Abstract We report the synthesis of ordered mesoporous ceria ( m CeO 2 ) with highly crystallinity and thermal stability using hybrid polymer templates consisting of organosilanes. Those organosilane-containing polymers can convert into silica-like nanostructures that further serve as thermally stable and mechanically strong templates to prevent the collapse of mesoporous frameworks during thermal-induced crystallization. Using a simple evaporation-induced self-assembly process, control of the interaction between templates and metal precursors allows the co-self-assembly of polymer micelles and Ce 3+ ions to form uniform porous structures. The porosity is well-retained after calcination up to 900 °C. After the thermal engineering at 700 °C for 12 h ( m CeO 2 -700-12 h), m CeO 2 still has a specific surface area of 96 m 2 g −1 with a pore size of 14 nm. m CeO 2 is demonstrated to be active for electrochemical oxidation of sulfite. m CeO 2 -700-12 h with a perfect balance of crystallinity and porosity shows the fastest intrinsic activity that is about 84 times more active than bulk CeO 2 and 5 times more active than m CeO 2 that has a lower crystallinity.
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Synthesis of nanopolycrystalline mesoporous diamond from periodic mesoporous carbon: Mesoporosity increases with increasing synthesis pressure
- Award ID(s):
- 1723185
- NSF-PAR ID:
- 10100471
- Date Published:
- Journal Name:
- Scripta Materialia
- Volume:
- 162
- Issue:
- C
- ISSN:
- 1359-6462
- Page Range / eLocation ID:
- 350 to 354
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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The production of ordered mesoporous carbons (OMCs) can be achieved by direct pyrolysis of self-assembled polymers. Typically, these systems require a majority phase capable of producing carbon, and a minority phase to form pores through a thermal decomposition step. While polyacrylonitrile (PAN)-based block copolymers (BCPs) have been broadly reported as OMC precursors, these materials have a relatively narrow processing window for developing ordered nanostructures and often require sophisticated chemistry for BCP synthesis, followed by long crosslinking times at high temperatures. Alternatively, olefinic thermoplastic elastomers (TPEs) can be convered to large-pore OMCs after two steps of sulfonation-induced crosslinking and carbonization. Building on this platform, this work focuses on the precursor design concept for the efficient synthesis of OMCs through employing low-cost and widely available polystyrene-block-polybutadiene-block-polystyrene (SBS), which contains unsaturated bonds along the polymer backbone. As a result, the presence of alkene groups greatly enhances the kinetics of sulfonation-induced crosslinking reaction, which can be completed within only 20 min at 150 °C, nearly an order of magnitude faster than a recently reported TPE system containing a fully saturated polymer backbone. The crosslinking reaction enables the production of OMCs with pore sizes (∼9.5 nm) larger than most conventional soft-templating systems, while also doping sulfur heteroatoms into the carbon framework of the final products. This work demonstrates efficient synthesis of OMCs from TPE precursors which have a great potential for scaled production, and the resulting products may have broad applications such as for drug delivery and energy storage.more » « less
- Free Publicly Accessible Full Text
-
Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.scriptamat.2018.10.024
