Predictive design of vip-responsive frameworks on the molecular level is still a major challenge for experimental and theoretical chemists.The isoreticular approach is one of the most promising approaches for design...Predictive design of vip-responsive frameworks on the molecular level is still a major challenge for experimental and theoretical chemists.The isoreticular approach is one of the most promising approaches for designing MOFs with desired textural properties and framework topology.In this work we successfully applied the isoreticular approach for the design of the new flexible frameworks DUT-180 and DUT-190,constructed by square planar or octahedral metal nodes and a tetracarboxylate ligand.The flexibility mechanism in DUT-190 was explored using in situ PXRD and NMR in parallel to physisorption of subcritical gases such as nitrogen(77 K),carbon dioxide(195 K)and xenon(206 K).Methane physisorption experiments,conducted in a broad temperature range indicate a softening of the DUT-190 framework compared to its analogue DUT-13.These experimental and computational findings can be used as a roadmap for discovery of new flexible frameworks with desired micromechanical properties.展开更多
Porous polymers have been recently recog- nized as one of the most important precursors for fabrication of heteroatom-doped porous carbons due to the intrinsic porous structure, easy available heteroatom- containing m...Porous polymers have been recently recog- nized as one of the most important precursors for fabrication of heteroatom-doped porous carbons due to the intrinsic porous structure, easy available heteroatom- containing monomers and versatile polymerization meth- ods. However, the heteroatom elements in as-produced porous carbons are quite relied on monomers. So far, the manipulating of heteroatom in porous polymer derived porous carbons are still very rare and challenge. In this work, a sulfur-enriched porous polymer, which was prepared from a diacetylene-linked porous polymer, was used as precursor to prepare S-doped and/or N-doped porous carbons under nitrogen and/or ammonia atmo- spheres. Remarkably, S content can sharply decrease from 36.3% to 0.05% after ammonia treatment. The N content and specific surface area of as-fabricated porous carbons can reach up to 1.32% and 1508 m^2·g^-1, respectively. As the electrode materials for electrical double-layer capacitors, as-fabricated porous carbons exhibit high specific capacitance of up to 431.6 F·g^-1 at 5 mW·s^-1 and excellent cycling stability of 99.74% capacitance retention after 3000 cycles at 100 mV·s^-1. Furthermore, as the electro- chemical catalysts for oxygen reduction reaction, as- fabricated porous carbons presented ultralow half-wave- potential of 0.78 V versus RHE. This work not only offers a new strategy for manipulating S and N doping features for the porous carbons derived from S-containing porous polymers, but also paves the way for the structure- performance interrelationship study of heteroatoms co- doped porous carbon for energy applications.展开更多
基金the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program(grant agreement No.742743)support by the Federal Ministry of Education and Research(Project TIMESWITCH No 05K21OD1)support by the Graduate Academy of the Technical University Dresden.E.B.and S.K.gratefully acknowledge financial support from DFG(FOR 2433).
文摘Predictive design of vip-responsive frameworks on the molecular level is still a major challenge for experimental and theoretical chemists.The isoreticular approach is one of the most promising approaches for designing MOFs with desired textural properties and framework topology.In this work we successfully applied the isoreticular approach for the design of the new flexible frameworks DUT-180 and DUT-190,constructed by square planar or octahedral metal nodes and a tetracarboxylate ligand.The flexibility mechanism in DUT-190 was explored using in situ PXRD and NMR in parallel to physisorption of subcritical gases such as nitrogen(77 K),carbon dioxide(195 K)and xenon(206 K).Methane physisorption experiments,conducted in a broad temperature range indicate a softening of the DUT-190 framework compared to its analogue DUT-13.These experimental and computational findings can be used as a roadmap for discovery of new flexible frameworks with desired micromechanical properties.
文摘Porous polymers have been recently recog- nized as one of the most important precursors for fabrication of heteroatom-doped porous carbons due to the intrinsic porous structure, easy available heteroatom- containing monomers and versatile polymerization meth- ods. However, the heteroatom elements in as-produced porous carbons are quite relied on monomers. So far, the manipulating of heteroatom in porous polymer derived porous carbons are still very rare and challenge. In this work, a sulfur-enriched porous polymer, which was prepared from a diacetylene-linked porous polymer, was used as precursor to prepare S-doped and/or N-doped porous carbons under nitrogen and/or ammonia atmo- spheres. Remarkably, S content can sharply decrease from 36.3% to 0.05% after ammonia treatment. The N content and specific surface area of as-fabricated porous carbons can reach up to 1.32% and 1508 m^2·g^-1, respectively. As the electrode materials for electrical double-layer capacitors, as-fabricated porous carbons exhibit high specific capacitance of up to 431.6 F·g^-1 at 5 mW·s^-1 and excellent cycling stability of 99.74% capacitance retention after 3000 cycles at 100 mV·s^-1. Furthermore, as the electro- chemical catalysts for oxygen reduction reaction, as- fabricated porous carbons presented ultralow half-wave- potential of 0.78 V versus RHE. This work not only offers a new strategy for manipulating S and N doping features for the porous carbons derived from S-containing porous polymers, but also paves the way for the structure- performance interrelationship study of heteroatoms co- doped porous carbon for energy applications.
