“…[ 17 ] The diffraction peaks at 18.0°, 30.0°, 35.4°, 37.2°, 43.0°, 53.5°, 57.0°, and 62.5° were correspond to the (1 1 1), (2 2 0), (3 1 1), (2 2 2), (4 0 0), (4 2 2), (5 1 1), and (4 4 0) planes of fully crystalline magnetite Fe 3 O 4 phase (JCPDS 85–1436). [ 18 ] The six diffraction peaks located at 12.2°, 35.6°, 36.7°, 43.5°, 63.0°, and 66.1° proved that Fe 3 O 4 @fibers were modified with the birnessite‐type MnO 2 (JCPDS 43–1456, δ–MnO 2 ). These peaks can be well indexed to the (0 0 1), (2 0 0), (1 1 –1), (1 1 –2), (3 1 –1), and (0 2 0) planes, respectively.…”