RESUMO
Conductive and porous nitrogen-rich materials have great potential as supercapacitor electrode materials. The exceptional efficiency of such compounds, however, is dependent on their larger surface area and the level of nitrogen doping. To address these issues, we synthesized a porous covalent triazine framework (An-CTFs) based on 9,10-dicyanoanthracene (An-CN) units through an ionothermal reaction in the presence of different molar ratios of molten zinc chloride (ZnCl2) at 400 and 500 °C, yielding An-CTF-10-400, An-CTF-20-400, An-CTF-10-500, and An-CTF-20-500 microporous materials. According to N2 adsorption-desorption analyses (BET), these An-CTFs produced exceptionally high specific surface areas ranging from 406-751 m2·g-1. Furthermore, An-CTF-10-500 had a capacitance of 589 F·g-1, remarkable cycle stability up to 5000 cycles, up to 95% capacity retention, and strong CO2 adsorption capacity up to 5.65 mmol·g-1 at 273 K. As a result, our An-CTFs are a good alternative for both electrochemical energy storage and CO2 uptake.
Assuntos
Estruturas Metalorgânicas , Triazinas , Adsorção , Antracenos , Dióxido de Carbono/química , Nitrogênio/química , Triazinas/químicaRESUMO
In recent years, conjugated microporous polymers (CMPs) have become important precursors for environmental and energy applications, compared with inorganic electrode materials, due to their ease of preparation, facile charge storage process, π-conjugated structures, relatively high thermal and chemical stability, abundance in nature, and high surface areas. Therefore, in this study, we designed and prepared new benzobisthiadiazole (BBT)-linked CMPs (BBT-CMPs) using a simple Sonogashira couplings reaction by reaction of 4,8-dibromobenzo(1,2-c;4,5-c')bis(1,2,5)thiadiazole (BBT-Br2) with ethynyl derivatives of triphenylamine (TPA-T), pyrene (Py-T), and tetraphenylethene (TPE-T), respectively, to afford TPA-BBT-CMP, Py-BBT-CMP, and TPE-BBT-CMP. The chemical structure and properties of BBT-CMPs such as surface areas, pore size, surface morphologies, and thermal stability using different measurements were discussed in detail. Among the studied BBT-CMPs, we revealed that TPE-BBT-CMP displayed high degradation temperature, up to 340 °C, with high char yield and regular, aggregated sphere based on thermogravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. Furthermore, the Py-BBT-CMP as organic electrode showed an outstanding specific capacitance of 228 F g-1 and superior capacitance stability of 93.2% (over 2000 cycles). Based on theoretical results, an important role of BBT-CMPs, due to their electronic structure, was revealed to be enhancing the charge storage. Furthermore, all three CMP polymers featured a high conjugation system, leading to improved electron conduction and small bandgaps.
Assuntos
Polímeros , Pirenos , Eletrodos , Elétrons , Polímeros/químicaRESUMO
In this study we investigated the synergistic effects of the chirality (molecular structure) and surface morphology (nanostructure) of a newly designed sensing platform for the stereoselective recognition of biomolecules. We synthesized 3,4-ethylenedioxythiophene monomers presenting an OH functional group on the side chain (EDOT-OH) with either R or S chirality and then electropolymerized them in a template-free manner to engineer poly(EDOT-OH) nanotubes and smooth films with R or S chirality. We used a quartz crystal microbalance (QCM) to examine the differential binding of fetal bovine serum, RGD peptide, insulin, and (R)- and (S)-mandelic acid (MA) on these chiral polymeric platforms. All of these biomolecules bound stereoselectively and with greater affinity toward the nanotubes than to the smooth films. The sensitive chiral recognition of (S)- and (R)-MA on the (R)-poly(EDOT-OH) nanotube surface occurred with the highest chiral discrepancy ratio of 1.80. In vitro experiments revealed a greater degree of protein deposition from MCF-7 cells on the chiral nanotube surfaces. We employed ab initio molecular dynamics simulations and density functional theory calculations to investigate the mechanism underlying the sensitive chiral recognition between the chiral sensing platforms and the chiral analyte molecules.
Assuntos
Biopolímeros , Compostos Bicíclicos Heterocíclicos com Pontes , Simulação por Computador , Técnicas de Microbalança de Cristal de QuartzoRESUMO
There is currently a pursuit of synthetic approaches for designing porous carbon materials with selective CO2 capture and/or excellent energy storage performance that significantly impacts the environment and the sustainable development of circular economy. In this study we prepared a new bio-based benzoxazine (AP-BZ) in high yield through Mannich condensation of apigenin, a naturally occurring phenol, with 4-bromoaniline and paraformaldehyde. We then prepared a PA-BZ porous organic polymer (POP) through Sonogashira coupling of AP-BZ with 1,3,6,8-tetraethynylpyrene (P-T) in the presence of Pd(PPh3)4. In situ Fourier transform infrared spectroscopy and differential scanning calorimetry revealed details of the thermal polymerization of the oxazine rings in the AP-BZ monomer and in the PA-BZ POP. Next, we prepared a microporous carbon/metal composite (PCMC) in three steps: Sonogashira coupling of AP-BZ with P-T in the presence of a zeolitic imidazolate framework (ZIF-67) as a directing hard template, affording a PA-BZ POP/ZIF-67 composite; etching in acetic acid; and pyrolysis of the resulting PA-BZ POP/metal composite at 500 °C. Powder X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy, and Brunauer-Emmett-Teller (BET) measurements revealed the properties of the as-prepared PCMC. The PCMC material exhibited outstanding thermal stability (Td10 = 660 °C and char yield = 75 wt%), a high BET surface area (1110 m2 g-1), high CO2 adsorption (5.40 mmol g-1 at 273 K), excellent capacitance (735 F g-1), and a capacitance retention of up to 95% after 2000 galvanostatic charge-discharge (GCD) cycles; these characteristics were excellent when compared with those of the corresponding microporous carbon (MPC) prepared through pyrolysis of the PA-BZ POP precursors with a ZIF-67 template at 500 °C.
