We report on the growth of CoFe_(2)O_(4)/Pt heterostructure and their magnetotransport properties.The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K...We report on the growth of CoFe_(2)O_(4)/Pt heterostructure and their magnetotransport properties.The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K.The anomalous Hall resistance decreases as the temperature increases.Furthermore,angle-dependent magnetoresistance indicates that the observed magnetotransport behaviors originate from the competition between the spin Hall magnetoresistance and magnetic proximity effect.展开更多
Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance...Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance of supported metal catalysts.This is particularly true for single-atom catalysts(SACs)and pseudo-single-atom catalysts(pseudo-SACs),where all metal atoms are dispersed on,and interact directly with the support.Consequently,the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts.In this work,we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation.We fabricated CoFe_(2)O_(4) supported Pt pseudo-SACs and nanoparticle catalysts,followed by a straightforward water treatment process.It was found that the covalent strong metal-support interaction(CMSI)in pseudo-SACs can be weakened,leading to a significant activity improvement in methane combustion reaction.This finding aligns with our recent observation of CoFe_(2)O_(4) supported Pt SACs.By contrast,the MSI in Pt nanoparticle catalyst was barely affected by the water treatment,giving rise to almost unchanged catalytic performance.This work highlights the critical role of metal size in determining the MSI modulation,offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.展开更多
Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared t...Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared through atom-trapping strategy and relevant vacancy defect inductive effect was proposed.The 0.6Pt/VO-Co_(3)O_(4)catalyst presented a reaction rate value of 32.2×10^(-5)mol·g_(cat)^(-1)·s^(-1)at 160℃for catalytic propane total oxidation,which was nearly 5 times the reaction rate of Co_(3)O_(4)(6.7×10^(-5)mol·g_(cat)^(-1)·s^(-1)).Also,it exhibited excellent water-resistance and catalytic stability.The Pt atoms were stabilized on the Co_(3)O_(4)surface by vacancy defects to improve dispersion.Meanwhile,the vacancy defect inductive effect induced stronger electron interaction between Pt and Co_(3)O_(4)on the surface,thus promote the redox ability at low-temperature.The mobility and oxygen-activating ability of surface lattice oxygen were also strengthened by the vacancy defect inductive effect.This facilitated the generation of more surface-active oxygen species for the cleavage of C-H bond and the deep oxidation of intermediate species.Overall,this study proposed a novel concept the fabrication of highly efficient catalysts for the purpose of catalytic oxidation.展开更多
For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driv...For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driven by NIR light,NYFYT produces up-conversion emission at 348,364,453 and 478 nm,effectively stimulating the photocatalytic degradation performance of AP and AP/PtNPs,Under xenon lamp irradiation,the apparent rate constants(k)for Ag_(3)PO_(4)/Pt nanoparticles-NaYF4:Yb,Tm(AP/PtNPs-NYFYT)in photocatalytic degradation of rhodamine B(Rh B)and phenol are 5.51 and 12.82 times higher than those of AP and 1.90 and 2.37 times higher than those of AP-NYFYT-50 wt%,respectively.In addition,under 980nm laser irradiation,rate constants are 3.26 and 4.16 times higher than those of AP-NYFYT-50 wt%,respectively.These results indicate that the combination of NYFYT and AP expands the absorption range of the composite photocatalyst and facilitates the NIR-driven photocatalytic process.The introduction of PtNPs effectively prevents the electron-hole recombination and the reduction of Ag+,accelerating the redox reaction and promoting the photocatalytic activity and stability of AP.展开更多
