Proton conductance and mechanism of the synthesized two Co(II)-CPs/Nafion composite membranes based on N-heterocyclic carboxylic acid-based ligand

Abstract

In this study, we synthesized two CPs, [Co(L)·H2O]n (1) and {[Co(L)·H2O](dpa)0.5}n (2) [H2L = 4,4'-(2,6-pyrazinediyl)dibenzoic acid, dpa = (E)-4-(2-(pyridin-4-yl)vinyl)pyridine] by a hydrothermal method. The materials were characterized by single-crystal X-ray diffraction (XRD), powder X-ray diffraction (PXRD), infrared (IR) spectroscopy, and elemental analysis. The conductivities and activation energies of 1–2/Nafion and pure Nafion were tested and calculated by electrochemical testing methods such as CV and EIS, respectively. The results show that compared with pure Nafion, the doping of CPs with Nafion leads to a certain degree of increase in the proton conductivity of the composite membranes, and in addition, the conductivity of 2 is better than that of 1. We have also analyzed the proton transport paths in the internal structure of 1–2 by simulation through theoretical calculations, which provides a platform for the study of the proton conductivity mechanism of the materials, and then provides ideas for designing different high-performance PEM materials.