The catalytic activity of noble-metal nanocrystals is mainly determined by their sizes and the facets exposed on the surface. For single crystals, it has been demonstrated that the Pd（100） surface is catalytically m...The catalytic activity of noble-metal nanocrystals is mainly determined by their sizes and the facets exposed on the surface. For single crystals, it has been demonstrated that the Pd（100） surface is catalytically more active than both Pd（110） and Pd（111） surfaces for the CO oxidation reaction. Here we report the synthesis of Pd nanocrystals enclosed by {100} facets with controllable sizes in the range of 6-18 nm by manipulating the rate of reduction of the precursor. UV-vis spectroscopy studies indicate that the rate of reduction of Na2PdC14 can be controlled by adjusting the concentrations of Br- and C1- ions added to the reaction mixture. Pd nanocrystals with different sizes were immobilized on ZnO nanowires and evaluated as catalysts for CO oxidation. We found that the activity of this catalytic system for CO oxidation showed a strong dependence on the nanocrystal size. When the size of the Pd nanocrystals was reduced from 18 nm to 6 nm, the maximum conversion rate was significantly enhanced by a factor of -10 and the corresponding maximum conversion temperature was lowered by -80℃.展开更多
As a promising fuel candidate,ammonia has been successtully used as anode feed in alkaline fuel cells.However,current technology in catalysts for ammonia electro-oxidation reaction(AOR)with respect to both cost and pe...As a promising fuel candidate,ammonia has been successtully used as anode feed in alkaline fuel cells.However,current technology in catalysts for ammonia electro-oxidation reaction(AOR)with respect to both cost and performance is inadequate to ensure large scale commercial application of direct ammonia fuel cells.Recent studies found that alloying Pt with different transition metals and controlling the morphology of catalysts can improve the AOR activity,and thus potentially can solve the cost issue.Herein,(100)-terminated Pt-M nanocubes(M=3d-transition metals Fe,Co,Ni,Zn)are synthesized via wet-chemistry method and their catalytic activities toward AOR are evaluated.The addition of Fe,Co,Ni and Zn elements can enhance the AOR activity due to decrease in oxophilicity of platinum and bifunctional mechanism.Pt-Zn exhibits the maximum mass activity and specific ativity with values of 0.41 A/mgpt and 169 mA/cm2 that are 1.6 and 1.8 times higher than Pt nanocubes,respectively.Pt-Fe,Pt-Co and PI-Ni nanocubes also ilustrate higher mass and specific activities compared to Pt nanocubes.展开更多
The ternary cobalt-nickel-iron phosphide nanocubes (P-Co0.9Ni0.9Fe1.2 NCs) with high intrinsic activity, conductivity, defect concentration and optimized ratio have been realized through a facile phosphorization treat...The ternary cobalt-nickel-iron phosphide nanocubes (P-Co0.9Ni0.9Fe1.2 NCs) with high intrinsic activity, conductivity, defect concentration and optimized ratio have been realized through a facile phosphorization treatment using ternary cobalt-nickel-iron nanocubes of Prussian blue analogs (PBA) as a precursor. The scanning electron microscopy and transmission electron microscopy results show that the P-Co0.9Ni0.9Fe1.2 NCs maintain a cubic structure with a rough surface, implying the rich surface defects as exposed active sites. The thermal phosphorization of the ternary PBA precursor not only provids carbon doping but also leads to the in situ construction of surface defects on the NCs. The carbon doping from the PBA precursor lowers the charge transfer resistance and optimizes the electronic transformation. The synergistic effect among the ternary metal ions and rich defects contributes to the enhanced electrocatalytic performance . The P-Co0.9Ni0.9Fe1.2NCs achieve low overpotentials of -200.7 and 273.1 mV at a current density of 10 mA cm^-2 for the hydrogen evolution reaction and the oxygen evolution reaction, respectively. The potential of overall water splitting reaches 1.52 V at a current density of 10 mA cm^-2. The longterm stability of the electrocatalysts was also evaluated. This work provides a facile method to design efficient transitionmetal- based bifunctional electrocatalysts for overall water splitting.展开更多
Metal-organic framework-derived composites have been widely used in electromagnetic wave(EMW)absorption,but the traditional synthetic strategy greatly limits the structure and species of MOFs.This research provided a ...Metal-organic framework-derived composites have been widely used in electromagnetic wave(EMW)absorption,but the traditional synthetic strategy greatly limits the structure and species of MOFs.This research provided a solvent-free method to synthesize Co-MOF and its derivatives.Using CoSnO_(3)as the precursor,the preparation of Co-MOF is achieved by bridging the cobalt(II)ion of CoSnO_(3)and the 2-methylimidazole skeleton.The CoSn/N-doped carbon(CoSn/NC)composites derived from CoSnO_(3)-MOF(Co-MOF with CoSnO_(3)as Co source)retain the original morphology of CoSnO_(3).Besides,the polarization effect produced by the N-doped carbon layers also benefits the excellent EMW absorption performance of the CoSn/NC composites.It is reflected in the minimum reflection loss(RL)of-48.2 dB at 2.2 mm and the effective bandwidth(EBA)of 5.84 GHz.This work provides a new channel to the construction of Co-MOFs,which could be extended to other Co-based oxides and vastly expand the species of MOFs based on metallic Co.展开更多
