Edge-substituents and center metal optimization boosting oxygen electrocatalysis in porphyrin-based covalent organic polymers

Hongyan Zhuo; Qiming Ye; Shaoze Wang; Han Yu; Tianle Yang; Binghan Jiang; Chuangyu Wei; Linlin Feng; Tenglong Jin; Xue Liu; Zhuang Shi; Hao Song; Zhen Fu; Wenmiao Chen; Yuexing Zhang; Yanli Chen

doi:10.1016/j.jcis.2024.11.109

Edge-substituents and center metal optimization boosting oxygen electrocatalysis in porphyrin-based covalent organic polymers

J Colloid Interface Sci. 2024 Nov 16;680(Pt B):137-145. doi: 10.1016/j.jcis.2024.11.109. Online ahead of print.

Authors

Hongyan Zhuo¹, Qiming Ye¹, Shaoze Wang¹, Han Yu¹, Tianle Yang¹, Binghan Jiang¹, Chuangyu Wei¹, Linlin Feng¹, Tenglong Jin¹, Xue Liu¹, Zhuang Shi¹, Hao Song¹, Zhen Fu¹, Wenmiao Chen², Yuexing Zhang³, Yanli Chen⁴

Affiliations

¹ School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, PR China.
² School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, PR China. Electronic address: wmchen@upc.edu.cn.
³ College of Chemistry and Chemical Engineering, Dezhou University, Dezhou 253023, PR China. Electronic address: zhangyuexing@sdu.edu.cn.
⁴ School of Materials Science and Engineering, China University of Petroleum (East China), Qingdao 266580, PR China. Electronic address: yanlichen@upc.edu.cn.

PMID: 39561641
DOI: 10.1016/j.jcis.2024.11.109

Abstract

The promising non-noble electrocatalyst with well-defined structure is significant for both oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) for the renewable energy devices like zinc-air batteries (ZABs). Herein, the four phenyl-linked cobaltporphyrin-based covalent organic polymers (COPs-1-4) with the different edge substituents (1 = -tBu, 2 = -Me, 3 = -F, and 4 = -CF₃) are firstly designed and synthesized via a simple, efficient one-pot method. With the increase of electron donating capacity of the substituents, the highest occupied molecular orbital energy (E_HOMO) gradually increases in the order of COP-4 < COP-3 < COP-2 < COP-1. Consequently, the optimal COP-1 with -tBu edge groups exhibits the highest half-wave potential (E_1/2) of 0.84 V (vs. RHE) among the four COPs, which is comparable with commercial Pt/C in alkaline media. The DFT calculations further reveal that with strong electron donating capacity, the Gibbs free energy decreases in the order of COP-4 > COP-3 > COP-2 > COP-1 by modulating the adsorption energy of OOH* at rate-determining step (RDS) to promote ORR activity. Furthermore, introducing Ni (II) and Co (II) into porphyrin centers afford the bimetallic CoNi-COP-1 with both Co-N₄, Ni-N₄ active sites and edge substituted -tBu. The synergistic effect of Co, Ni bimetallic active sites and strong electron-donating -tBu substituents renders the CoNi-COP-1 the highest HOMO and smallest energy gap between the E_LUMO and E_F among the as-prepared five COPs, which leads to more filling electrons of its LUMO level, and thus exhibits the excellent ORR and OER bifunctional catalytic activities with an E_1/2 as high as 0.85 V and an overpotential (η) of 0.34 V at 10 mA cm^-2 in alkaline media, superior to monometallic Co-containing COPs-1-4. In particular, the assembled ZABs with bifunctional catalyst CoNi-COP-1 possesses high power density (94.10 mW cm^-2), high specific capacity (841.71 mAh g_Zn^-1) and long durability of over 160,000 s. This work exemplifies the rational design of pyrolysis-free non-noble metal COP-based electrocatalyst through optimizing the intrinsic metal center and its secondary coordination environment.

Keywords: Covalent organic polymers; Oxygen reduction reaction; Porphyrin; Zinc-air battery.