Facile Synthesis of Porous Mn₃O₄ Nanocrystal–Graphene Nanocomposites for Electrochemical Supercapacitors

Abstract

Abstract In this work, we describe our efforts to produce Mn 3 O 4 –graphene nanocomposites based on a convenient andfeasible solution based synthetic route under mild conditions. According to transmission electron microscopy (TEM) and high angle annular dark field scanning transmission electron microscopy (HAADF‐STEM) results porous Mn 3 O 4 nanocrystals (NCs), 20–40 nm in size, are uniformly deposited on both sides of the graphene nanosheet (GNS) matrix. Significantly, the as‐prepared Mn 3 O 4 –graphene nanocomposites exhibit remarkable pseudocapacitive activity including high specific capacitance (236.7 F g –1 at 1 A g –1 ), good rate capability (133 F g –1 at 8 A g –1 ), and excellent cyclability (the specific capacitance only decreases by 6.32 % of the initial capacitance after 1000 cycles). The excellent pseudocapacitive performance of the Mn 3 O 4 –graphene nanocomposites electrode is probably due to the positive synergistic effects between the Mn 3 O 4 and GNS. Namely, the intimate combination of the conductive graphene network with uniformly dispersed porous Mn 3 O 4 NCs not only greatly improves the electrochemical utilization of Mn 3 O 4 , but also increases the double‐layer capacitance of the graphene sheets. These characteristics make this nanocomposite a very promising electrode material for high performance supercapacitors.