Yanli Chen

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 two-dimensional 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 2,3,9,10,16,17,23,24-octacarboxyphthalocyaninato cobalt(II) with 1,4-phenylenediamine 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 CO2 adsorption capacity for CoPc-PI-COFs, the cathodes made up of COFs and carbon black display a similar CO2-to-CO Faradaic efficiency of 87–97% at applied potentials between −0.60 and −0.90 V (vs RHE) in 0.5 M KHCO3 solution. However, in comparison with the CoPc-PI-COF-2&carbon black electrode, the CoPc-PI-COF-1 counterpart provides a larger current density (jCO) 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.

LB films of three amphiphilic tris(phthalocyaninato) rare earth triple-decker complexes with crown-ethers as hydrophilic heads and long alkyl chains as hydrophobic tails have been prepared and found to display very well ordered layer structures, as proved by π−A isotherms, UV−vis and polarized absorption spectra, X-ray diffraction experiments, and microscopic morphology characterization. These LB films have been fabricated into field-effect transistor (FET) devices, which show carrier mobilities as high as 0.24−0.60 cm2 V-1 s-1, among the highest mobilities achieved thus far for all LB film-based OFETs.

A green strategy has been developed for synthesizing nitrogen-doped carbon dots (N-CDs) via hydrothermal treatment of willow leaves. The supernatant exhibits strong blue fluorescence under UV radiation and can be directly used as a fluorescent ink, while the solid product with pyrolysis possesses excellent electrocatalytic activity for a highly efficient oxygen reduction reaction with great stability and methanol/CO tolerance superior to a commercial Pt/C catalyst.