Yaozu Liao

Conjugated microporous polytriphenylamine networks

Conjugated microporous polytriphenylamine networks with surface areas of 530 m(2) g(-1) were synthesized via Buchwald-Hartwig coupling, resulting in high CO2 uptake (up to 6.5 wt%) and CO2-N2 selectivity (75) at 1 bar and 303 K.

Nitrogen-Rich Conjugated Microporous Polymers: Facile Synthesis, Efficient Gas Storage, and Heterogeneous Catalysis

Nitrogen-rich conjugated microporous polymers (NCMPs) have attracted great attention in recent years owing to their polarity, basicity, and ability to coordinate metal ions. Herein, three NCMPs, structurally close to polyaniline, were facilely synthesized via chemical oxidative polymerization between multiconnected aniline precursors. The NCMPs with high N content (11.84 wt %), intrinsic ultramicroporosity (<1 nm), and moderate surface area (485 m2 g-1) show wide-ranging adsorption functionality, e.g., CO2 uptake (11 wt %) and CO2-selectivity over N2 (360, 1 bar), 1.0 wt % H2 storage, as well as 215 wt % iodine vapor uptake at ambient pressure. Moreover, these NCMPs act as support for palladium catalysts and can maintain >94% activity in Suzuki-Miyaura coupling reactions after six continuous runs.

Efficient Supercapacitor Energy Storage Using Conjugated Microporous Polymer Networks Synthesized from Buchwald–Hartwig Coupling

Supercapacitors have received increasing interest as energy storage devices due to their rapid charge-discharge rates, high power densities, and high durability. In this work, novel conjugated microporous polymer (CMP) networks are presented for supercapacitor energy storage, namely 3D polyaminoanthraquinone (PAQ) networks synthesized via Buchwald-Hartwig coupling between 2,6-diaminoanthraquinone and aryl bromides. PAQs exhibit surface areas up to 600 m2 g-1 , good dispersibility in polar solvents, and can be processed to flexible electrodes. The PAQs exhibit a three-electrode specific capacitance of 576 F g-1 in 0.5 m H2 SO4 at a current of 1 A g-1 retaining 80-85% capacitances and nearly 100% Coulombic efficiencies (95-98%) upon 6000 cycles at a current density of 2 A g-1 . Asymmetric two-electrode supercapacitors assembled by PAQs show a capacitance of 168 F g-1 of total electrode materials, an energy density of 60 Wh kg-1 at a power density of 1300 W kg-1 , and a wide working potential window (0-1.6 V). The asymmetric supercapacitors show Coulombic efficiencies up to 97% and can retain 95.5% of initial capacitance undergo 2000 cycles. This work thus presents novel promising CMP networks for charge energy storage.

Macrocyclic amine-linked oligocarbazole hollow microspheres: facile synthesis and efficient lead sorbents.

Novel macrocyclic amine-linked oligocarbazole hollow microspheres are synthesized via a one-step oxidative method in aqueous solution. Upon altering the oxidants and acidic media, the average diameters of the obtained hollow microspheres are tunable from 0.23 to 2.0 μm. With attractive amine and carbazole functionalities, exposed surface area, thermostability, and photoluminescent properties, the amine-linked oligocarbazole hollow microspheres are directly assembled to yield heavy metal sorbents with excellent selectivity and recyclability, shown to efficiently remove lead from contaminated water.

Targeted control over the porosities and functionalities of conjugated microporous polycarbazole networks for CO2-selective capture and H2 storage

We report a conjugated microporous polycarbazole network and its pyridine-, bipyridine-, and cyano-functionalized networks exhibiting large surface area (1126 m2 g−1), isosteric heat of CO2 adsorption (∼32 kJ mol−1), and CO2-uptake capacity (14 wt% at 1 bar and 273 K). IAST calculations using single-component-isotherms reveal that the functionalized polycarbazole networks have a very high CO2 selectivity over N2 (164) under ambient conditions. These porous networks also possess moderate H2 storage capacity (1.35 wt% at 1 bar and 77 K) and high isosteric heat of H2 adsorption (10.3 kJ mol−1). Our finding provides a new targeted route to control the porosities and functionalities of microporous polymers for efficient gas uptake.

Cobalt Nanocrystals Encapsulated in Heteroatom-Rich Porous Carbons Derived from Conjugated Microporous Polymers for Efficient Electrocatalytic Hydrogen Evolution

Cobalt nanocrystals encapsulated in N,O-dual-doped porous carbons as efficient and stable electrocatalysts for hydrogen evolution reaction (HER) are reported. A heteroatom-rich-conjugated microporous polymer is first chemically deposited on a carbon fiber cloth, and after addition of a cobalt salt, pyrolyzed to produce a heteroatom-doped C/Co nanocrystal composite. With this process, the use of additional binders for preparation of electrodes can be avoided. With a trace cobalt loading (0.46 wt%), the electrodes achieve a low Tafel slope of 46 mV dec-1 and overpotential of only 69 mV at a current density of 10 mA cm-2 in 0.5 m H2 SO4 . Experimental and computational studies reveal that the superior HER behavior is due to a decreased free energy of hydrogen adsorption, induced by i) electrons transferred from the cobalt nanocrystals to graphite layers and ii) N,O-dual doping reduced the Fermi level of neighboring C atoms.