Porous α-FeO Hollow Rods/Reduced Graphene Oxide Composites Templated by MoO Nanobelts for High-Performance Supercapacitor Applications.

Porous α-FeO hollow rods/reduced graphene oxide (α-FeO HR/RGO) composites with unique morphological characteristics and a high surface area are prepared through a template strategy, which was systematically studied and found to have outstanding supercapacitive properties. When served as active material in a three-electrode setup, the optimized α-FeO HR/RGO-30, comprised 76.5 wt% α-FeO and 23.2 wt% RGO, was able to offer the largest specific capacitance of 426.3 F g, an excellent rate capability as well as satisfactory cycle life with capacitance retention of 87.7% and Coulombic efficiency of 98.9% after continuously charging/discharging at 10 A g for beyond 10,000 cycles. Such electrochemical behaviors of the α-FeO HR/RGO-30 electrode can rival or even surpass those of many FeO-based electrodes documented in the previous literature. Later, a symmetric supercapacitor cell of α-FeO HR/RGO-30//α-FeO HR/RGO-30 was fabricated. The assembled device offers the maximum energy density of 18.7 Wh kg, and also exhibits commendable rate capability, and features stable cycling durability (with capacitance retention of 83.2% together with a Coulombic efficiency of 99.3% after 10,000-cycle charge/discharge at 5 A g). These notable electrochemical performances enable the α-FeO HR/RGO-30 composite to be a high-potential material for advanced energy storage systems.