Assuntos
Benzoxazinas/química , Dióxido de Carbono/química , Carbono/química , Metais/química , Adsorção , Benzoxazinas/síntese química , Varredura Diferencial de Calorimetria , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Eletricidade , Eletroquímica , Nitrogênio/química , Polímeros/química , Porosidade , Espectroscopia de Prótons por Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura , Termogravimetria , Difração de Raios XRESUMO
In this study, we used effective and one-pot Heck coupling reactions under moderate reaction conditions to construct two new hybrid porous polymers (named OVS-P-TPA and OVS-P-F HPPs) with high yield, based on silsesquioxane cage nanoparticles through the reaction of octavinylsilsesquioxane (OVS) with different brominated pyrene (P-Br4), triphenylamine (TPA-Br3), and fluorene (F-Br2) as co-monomer units. The successful syntheses of both OVS-HPPs were tested using various instruments, such as X-ray photoelectron (XPS), solid-state 13C NMR, and Fourier transform infrared spectroscopy (FTIR) analyses. All spectroscopic data confirmed the successful incorporation and linkage of P, TPA, and F units into the POSS cage in order to form porous OVS-HPP materials. In addition, the thermogravimetric analysis (TGA) and N2 adsorption analyses revealed the thermal stabilities of OVS-P-F HPP (Td10 = 444 °C; char yield: 79 wt%), with a significant specific surface area of 375 m2 g-1 and a large pore volume of 0.69 cm3 g-1. According to electrochemical three-electrode performance, the OVS-P-F HPP precursor displayed superior capacitances of 292 F g-1 with a capacity retention of 99.8% compared to OVS-P-TPA HPP material. Interestingly, the OVS-P-TPA HPP showed a promising HER value of 701.9 µmol g-1 h-1, which is more than 12 times higher than that of OVS-P-F HPP (56.6 µmol g-1 h-1), based on photocatalytic experimental results.
RESUMO
In this study, we prepared a series of conjugated microporous polymers (CMPs) through Sonogashira-Hagihara cross-couplings of a tetrabenzonaphthalene (TBN) monomer with pyrene (Py), tetraphenylethylene (TPE), and carbazole (Car) units and examined their chemical structures, thermal stabilities, morphologies, crystallinities, and porosities. TBN-TPE-CMP possessed a high surface area (1150 m2 g-1) and thermal stability (Td10 = 505 °C; char yield = 68 wt %) superior to those of TBN-Py-CMP and TBN-Car-CMP. To improve the conductivity of the TBN-CMP materials, we blended them with highly conductive single-walled carbon nanotubes (SWCNTs). Electrochemical measurements revealed that the TBN-Py-CMP/SWCNT nanocomposite had high capacitance (430 F g-1) at a current density of 0.5 A g-1 and outstanding capacitance retention (99.18%) over 2000 cycles; these characteristics were superior to those of the TBN-TPE-CMP/SWCNT and TBN-Car-CMP/SWCNT nanocomposites.
RESUMO
In this study we synthesized two tetraphenyl-p-phenylenediamine-based covalent organic frameworks (TPPDA-TPPyr and TPPDA-TPTPE COFs) for potential use in high-performance electrochemical supercapacitors. This excellent performance arose from their structures containing redox-active triphenylamine derivatives and their high surface areas.
RESUMO
In this paper we report the construction of a hollow microtubular triazine- and benzobisoxazole-based covalent organic framework (COF) presenting a sponge-like shell through a template-free [3+2] condensation of the planar molecules 2,4,6-tris(4-formylphenyl)triazine (TPT-3CHO) and 2,5-diaminohydroquinone dihydrochloride (DAHQ-2HCl). The synthesized COF exhibited extremely high crystallinity, a high surface area (ca. 1855â m2 g-1 ), and ultrahigh thermal stability. Interestingly, a time-dependent study of the formation of the hollow microtubular COF having a sponge-like shell revealed a transformation from initial ribbon-like crystallites into a hollow tubular structure, and confirmed that the hollow nature of the synthesized COF was controlled by inside-out Ostwald ripening, while the non-interaction of the crystallites on the outer surface was responsible for the sponge-like surface of the tubules. This COF exhibited significant supercapacitor performance: a high specific capacitance of 256â F g-1 at a current density of 0.5â A g-1 , excellent cycling stability (98.8 % capacitance retention over 1850â cycles), and a high energy density of 43â Wh kg-1 . Such hollow structural COFs with sponge-like shells appear to have great potential for use as high-performance supercapacitors in energy storage applications.