2 research outputs found
Extraction of Linear Carbon Chains Unravels the Role of the Carbon Nanotube Host
Linear
carbon chains (LCCs) have been shown to grow inside double-walled
carbon nanotubes (DWCNTs), but isolating them from this hosting material
represents one of the most challenging tasks toward applications.
Herein we report the extraction and separation of LCCs inside single-walled
carbon nanotubes (LCCs@SWCNTs) extracted from a double-walled host
LCCs@DWCNTs by applying a combined tip-ultrasonic and density gradient
ultracentrifugation (DGU) process. High-resolution transmission electron
microscopy, optical absorption, and Raman spectroscopy show that not
only short LCCs but clearly long LCCs (LLCCs) can be extracted and
separated from the host. Moreover, the LLCCs can even be condensed
by DGU. The Raman spectral frequency of LCCs remains almost unchanged
regardless of the presence of the outer tube of the DWCNTs. This suggests
that the major importance of the outer tubes is making the whole synthesis
viable. We have also been able to observe the interaction between
the LCCs and the inner tubes of DWCNTs, playing a major role in modifying
the optical properties of LCCs. Our extraction method suggests the
possibility toward the complete isolation of LCCs from CNTs
Monomer Symmetry-Regulated Defect Engineering: In Situ Preparation of Functionalized Covalent Organic Frameworks for Highly Efficient Capture and Separation of Carbon Dioxide
Developing
crystalline porous materials with highly efficient CO2 selective
adsorption capacity is one of the key challenges
to carbon capture and storage (CCS). In current studies, much more
attention has been paid to the crystalline and porous properties of
crystalline porous materials for CCS, while the defects, which are
unavoidable and ubiquitous, are relatively neglected. Herein, for
the first time, we propose a monomer-symmetry regulation strategy
for directional defect release to achieve in situ functionalization
of COFs while exposing uniformly distributed defect-aldehyde groups
as functionalization sites for selective CO2 capture. The
regulated defective COFs possess high crystallinity, good structural
stability, and a large number of organized and functionalized aldehyde
sites, which exhibit one of the highest selective separation values
of all COF sorbing materials in CO2/N2 selective
adsorption (128.9 cm3/g at 273 K and 1 bar, selectivity:
45.8 from IAST). This work not only provides a new strategy for defect
regulation and in situ functionalization of COFs but also provides
a valuable approach in the design and preparation of new adsorbents
for CO2 adsorption and CO2/N2 selective
separation