Facile synthesis of MnPO4·H2O nanosheets/MWCNTs composite as electrode material for high-performance supercapacitors

We report the fabrication of high stable manganese phosphate (MnPO4·H2O) nanosheets MnPO4·H2O/MWCNTs nanocomposites by a one-step facile hydrothermal synthesis followed by an annealing process. XRD results confirm that pure and composites show a monoclinic structure with a space group of C2/c (Z = 4). SEM and TEM images reveal that the disordered structure made of nanosheets with a lateral dimension of 100–150 nm and a thickness of ca. 10-15 nm can be observed in pristine MnPO4·H2O. Raman spectra again prove that monoclinic phases of MnPO4·H2O and presence of MWCNTs in the MnPO4·H2O/MWCNTs composite. The Pore Size and Surface distribution are studied through BET analysis, and the results show that the MnPO4·H2O/MWCNTs composite shows highest specific area (135 m2 g−1) and lower pore size 7.8 nm (compared to pristine MnPO4·H2O). The XPS result reveals that Mn is 2+ in a state in the spinel MnPO4·H2O. The MnPO4·H2O/MWCNTs composite delivers the capacity of about 765 F g−1 at a specific current of 2 A g−1 and capacity retention of about 94% after 5000 cycles. This study opens a new window for the fabrication of phosphate based materials for supercapacitors applications.