Figure 1: X-ray diffraction patterns of as-prepared Fe₃O₄ nanoparticles and N-S-G/Fe₃O₄ composite, respectively.

(a) Fe₃O₄ nanoparticles with cubic structure (JCPDS 19-0629), (b) N-S-G/Fe₃O₄ composite with cubic structure (JCPDS 19-0629), as indexed in the patterns.