Photoinduced Decarbonylative Rearrangement of Bicyclo[2.2.2]Octenones: Synthesis of the Marasmane Skeleton

The marasmane sesquiterpenoid structure can be found in the skeleton of a variety of natural products bearing interesting bioactivity. The unique fused-5,6,3-tricyclic ring structure, in which the rings are <i>cis</i>-fused and the five- and three-membered rings are mutually <i>trans</i>, provides a synthetic challenge for organic chemists. In this work, we took advantage of the photoinduced decarbonylative rearrangement of bicyclo[2.2.2]­octenone to develop a new methodology for construction of the highly functionalized fused-5,6,3-tricyclic ring structure in a concise reaction sequence

Oxygen Reduction Reaction of Block Copolymer Template-Directed Porous Carbon Catalysts

Functional nitrogen-doped hierarchically porous carbon materials (NHPCMs) have received much attention in recent years because of their electrochemical and catalytic activities, which offer potential applications in the field of fuel cells. Herein we demonstrate the NHPCMs with superior performance of the oxygen reduction reaction (ORR) through spontaneous coassembly of polystyrene-block-poly­(ethylene oxide) (PS-b-PEO) micelles along with self-polymerization of dopamine (DA). In this study, we aim to deeply understand the effects of HCl addition, DA content, and aging environment on morphologies of NHPCMs through studying self-assembly and phase behavior of PS-b-PEO/DA mixtures in cosolvent using synchrotron small-angle X-ray scattering and transmission X-ray microscopy. The morphology of hierarchical pores can be successfully obtained by fine controls over DA content and pyrolysis temperature. Correlations of morphologies and processes with the ORR performance indicate that hierarchically porous carbon materials exhibit the highest ORR performance with Jk = 8.1 mA cm–2 (measured at −0.4 V of SCE), low onset potential η = −0.11 V, and four-electron transfer pathway over a wide voltage range

Media 1: Membrane ripples of a living cell measured by non-interferometric widefield optical profilometry

Originally published in Optics Express on 26 December 2005 (oe-13-26-10665

Oxygen Reduction Reaction of Block Copolymer Template-Directed Porous Carbon Catalysts

Functional nitrogen-doped hierarchically porous carbon materials (NHPCMs) have received much attention in recent years because of their electrochemical and catalytic activities, which offer potential applications in the field of fuel cells. Herein we demonstrate the NHPCMs with superior performance of the oxygen reduction reaction (ORR) through spontaneous coassembly of polystyrene-block-poly­(ethylene oxide) (PS-b-PEO) micelles along with self-polymerization of dopamine (DA). In this study, we aim to deeply understand the effects of HCl addition, DA content, and aging environment on morphologies of NHPCMs through studying self-assembly and phase behavior of PS-b-PEO/DA mixtures in cosolvent using synchrotron small-angle X-ray scattering and transmission X-ray microscopy. The morphology of hierarchical pores can be successfully obtained by fine controls over DA content and pyrolysis temperature. Correlations of morphologies and processes with the ORR performance indicate that hierarchically porous carbon materials exhibit the highest ORR performance with Jk = 8.1 mA cm–2 (measured at −0.4 V of SCE), low onset potential η = −0.11 V, and four-electron transfer pathway over a wide voltage range

Oxygen Reduction Reaction of Block Copolymer Template-Directed Porous Carbon Catalysts

Functional nitrogen-doped hierarchically porous carbon materials (NHPCMs) have received much attention in recent years because of their electrochemical and catalytic activities, which offer potential applications in the field of fuel cells. Herein we demonstrate the NHPCMs with superior performance of the oxygen reduction reaction (ORR) through spontaneous coassembly of polystyrene-block-poly­(ethylene oxide) (PS-b-PEO) micelles along with self-polymerization of dopamine (DA). In this study, we aim to deeply understand the effects of HCl addition, DA content, and aging environment on morphologies of NHPCMs through studying self-assembly and phase behavior of PS-b-PEO/DA mixtures in cosolvent using synchrotron small-angle X-ray scattering and transmission X-ray microscopy. The morphology of hierarchical pores can be successfully obtained by fine controls over DA content and pyrolysis temperature. Correlations of morphologies and processes with the ORR performance indicate that hierarchically porous carbon materials exhibit the highest ORR performance with Jk = 8.1 mA cm–2 (measured at −0.4 V of SCE), low onset potential η = −0.11 V, and four-electron transfer pathway over a wide voltage range

Photoinduced Decarbonylative Rearrangement of Bicyclo[2.2.2]Octenones: Synthesis of the Marasmane Skeleton

The marasmane sesquiterpenoid structure can be found in the skeleton of a variety of natural products bearing interesting bioactivity. The unique fused-5,6,3-tricyclic ring structure, in which the rings are <i>cis</i>-fused and the five- and three-membered rings are mutually <i>trans</i>, provides a synthetic challenge for organic chemists. In this work, we took advantage of the photoinduced decarbonylative rearrangement of bicyclo[2.2.2]­octenone to develop a new methodology for construction of the highly functionalized fused-5,6,3-tricyclic ring structure in a concise reaction sequence

