High-Performance Supercapacitor Electrode Materials: Cu/MnXx (X = O, S, C)-rGO Nanocomposites Derived from CuMn-BTC Metal–Organic Framework

Electrochemical supercapacitors, given their high power density and excellent cycling stability, have broad applications from electronic devices to electric vehicles. In this study, we have developed novel nanocomposites to serve as electrodes of high-performance supercapacitors. The nanocomposites, referred to as Cu/MnX x (X = O, S, C)-rGO (rGO: reduced graphene oxide), were fabricated through direct oxidation, sulfidation, and carbonization at elevated temperatures from their metal–organic framework origin, i.e., Cu/Mn-BTC-rGO (BTC: benzene–1,3,5-tricarboxylic acid). This process is cost-effective and scalable, and can be fine-tuned to achieve a variety of nanocomposites with the desired chemistry and structural characteristics. The carbonized product, Cu/MnC x -rGO, is made up of nanoparticles of MnO and copper in close contact supported on rGO nanosheets via strong coupling. This material demonstrates excellent charge storage, rate capability, and cycling stability, i.e., high specific capacitance of 718.6 F g −1 at a current density of 1 A g −1 , with 92.6% capacitance retention after 1000 cycles. The hierarchical 3D structured Cu/MnC x -rGO nanocomposite has unique chemistry, high surface area, and high electrical conductivity, and hence ensures rapid ion and electron transport beneficial to both pseudocapacitive and double-layer capacitive performance.