Tw o-dimensional (2D) nanomaterials are attracting mucha ttention due to their excellent electronic and optical properties.H ere,w er eport the first experimental preparation of two free-standing mercurated graphyne nanosheets via the interface-assisted bottom-up method, which integrates both the advantages of metal center and graphyne.T he continuous large-area nanosheets derived from the chemical growth show the layered molecular structural arrangement, controllable thickness and enhanced p-conjugation, whichr esult in their stable and outstanding broadband nonlinear saturable absorption (SA) properties (at both 532 and 1064 nm). The passively Q-switched (PQS) performances of these two nanosheets as the saturable absorbers are comparable to or higher than those of the state-of-the-art 2D nanomaterials (suchasgraphene,black phosphorus,MoS 2 , g-graphyne,etc.). Our results illustrate that the two metallated graphynes could act not only as anew class of 2D carbon-richmaterials,but also as inexpensive and easily available optoelectronic materials for device fabrication.
Polyacrylonitrile (PAN) electrospinning in combination with sol-gel method has been a common technique to produce inorganic nanoparticles containing composite carbon nanofibers (CNFs) for diverse applications. To investigate the morphology evolution and crystal transformation of inorganic components along with CNF formation, bioactive glass (BG) containing CNFs (CNF/BG) were prepared by sintering as-spun PAN/precursor composite nanofibers in a nitrogen atmosphere at temperatures of 800, 1000 and 1200 C. Comprehensive characterizations were performed with TEM, SEM-EDXA and XRD. For samples sintered at 800 C, numerous BG nanoparticles were observed inside the CNFs and mainly in an amorphous state. With the sintering temperature raised to 1000 C, a number of spherical BG nanoparticles were detected on the surface of the resulting CNFs, with a crystal structure of wollastonite (b-CaSiO 3 ) polycrystals. When the samples were sintered at 1200 C, the BG nanoparticles on the surface of CNFs merged into forms with cuboid-like geometry, mainly consisting of pseudowollastonite (Ca 3 (Si 3 O 9 )) single crystals. Based on the geometry evolution and dynamic size distribution function analyses (Ostwald ripening and Smoluchowski equations), it was concluded that the growth of BG nanoparticles conformed to the ripening mechanism at 800 C and migrationcoalescence mechanism at 1200 C, while the process involved both ripening and migrationcoalescence mechanisms at 1000 C.
Low saturable intensity, large TPA coefficient and the absorption cross-section demonstrate that tellurene is an advanced broadband nonlinear absorption material and has potential applications in the nonlinear optics field, especially in the infrared band.
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