A new synthetic strategy has been developed to encapsulate supported Pt nanoparticles in heterogeneous catalysts to prevent their sintering. Model catalysts were first prepared by dispersing -3-nm Pt nanoparticles on ...A new synthetic strategy has been developed to encapsulate supported Pt nanoparticles in heterogeneous catalysts to prevent their sintering. Model catalysts were first prepared by dispersing -3-nm Pt nanoparticles on -120-nm silica beads. These were then covered with a fresh layer of mesoporous silica, a few tens of nanometers thick, and etched to re-expose the metal surface to the reaction mixtures. TEM images were used to confirm the success of each of the synthesis steps, and both CO titrations and kinetic measurements for the catalytic conversion of cis- and trans-2-butenes with hydrogen were employed to test the degree of re-activation of the catalyst obtained after the etching treatment, which had to be tuned to give simultaneous maximum activity and maximum catalyst stability. The resulting encapsulated platinum nanoparticles were shown to resist sintering during calcination at temperatures as high as 1075 K, whereas the unprotected catalysts were seen to sinter by 875 K.展开更多
A facile and scalable approach to synthesize silicon composite anodes has been developed by encapsulating Si particles via in situ polymerization and carbonization of phloroglucinol-formaldehyde gel, followed by incor...A facile and scalable approach to synthesize silicon composite anodes has been developed by encapsulating Si particles via in situ polymerization and carbonization of phloroglucinol-formaldehyde gel, followed by incorporation of graphene nanoplatelets. As a result of its structural integrity, high packing density and an intimate electrical contact consolidated by the conductive networks, the composite anode yielded excellent electrochemical performance in terms of charge storage capability, cycling life and coulombic efficiency. A half cell achieved reversible capacities of 1,600 mAh·g-1 and 1,000 mAh·g-1 at 0.5 A·g-1 and 2.1 A·g-1, respectively, while retaining more than 70% of the initial capacities over 1,000 cycles. Complete lithium-ion pouch cells coupling the anode with a lithium metal oxide cathode demonstrated excellent cycling performance and energy output, representing significant advance in developing Si-based electrode for practical application in high-performance lithium-ion batteries.展开更多
2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) na...2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) nanoparticles. By increasing the weight ratio of TTF to the precursor of silica nanoparticles (the quantities of the precursors were kept the same), the fluorescence intensity of nanoparticles increased correspondingly, due to the formation of larger AIE dots in the cores of ORMOSIL nanoparticles. The fluorescent and biocompatible nanoprobes were then utilized for in vitro imaging of HeLa cells. Two-photon fluorescence microscopy clearly illustrated that the nanoparticles have the capacity of nucleus permeability, as well as cytoplasm staining towards tumor cells. Our experimental results may offer a promising method for fast and bright fluorescence imaging, as well as bio-molecule/drug delivery to cell nucleus.展开更多
文摘A new synthetic strategy has been developed to encapsulate supported Pt nanoparticles in heterogeneous catalysts to prevent their sintering. Model catalysts were first prepared by dispersing -3-nm Pt nanoparticles on -120-nm silica beads. These were then covered with a fresh layer of mesoporous silica, a few tens of nanometers thick, and etched to re-expose the metal surface to the reaction mixtures. TEM images were used to confirm the success of each of the synthesis steps, and both CO titrations and kinetic measurements for the catalytic conversion of cis- and trans-2-butenes with hydrogen were employed to test the degree of re-activation of the catalyst obtained after the etching treatment, which had to be tuned to give simultaneous maximum activity and maximum catalyst stability. The resulting encapsulated platinum nanoparticles were shown to resist sintering during calcination at temperatures as high as 1075 K, whereas the unprotected catalysts were seen to sinter by 875 K.
文摘A facile and scalable approach to synthesize silicon composite anodes has been developed by encapsulating Si particles via in situ polymerization and carbonization of phloroglucinol-formaldehyde gel, followed by incorporation of graphene nanoplatelets. As a result of its structural integrity, high packing density and an intimate electrical contact consolidated by the conductive networks, the composite anode yielded excellent electrochemical performance in terms of charge storage capability, cycling life and coulombic efficiency. A half cell achieved reversible capacities of 1,600 mAh·g-1 and 1,000 mAh·g-1 at 0.5 A·g-1 and 2.1 A·g-1, respectively, while retaining more than 70% of the initial capacities over 1,000 cycles. Complete lithium-ion pouch cells coupling the anode with a lithium metal oxide cathode demonstrated excellent cycling performance and energy output, representing significant advance in developing Si-based electrode for practical application in high-performance lithium-ion batteries.
基金the National Basic Research Program of China (973 Program, 2013CB834704 and 2011CB503700)the National Natural Science Foundation of China (61275190)
文摘2,3-Bis(4-(phenyl(4-(1,2,2-triphenylvinyl)phenyl)amino)phenyl) fumaronitrile (TPE-TPA-FN or TTF), which possesses aggregation-induced emission (AIE) characteristic, is doped in organically modified silica (ORMOSIL) nanoparticles. By increasing the weight ratio of TTF to the precursor of silica nanoparticles (the quantities of the precursors were kept the same), the fluorescence intensity of nanoparticles increased correspondingly, due to the formation of larger AIE dots in the cores of ORMOSIL nanoparticles. The fluorescent and biocompatible nanoprobes were then utilized for in vitro imaging of HeLa cells. Two-photon fluorescence microscopy clearly illustrated that the nanoparticles have the capacity of nucleus permeability, as well as cytoplasm staining towards tumor cells. Our experimental results may offer a promising method for fast and bright fluorescence imaging, as well as bio-molecule/drug delivery to cell nucleus.
