Micropores, especially ultramicropores with pore size smaller than 1 nm, play a crucial role in hydrogen storage. In this contribution, we report on bulk production of two-dimensional (2D) polyphenylene networks (PPNs) through a solution-based Wurtz reaction. A self-assembled mechanism is proposed for the formation of 2D PPNs based on molecular dynamics simulations. The morphology, structure, surface chemistry, and textural properties of the PPNs are greatly influenced by anneal treatment at 450−550 °C in terms of deep thermal dechlorination and cyclodechlorination. The annealed PPNs are featured with moderate specific surface area (S BET ) and wealthy micropores, which can be finely tuned by varying the anneal temperature. For PPNs, there is no direct correlation between the H 2 -uptake capacity and individual textural parameters such as S BET , S micropore , V total pore , V micropore , and V mesopore . The H 2 -uptake capacity is highly dependent on the distribution of ultramicropores and the pore volume of ultramicropores in the range of 0.5−0.8 nm (V ultramicropore 0.5−0.8nm ). The PPNs annealed at 500−520 °C, possessing moderate S BET (459.3−564.9 m 2 g −1 ), relatively high V ultramicropore 0.5−0.8nm , and ultramicropores concentrated at 0.69−0.71 nm, exhibit superior H 2 -storage capacity (4.28−5.39 mmol g −1 ) at 77 K and 1 atm.
Surface modification with conductive
polymers has been widely used
to improve the electrochemical performance of cathode materials for
lithium-ion batteries. However, the conductive polymer-modified cathodes
universally employ a solution-based oxidation polymerization method,
making suspicious Li+ leaching of the cathodes during the
modification process. In this paper, we report on a simple method
for scalable fabrication of polythiophene-coated LiMn2O4 (LMO/PTh) through a room-temperature-and-pressure chemical
vapor deposition approach. Thiophene can be oxidized by surface Mn4+ ions of LMO, yielding in situ PTh formation
upon LMO. The resulting LMO/PTh composites are characterized with
XRD, SEM, TEM, ICP–OES, XPS, and AES techniques. A thin layer
of PTh with an average thickness of ca. 1.5 nm can be coated onto
the LMO particles, using 300 μL of thiophene relative to 10
g of LMO powders. The LMO/PTh-300 composite manifests improved aging
resistance and electrochemical performance at both room temperature
and 55 °C, compared with pristine LMO. The improved properties
are attributed to the PTh coating, which not only functions as a moisture-buffering
layer but also serves as an absorber to eliminate HF in the electrolyte.
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