Improving electrochemical performance of hollow Cr2O3/CrN nanoshells as electrode materials for supercapacitors

A hollow Cr2O3/CrN nanoshell was synthesized directly in the ammonia atmosphere. X-ray diffraction analysis indicated that the crystalline phase was gradually transformed from the hexagonal Cr2O3 to cubic CrN, in company with the shrinking of the lattice cells with the increase of ammonification time. Based on its more stable crystalline structure and well conductivity of the CrN relative to the Cr2O3, the electrochemical performance of Cr2O3/CrN composites was modified, including increased specific capacitance, enhanced cycle stability and improved electrical conductivity. While the ratio of oxygen to nitrogen is 81.89%, the Cr2O3/CrN composites own the highest specific capacitance of 333.2 F/g at 10 mV/s and maintain an initial capacitance of 84.7% after 5000 charge-discharge cycles, attributing to the maximum specific surface area. The variation of electrochemical properties of Cr2O3/CrN composites was systematically studied. These results provided a new route for designing transition metal oxides/transition metal nitrides composites as electrode materials for supercapacitors.