Tunable Interlayer Shifting in Two-Dimensional Covalent Organic Frameworks Triggered by CO2 Sorption

10.1021/jacs.2c08214Journal of the American Chemical Society1444420363–2037

Interlayer shifting in two-dimensional covalent organic frameworks

10.1021/jacs.0c03691Journal of the American Chemical Society1423012995-1300

Ordered mesoporous alumina with tunable morphologies and pore sizes for CO₂ capture and dye separation

We describe a versatile and scalable strategy toward long-range and periodically ordered mesoporous alumina (Al2O3) structures by evaporation-induced self-assembly of a structure-directing ABA triblock copolymer (F127) mixed with aluminum tri-sec-butoxide-derived sol additive. We found that the separate preparation of the alkoxide sol-gel reaction before mixing with the block copolymer enabled access to a relatively unexplored parameter space of copolymer-to-additive composition, acid-to-metal molar ratio, and solvent, yielding ordered mesophases of two-dimensional (2D) lamellar, hexagonal cylinder, and 3D cage-like cubic lattices, as well as multiscale hierarchical ordered structures from spinodal decomposition-induced macro- and mesophase separation. Thermal annealing in air at 900 °C yielded well-ordered mesoporous crystalline γ-Al2O3 structures and hierarchically porous γ-Al2O3 with 3D interconnected macroscale and ordered mesoscale pore networks. The ordered Al2O3 structures exhibited tunable pore sizes in three different length scales, <2 nm (micropore), 2-11 nm (mesopore), and 1-5 μm (macropore), as well as high surface areas and pore volumes of up to 305 m2/g and 0.33 cm3/g, respectively. Moreover, the resultant mesoporous Al2O3 demonstrated enhanced adsorption capacities of carbon dioxide and Congo red dye. Such hierarchically ordered mesoporous Al2O3 are well-suited for green environmental solutions and urban sustainability applications, for example, high-temperature solid adsorbents and catalyst supports for carbon dioxide sequestration, fuel cells, and wastewater separation treatments.Nanyang Technological UniversityThis work was supported by a member-directed research grant from ExxonMobil through the Singapore Energy Center (EM11161.TO6) and a startup grant from Nanyang Technological University, Singapore. This work made use of research facilities at the Facility for Analysis, Characterization, Testing and Simulation (FACTS), Nanyang Technological University, Singapore. C.T. gratefully acknowledges an overseas training program grant from King Mongkut’s Institute of Technology Ladkrabang

Ultrafast Crystallization of Ordered Mesoporous Metal Oxides and Carbon in Seconds

This Communication describes a facile strategy coupling block copolymer-directed self-assembly with high-power Joule heating to form highly crystalline and long-range ordered mesoporous oxide and carbon nanostructures in just a few seconds. The combined approach is compatible with various self-assembled hybrid systems, generating mesoporous composites of γ-Al2O3-carbon, γ-Al2O3/MgO-carbon and anatase-TiO2-carbon with p6mm symmetry, as well as mesoporous non-close-packed carbon structures. Removing the polymer/carbon gives well-defined mesoporous all-γ-Al2O3 and all-anatase-TiO2 structures. Impregnation of chloroplatinic acid followed by Joule heating yields platinum nanoparticles decorated on the channel walls of mesoporous γ-Al2O3-carbon structures. The rapid formation of thermally stable and periodically ordered crystalline oxide, carbon and oxide-carbon structures. <br /

Covalent organic framework atropisomers with multiple gas-triggered structural flexibilities

10.1038/s41563-023-01523-2Nature Materials22636–64

Ultrafast crystallization of ordered mesoporous metal oxides and carbon from block copolymer self-assembly and joule heating

Conventional heat treatments to generate well-ordered and crystalline mesoporous oxide and carbon structures are limited by long durations and annealing temperatures that can cause mesostructural collapse. This paper describes a facile strategy coupling block copolymer-directed self-assembly with high-power Joule heating to form highly crystalline and well-ordered mesoporous oxide and carbon nanostructures within second timeframes. The combined approach is compatible with various functional self-assembled hybrid systems with a range of crystallization temperatures, generating mesoporous composites of γ-Al2O3-carbon, γ-Al2O3/MgO-carbon, and anatase-TiO2-carbon with p6mm symmetry, non-close-packed mesoporous carbon, as well as hierarchical mesoporous α-Fe2O3-carbon structures. Removing the polymer/carbon gives well-defined, highly crystalline mesoporous all-γ-Al2O3 and all-anatase-TiO2 structures. Impregnation of chloroplatinic acid followed by Joule heating yields platinum nanoparticles decorated on the channel walls of mesoporous γ-Al2O3-carbon structures. The resultant Joule-heating-induced well-ordered crystalline mesoporous oxide and oxide-carbon structures have high thermal and structural stabilities and exhibit better performances in CO2 adsorption capacity and lithium-ion batteries than conventional heat-treated counterparts. This approach represents an energy-efficient and time-saving route toward ordered porous materials with high surface area and pore accessibility for a wide range of environmental applications such as carbon sequestration, renewable energy storage, and environmental filtration.Nanyang Technological UniversityNational Research Foundation (NRF)Submitted/Accepted versionThis work was supported by a member-directed research grant from ExxonMobil through the Singapore Energy Center (EM11161.TO6) and a startup grant from Nanyang Technological University, Singapore. S.M. and W.M.Jr. wish to acknowledge financial support from the National Research Foundation of Singapore (NRF) Investigatorship Award (NRFI 2017-08)