Facile method to synthesize conjugated poly (1,4-phenyldiimine) porphyrin cobalt with “electron–pump” for enhancing bifunctional catalytic oxygen reaction performance
image: Methylene alcohol terminated poly (1,4-phenyldiimine) porphyrin cobalt (M-PImPorCo), with high thermal and chemical stability, was synthesized by RuCl3 catalyzed redox reaction of TNO2PorCo and 1, 4-phenyldimethanol. The electron cloud of electron-rich 3D-G and —CH2—OH edge groups are absorbed by C=N and transferred to the Co-N4 site as an "electron pump" synergetic relationship, which enhances the bifunction oxygen performance of M-PImPorCo/3D-G.
Credit: Nano Research, Tsinghua University Press
Clean energy technologies, like fuel cells and overall water splitting (OWS), are vital for tackling the energy crisis and advancing sustainability. Their performance relies on two slow reactions: oxygen reduction (ORR) in fuel cell cathodes and oxygen evolution (OER) in OWS anodes, which limit efficiency and real-world use. Current commercial catalysts, Pt-based for ORR and Ru/Ir-based for OER, are costly and scarce, blocking large-scale deployment. Metalloporphyrins (PorM), natural ORR catalysts, offer promise but require high-temperature activation, causing decomposition into metal-nitrogen-carbon clusters (M-N-Cs). This reduces metal utilization, obscures active sites, and harms stability. To address this issue, Prof. Zhongfang Li’s team (Shandong University of Technology) provides linking metalloporphyrins into fully conjugated covalent organic frameworks (COFs) with sp2 bonds to be fully conjugated COFs.
The team published their work in Nano Research on November 4, 2025.
"To solve issues such as poor thermal stability in porphyrin complex-based COFs catalysts with monocyclic or non-fully conjugated structures, a series of COFs (M-PImPorCo, N-M-PImPorCo, and N-PImPorCo) linked by Schiff base groups and modified with different edge substituents were synthesized via a redox reaction between meso-5,10,15,20-tetrakis(4-nitrophenyl) porphyrin cobalt and 1,4-benzenedimethanol, catalyzed by RuCl3. PImPorCo exhibits no weight loss below 610°C. The catalyst PImPorCo/3D-G was obtained by anchoring PImPorCo onto the surface of three-dimensional graphene (3D-G) followed by activation at 600 °C. Experimental results demonstrate that PImPorCo within the catalyst remains undecomposed and stacked, laying nearly monolayered on the 3D-G surface, with strong π-π interactions formed between PImPorCo and 3D-G. For ORR, PImPorCo/3D-G achieves a half-wave potential (E1/2) of 0.91 V vs. RHE, while for OER catalysis, it shows an overpotential (η10) of 260 mV, resulting in a bifunctional overpotential (△E) of 0.58 V for oxygen reactions. The catalytic activity order for oxygen reactions follows: PImPorCo/3D-G>N-M-PImPorCo/3D-G>N-PImPorCo/3D-G, indicating that electron-donating groups are beneficial for enhancing the catalytic performance in oxygen reactions. A liquid zinc-air battery (L-ZABs) assembled with PImPorCo/3D-G delivers a peak power density (Pmax) of 278.8 mW cm-2. Density functional theory (DFT) calculations reveal that the electron-withdrawing -C=N- group can attract electron clouds from the electron-donating -CH2OH groups at the edges to the Co-N4 active sites. Additionally, -C=N- can optimize the protonation process of oxygen reaction intermediates, and the D-π-A structure (donor-π-acceptor structure) contributes to the enhanced catalytic performance of PImPorCo/3D-G." said Prof. Zhongfang Li, the corresponding author of the work, professor at Shandong University of Technology.
This work provides a new idea for the synthesis of Schiff-base porphyrin-based COF catalysts and promotes their application in oxygen reaction catalytic energy storage devices, expecting to advance the development of efficient and low-cost energy conversion technologies.
Other contributors include Yinggang Sun, Peng Sun, Jigang Wang, Yanqiong Zhuang, Likai Wang, and Ang Li from the school of chemistry and chemical engineering, Shandong University of Technology.
This work was financially supported by the National Natural Science Foundation of China (Grant Nos. 22172093 and 21776167) and the Natural Science Foundation of Shandong Province, China (Grant No. ZR2023MB061).
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.