The ammonia electrolysis is a highly efficient and energy-saving method for ultra-pure hydrogen generation, which highly relies on electrocatalytic performance of electrocatalysts. In this work, high-quality platinum(...The ammonia electrolysis is a highly efficient and energy-saving method for ultra-pure hydrogen generation, which highly relies on electrocatalytic performance of electrocatalysts. In this work, high-quality platinum(Pt) nanocubes(Pt-NCs) with 4.5 nm size are achieved by facile hydrothermal synthesis. The physical morphology and structure of Pt-NCs are exhaustively characterized, revealing that Pt-NCs with special {100} facets have excellent uniformity, good dispersity and high crystallinity. Meanwhile, the electrocatalytic performance of Pt-NCs for ammonia electrolysis are carefully investigated in alkaline solutions, which display outstanding electroactivity and stability for both ammonia electrooxidation reaction(AEOR) and hydrogen evolution reaction(HER) in KOH solution. Furthermore, a symmetric Pt-NCs||Pt-NCs ammonia electrolyzer based on bifunctional Pt-NCs electrocatalyst is constructed, which only requires 0.68 V electrolysis voltage for hydrogen generation. Additionally, the symmetric Pt-NCs||Pt-NCs ammonia electrolyzer has excellent reversible switch capability for AEOR at anode and HER at cathode, showing outstanding alternating operation ability for ammonia electrolysis.展开更多
Molybdenum disulfide （MoS2）, a typical transition-metal dichalcogenide, has attracted increasing attention in the field of nanomedicine because of its preeminent properties. In this study, magnetic resonance imaging...Molybdenum disulfide （MoS2）, a typical transition-metal dichalcogenide, has attracted increasing attention in the field of nanomedicine because of its preeminent properties. In this study, magnetic resonance imaging （MRI）-guided chemo-photothermal therapy of human breast cancer xenograft in nude mice was demonstrated using a novel core/shell structure of Fe3O4@MoS2 nanocubes （IOMS NCs） via the integration of MoS2 （MS） film onto iron oxide （IO） nanocubes through a facile hydrothermal method. After the necessary PEGylation modification of the NCs for long-circulation purposes, such PEGylated NCs were further capped by 2-deoxy-D-glucose （2-DG）, a non-metabolizable glucose analogue to increase the accumulation of the as-prepared NCs at the tumor site, as 2-DG molecules could be particularly attractive to resource-hungry cancer cells. Such 2-DG- modified PEGylated NCs （IOMS-PEG-2DG NCs） acted as drug-carriers for doxorubicin （DOX）, which could be easily loaded within the NCs. The obtained IOMS-PEG（DOX）-2DG NCs exhibited a 3？2 relaxivity coefficient of 48.86 （mM）^-1·s^-1 and excellent photothermal performance. 24 h after intravenous injection of IOMS-PEG（DOX）-2DG NCs, the tumor site was clearly detected by enhanced T2-weighted MRI signal. Upon exposure to an NIR 808-nm laser for 5 rain at a low power density of 0.5 W·cm^-2 a marked temperature increase was noticed within the tumor site, and the tumor growth was efficiently inhibited by the chemo-photothermal effect. Therefore, our study highlights an excellent theranostic platform with great potential for targeted MRI-guided precise chemo-photothermal therapy of breast cancer.展开更多
The development of MXene-based heterostructures for electrocatalysis has garnered significant attention owing to their potential as high-performance catalysts that play a pivotal role in hydrogen energy.Herein,we pres...The development of MXene-based heterostructures for electrocatalysis has garnered significant attention owing to their potential as high-performance catalysts that play a pivotal role in hydrogen energy.Herein,we present a multistep strategy for the synthesis of a Ti_(3)C_(2) MXene ribbon/NiFePx@graphitic N-doped carbon(NC)heterostructure that enables the formation of three-dimensional(3D)Ti_(3)C_(2) MXene ribbon networks and bimetallic phosphide nanoarrays.With the assistance of HF etching and KOH shearing,the MXene sheets were successfully transformed into 3D MXene networks with interlaced MXene ribbons.Notably,a hydrothermal method,ion exchange route,and phosphorization process were used to anchor NiFeP_(x)@NC nanocubes derived from Ni(OH)_(2)/NiFe-based Prussian blue(NiFe-PB)onto the MXene ribbon network.The resulting MXene ribbon/NiFeP_(x)@NC heterostructure demonstrated enhanced oxygen evolution reaction(OER)activity,characterized by a low overpotential(164 mV at a current density of 10 mA cm^(-2))and a low Tafel slope(45 mV dec^(-1)).At the same time,the MXene ribbons/NiFeP_(x)@NC heterostructure exhibited outstanding long-term stability,with a 12 mV potential decay after 5000 cyclic voltammetry(CV)cycles.This study provides a robust pathway for the design of efficient MXene-based heterostructured electrocatalysts for water splitting.展开更多
Nitrate(NO_(3)^(−))electroreduction reaction(NO_(3)^(−)RR)provides an attractive and sustainable route for NO_(3)^(−)pollution mitigation or energy-saved ammonia(NH3)synthesis.In this work,high-quality B and Fe co-dop...Nitrate(NO_(3)^(−))electroreduction reaction(NO_(3)^(−)RR)provides an attractive and sustainable route for NO_(3)^(−)pollution mitigation or energy-saved ammonia(NH3)synthesis.In this work,high-quality B and Fe co-doped Co_(2) P hollow nanocubes(B/Fe-Co_(2) P HNCs)are successfully synthesized though simultaneous boronation-phosphorization treatment,which reveal outstanding selectivity,activity,stability for the NO_(3)^(−)to NH_(3) conversion in neutral electrolyte because of big surface area,fast mass transport,superhydrophilic surface,and optimized electronic structure.B/Fe-Co_(2) P HNCs can achieve the high NH3 yield rate(22.67 mg h^(−1) mg_(cat)^(−1))as well as Faradaic efficiency(97.54%)for NO_(3)^(−)RR,greatly outperforming most of non-precious metal based NO_(3)^(−)RR electrocatalysts.展开更多
