable band gap and high surface areas to improve the photocatalytic activity.In this study,the ternary heterojunction Pd@UiO-66-NH_(2)@ZnIn_(2)S_(4)nanocomposites were facilely prepared for the first time by a two-step method.The visible-light-promoted hydrogen production rate of 0.3%Pd@UiO-66-NH_(2)@ZnIn_(2)S_(4)reaches up to 5.26 mmol g^(-1)h^(-1),which is evidently much higher than pure UiO-66-NH_(2),ZnIn_(2)S_(4)and binary UiO-66-NH_(2)/ZnIn_(2)S_(4)composites.Such a huge improvement in the photocatalytic performance is mainly attributed to the matched band gap of ZnIn_(2)S_(4)and UiO-66-NH_(2),and the introduction of Pd NPs into photocatalysts that broaden spectral response range and promote the photon induced charge carrier separation.This work may provide a feasible approach for the design and construction of metal-organic-frameworks-based photocatalytic materials.
基金financially supported by the National Natural Science Foundation of China (Nos.50963002,51073074)Jiangxi Provincial Department of Education (Nos.GJJ11590,GJJ10678)
文摘A promising electrochemical sensor was fabricated by electrodeposition of Pd nanoparticles (PdNPs) on poly(thiophene-3-acetic acid) (PTAA)-modified glassy carbon electrode (GCE), forming a PdNPs/PTAA composites-modified GCE (PdNPs/PTAA/GCE). Scanning electron microscope (SEM) and electrochemical techniques were used for the characterization of these composites. It was found that the PdNPs/PTAA layer was very uniform. ]Electrochemical experiments showed that this proposed PdNPs/PTAA composites-modified electrode exhibited excellent electrocatalytic activity towards the oxidation of hydrazine. Under the optimum conditions, the proposed sensor can be applied to the quantification of hydrazine with a wide linear range from 8.0 × 10-9 mol/L to 1.0 × 10-5 mol/L with a low detection limit of 2.67 × 10-9 mol/L. The experiment results also showed that the sensor exhibited good reproducibility and long-term stability, as well as high selectivity with no interference from other potential competing species.
基金Project supported by National Natural Science Foundation of China (20877006, 20833011)Beijing Municipal Natural Science Foundation (2101002)+2 种基金the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality (PHR201107104, PHR200907105)National High Technology Research and Development Program (2011AA03A406)National Industrial Project of New Rare Earth Materials
文摘Pd/CeO2 catalysts with flower-like morphology were fabricated via an ultrasonic-assisted membrane reduction (UAMR) and hydrothermal methods. The catalysts were physically characterized and evaluated for three-way catalytic activities versus tradi- tional Pd/CeO2 catalysts. Flower-like Pd/CeO2 catalysts exhibited a higher catalytic performance and better thermal stability than the Pd/CeO2 prepared by conventional impregnation. The flower-like Pd/CeO2 catalysts were constructed from 20-50 nm thick nanosheet petals. These petals were in turn constructed from 10 nm CeO2 nanoparticles that self-assembled into the flower-like morphology re- sulting in abundant pores in all directions. The Pd nanoparticles were anchored and dispersed on both the interior and surface of the pores and had minimal sintering. When these catalysts were aged, the structure and morphology of the catalysts remained unchanged with important industrial implications for this new type of material including improved catalytic performance and high thermal stabil- ity. Regardless of the Pd loading, both the fresh and aged Pd/CeO2 catalysts prepared by the UAMR-hydrothermal method exhibited better performance than the corresponding samples prepared by conventional impregnation means.
基金supported by PON—BONEtt,Sviluppo di Micro e Nanotecnolgie per la Predittivita`,la Diagnosi,la Terapia e i Trattamenti Rigenerativi delle Alterazioni Patologiche dell’Osso e Osteo-Articolari(No.ARS01_00693).
文摘Nanotechnology plays a key role in the development of innovative scaffolds for bone tissue engineering(BTE)allowing the incorporation of nanomaterials able to improve cell proliferation and differentiation.In this study,Mg-HA-Coll type I scaffolds(Mg-HA-based scaffolds)were nanofunctionalized with gold nanorods(Au NRs),palladium nanoparticles(Pd NPs)and maghemite nanoparticles(MAG NPs).Nanofunctionalized Mg-HA-based scaffolds(NF-HA-Ss)were tested for their ability to promote both the proliferation and the differentiation of adipose-derived mesenchymal stem cells(hADSCs).Results clearly highlight that MAG nanofunctionalization substantially improves cell proliferation up to 70% compared with the control(Mg-HA-based scaffold),whereas both Au NRs and Pd NPs nanofunctionalization induce a cell growth inhibition of 94% and 89%,respectively.Similar evidences were found for the osteoinductive properties showing relevant calcium deposits(25% higher than the control)for MAG nanofunctionalization,while a decreasing of cell differentiation(20% lower than the control)for both Au NRs and Pd NPs derivatization.These results are in agreement with previous studies that found cytotoxic effects for both Pd NPs and Au NRs.The excellent improvement of both osteoconductivity and osteoinductivity of the MAG NF-HA-S could be attributed to the high intrinsic magnetic field of superparamagnetic MAG NPs.These findings may pave the way for the development of innovative nanostructured scaffolds for BTE.