Reusable CoxNi1−x dye adsorbents as supercapacitor electrode materials
Herein, a novel method was developed to synthesize a CoNi binary metal/Co–Ni oxide@carbon (M/MO@C-600) composite by sintering CoNi nanoparticles with Congo Red (CR) at 600 °C and under a N2 atmosphere; this composite was then utilized to prepare electrode materials. Herein, C and O originated from the CR molecule. The M/MO@C-600 composite with a flaky structure delivered a capacitance of 1134.9 F g−1 at 1 A g−1 and a cycling stability with 66% retention even at the high current density of 10 A g−1 after 2000 cycles. Furthermore, a simple asymmetric supercapacitor (ASC) was developed with the M/MO@C-600 composite as the positive electrode material and commercial activated carbon as the negative electrode material. A high specific capacitance of 111.2 F g−1 (at 0.5 A g−1) and excellent energy density of 44.6 W h kg−1 (at 0.425 kW kg−1) were obtained for the ASC device, and 100% capacitance was retained even after 10000 cycles at 6 A g−1. This method for the preparation of electrode materials may facilitate to simultaneously relieve the environmental and energy pressure.