This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of ...This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of polydopamine was used as both an adherent agent and an electron transfer mediator,due to itsπ-conjugated electron system.The highest production yield was achieved using a TNT@PDA/Nc/Au40%electrode,with Faradaic efficiencies of 47.4%(110.5μM cm^(-2))and 27.8%(50.4μM cm^(-2))for methanol and methane,respectively.The performance of the photoelectrodes was shown to be Cu_(2)O facet-dependent,with cubic structures leading to greater conversion of CO_(2)to methanol(43%)and methane(27%),compared to the octahedral morphology,while a higher percentage of metallic gold on the nanostructured Cu_(2)O surface was mainly important for CH4production.Density functional theory(DFT)calculations supported these findings,attributing the superior photoelectrocatalytic performance of the TNT@PDA/Nc/Au40%electrode for CH4generation to the formation of an OCH3intermediate bonded to Au atoms.Studies using isotope-labeling and analysis by gas chromatograph-mass(GC-MS)demonstrated that13CO_(2)was the source for photoelectrocatalytic generation of13CH3OH and13CH313CH2OH.展开更多
The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical perfo...The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical performance.Herein,metallic Cu_(2)Se encapsulated with N-doped carbon(Cu_(2)Se@NC)was prepared using Cu_(2)O nanocubes as templates through a combination of dopamine polymerization and hightemperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu_(2)Se@NC with excellent electrochemical performance in sodium ion batteries(SIBs)and potassium ion batteries(PIBs).The composite exhibited excellent rate performance(187.7 mA h g^(-1)at 50 A g^(-1)in SIBs and 179.4 mA h g^(-1)at 5 A g^(-1)in PIBs)and cyclic stability(246,8 mA h g^(-1)at 10 A g^(-1)in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction(XRD)and ex situ transmission electron microscope(TEM).In particular,the final products in PIBs of K_(2)Se and K_(2)Se_(3)species were determined after discharging,which is different from that in SIBs with the final species of Na_(2)Se.The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu_(2)Se,leading to the introduction of built-in electric field on heterojunction to improve electron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na~+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.展开更多
To develop high-performance metal-organic frameworks(MOFs)for catalysis is of great importance.Here,we synthesized the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)(BTC=benzene-1,3,5-tricarboxylate)nanocubes in a deep eutectic s...To develop high-performance metal-organic frameworks(MOFs)for catalysis is of great importance.Here,we synthesized the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)(BTC=benzene-1,3,5-tricarboxylate)nanocubes in a deep eutectic solvent of ZnCl_(2)/ethylene glycol solution.The route can proceed at room temperature and the reaction time needed is shortened to be 30 min,which is superior to the conventional solvothermal route that usually needs high temperature and long reaction time.The formation mechanism of the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes in deep eutectic solvent(DES)was investigated by in situ synchrotron X-ray diffraction/small angle X-ray scattering/X-ray absorption fine structure conjunction technique.The mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes exhibit high catalytic activity and reusability for cyanosilylation reaction of benzaldehyde and aerobic oxidation reaction of benzylic alcohol.展开更多
Surface-enhanced Raman spectroscopy （SERS） as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a great challenge for creating a universa...Surface-enhanced Raman spectroscopy （SERS） as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a great challenge for creating a universal sub- strate with long-term stability and reproducible SERS signals. In this work, Ag nanocubes and graphene oxide （GO） suspension were mixed to form a stable solution and further vacuum filtrated to obtain a free-standing hybrid paper. The Ag/GO hybrid papers exhibit excellent SERS activity because of the synergistic effect of Ag nanocubes and GO sheets. GO sheets can act as both SERS enhancement substrate and framework for supporting Ag nanocubes. Moreover, GO sheets can protect Ag nanoparticles from oxidation under ambient condition for prolonged life time SERS substrate. Furthermore, we demonstrate the use of the free-standing and flexible Ag/GO hybrid paper to en- able direct, real-time and reliable detection of trace amounts of analytes in aqueous systems. This novel SERS sub- strate is expected to be applied in real-time analysis and expands the flexibility of SERS for useful applications in the materials and life science.展开更多
Surface-enhanced Raman scattering(SERS)provides a novel method for low concentration molecular detection.The performances were highly dependent on the sizes,geometries and distributions of metal nanostructures.Here,hi...Surface-enhanced Raman scattering(SERS)provides a novel method for low concentration molecular detection.The performances were highly dependent on the sizes,geometries and distributions of metal nanostructures.Here,highly sensitive SERS fber probe based on silver nanocubes(Ag NCs)was fabricated,by assembled nanostructures on planar and tapered fber tips.Ag NCs were synthesized by polyol method,and controlled by reductant content,reaction temperatures and crystal growth durations.Tapered fbers with diferent cone angles were prepared by chemical etching.The electromagnetic distribution simulation indicated that nanocubes had stronger electric feld between two cubes and vertex corners than nanosphere,under 532 nm laser excitation.The intensity could reach 53.52 V/m,for cubes with 70 nm edge length.The SERS performance of probes was characterized using crystal violet analyte.The detectable lowest concentration could reach 10^(-9) and 10^(-10) M for planar and tapered fber probes,respectively.The corresponding enhancement factor could be 9.02×10^(7) and 6.22×10^(8).The relationship between SERS peak intensities and analyte concentrations showed well linear,which indicated both fber probes could be applied for both qualitative and quantitative analysis.Furthermore,optimal cone angle of tapered fber SERS probe was 8.3°.The tapered fber SERS probes have highly sensitive activity and great potential in substance detection.展开更多