The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO tech...The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO techniques combined with propane dehydrogenation tests.It has been shown that SUZ-4-supported PtSnNa（PtSnNa/SUZ-4） was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5,owing to its higher catalytic activity and stability.Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts.The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity.In contrast to ZSM-5-supported catalysts,Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition.This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H_2PtCl_6 into the zeolite.In contrast,the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels,followed by transformation to highly dispersed Pt clusters during calcination.In the case of the PtSnNa/ZSM-5,the interactions between Sn oxides and the support were lessened,owing to the weaker acidity of the ZSM-5 zeolite.The dispersed Sn oxides were therefore easier to reduce to the metallic state,thus decreasing the catalytic activity for hydrocarbon dehydrogenation.展开更多
Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terep...Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.展开更多
Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improv...Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improved the catalytic activity significantly.When using Pt/Ce-Zr-SO_4^（2-） with 10 wt%SO_4^（2-）,the temperature for 90%conversion of propene and CO decreased by 75℃ compared with Pt/Ce-Zr.The conversion exceeded 95%at 240℃ even after 0.02%sulfur dioxide poisoning for 20 h.Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO_4^（2-） support,and the increased number of Pt particles built up more Pt^（-）-（SO_4^（2-））^（-） couples,which resulted in excellent activity.The increased total acidity and new Bronsted acid sites on the surface provided the Pt/Ce-Zr-SO_4^（2-） with good sulfur resistance.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.62525406,T2394473,624B2070,and 62274085)the National Key Research and Development Program of China(Grant No.2022YFA1402404)the Innovation Program for Quantum Science and Technology of China(Grant No.2024ZD0301300)。
文摘We report on the growth of CoFe_(2)O_(4)/Pt heterostructure and their magnetotransport properties.The magnetoresistance under high magnetic fields exhibits a sign change when the temperature increases from 5 K to 10 K.The anomalous Hall resistance decreases as the temperature increases.Furthermore,angle-dependent magnetoresistance indicates that the observed magnetotransport behaviors originate from the competition between the spin Hall magnetoresistance and magnetic proximity effect.
文摘Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance of supported metal catalysts.This is particularly true for single-atom catalysts(SACs)and pseudo-single-atom catalysts(pseudo-SACs),where all metal atoms are dispersed on,and interact directly with the support.Consequently,the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts.In this work,we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation.We fabricated CoFe_(2)O_(4) supported Pt pseudo-SACs and nanoparticle catalysts,followed by a straightforward water treatment process.It was found that the covalent strong metal-support interaction(CMSI)in pseudo-SACs can be weakened,leading to a significant activity improvement in methane combustion reaction.This finding aligns with our recent observation of CoFe_(2)O_(4) supported Pt SACs.By contrast,the MSI in Pt nanoparticle catalyst was barely affected by the water treatment,giving rise to almost unchanged catalytic performance.This work highlights the critical role of metal size in determining the MSI modulation,offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.
文摘Directional design of efficient catalysts for volatile organic compounds degradation remains a complex,yet effective and challenging process.Herein,oxygen-rich vacancy Co_(3)O_(4)-anchored Pt catalysts were prepared through atom-trapping strategy and relevant vacancy defect inductive effect was proposed.The 0.6Pt/VO-Co_(3)O_(4)catalyst presented a reaction rate value of 32.2×10^(-5)mol·g_(cat)^(-1)·s^(-1)at 160℃for catalytic propane total oxidation,which was nearly 5 times the reaction rate of Co_(3)O_(4)(6.7×10^(-5)mol·g_(cat)^(-1)·s^(-1)).Also,it exhibited excellent water-resistance and catalytic stability.The Pt atoms were stabilized on the Co_(3)O_(4)surface by vacancy defects to improve dispersion.Meanwhile,the vacancy defect inductive effect induced stronger electron interaction between Pt and Co_(3)O_(4)on the surface,thus promote the redox ability at low-temperature.The mobility and oxygen-activating ability of surface lattice oxygen were also strengthened by the vacancy defect inductive effect.This facilitated the generation of more surface-active oxygen species for the cleavage of C-H bond and the deep oxidation of intermediate species.Overall,this study proposed a novel concept the fabrication of highly efficient catalysts for the purpose of catalytic oxidation.
