Shun Wan

Mesoporous graphene-like carbon sheet: high-power supercapacitor and outstanding catalyst support

Nowadays, continuous scientific endeavors are being directed toward low-cost, mild, scalable and reliable synthesis of graphene-based materials, in order to advance various graphene-related applications. So far, specific surface areas of current bulk graphene powders or graphene-like nanosheets are much lower than the theoretical value (2630 m2 g−1) of individual graphene, remaining a challenge for carbon chemists. Herein, mesoporous graphene-like carbon sheets with high specific surface area (up to 2607 m2 g−1) and high pore volume (up to 3.12 cm3 g−1) were synthesized by using polyimide chemistry in the molten salt “solvent.” In this process, abundant pyromellitic dianhydride and aromatic diamine undergo polycondensation together with further carbonization in molten KCl–ZnCl2, in which in situ formed linear aromatic polyimide with a sp2 hybridized carbon skeleton could be directly coupled and rearranged into a two-dimensional graphene-like nanosheet around the “salt scaffold”. Carbon nanosheets with well-defined mesopores (∼3.5 nm) could be easily obtained by washing salt melts in water, while the salts could be recovered and reused for the subsequent reaction. The nitrogen atoms in amine also afforded the resulting carbon with uniform foreign atoms (nitrogen content = ∼6%). Moreover, holey carbon sheets with well-dispersed and through-plane nanoholes (diameter: 5–10 nm) could be constructed by using different monomers. Being a potential electrode material in supercapacitors, the as-made carbon nanosheet possessed a significant specific capacitance (131.4–275.5 F g−1) even at a scan rate of 2000 mV s−1. Additionally, powerful nanohybrids of carbon sheet–Co3O4 were also prepared with good performance in the aerobic oxidation of alcohols and amines to aldehydes and imines, respectively.

Porous Liquids: A Promising Class of Media for Gas Separation

A porous liquid containing empty cavities has been successfully fabricated by surface engineering of hollow structures with suitable corona and canopy species. By taking advantage of the liquid-like polymeric matrices as a separation medium and the empty cavities as gas transport pathway, this unique porous liquid can function as a promising candidate for gas separation. Moreover, such a facile synthetic strategy can be further extended to the fabrication of other types of nanostructure-based porous liquid, opening up new opportunities for preparation of porous liquids with attractive properties for specific tasks.

Advancing polymers of intrinsic microporosity by mechanochemistry

Herein, we report a fast (15 min) and solvent-free mechanochemical approach to construct polymers of intrinsic microporosity (PIMs) with high molecular mass and low polydispersity by solid grinding. The enhanced reaction efficiency results from the instantaneous frictional heating and continuous exposure of active sites within those solid reactants.

Charged Porous Polymers using a Solid CO Cross‐Coupling Reaction

Herein, we report a green, fast, efficient mechanochemical strategy for charged porous polymers (CPPs). A cationic CPP with basic anions and an anionic CPP with Li(+) cations were fabricated by solid grinding under solvent-free conditions. Compared with solution-based synthesis, mechanochemical grinding can shorten the reaction time from dozens of hours to several minutes (60-90 min) to form polymers possessing a high molecular mass and low polydispersity. During the construction of CPPs, a Pd-catalyzed solid polycondensation based on unactivated organic linkers was introduced. In particular, CPPs with basic phenolic or proline anions showed good activity and stability in SO2 capture, and Li(+) -functionalized CPPs can be post-modified to CPPs with other metal ions by ion exchange, highlighting the tailorable feature of ionic-modified CPPs.

New promising lithium malonatoborate salts for high voltage lithium ion batteries

Three new lithium salts, lithium difluoro-2-methyl-2-fluoromalonatoborate (LiDFMFMB), lithium difluoro-2-ethyl-2-fluoromalonatoborate (LiDFEFMB), and lithium difluoro-2-propyl-2-fluoromalonatoborate (LiDFPFMB), have been synthesized and evaluated for application in lithium ion batteries. These new salts are soluble in a mixture of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) (1 : 2 by wt) and 1.0 M salt solutions can be easily prepared. The ionic conductivities of these new salts are close to those of LiBF4 and LiPF6. Cyclic voltammograms reveal that these new salt based electrolytes can passivate both natural graphite and high voltage spinel LiNi0.5Mn1.5O4 (LNMO) to form effective solid electrolyte interphases (SEIs). In addition, these new salt-based electrolytes exhibit good cycling stability with high coulombic efficiencies in both LiNi0.5Mn1.5O4 and graphite based half-cells and full cells.

Coordination-supported organic polymers: mesoporous inorganic–organic materials with preferred stability

A simple and versatile strategy, borrowing ideas from the chemistry of MOFs and COFs, is developed for the synthesis of coordination-supported organic polymers (COPs) via coordination between Al3+ and 5-amino-8-hydroxyquinoline together with organic imine- or imide-based polycondensation. The COPs with high surface areas (up to 1123 m2 g−1) and abundant mesopores (2.5 nm or 14 nm) possess good crystalline and porous structure after being soaked in boiling water.

Correction: New promising lithium malonatoborate salts for high voltage lithium ion batteries

Correction for ‘New promising lithium malonatoborate salts for high voltage lithium ion batteries’ by Xiao-Guang Sun et al., J. Mater. Chem. A, 2017, 5, 1233–1241.