Typically, varying pretreatment conditions probably results in the different catalytic performances for the bimetallic catalysts, and this originates from the surface evolution of catalysts during catalytic process. H...Typically, varying pretreatment conditions probably results in the different catalytic performances for the bimetallic catalysts, and this originates from the surface evolution of catalysts during catalytic process. Hence, it is crucial to correlate surface chemistry(e.g., composition, chemical valence, etc.) of bimetallic nanocatalysts with their corresponding performances upon different pretreatments for the fundamental understanding of catalysis. Herein, compositionvaried(100) facet terminated Pd-Rh nanocubes(NCs) with the similar shape and sizes were prepared by a facile one-pot hydrothermal method to exclude the possible size and shape effect. Surface composition and valence state of these Pd0.8 Rh0.2, Pd0.6 Rh0.4, and Pd0.2 Rh0.8 NCs were tracked under different reaction conditions and during catalysis using a homebuilt ambient pressure X-ray photoelectron spectrometer(APXPS). The correlation of active surface of Pd-Rh NCs and their corresponding catalytic performance was established.展开更多
The hydrogen evolution reaction (HER),which generates molecular hydrogen through the electrochemical reduction of water,is an important clean-energy technology.Platinum (Pt) is an ideal material for HER electrocatalys...The hydrogen evolution reaction (HER),which generates molecular hydrogen through the electrochemical reduction of water,is an important clean-energy technology.Platinum (Pt) is an ideal material for HER electrocatalysts in terms of low overpotential and fast kinetics.An effective method to improve the atom utilization efficiency of Pt is to fabricate Pt-based core-shell or nanocage structures with ultra-thin walls.This paper describes the construction of bilayer palladium (Pd)-Pt alloy nanocages catalyst with enhanced HER catalytic activity.The nanocages were fabricated by etching away the Pd templates of multishelled nanocubes composed of alternate shells of Pd and Pt with well-defined (100) facets.The bilayer Pd-Pt nanocages with sub-nanometer shells have a high dispersion of the active atoms on the outside and inside surfaces of outer layer and inner layer,respectively.Moreover,the Pd-Pt alloy lowers the overpotential for HER and speeds up the reaction rate of HER due to the synergies between Pd and Pt.The rational design of bilayer nanocages provided a novel route for boosting the atom utilization efficiency of Pt catalysts.展开更多
Porous metal phosphide cubes with exposed vertices and edges containing abundant catalytically active sites are promising electrocatalysts. Herein, by integrating the advantages of the phosphorus-rich cobalt phosphide...Porous metal phosphide cubes with exposed vertices and edges containing abundant catalytically active sites are promising electrocatalysts. Herein, by integrating the advantages of the phosphorus-rich cobalt phosphides and bimetallic oxides to form hybrid architectures, we prepared CoP3/CoSnO2 via phosphating CoSn(OH)6 nanocubes, which has unique porous nanocubic structure. The optimized CoP3/CoSnO2 porous nanaocubes showed excellent electrocatalytic activity for OER/ORR. What’s more, the electrochemical performances of CoP3/CoSnO2 porous nanaocubes as air cathode catalyst for zinc air batteries were better than that of commercial RuO2 and 20 wt% Pt/C with a mass ratio of 1:1 as the air cathode catalyst. This work offers a new strategy to fabricate metal phosphide with porous nanocubic structures.展开更多
文摘The catalytic activity of noble-metal nanocrystals is mainly determined by their sizes and the facets exposed on the surface. For single crystals, it has been demonstrated that the Pd（100） surface is catalytically more active than both Pd（110） and Pd（111） surfaces for the CO oxidation reaction. Here we report the synthesis of Pd nanocrystals enclosed by {100} facets with controllable sizes in the range of 6-18 nm by manipulating the rate of reduction of the precursor. UV-vis spectroscopy studies indicate that the rate of reduction of Na2PdC14 can be controlled by adjusting the concentrations of Br- and C1- ions added to the reaction mixture. Pd nanocrystals with different sizes were immobilized on ZnO nanowires and evaluated as catalysts for CO oxidation. We found that the activity of this catalytic system for CO oxidation showed a strong dependence on the nanocrystal size. When the size of the Pd nanocrystals was reduced from 18 nm to 6 nm, the maximum conversion rate was significantly enhanced by a factor of -10 and the corresponding maximum conversion temperature was lowered by -80℃.
基金Research Grant Council(Nos.26206115 and 16304117)of the Hong Kong Special Administrative Region.
文摘As a promising fuel candidate,ammonia has been successtully used as anode feed in alkaline fuel cells.However,current technology in catalysts for ammonia electro-oxidation reaction(AOR)with respect to both cost and performance is inadequate to ensure large scale commercial application of direct ammonia fuel cells.Recent studies found that alloying Pt with different transition metals and controlling the morphology of catalysts can improve the AOR activity,and thus potentially can solve the cost issue.Herein,(100)-terminated Pt-M nanocubes(M=3d-transition metals Fe,Co,Ni,Zn)are synthesized via wet-chemistry method and their catalytic activities toward AOR are evaluated.The addition of Fe,Co,Ni and Zn elements can enhance the AOR activity due to decrease in oxophilicity of platinum and bifunctional mechanism.Pt-Zn exhibits the maximum mass activity and specific ativity with values of 0.41 A/mgpt and 169 mA/cm2 that are 1.6 and 1.8 times higher than Pt nanocubes,respectively.Pt-Fe,Pt-Co and PI-Ni nanocubes also ilustrate higher mass and specific activities compared to Pt nanocubes.
