Fig. 4: Potential-dependent magnetization measurements using a SQUID.

a, b Potential-dependent magnetic hysteresis curves for Mn3O4 NPs a, and Ni–Mn3O4 NPs/NiO b, measured at 5 K. Compared to Mn3O4 NPs, Ni–Mn3O4 NPs/NiO shows significantly diminished magnetization under the applied anodic potential. The black and blue histograms in inset figures show the magnetization values at 5 T and 0 T (Mrs), respectively.