Fig. 2: Morphological and structural characterization of FeCoNiMnRu/CNFs.

a FE-SEM, b TEM and c, d HRTEM images of FeCoNiMnRu/CNFs. The inset in (c) is the corresponding FFT pattern of a FeCoNiMnRu HEA NP. e HAADF-STEM and the corresponding STEM-EDX mapping images of a FeCoNiMnRu HEA NP supported on CNFs. f XRD patterns of FeCoNiMnRu/CNFs with detailed Rietveld refinements. g Real-time in situ XRD patterns for FeCoNiMnRu/CNFs with temperatures ranging from 25 to 1000 °C. h The corresponding enlarged in situ XRD patterns of FeCoNiMnRu/CNFs. The heating rate was kept at 30 °C min-1 during the whole process. i The thermodynamically driven phase transition of FeCoNiMnRu NPs in CNF nanofiber reactors.