基金supported by the Natural Science Foundation of Shandong Province(ZR2017MB059)the Major Program of Shandong Province Natural Science Foundation(ZR2018ZC0639)+2 种基金the National Natural Science Foundation of China(21776314)the Fundamental Research Funds for the Central Universities(18CX05016A)the Postgraduate Innovation Project of China University of Petroleum(YCX2018074)
文摘The ternary cobalt-nickel-iron phosphide nanocubes (P-Co0.9Ni0.9Fe1.2 NCs) with high intrinsic activity, conductivity, defect concentration and optimized ratio have been realized through a facile phosphorization treatment using ternary cobalt-nickel-iron nanocubes of Prussian blue analogs (PBA) as a precursor. The scanning electron microscopy and transmission electron microscopy results show that the P-Co0.9Ni0.9Fe1.2 NCs maintain a cubic structure with a rough surface, implying the rich surface defects as exposed active sites. The thermal phosphorization of the ternary PBA precursor not only provids carbon doping but also leads to the in situ construction of surface defects on the NCs. The carbon doping from the PBA precursor lowers the charge transfer resistance and optimizes the electronic transformation. The synergistic effect among the ternary metal ions and rich defects contributes to the enhanced electrocatalytic performance . The P-Co0.9Ni0.9Fe1.2NCs achieve low overpotentials of -200.7 and 273.1 mV at a current density of 10 mA cm^-2 for the hydrogen evolution reaction and the oxygen evolution reaction, respectively. The potential of overall water splitting reaches 1.52 V at a current density of 10 mA cm^-2. The longterm stability of the electrocatalysts was also evaluated. This work provides a facile method to design efficient transitionmetal- based bifunctional electrocatalysts for overall water splitting.
基金financially supported by the National Natural Science Foundation of China(No.51407134)Natural Science Foundation of Shandong Province(No.ZR2019YQ24)+4 种基金Taishan Scholars and Young Experts Program of Shandong Province(No.tsqn202103057)China Postdoctoral Science Foundation(No.2016M590619)the Qingchuang Talents Induction Program of Shandong Higher Education Institution(Research and Innovation Team of Structural-Functional Polymer Composites)the support from The Thousand Talents Plan,The World-Class University and Discipline,The Taishan Scholar’s Advantageous and Distinctive Discipline Program of Shandong ProvinceThe World-Class Discipline Program of Shandong Province。
文摘Metal-organic framework-derived composites have been widely used in electromagnetic wave(EMW)absorption,but the traditional synthetic strategy greatly limits the structure and species of MOFs.This research provided a solvent-free method to synthesize Co-MOF and its derivatives.Using CoSnO_(3)as the precursor,the preparation of Co-MOF is achieved by bridging the cobalt(II)ion of CoSnO_(3)and the 2-methylimidazole skeleton.The CoSn/N-doped carbon(CoSn/NC)composites derived from CoSnO_(3)-MOF(Co-MOF with CoSnO_(3)as Co source)retain the original morphology of CoSnO_(3).Besides,the polarization effect produced by the N-doped carbon layers also benefits the excellent EMW absorption performance of the CoSn/NC composites.It is reflected in the minimum reflection loss(RL)of-48.2 dB at 2.2 mm and the effective bandwidth(EBA)of 5.84 GHz.This work provides a new channel to the construction of Co-MOFs,which could be extended to other Co-based oxides and vastly expand the species of MOFs based on metallic Co.
基金sponsored by the National Natural Science Foundation of China (21875133 and 51873100)the Fundamental Research Funds for the Central Universities (GK201901002 and GK201902014)the 111 Project (B14041)。
文摘The ammonia electrolysis is a highly efficient and energy-saving method for ultra-pure hydrogen generation, which highly relies on electrocatalytic performance of electrocatalysts. In this work, high-quality platinum(Pt) nanocubes(Pt-NCs) with 4.5 nm size are achieved by facile hydrothermal synthesis. The physical morphology and structure of Pt-NCs are exhaustively characterized, revealing that Pt-NCs with special {100} facets have excellent uniformity, good dispersity and high crystallinity. Meanwhile, the electrocatalytic performance of Pt-NCs for ammonia electrolysis are carefully investigated in alkaline solutions, which display outstanding electroactivity and stability for both ammonia electrooxidation reaction(AEOR) and hydrogen evolution reaction(HER) in KOH solution. Furthermore, a symmetric Pt-NCs||Pt-NCs ammonia electrolyzer based on bifunctional Pt-NCs electrocatalyst is constructed, which only requires 0.68 V electrolysis voltage for hydrogen generation. Additionally, the symmetric Pt-NCs||Pt-NCs ammonia electrolyzer has excellent reversible switch capability for AEOR at anode and HER at cathode, showing outstanding alternating operation ability for ammonia electrolysis.
基金This study was supported by the National Natural Science Foundation of China （NSFC） （No. 81671829）.