Photoinduced Decarbonylative Rearrangement of Bicyclo[2.2.2]Octenones: Synthesis of the Marasmane Skeleton

The marasmane sesquiterpenoid structure can be found in the skeleton of a variety of natural products bearing interesting bioactivity. The unique fused-5,6,3-tricyclic ring structure, in which the rings are <i>cis</i>-fused and the five- and three-membered rings are mutually <i>trans</i>, provides a synthetic challenge for organic chemists. In this work, we took advantage of the photoinduced decarbonylative rearrangement of bicyclo[2.2.2]­octenone to develop a new methodology for construction of the highly functionalized fused-5,6,3-tricyclic ring structure in a concise reaction sequence

Study on Microstructural Deformation of Working Sn and SnSb Anode Particles for Li-Ion Batteries by in Situ Transmission X-ray Microscopy

Sn-containing compounds are potential high-capacity anode materials for Li-ion batteries. They, however, suffer from significant dimensional variations during electrochemical lithiation and delithiation, causing cycling instability. Understanding the dynamics of these deformation processes may provide valuable information in the establishment of viable high-energy anodes. In this paper, the evolution of interior microstructures of two types of Sn-containing particles, including Sn and SnSb, during initial cycles of electrochemical lithiation/delithation has been revealed by in situ synchrotron transmission X-ray microscopy, complemented by in situ synchrotron X-ray diffraction to provide phase information. The microstructures and deformation rates are shown to depend on particle composition, size, and alloy stoichiometry with Li. During first lithiation, both particles exhibit core (metal)–shell (lithiated compounds) interior structures. Initial formation of a dense surface layer containing LixSn phases of low Li-stoichiometry on the Sn particle hinders further lithiation kinetics, resulting in delayed expansion of large particles. In contrast, Sb in SnSb is readily lithiated to form a porous Li-rich (Li3Sb) surface layer at higher potential than Sn, which enables the acceleration of lithiation and removal of the size dependence of the lithiation process. Both lithiated particles only partially contract upon delithiation, and their interiors evolve into porous structures due to metal recrystallization. Such porous structures allow for fast lithiation and mitigated dimensional variations upon subsequent cycles. Neither of the two anode particles pulverize upon cycling

Study on Microstructural Deformation of Working Sn and SnSb Anode Particles for Li-Ion Batteries by in Situ Transmission X-ray Microscopy

Sn-containing compounds are potential high-capacity anode materials for Li-ion batteries. They, however, suffer from significant dimensional variations during electrochemical lithiation and delithiation, causing cycling instability. Understanding the dynamics of these deformation processes may provide valuable information in the establishment of viable high-energy anodes. In this paper, the evolution of interior microstructures of two types of Sn-containing particles, including Sn and SnSb, during initial cycles of electrochemical lithiation/delithation has been revealed by in situ synchrotron transmission X-ray microscopy, complemented by in situ synchrotron X-ray diffraction to provide phase information. The microstructures and deformation rates are shown to depend on particle composition, size, and alloy stoichiometry with Li. During first lithiation, both particles exhibit core (metal)–shell (lithiated compounds) interior structures. Initial formation of a dense surface layer containing LixSn phases of low Li-stoichiometry on the Sn particle hinders further lithiation kinetics, resulting in delayed expansion of large particles. In contrast, Sb in SnSb is readily lithiated to form a porous Li-rich (Li3Sb) surface layer at higher potential than Sn, which enables the acceleration of lithiation and removal of the size dependence of the lithiation process. Both lithiated particles only partially contract upon delithiation, and their interiors evolve into porous structures due to metal recrystallization. Such porous structures allow for fast lithiation and mitigated dimensional variations upon subsequent cycles. Neither of the two anode particles pulverize upon cycling

Study on Microstructural Deformation of Working Sn and SnSb Anode Particles for Li-Ion Batteries by in Situ Transmission X-ray Microscopy

Sn-containing compounds are potential high-capacity anode materials for Li-ion batteries. They, however, suffer from significant dimensional variations during electrochemical lithiation and delithiation, causing cycling instability. Understanding the dynamics of these deformation processes may provide valuable information in the establishment of viable high-energy anodes. In this paper, the evolution of interior microstructures of two types of Sn-containing particles, including Sn and SnSb, during initial cycles of electrochemical lithiation/delithation has been revealed by in situ synchrotron transmission X-ray microscopy, complemented by in situ synchrotron X-ray diffraction to provide phase information. The microstructures and deformation rates are shown to depend on particle composition, size, and alloy stoichiometry with Li. During first lithiation, both particles exhibit core (metal)–shell (lithiated compounds) interior structures. Initial formation of a dense surface layer containing LixSn phases of low Li-stoichiometry on the Sn particle hinders further lithiation kinetics, resulting in delayed expansion of large particles. In contrast, Sb in SnSb is readily lithiated to form a porous Li-rich (Li3Sb) surface layer at higher potential than Sn, which enables the acceleration of lithiation and removal of the size dependence of the lithiation process. Both lithiated particles only partially contract upon delithiation, and their interiors evolve into porous structures due to metal recrystallization. Such porous structures allow for fast lithiation and mitigated dimensional variations upon subsequent cycles. Neither of the two anode particles pulverize upon cycling