Nucleotide-Based Carbon Dot-Assisted Synthesis of High Surface Area Porous α-Ni(OH)2 as an Efficient Battery-Type Supercapacitor Electrode

Herein, a method for synthesizing highly porous single phase of alpha-Ni(OH)(2) via hydrothermal route is presented. Nitrogen- and phosphorous-functionalized carbon dots (N,P-CDGMP) are first synthesized by thermal refluxing of 1,5 '-guanosine monophosphate (GMP) in ethylene glycol. Then Ni(OH)(2) is synthesized in the presence of N,P-CDGMP by hydrothermal method. Microflower-like morphology of porous nanocomposite of Ni(OH)(2)-[N,P-CDGMP] with significantly enhanced Brunauer-Emmett-Teller surface area (454 m(2) g(-1)) is formed, which is 32 times higher than that of the pristine Ni(OH)(2). The cyclic voltammetry plot suggests battery-type supercapacitor with a specific capacity of 632 C g(-1), which is 6 times higher than the pristine Ni(OH)(2) (107 C g(-1)). The enhanced specific capacity of Ni(OH)(2)-[N,P-CDGMP] is attributable to better intercalation-deintercalation of electrolyte ions in the suitable pore volumes. Electrode kinetic studies measured at a scan rate of 0.005 V s(-1) suggest that about 86% of charge is stored via diffusion-controlled process and the charge storage by surface-controlled capacitive process is higher at higher scan rate (e.g., at 0.1 V s(-1)). The application of Ni(OH)(2)-[N,P-CDGMP] is demonstrated by fabricating a hybrid supercapacitor device Ni(OH)(2)-[N,P-CDGMP]//porous activated carbon from eucalyptus wood. The retention of specific capacitance of the device is 75% after 3000 cycles with maximum energy density of 31 Wh kg(-1) and power density of 0.76 kW kg(-1).