文摘Molybdenum disulfide （MoS2）, a typical transition-metal dichalcogenide, has attracted increasing attention in the field of nanomedicine because of its preeminent properties. In this study, magnetic resonance imaging （MRI）-guided chemo-photothermal therapy of human breast cancer xenograft in nude mice was demonstrated using a novel core/shell structure of Fe3O4@MoS2 nanocubes （IOMS NCs） via the integration of MoS2 （MS） film onto iron oxide （IO） nanocubes through a facile hydrothermal method. After the necessary PEGylation modification of the NCs for long-circulation purposes, such PEGylated NCs were further capped by 2-deoxy-D-glucose （2-DG）, a non-metabolizable glucose analogue to increase the accumulation of the as-prepared NCs at the tumor site, as 2-DG molecules could be particularly attractive to resource-hungry cancer cells. Such 2-DG- modified PEGylated NCs （IOMS-PEG-2DG NCs） acted as drug-carriers for doxorubicin （DOX）, which could be easily loaded within the NCs. The obtained IOMS-PEG（DOX）-2DG NCs exhibited a 3？2 relaxivity coefficient of 48.86 （mM）^-1·s^-1 and excellent photothermal performance. 24 h after intravenous injection of IOMS-PEG（DOX）-2DG NCs, the tumor site was clearly detected by enhanced T2-weighted MRI signal. Upon exposure to an NIR 808-nm laser for 5 rain at a low power density of 0.5 W·cm^-2 a marked temperature increase was noticed within the tumor site, and the tumor growth was efficiently inhibited by the chemo-photothermal effect. Therefore, our study highlights an excellent theranostic platform with great potential for targeted MRI-guided precise chemo-photothermal therapy of breast cancer.
基金supported by the National Natural Science Foun-dation of China(No.22269010)the Jiangxi Provincial Natural Science Foundation(No.20224BAB214021)+1 种基金the Training Program for Academic and Technical Leaders of Major Disciplines in Jiangxi Province(No.20212BCJ23020)the Science and Technology Project of the Jiangxi Provincial Department of Education(No.GJJ211305).
文摘The development of MXene-based heterostructures for electrocatalysis has garnered significant attention owing to their potential as high-performance catalysts that play a pivotal role in hydrogen energy.Herein,we present a multistep strategy for the synthesis of a Ti_(3)C_(2) MXene ribbon/NiFePx@graphitic N-doped carbon(NC)heterostructure that enables the formation of three-dimensional(3D)Ti_(3)C_(2) MXene ribbon networks and bimetallic phosphide nanoarrays.With the assistance of HF etching and KOH shearing,the MXene sheets were successfully transformed into 3D MXene networks with interlaced MXene ribbons.Notably,a hydrothermal method,ion exchange route,and phosphorization process were used to anchor NiFeP_(x)@NC nanocubes derived from Ni(OH)_(2)/NiFe-based Prussian blue(NiFe-PB)onto the MXene ribbon network.The resulting MXene ribbon/NiFeP_(x)@NC heterostructure demonstrated enhanced oxygen evolution reaction(OER)activity,characterized by a low overpotential(164 mV at a current density of 10 mA cm^(-2))and a low Tafel slope(45 mV dec^(-1)).At the same time,the MXene ribbons/NiFeP_(x)@NC heterostructure exhibited outstanding long-term stability,with a 12 mV potential decay after 5000 cyclic voltammetry(CV)cycles.This study provides a robust pathway for the design of efficient MXene-based heterostructured electrocatalysts for water splitting.
基金supported by Natural Science Foundation of Shanxi Province(No.202203021222213)Taiyuan University of Science and Technology Scientific Research Initial Funding(No.20222091)+2 种基金National Natural Science Foundation of China(No.22073061)Science and Technology Innovation Team of Shaanxi Province(No.2023-CX-TD-27)Fundamental Research Funds for the Central Universities(No.GK202202001).
文摘Nitrate(NO_(3)^(−))electroreduction reaction(NO_(3)^(−)RR)provides an attractive and sustainable route for NO_(3)^(−)pollution mitigation or energy-saved ammonia(NH3)synthesis.In this work,high-quality B and Fe co-doped Co_(2) P hollow nanocubes(B/Fe-Co_(2) P HNCs)are successfully synthesized though simultaneous boronation-phosphorization treatment,which reveal outstanding selectivity,activity,stability for the NO_(3)^(−)to NH_(3) conversion in neutral electrolyte because of big surface area,fast mass transport,superhydrophilic surface,and optimized electronic structure.B/Fe-Co_(2) P HNCs can achieve the high NH3 yield rate(22.67 mg h^(−1) mg_(cat)^(−1))as well as Faradaic efficiency(97.54%)for NO_(3)^(−)RR,greatly outperforming most of non-precious metal based NO_(3)^(−)RR electrocatalysts.
