Two-Dimensional Covalent Organic Frameworks with Cobalt(II)-Phthalocyanine Sites for Efficient Electrocatalytic Carbon Dioxide Reduction

Abstract

The rapid development in synthesis methodology and applications for covalent organic frameworks (COFs) has been witnessed in recent years. However, the synthesis of highly stable functional COFs still remains a great challenge. Herein twodimensional polyimide-linked phthalocyanine COFs (denoted as CoPc-PI-COF-1 and CoPc-PI-COF-2) have been devised and prepared through the solvothermal reaction of the tetraanhydrides of 2, 3,9,10,16,17,23, with 1,4phenylenediamine and 4,4′-biphenyldiamine, respectively. The resultant CoPc-PI-COFs with a four-connected sql net exhibit AA stacking configurations according to powder X-ray diffraction studies, showing permanent porosity, thermal stability above 300 °C, and excellent resistance to a 12 M HCl aqueous solution for 20 days. Current−voltage curves reveal the conductivity of CoPc-PI-COF-1 and CoPc-PI-COF-2 with the value of 3.7 × 10 −3 and 1.6 × 10 −3 S m −1 , respectively. Due to the same Co(II) electroactive sites together with similar permanent porosity and CO 2 adsorption capacity for CoPc-PI-COFs, the cathodes made up of COFs and carbon black display a similar CO 2 -to-CO Faradaic efficiency of 87−97% at applied potentials between −0.60 and −0.90 V (vs RHE) in 0.5 M KHCO 3 solution. However, in comparison with the CoPc-PI-COF-2&carbon black electrode, the CoPc-PI-COF-1 counterpart provides a larger current density (j CO ) of −21.2 mA cm −2 at −0.90 V associated with its higher conductivity. This cathode also has a high turnover number and turnover frequency, amounting to 277 000 and 2.2 s −1 at −0.70 V during 40 h of measurement. The present result clearly discloses the great potential of 2D porous crystalline solids in electrocatalysis.

Electrochemiluminescence Enhanced by the Synergetic Effect of Porphyrin and Multi‐walled Carbon Nanotubes for Uric Acid Detection

“…The SEM images showed that ZnBCBTP@MWCNTs sample had tubular morphology, identical to that of the parent MWCNTs. Meanwhile, comparing to the pristine MWCNTs, ZnBCBTP@MWCNTs clearly presented that almost all MWCNTs are fully coated with ZnBCBTP due to their strong π-π interaction [24]. The results also were confirmed by the TEM images, Figure S1B.…”

Ionic Covalent Organic Frameworks for Energy Devices

“…[252,253] Many synthetic methods have been developed for the formation of 2D and 3D COFs, such as solvothermal, microwave, ionothermal, interfacial, and room-temperature methods. Solvothermal methods involve the reversible reaction of soluble monomers in a Pyrex tube of suitable volume at high temperatures (>100 °C), after degassing by multiple freeze-pump-thaw cycles, [254,255] whereas microwave methods are used to rapidly synthesize crystalline COFs within a short reaction time (<1 h). [256] An example of an ionothermal method is the synthesis of covalent triazine frameworks in molten ZnCl 2 (as the solvent), where the latter also mediates the required trimerization reaction, [257] whereas the interfacial method involves the synthesis of COFs as thin films at the interface of two immiscible solvents.…”

Covalent Organic Framework Based Functional Materials: Important Catalysts for Efficient CO2Utilization

“…b,c) Electrocatalytic performances of the samples. Reprinted with permission [35] . Copyright 2021 American Chemical Society.…”