基金Project supported by Hebei Province High-level Talent(Postdoctor)Funding Project(B2022003025)。
文摘For developing and utilizing near-infrared(NIR)energy in sunlight,NaYF4:Yb,Tm(NYFYT)up-conversion Iuminescent powder was combined with Ag_(3)PO_(4)(AP)and Ag_(3)PO_(4)/Pt nanoparticles(AP/PtNPs)as a photocatalyst.Driven by NIR light,NYFYT produces up-conversion emission at 348,364,453 and 478 nm,effectively stimulating the photocatalytic degradation performance of AP and AP/PtNPs,Under xenon lamp irradiation,the apparent rate constants(k)for Ag_(3)PO_(4)/Pt nanoparticles-NaYF4:Yb,Tm(AP/PtNPs-NYFYT)in photocatalytic degradation of rhodamine B(Rh B)and phenol are 5.51 and 12.82 times higher than those of AP and 1.90 and 2.37 times higher than those of AP-NYFYT-50 wt%,respectively.In addition,under 980nm laser irradiation,rate constants are 3.26 and 4.16 times higher than those of AP-NYFYT-50 wt%,respectively.These results indicate that the combination of NYFYT and AP expands the absorption range of the composite photocatalyst and facilitates the NIR-driven photocatalytic process.The introduction of PtNPs effectively prevents the electron-hole recombination and the reduction of Ag+,accelerating the redox reaction and promoting the photocatalytic activity and stability of AP.
基金supported by the Jiangsu Planned Projects for Postdoctoral Research Funds(1301080C)NNSFC(21202141,21173182)+1 种基金Key Science&Technology Specific Projects of Yangzhou(YZ20122029)the Innovation Foundation of Yangzhou University(2015CXJ009)~~
文摘The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD,nitrogen adsorption,NH3-TPD,TG,H2-TPR and TPO techniques combined with propane dehydrogenation tests.It has been shown that SUZ-4-supported PtSnNa（PtSnNa/SUZ-4） was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5,owing to its higher catalytic activity and stability.Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts.The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity.In contrast to ZSM-5-supported catalysts,Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition.This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H_2PtCl_6 into the zeolite.In contrast,the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels,followed by transformation to highly dispersed Pt clusters during calcination.In the case of the PtSnNa/ZSM-5,the interactions between Sn oxides and the support were lessened,owing to the weaker acidity of the ZSM-5 zeolite.The dispersed Sn oxides were therefore easier to reduce to the metallic state,thus decreasing the catalytic activity for hydrocarbon dehydrogenation.
文摘Pt/Pt 4+-TiO2 photocatalyst prepared by a modified sol-gel process was investigated by X-ray diffraction, UV-Vis diffuse reflectance spectra, X-ray photoelectron spectroscopy, time-resolved photoconductivity and terephthalic acid fluorescence probing. The photocatalytic activities of catalysts were evaluated by using ethylene oxidation studies under visible light irradiation（λ>450 nm） from 40 to 62 ℃. It is found that the platinum doping in titania caused significant absorption shift to the visible region and the surface recombination of photogenerated carriers was inhibited. The results show that ethylene was not converted on conventional TiO2 while the conversion was 90% and the complete mineralization was achieved over Pt-Pt 4+/TiO2 at 62 ℃ in our experiment. Besides the exponential increase of thermalcatalytic activity, pure photocatalytic activity of the planitized sample enhanced linearly with the increase of temperature.
基金supported by the National Natural Science Foundation of China(21506194,21676255)the Provincial Natural Science Foundation of Zhejiang Province(LY16B070011)the Commission of Science and Technology of Zhejiang Province(2017C33106,2017C03007)~~
文摘Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improved the catalytic activity significantly.When using Pt/Ce-Zr-SO_4^（2-） with 10 wt%SO_4^（2-）,the temperature for 90%conversion of propene and CO decreased by 75℃ compared with Pt/Ce-Zr.The conversion exceeded 95%at 240℃ even after 0.02%sulfur dioxide poisoning for 20 h.Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO_4^（2-） support,and the increased number of Pt particles built up more Pt^（-）-（SO_4^（2-））^（-） couples,which resulted in excellent activity.The increased total acidity and new Bronsted acid sites on the surface provided the Pt/Ce-Zr-SO_4^（2-） with good sulfur resistance.