基金FAPESP,Brazil(#2023/10027-5,#2014/50945-4,#2020/15230-5,and#2021/000675-4)CNPq,Brazil(#465571/2014-0,#303269/2021-9,and#307837/2014-9)+6 种基金Instituto Serrapilheira(grant number Serra-2211-41925)FAPEMIG,Brazil(#PPM-00831-15)for support of this workCNPq,Brazil(#105944/2022-0)and PROPEUNESP(13/2022)FAPESP(#2019/00463-7,#2018/22845-6,and#2021/08007-0,respectively)for scholarshipsthe National Institute for Alternative Technologies of Detection,Toxicological Evaluation and Removal of Micropollutants and Radioactives(INCT-DATREM)the support of the Research Centre for Greenhouse Gas Innovation(RCGI),hosted by the University of Sao Paulo(USP)and sponsored by FAPESP and Shell Brasilthe strategic support given by ANP,Brazil(Brazilian National Oil,Natural Gas,and Biofuels Agency)through the R&D levy regulation。
文摘This work describes the use of TiO_(2)nanotubes-based electrodes(TNT)modified with Cu_(2)O nanostructures and gold nanoparticles for the photoelectroreduction of CO_(2)to produce value-added compounds.A thin layer of polydopamine was used as both an adherent agent and an electron transfer mediator,due to itsπ-conjugated electron system.The highest production yield was achieved using a TNT@PDA/Nc/Au40%electrode,with Faradaic efficiencies of 47.4%(110.5μM cm^(-2))and 27.8%(50.4μM cm^(-2))for methanol and methane,respectively.The performance of the photoelectrodes was shown to be Cu_(2)O facet-dependent,with cubic structures leading to greater conversion of CO_(2)to methanol(43%)and methane(27%),compared to the octahedral morphology,while a higher percentage of metallic gold on the nanostructured Cu_(2)O surface was mainly important for CH4production.Density functional theory(DFT)calculations supported these findings,attributing the superior photoelectrocatalytic performance of the TNT@PDA/Nc/Au40%electrode for CH4generation to the formation of an OCH3intermediate bonded to Au atoms.Studies using isotope-labeling and analysis by gas chromatograph-mass(GC-MS)demonstrated that13CO_(2)was the source for photoelectrocatalytic generation of13CH3OH and13CH313CH2OH.
基金The Natural Science Foundation of Henan Province(222300420083)the Opening Foundation of State Key Laboratory of Chemistry and Utilization of Carbon-based Energy Resource of Xinjiang University(KFKT2021004)。
文摘The large volumetric variations experienced by metal selenides within conversion reaction result in inferior rate capability and cycling stability,ultimately hindering the achievement of superior electrochemical performance.Herein,metallic Cu_(2)Se encapsulated with N-doped carbon(Cu_(2)Se@NC)was prepared using Cu_(2)O nanocubes as templates through a combination of dopamine polymerization and hightemperature selenization.The unique nanocubic structure and uniform N-doped carbon coating could shorten the ion transport distance,accelerate electron/charge diffusion,and suppress volume variation,ultimately ensuring Cu_(2)Se@NC with excellent electrochemical performance in sodium ion batteries(SIBs)and potassium ion batteries(PIBs).The composite exhibited excellent rate performance(187.7 mA h g^(-1)at 50 A g^(-1)in SIBs and 179.4 mA h g^(-1)at 5 A g^(-1)in PIBs)and cyclic stability(246,8 mA h g^(-1)at 10 A g^(-1)in SIBs over 2500 cycles).The reaction mechanism of intercalation combined with conversion in both SIBs and PIBs was disclosed by in situ X-ray diffraction(XRD)and ex situ transmission electron microscope(TEM).In particular,the final products in PIBs of K_(2)Se and K_(2)Se_(3)species were determined after discharging,which is different from that in SIBs with the final species of Na_(2)Se.The density functional theory calculation showed that carbon induces strong coupling and charge interactions with Cu_(2)Se,leading to the introduction of built-in electric field on heterojunction to improve electron mobility.Significantly,the theoretical calculations discovered that the underlying cause for the relatively superior rate capability in SIBs to that in PIBs is the agile Na~+diffusion with low energy barrier and moderate adsorption energy.These findings offer theoretical support for in-depth understanding of the performance differences of Cu-based materials in different ion storage systems.
基金support by Ministry of Science and Technology of China(No.2017YFA0403003)the National Natural Science Foundation of China(Nos.22033009 and 22121002).
文摘To develop high-performance metal-organic frameworks(MOFs)for catalysis is of great importance.Here,we synthesized the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)(BTC=benzene-1,3,5-tricarboxylate)nanocubes in a deep eutectic solvent of ZnCl_(2)/ethylene glycol solution.The route can proceed at room temperature and the reaction time needed is shortened to be 30 min,which is superior to the conventional solvothermal route that usually needs high temperature and long reaction time.The formation mechanism of the mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes in deep eutectic solvent(DES)was investigated by in situ synchrotron X-ray diffraction/small angle X-ray scattering/X-ray absorption fine structure conjunction technique.The mesoporous Cu_(3−x)Zn_(x)(BTC)_(2)nanocubes exhibit high catalytic activity and reusability for cyanosilylation reaction of benzaldehyde and aerobic oxidation reaction of benzylic alcohol.
基金Acknowledgement The authors are grateful for the financial support from the National Natural Science Foundation of China （Nos. 51125011, 51433001）, and the National Research Foundation, Singapore （No. NRF-NRFF2012-04）, Nanyang Technological University＇s start-up grant.
文摘Surface-enhanced Raman spectroscopy （SERS） as a powerful analytical tool has gained extensive attention. Despite of many efforts in the design of SERS substrates, it remains a great challenge for creating a universal sub- strate with long-term stability and reproducible SERS signals. In this work, Ag nanocubes and graphene oxide （GO） suspension were mixed to form a stable solution and further vacuum filtrated to obtain a free-standing hybrid paper. The Ag/GO hybrid papers exhibit excellent SERS activity because of the synergistic effect of Ag nanocubes and GO sheets. GO sheets can act as both SERS enhancement substrate and framework for supporting Ag nanocubes. Moreover, GO sheets can protect Ag nanoparticles from oxidation under ambient condition for prolonged life time SERS substrate. Furthermore, we demonstrate the use of the free-standing and flexible Ag/GO hybrid paper to en- able direct, real-time and reliable detection of trace amounts of analytes in aqueous systems. This novel SERS sub- strate is expected to be applied in real-time analysis and expands the flexibility of SERS for useful applications in the materials and life science.
