Biomimetic Synthesis of Prismatic Calcite Mesocrystals in the Presence of Nonionic Copolymer

2012 ◽  
Vol 535-537 ◽  
pp. 1512-1515
Author(s):  
Yi Ping Wu ◽  
Xiao Hong Wang ◽  
Qun Zhang
Keyword(s):  
Calcium Carbonate ◽  
Functional Groups ◽  
Triblock Copolymer ◽  
Biomimetic Synthesis ◽  
Synthesis Process ◽  
Synthetic Strategy ◽  
Oxygen Functional Groups ◽  
Special Morphology ◽  
Ether Oxygen ◽  
Oxygen Groups

A triblock copolymer of F127 was used as a model additive to influence the growth of calcium carbonate (CaCO3) in a biomimetic synthesis process. The results demonstrate that F127 preferentially interacted with selected faces of calcite and induces the growth along the crystallographic c direction into prisms with mesocrystal architectures. Although only containing ether-oxygen functional groups, F127 is considered as an analogue to an array of polyanions contributing to the special morphogenesis of CaCO3. Consequently, this result provides a wider sense in the significance of the ether-oxygen groups into biomineralization mechanism and an alternative synthetic strategy for special morphology of CaCO3 materials.

scholarly journals High Temperature Vacuum Annealing and Hydrogenation Modification of Exfoliated Graphite Nanoplatelets

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Xiaobing Li ◽  
Sanjib Biswas ◽  
Lawrence T. Drzal
Keyword(s):  
High Temperature ◽  
Functional Groups ◽  
Vacuum Annealing ◽  
Atmospheric Oxygen ◽  
Graphite Nanoplatelets ◽  
Highly Active ◽  
Oxygen Functional Groups ◽  
Defect Sites ◽  
Capacitance Characteristics ◽  
Oxygen Groups

Highly active defect sites on the edges of graphene automatically capture oxygen from air to form various oxygen groups. A two-step procedure to remove various oxygen functional groups from the defect sites of exfoliated graphene nanoplatelets (GNPs) has been developed to reduce the atomic oxygen concentration from 9.5% to 4.8%. This two-step approach involves high temperature vacuum annealing followed by hydrogenation to protect the reduced edge carbon atoms from recombining with the atmospheric oxygen. The reduced GNPs exhibit decreased surface resistance and graphitic potential-dependent capacitance characteristics compared to the complex potential-dependent capacitance characteristics exhibited by the unreduced GNPs as a result of the removal of the oxygen functional groups present primarily at the edges. These reduced GNPs also exhibit high electrochemical cyclic stability for electrochemical energy storage applications.

Generation of Phosphoranyl Radicals via Photoredox Catalysis Enables Voltage–Independent Activation of Strong C–O Bonds

2018 ◽  
Author(s):  
Erin Stache ◽  
Alyssa B. Ertel ◽  
Tomislav Rovis ◽  
Abigail G. Doyle
Keyword(s):  
Carboxylic Acids ◽  
Functional Groups ◽  
Single Step ◽  
Direct Access ◽  
Photoredox Catalysis ◽  
Acyl Radical ◽  
Synthetic Strategy ◽  
Acyl Radicals ◽  
Benzyl Radicals ◽  
Aliphatic Carboxylic Acids

Alcohols and carboxylic acids are ubiquitous functional groups found in organic molecules that could serve as radical precursors, but C–O bonds remain difficult to activate. We report a synthetic strategy for direct access to both alkyl and acyl radicals from these ubiquitous functional groups via photoredox catalysis. This method exploits the unique reactivity of phosphoranyl radicals, generated from a polar/SET crossover between a phosphine radical cation and an oxygen centered nucleophile. We first show the desired reactivity in the reduction of benzylic alcohols to the corresponding benzyl radicals with terminal H-atom trapping to afford the deoxygenated product. Using the same method, we demonstrate access to synthetically versatile acyl radicals which enables the reduction of aromatic and aliphatic carboxylic acids to the corresponding aldehydes with exceptional chemoselectivity. This protocol also transforms carboxylic acids to heterocycles and cyclic ketones via intramolecular acyl radical cyclizations to forge new C–O, C–N and C–C bonds in a single step.

scholarly journals Electrochemical Evaluation of Surface Modified Free-Standing CNT Electrode for Li–O2 Battery Cathode

Energies ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 4196
Author(s):  
Ji Hyeon Lee ◽  
Hyun Wook Jung ◽  
In Soo Kim ◽  
Min Park ◽  
Hyung-Seok Kim
Keyword(s):  
Functional Groups ◽  
Atomic Layer ◽  
Free Standing ◽  
Coating Technology ◽  
Oxygen Functional Groups ◽  
Layer Deposition ◽  
Discharge Product ◽  
Effect Of Oxygen ◽  
Surface Modified ◽  
Electrochemical Evaluation

In this study, carbon nanotubes (CNTs) were used as cathodes for lithium–oxygen (Li–O2) batteries to confirm the effect of oxygen functional groups present on the CNT surface on Li–O2 battery performance. A coating technology using atomic layer deposition was introduced to remove the oxygen functional groups present on the CNT surface, and ZnO without catalytic properties was adopted as a coating material to exclude the effect of catalytic reaction. An acid treatment process (H2SO4:HNO3 = 3:1) was conducted to increase the oxygen functional groups of the existing CNTs. Therefore, it was confirmed that ZnO@CNT with reduced oxygen functional groups lowered the charging overpotential by approximately 230 mV and increased the yield of Li2O2, a discharge product, by approximately 13%. Hence, we can conclude that the ZnO@CNT is suitable as a cathode material for Li–O2 batteries.

ChemInform Abstract: Graphene Oxide Catalyzed C-H Bond Activation: The Importance of Oxygen Functional Groups for Biaryl Construction.

ChemInform ◽  
2016 ◽  
Vol 47 (26) ◽  
Author(s):  
Yongjun Gao ◽  
Pei Tang ◽  
Hu Zhou ◽  
Wei Zhang ◽  
Hanjun Yang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Functional Groups ◽  
Bond Activation ◽  
Oxygen Functional Groups
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