Fe-Cluster Pushing Electrons to N-Doped Graphitic Layers with Fe3C(Fe) Hybrid Nanostructure to Enhance O2 Reduction Catalysis of Zn-Air Batteries

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• 作者：Jie Yang ; Jiangtao Hu ; Mouyi Weng ; Rui Tan ; Leilei Tian ; Jinlong Yang ; Joseph Amine ; Jiaxin Zheng ; Haibiao Chen ; Feng Pan
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2017
• 出版时间：February 8, 2017
• 年：2017
• 卷：9
• 期：5
• 页码：4587-4596
• 全文大小：766K
• ISSN：1944-8252

文摘

Non-noble metal catalysts with catalytic activity toward oxygen reduction reaction (ORR) comparable or even superior to that of Pt/C are extremely important for the wide application of metal–air batteries and fuel cells. Here, we develop a simple and controllable strategy to synthesize Fe-cluster embedded in Fe₃C nanoparticles (designated as Fe₃C(Fe)) encased in nitrogen-doped graphitic layers (NDGLs) with graphitic shells as a novel hybrid nanostructure as an effective ORR catalyst by directly pyrolyzing a mixture of Prussian blue (PB) and glucose. The pyrolysis temperature was found to be the key parameter for obtaining a stable Fe₃C(Fe)@NDGL core–shell nanostructure with an optimized content of nitrogen. The optimized Fe₃C(Fe)@NDGL catalyst showed high catalytic performance of ORR comparable to that of the Pt/C (20 wt %) catalyst and better stability than that of the Pt/C catalyst in alkaline electrolyte. According to the experimental results and first principle calculation, the high activity of the Fe₃C(Fe)@NDGL catalyst can be ascribed to the synergistic effect of an adequate content of nitrogen doping in graphitic carbon shells and Fe-cluster pushing electrons to NDGL. A zinc–air battery utilizing the Fe₃C(Fe)@NDGL catalyst demonstrated a maximum power density of 186 mW cm^–2, which is slightly higher than that of a zinc–air battery utilizing the commercial Pt/C catalyst (167 mW cm^–2), mostly because of the large surface area of the N-doped graphitic carbon shells. Theoretical calculation verified that O₂ molecules can spontaneously adsorb on both pristine and nitrogen doped graphene surfaces and then quickly diffuse to the catalytically active nitrogen sites. Our catalyst can potentially become a promising replacement for Pt catalysts in metal-air batteries and fuel cells.