Two-Dimensional Closed Conjugated Covalent Organic Polymers for Oxygen Reduction Reaction

Yang Li,Xiaohong Shao,Peng Peng,Feng Huo,Zhonghua Xiang

doi:10.3389/fmats.2019.00244

Abstract

Two-dimensional Covalent Organic Polymers (COPs) which are used to catalyze oxygen reduction reaction (ORR) in regenerative fuel cells have been researched by efforts. However, due to the lack of closed conjugated molecular structures, most pyrolysis-free COPs demonstrate limited catalytic performance. In this work, four alternative COPs containing different conjugated π-bonds are designed (termed as COP-Bn, n=3, 4, 5, 6) and studied based on Charge Density Analysis, Density of States (DOS), Band Structure Analysis, First-principle and Density Functional Theory (DFT) calculations towards catalyzing ORR. Our outcomes reveal that COPs with larger conjugated structures (e.g. COP-B5 and COP-B6) can achieve higher activity during ORR catalysis.

Highlights

Clean energy technologies, such as fuel cells and metal-air batteries, are promising alternative energy sources for auto industry and electronic products (Sealy, 2008; Dunn et al, 2011; Tachibana et al, 2012; Katsounaros et al, 2014; Kong et al, 2018; Li et al, 2018, 2019)
Density of States (DOS) and Band Structure analysis, we proved that covalent organic polymers (COPs)-B5 and COP-B6 were likely to be a proper COP model associated with oxygen reduction reaction (ORR) catalysis
The related free energy curve figures indicated that COP-B5 and COPB6 were the COP models which can catalyze ORR

Summary

Introduction

Clean energy technologies, such as fuel cells and metal-air batteries, are promising alternative energy sources for auto industry and electronic products (Sealy, 2008; Dunn et al, 2011; Tachibana et al, 2012; Katsounaros et al, 2014; Kong et al, 2018; Li et al, 2018, 2019). Nitrogen doped grapheme (Novoselov et al, 2004; Balandin et al, 2008; Lee et al, 2008; Park and Ruoff, 2009; Rao et al, 2009; Liang et al, 2011; Zhu et al, 2011; Yoo et al, 2012; Lung-Hao Hu et al, 2013) and two-dimensional covalent organic polymers (COPs) (Xiang and Cao, 2012, 2013; Xiang et al, 2012a,b; Zhou et al, 2013; Peng et al, 2017) have emerged with high activities for catalyzing ORR These carbon-based catalysts contain abundant sources and flexibility in molecular design, and demonstrate higher efficiency, stability, and tolerance to crossover/CO-poisoning effects than commercial platinum group metal (PGM) catalysts (Peng et al, 2019a,b).

Methods

Results

Conclusion