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 α‐Ni(OH) 2 via hydrothermal route is presented. Nitrogen‐ and phosphorous‐functionalized carbon dots (N,P‐CD GMP ) 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‐CD GMP by hydrothermal method. Microflower‐like morphology of porous nanocomposite of Ni(OH) 2 ‐[N,P‐CD GMP ] 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‐CD GMP ] 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‐CD GMP ] is demonstrated by fabricating a hybrid supercapacitor device Ni(OH) 2 ‐[N,P‐CD GMP ]//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 .