在 FeNC 基质中合成分级结构的 Fe3C/CNTs 复合材料用作高效 ORR 电催化剂,RSC Advances

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在 FeNC 基质中合成分级结构的 Fe3C/CNTs 复合材料用作高效 ORR 电催化剂
RSC Advances ( IF 3.9 ) Pub Date : 2023-01-26 , DOI: 10.1039/d2ra07848a
Tanlun Wang ₁ , Lincheng Xu ₁ , Chenxiang Sun ₁ , Xiyuan Li ₁ , Yong Yan ₂ , Fan Li ₁

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Fe-N-C 具有大量的 FeN _x活性位点，因此被认为是一种高性能的氧还原反应 (ORR) 催化剂，将 Fe ₃ C 与 Fe-N-C 结合通常可以提高 ORR 活性。然而，催化机制仍然未知，限制了进一步的研究和开发。在这项研究中，将沉淀-溶剂热法与热解结合使用，以生产一系列衍生自与 Fe 3 C 复合的沸石咪唑酯骨架 (ZIF) 的 Fe-N-C 催化剂。所制备的催化剂具有多_尺度结构ZIF 状碳颗粒和棒状结构，以及竹状碳纳米管 (CNT) 和用 Fe _{3包裹的碳层}同时一系列研究揭示了C粒子的棒状结构和Fe ₃ C相的起源。分级结构有利于提高催化剂的ORR电催化性能。最佳样品的最高半波电位为 0.878 V vs. RHE，高于商业 Pt/C（0.861 V vs. RHE）。最佳样品的 ECSA 为 1.08 cm ² μg ^-1，电子转移数接近 4，并且动力学正常。最佳样品对 ORR 表现出高耐久性和甲醇耐受性。最后，用配位离子阻断不同的 Fe 活性位点表明 Fe( II ) 是主要活性位点，表明 Fe₃ C主要作为助催化剂优化Fe-N-C的电子结构，从而协同提高ORR活性。

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Synthesis of hierarchically structured Fe3C/CNTs composites in a FeNC matrix for use as efficient ORR electrocatalysts

Fe–N–C has a high number of FeN_x active sites and has thus been regarded as a high-performance oxygen reduction reaction (ORR) catalyst, and combining Fe₃C with Fe–N–C typically boosts ORR activity. However, the catalytic mechanism remains unknown, limiting further research and development. In this study, a precipitation-solvothermal process was used in conjunction with pyrolysis to produce a series of Fe–N–C catalysts derived from a zeolitic imidazolate framework (ZIF) that was composited with Fe₃C. The prepared catalysts had a multiscale structure of ZIF-like carbon particles and rod-like structures, as well as bamboo-like carbon nanotubes (CNTs) and carbon layers wrapped with Fe₃C particles while a series of studies revealed the origin of the rod-like structures and Fe₃C phase. The hierarchical structure was beneficial to the enhanced electrocatalytic performance of catalysts for ORR. The optimal sample had the highest half-wave potential of 0.878 V vs. RHE, which was higher than that of commercial Pt/C (0.861 V vs. RHE). The ECSA of the optimal sample was 1.08 cm² μg⁻¹, with an electron transfer number close to 4, and functioning kinetics. The optimal sample exhibited high durability and methanol tolerance for the ORR. Finally, blocking different Fe active sites with coordination ions demonstrated that Fe(II) was the main active site, indicating that Fe₃C primarily served as a cocatalyst to optimize the electron structure of Fe–N–C, thereby synergistically improving the ORR activity.

更新日期：2023-01-26

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