Fig. 2

Morphological characteristics of Fe₂O₃@SBA-15. a Fresh Fe₂O₃@SBA-15 and HR-TEM images of two typical Fe₂O₃ nanoparticles (Scale bar represents 1 nm); b Fe₂O₃@SBA-15 after 75 redox cycles and HR-TEM images of two typical Fe₂O₃ nanoparticles (Scale bar represents 5 nm).