Single-crystal Cr2O3 nanoplates with differing crystalinities, derived from trinuclear complexes and embedded in a carbon matrix, as an electrode material for supercapacitors

As one kind of important p-type semiconductors, Cr2O3 has been widely used for optical and electronic devices due to its high electrical conductivity and special optoelectronic characteristics, as well as high chemical and thermal stability. In this paper, single-crystalline Cr2O3 nanoplates embedded in carbon matrix were successfully synthesized through direct thermal decomposition of a trinuclear cluster complex of [Cr3O(CH3CO2)(6) (H2O)(3)NO3 center dot CH3COOH ([Cr3O]) in Ar atmosphere. The synergetic effect of the plate-like structure and embedding in carbon matrix contributes to the enhanced electrochemical performance of the Cr2O3-C nanoplates. Owing to different crystallinity and composition, the obtained products at 400, 500, 600, and 700 degrees C with different carbon content of 12.52, 8.26, 5.35 and 3.27% exhibited enhanced battery-type electrode materials in three-electrode system with high specific capacitance (823.11, 781.65, 720.72, and 696.73 F g(-1) at 1 A g(-1)) and remarkable cycling stability (about 0.3, 2.7, 4.5 and 5.6% loss of its initial capacitance after 5000 charge-discharge cycles at a current density of 5 A g(-1)). Furthermore, an assembled asymmetric device (Cr2O3-C nanoplates (positive electrode)//activated carbon (AC, negative one)) with an extended operating voltage window of 1.8 V achieves a specific capacitance of 58.06 F g(-1) at the current density of 1 A r, and an energy density of 26.125 W h kg(-1) at power density of 0.9 kW kg(-1), as well as superior cycling stability with 91.4% capacitance retention after 10,000 cycles. The results indicate that the Cr2O3 nanoplates embedded in carbon matrix show promising potential to construct high-performance energy storage devices. (C) 2017 Elsevier Inc. All rights reserved.