基金This research was financially supported by the opening funding of the state key laboratory of silicate materials for architecture(SYSJJ2018-06)the Fundamental Research Funds for the Central Universities(WUT:2016IVA096),China.
文摘Surface-enhanced Raman scattering(SERS)provides a novel method for low concentration molecular detection.The performances were highly dependent on the sizes,geometries and distributions of metal nanostructures.Here,highly sensitive SERS fber probe based on silver nanocubes(Ag NCs)was fabricated,by assembled nanostructures on planar and tapered fber tips.Ag NCs were synthesized by polyol method,and controlled by reductant content,reaction temperatures and crystal growth durations.Tapered fbers with diferent cone angles were prepared by chemical etching.The electromagnetic distribution simulation indicated that nanocubes had stronger electric feld between two cubes and vertex corners than nanosphere,under 532 nm laser excitation.The intensity could reach 53.52 V/m,for cubes with 70 nm edge length.The SERS performance of probes was characterized using crystal violet analyte.The detectable lowest concentration could reach 10^(-9) and 10^(-10) M for planar and tapered fber probes,respectively.The corresponding enhancement factor could be 9.02×10^(7) and 6.22×10^(8).The relationship between SERS peak intensities and analyte concentrations showed well linear,which indicated both fber probes could be applied for both qualitative and quantitative analysis.Furthermore,optimal cone angle of tapered fber SERS probe was 8.3°.The tapered fber SERS probes have highly sensitive activity and great potential in substance detection.
基金supported by the National Natural Science Foundation of China (21573005, 21771009, and 21621061) the National Key Research and Development Program of MOST of China (2016YFB0701100)+2 种基金 Beijing Natural Science Foundation (2162019)Financial aids from the US National Science Foundation (NSF MCB0824837)the Georgia Cancer Coalition (GCC) Distinguished Cancer Clinicians and Scientists are also appreciated
文摘Typically, varying pretreatment conditions probably results in the different catalytic performances for the bimetallic catalysts, and this originates from the surface evolution of catalysts during catalytic process. Hence, it is crucial to correlate surface chemistry(e.g., composition, chemical valence, etc.) of bimetallic nanocatalysts with their corresponding performances upon different pretreatments for the fundamental understanding of catalysis. Herein, compositionvaried(100) facet terminated Pd-Rh nanocubes(NCs) with the similar shape and sizes were prepared by a facile one-pot hydrothermal method to exclude the possible size and shape effect. Surface composition and valence state of these Pd0.8 Rh0.2, Pd0.6 Rh0.4, and Pd0.2 Rh0.8 NCs were tracked under different reaction conditions and during catalysis using a homebuilt ambient pressure X-ray photoelectron spectrometer(APXPS). The correlation of active surface of Pd-Rh NCs and their corresponding catalytic performance was established.
基金We acknowledge the National Key R&D Program of China(No.2016YFB0600901)the National Natural Science Foundation of China(Nos.U1463205,21525626,and 21606169)for financial supportthe Program of Introducing Talents of Discipline to Universities(B06006)for financial support.
文摘The hydrogen evolution reaction (HER),which generates molecular hydrogen through the electrochemical reduction of water,is an important clean-energy technology.Platinum (Pt) is an ideal material for HER electrocatalysts in terms of low overpotential and fast kinetics.An effective method to improve the atom utilization efficiency of Pt is to fabricate Pt-based core-shell or nanocage structures with ultra-thin walls.This paper describes the construction of bilayer palladium (Pd)-Pt alloy nanocages catalyst with enhanced HER catalytic activity.The nanocages were fabricated by etching away the Pd templates of multishelled nanocubes composed of alternate shells of Pd and Pt with well-defined (100) facets.The bilayer Pd-Pt nanocages with sub-nanometer shells have a high dispersion of the active atoms on the outside and inside surfaces of outer layer and inner layer,respectively.Moreover,the Pd-Pt alloy lowers the overpotential for HER and speeds up the reaction rate of HER due to the synergies between Pd and Pt.The rational design of bilayer nanocages provided a novel route for boosting the atom utilization efficiency of Pt catalysts.
基金supported by the National Natural Science Foundation of China (NSFC-21671170, 21673203, 21875207, 21201010)the Top-notch Academic Programs Project of Jiangsu Higher Education Institutions (TAPP)+4 种基金Program for New Century Excellent Talents of the University in China (NCET-13-0645)Postgraduate Research & Practice Innovation Program of Jiangsu Province (XSJCX17-015)the Priority Academic Program Development of Jiangsu Higher Education InstitutionsYangzhou University Graduate Student International Academic Exchange Special Fund Projectthe Technical Support we received at the Testing Center of Yangzhou University.
文摘Porous metal phosphide cubes with exposed vertices and edges containing abundant catalytically active sites are promising electrocatalysts. Herein, by integrating the advantages of the phosphorus-rich cobalt phosphides and bimetallic oxides to form hybrid architectures, we prepared CoP3/CoSnO2 via phosphating CoSn(OH)6 nanocubes, which has unique porous nanocubic structure. The optimized CoP3/CoSnO2 porous nanaocubes showed excellent electrocatalytic activity for OER/ORR. What’s more, the electrochemical performances of CoP3/CoSnO2 porous nanaocubes as air cathode catalyst for zinc air batteries were better than that of commercial RuO2 and 20 wt% Pt/C with a mass ratio of 1:1 as the air cathode catalyst. This work offers a new strategy to fabricate metal phosphide with porous nanocubic structures.
