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Chiral transcription and enantioselective separation have garnered significant research interests and showed potential for a broad range of practical applications. Here, we present a novel and facile strategy for chiral templating and enantiomers resolution by coating metal-ion-mediated l -phenylalanine derivatives (LPF/M) with graphene oxide (GO) via simply mixing. The LPF/M hydrogels precipitate from the liquid by encapsulation of GO through coordination interactions and hydrogen bonds, making heterogeneous transfer and separation possible. The chirality inversion of the internal LPF/M nanostructure could be triggered by different addition of metal ions, which further provides means for controlled chiral transfer of guest molecules on the outer GO surfaces as demonstrated in the transcription of thioflavin T (ThT) and 3-aminopyridine (AP) at the supramolecular level. Changing the metal ions also provides control over enantiomer selectivity with outstanding efficiency and reproducibility, as revealed by the separation of racemic mixtures of phenylanine (>98%), lysine (>96%), and histidine (>97%). In addition, the resultant hybrid materials exhibit excellent environmental stability and reusability (more than 20 times) with significant separation efficiency. More importantly, the GO-coated LPF/M could determine the enantiomeric composition of various chiral substrates. The proposed strategy opens up a promising avenue for practical chiral separation application. Image 1 [ABSTRACT FROM AUTHOR]

Microstructural defects (MSDs) in graphene are a primary negative factor for the crystal quality and electrical properties of graphene and there is little knowledge about their formation. Here we report the formation mechanism of MSDs in graphene domains during the CVD growth on Cu substrate. Hydrogen-etching results show that an etched graphene hole corresponds to the position of a MSD that appears not only at the nucleation sites of graphene. Based on density-functional calculations, a hidden growth mechanism of MSDs that is driven by defects/impurities (e.g., Cu clusters/particles) on substrate surfaces is proposed. Our model indicates that the number of MSDs in a graphene domain depends on the density of surface defects on the Cu substrate and we demonstrate that MSDs in graphene can be significantly reduced by the careful substrate polishing. [ABSTRACT FROM AUTHOR]

The N-doped graphene domain is synthesized through co-growth of ammonia and methane by chemical vapor deposition (CVD). Results showed that the nitrogen concentration, defect density, and doping level increased with the decrease in growth temperature. Notably, the position of N1s main peak from X-ray photoelectron spectroscopy (XPS) showed a significant linear blueshift as the temperature decreased, indicating that the main doping nitrogen configuration gradually evolved from pyridinic N to pyrrolic N consistent with the theoretical explanation. In addition, the nitrogen configuration was not influenced by the NH 3 flow rate, which was mainly pyridinic N at the high temperature. With increasing NH 3 flow rate the redshift of the Raman peak was caused by the elongation of the C C bonds. This work presented a process to control the predominant bonding configuration of doping nitrogen by mainly choosing the growth temperature through CVD. [ABSTRACT FROM AUTHOR]