CHEMICAL SCIENCE

The latest research results of oxygen reduction are the high-efficiency electrocatalysis of in-situ construction of Fe3N/FeCo hybrid carbon materials by porous nanospheres


On August 23, 2022, Nano Research Energy, a high-starting energy journal hosted by Tsinghua Universityhttps://www.sciopen.com/journal/2790-8119The Young Editorial Board, Associate Professor Liu Yijiang of Xiangtan University, published a research group entitled “Metal-coordinated porous polydopamine nanospheres derived Fe3N-FeCo encapsulated N-doped carbon as a highly efficient electrocatalyst for oxygen reduction.” reaction”.

Figure 1. (a) Schematic diagram of the preparation of Fe3N-FeCo@NC; TEM (b) and HRTEM (c) photos of Fe3N-FeCo@NC; LSV curve of Fe3N-FeCo@NC (d); Power density of zinc-air batteries based on Fe3N-FeCo@NC (e).

The oxygen reduction reaction (ORR) is an important semi-reaction of a metal-air battery, but the reaction kinetics is slow. Pt-based catalysts can effectively improve ORR kinetics, but there are problems such as low stability, shortage of resources, and high prices, which limit the commercial application of metal-air batteries. Therefore, the development of non-precious metal ORR catalysts is crucial. Among the various non-precious metal catalysts that have been developed, metal nitride-doped carbon materials (MNx-C) are considered to be the most likely to replace Pt-based catalysts because of their high conductivity, excellent oxygen reduction catalytic activity and economic applicability. Among them, the carbon material (Fe3N-C) modified by iron nitride (Fe3N) has an ORR catalytic activity comparable to Pt/C. However, the formation of Fe3N particles usually requires high-temperature ammonization, which not only increases the cost of preparation but also poses a safety hazard. How to prepare Fe3N nanoparticle modified carbon materials by non-high temperature ammonization methods and significantly improve their ORR catalytic activity has become a new concern.

Therefore, Liu Yijiang’s research group proposed a simple and effective method for in situ preparation of Fe3N and FeCo nanoparticle modified hybrid carbon materials for efficient oxygen reduction catalytic reactions. First, porous polypamine metal nanospheres (such as Fe-PDA@Co) were prepared by emulsion assembly and self-polymerization, and then the polydopamine, metal and melamine interaction were used to coat the surface of the polydopamine metal nanospheres with melamine to obtain Fe-PDA@Co@melamine complexes, and finally Fe3N and FeCo modified porous carbon bulbs and carbon nanosheets coexisted by high temperature pyrolysis, and the hybrid carbon material Fe3N-FeCo@NC was obtained. In this work, Fe3N nanoparticles can be formed in situ without high-temperature ammonization, mainly due to the strategy of combining emulsion assembly and self-polymerization, so that iron is evenly dispersed in polydopamine porous balls, and melamine also interacts with iron, so no additional high-temperature ammonization is required. Fe3N-FeCo@NC has a large specific surface area and multi-stage pore structure, and has active species such as Fe3N, FeCo, M-Nx, etc., so it has excellent oxygen reduction electrocatalytic activity. In the 0.1M KOH medium, the starting potential of Fe3N-FeCo@NC is 1.05 V, the half-wave potential is 0.89 V, exceeding the starting potential of Pt/C (0.97 V) and half-wave potential (0.85 V), and also far exceeding the reference samples Fe/NC (precursors do not contain Co and melamine) and Fe, Co/NC (precursor does not contain melamine), which is one of the highest values of the ORR performance of MNx-C materials. In addition, the stability and methanol resistance of Fe3N-FeCo@NC also far exceed Pt/C. Zinc-air batteries based on Fe3N-FeCo@NC as air cathodes have an open-circuit voltage of 1.50 V, a power density of 141 mW·cm−2, and a specific capacity of 806.6 mAh·g−1Zn, which is significantly higher than that of Pt/C assembled batteries (open-circuit voltage of 1.48 V, power density of 113 mW·cm−2, specific capacity of 660.6 mAh·g−1Zn). At the same time, zinc-air batteries based on Fe3N-FeCo@NC have excellent magnification performance and stability. The above results show that Fe3N-FeCo@NC is an efficient and stable ORR electrocatalyst, which is conducive to promoting the practical application of zinc-air batteries.

Related paper information:

F. Guo, M. Zhang, S. Yi, et al. Metal-coordinated porous polydopamine nanospheres derived Fe3N-FeCo encapsulated N-doped carbon as a highly efficient electrocatalyst for oxygen reduction reaction. Nano Research Energy 2022, 1: e9120027. DOI: 10.26599/NRE.2022.9120027.

https://doi.org/10.26599/NRE.2022.9120027

As a sister journal of Nano Research, Nano Research Energy (ISSN: 2791-0091; e-ISSN: 2790-8119; Official website: https://www.sciopen.com/journal/2790-8119It was launched in March 2022 and is co-edited by Professor Qu Liangti of Tsinghua University and Professor Chunyi Zhi of the City University of Hong Kong. Nano Research Energy is an international multidisciplinary, all-English open access journal, focusing on the cutting-edge research and application of nanomaterials and nanoscience technology in new energy-related fields, benchmarking against the top international energy journals, and committed to publishing high-level original research and review papers. Before 2023, the APC fee will be waived, and all teachers are welcome to submit articles. Please contact: NanoResearchEnergy@tup.tsinghua.edu.cn.

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