Graphitic Carbon with MnO/Mn₇ C₃ Prepared by Laser-Scribing of MOF for Versatile Supercapacitor Electrodes

Pseudocapacitive materials encapsulated in conductive carbon matrix are of paramount importance to develop energy storage devices with high performance and long lifespan. Here, via simple laser-scribing, the Mn-based metal-organic framework [EG-MOF-74(Mn)] is transformed into pseudocapacitive hybrid MnO/Mn₇ C₃ encapsulated in highly conductive graphitic carbon. It is revealed that the rapid carbothermic reduction of MnO (C + MnO → C' + Mn₇ C₃ + CO) leads to the formation of the intermediate pseudocapacitive MnO/Mn₇ C₃ and the concurrent catalytic graphitization of disordered carbon. This reaction produces a new type of pseudocapacitive material in the form of MnO/Mn₇ C₃ fully embedded in highly conductive graphitic carbon. Thanks to the synergistic effect of the MnO/Mn₇ C₃ nanoparticles and the graphitic carbon, the composite exhibits a high specific capacitance of 403 F g^-1 with excellent stability. Asymmetric coin-cell supercapacitors based on the composite demonstrate high energy (29.2 Wh kg^-1 ) and power densities (8000 W kg^-1 ) with a long lifespan. Prototypes of flexible paper-based supercapacitors made of the composite also show great potential toward applications of flexible electronics.