Effect of Ce doping in MnO₂ nanosheet over Ni foam for supercapacitor application

A hydrothermal approach is reported for producing Ce-doped MnO₂ (0.5 to 2 mol%) directly on Ni foam for possible application in supercapacitors. X-ray diffraction studies demonstrate that Ce-doped MnO₂ exhibits an orthorhombic phase characterized by the p n n m space group. The crystallite size varies in the range of 18 to 26 nm, with no CeO₂ phase. Raman spectroscopy indicates the formation of MnO₂. Field emission scanning electron microscopy (FE-SEM) results show the porous layer structures composed of linked MnO₂ nanosheets that evenly coat the Ni foam, resulting in a two-dimensional hierarchical architecture. The successful doping of Ce³⁺ and the presence of Mn⁴⁺ in the MnO₂ crystal are predicted by X-ray photoelectron spectroscopy. The nanosheets exhibit a maximum specific capacitance of 137.4 F/g at a scan rate of 5 mV/s. MnCe-1.0 demonstrates a capacity retention of 91.54% after 3200 cycles at a scan rate of 50 mV/s.