Equal-channel angular pressing(ECAP) is now recognized as an effective technique for fabricating ultrafine grained materials. The results show that prevalent macroscopic shear banding occurs in ECAP as long as the pre...Equal-channel angular pressing(ECAP) is now recognized as an effective technique for fabricating ultrafine grained materials. The results show that prevalent macroscopic shear banding occurs in ECAP as long as the pressing passes reach 2, and the severe macroscopic shear band extends from bottom to top surface and slants to the longitudinal axis of specimen at an angle of about 45°, develops at regular intervals, with a high shear strain accommodation of about 3.7 within the band. Different families of macroscopic shear bands may cut across each other, and over 60% of sample volume is occupied by macroscopic shear band when the ECAP reaches 4 passes.展开更多
Anisotropic metallic Nanoparticles （NPs） have unique optical properties, such as Surface Enhanced Raman Scattering （SERS） spearoscopy. In this paper, star-shaped and sphere gold NPs were prepared by seed-mediated ...Anisotropic metallic Nanoparticles （NPs） have unique optical properties, such as Surface Enhanced Raman Scattering （SERS） spearoscopy. In this paper, star-shaped and sphere gold NPs were prepared by seed-mediated growth and Frence methods respectively. The reaction process arid the effect of reagent in seed-mediated growth of gold naaostar particles were systematically described. After fabricaring NPs the authors test their Raman enhancement using Ch-ystal Violet （CV） moleolles apart. The experimental results indicated that star-shaped Au NPs had strtmger Raman enhancement spectrum than that of sphere Au NPs.展开更多
This paper demonstrates a one-pot approach to produce highly dispersed dendritic palladium-platinum bi- metallic nanoparticles （NPs） with small particle size, tunable composition and high catalytic activity. Herein,...This paper demonstrates a one-pot approach to produce highly dispersed dendritic palladium-platinum bi- metallic nanoparticles （NPs） with small particle size, tunable composition and high catalytic activity. Herein, the PdPt bi- metallic NPs have been obtained using bayberry tannin （BT） as both the reducing agent and surfactant. Additionally, the PdPt bimetallic NPs with different Pd/Pt atomic ratios can be prepared by just varying the amounts of the Pd and Pt pre- cursors. Most importantly, the as-prepared Pd52Pt4s catalyst exhibits the optimal catalytic activities compared with the other compositional PdPt NPs （Pds2Ptls, Pd69Ph~, and Pd36 Pt64） and commercial Pt/C （20 wt.%） catalyst for the methanol oxidation reaction （MOR）. Meanwhile, Pd52Pt4s also shows better CO tolerance, which can be attributed to the unique dendritic structure and the synergistic effect between Pd and Pt. With evident advantages of the facile preparation and enhanced catalytic performance, it holds great promise as a high-performance catalyst for electrochemical energy con- version.展开更多
文摘Equal-channel angular pressing(ECAP) is now recognized as an effective technique for fabricating ultrafine grained materials. The results show that prevalent macroscopic shear banding occurs in ECAP as long as the pressing passes reach 2, and the severe macroscopic shear band extends from bottom to top surface and slants to the longitudinal axis of specimen at an angle of about 45°, develops at regular intervals, with a high shear strain accommodation of about 3.7 within the band. Different families of macroscopic shear bands may cut across each other, and over 60% of sample volume is occupied by macroscopic shear band when the ECAP reaches 4 passes.
文摘Anisotropic metallic Nanoparticles （NPs） have unique optical properties, such as Surface Enhanced Raman Scattering （SERS） spearoscopy. In this paper, star-shaped and sphere gold NPs were prepared by seed-mediated growth and Frence methods respectively. The reaction process arid the effect of reagent in seed-mediated growth of gold naaostar particles were systematically described. After fabricaring NPs the authors test their Raman enhancement using Ch-ystal Violet （CV） moleolles apart. The experimental results indicated that star-shaped Au NPs had strtmger Raman enhancement spectrum than that of sphere Au NPs.
基金supported by the National Natural Science Foundation of China (51571151, 51701139, 51671143, 51371119 and U1601216)
文摘This paper demonstrates a one-pot approach to produce highly dispersed dendritic palladium-platinum bi- metallic nanoparticles （NPs） with small particle size, tunable composition and high catalytic activity. Herein, the PdPt bi- metallic NPs have been obtained using bayberry tannin （BT） as both the reducing agent and surfactant. Additionally, the PdPt bimetallic NPs with different Pd/Pt atomic ratios can be prepared by just varying the amounts of the Pd and Pt pre- cursors. Most importantly, the as-prepared Pd52Pt4s catalyst exhibits the optimal catalytic activities compared with the other compositional PdPt NPs （Pds2Ptls, Pd69Ph~, and Pd36 Pt64） and commercial Pt/C （20 wt.%） catalyst for the methanol oxidation reaction （MOR）. Meanwhile, Pd52Pt4s also shows better CO tolerance, which can be attributed to the unique dendritic structure and the synergistic effect between Pd and Pt. With evident advantages of the facile preparation and enhanced catalytic performance, it holds great promise as a high-performance catalyst for electrochemical energy con- version.
