D-ribose directed one-step fabrication of modifier-free C/NiCo2O4 nanowires with advanced electrochemical performance

A compound electrode of carbonaceous materials and NiCo 2 O 4 is extensively studied because of higher capacitance and better rate capability compared to those of pure NiCo 2 O 4 . However, the tedious preparation process, harsh synthesis condition, high consumption, and especially limited electrochemical property by using modifiers hinder its practical application. Herein, modifier-free electrodes (C/NiCo 2 O 4 ) with various morphologies based on D-ribose are successfully synthesized via a one-step hydrothermal-calcination method. D-ribose concurrently acts as carbon source and structure-directing agent. The structure of NiCo 2 O 4 changes from the nanosheets into nanowires after adding D-ribose. Each element is evenly distributed throughout C/NiCo 2 O 4 , significantly improving the electrical conductivity. Furthermore, there is a strong interaction between carbon and NiCo 2 O 4 , which keeps the structure stable. Benefiting from the structural characteristics, the C/NiCo 2 O 4 composites display the improved electrochemical performance. Remarkably, the maximum specific capacitance of C/NiCo 2 O 4 -2 is 1583.9 F g −1 at 2 A g −1 in 3 M KOH aqueous solution, and it exhibits remarkable rate capability of 1354.8 F g −1 even at 20 A g −1 . After 20,000 charge-discharge cycles at 20 A g −1 , a high capacity retention of 90.6% can be achieved. The C/NiCo 2 O 4 -2 is a promising electrode material for supercapacitor. In addition, a dynamic growth mechanism of C/NiCo 2 O 4 under the coordinate bond of metal ions with D-ribose is discussed in the paper.