Carbon Dots/NiCo₂O₄Nanocomposites with Various Morphologies for High Performance Supercapacitors

Abstract

A series of carbon dots/NiCo O composites with various morphologies are prepared and tested for supercapacitors. These samples have good electrical conductivities and efficient ions transport paths, so they exhibit high specific capacitances, superior rate performances, and high cycling stabilities. The optimal composite for hybrid supercapacitor exhibits a high energy density up to 62.0 Wh kg .

Highly Hydrophilic Carbon Dots' Decoration on NiCo2O4 Nanowires for Greatly Increased Electric Conductivity, Supercapacitance, and Energy Density

“…Actually, it can be observed from Figure S2 (Supporting Information) that the color of the CDs/NiCo 2 O 4 precursor changes significantly when different contents of CDs added into the system. Similarly, Figure S3 (Supporting Information) confirms that the decorated mass ratios of CDs have an impact on the morphology of CDs/NiCo 2 O 4 samples . As illustrated in Figure c, the CDs only show a broad scattering peak, indicating the absence of inorganic salts in the CDs .…”

“…Unfortunately, the BET surface area of CNCO‐5 is significantly reduced to 72.5 m 2 g −1 , which may be attributed to the occlusion of NiCo 2 O 4 caused by the aggregation of excessive CDs on NiCo 2 O 4 nanowires. The above results show that the existence of CDs in the reaction process increases the surface area of CDs/NiCo 2 O 4 samples, which is conducive to the improvement of electrochemical behavior …”

“…The O1 (529.5 eV) peak originates from typical metal–oxygen bonds and O2 (530.9 eV) is related to the oxygen in hydroxyl groups, which is similar to that of CDs. Meanwhile, the O3 (531.9 eV) and O4 (533.2 eV) peaks reflect the contributions of the oxygen vacancy and physic‐/chemisorbed water on the surface, respectively . