Development of an interfacial osmosis diffusion method to prepare imine-based covalent organic polymer electrocatalysts for the oxygen evolution reaction

Herein, we report an interfacial osmosis diffusion strategy for sythesising a new covalent organic polymer (COP) at the solvent interface under room temperature ambient conditions. The feasibility of this new approach was first demonstrated by synthesizing a known covalent organic framework (COF) material, TpPa-1. Then, a novel imine-based COP named BEAB (BEA = bis-(2-ethynylaniline), BEB=bis (2-ethynylbenzaldehyde), BEA+BEB=BEAB) with precisely controlled distribution of nitrogen was prepared using the same method, after which Co, Fe and Ni transition metals were incorporated into the structure to form BEAB-metal complexes, which were then explored as electrocatalysts for the oxygen evolution reaction (OER). Among the various BEAB-metal complexes, BEAB-Co exhibited the best OER performance with a low overpotential of 320 mV at 10 mA cm(-2), a Tafel slope of 57 mV dec(-1) with only a small potential difference of 7 mV at 10 mA cm(-2) after 10 h of continuous electrolysis, indicating the excellent durability and structural integrity of the complex. These promising properties could be attributed to efficient charge transport on the conductive pi-conjugated polymeric chain, and the abundant N chelating sites on the BEAB. This work provides a facile and fast way to produce a COP in large quantities in an efficient manner, which would greatly benefit the large-scale practical application of these kinds of functional materials. (C) 2020 Elsevier Ltd. All rights reserved.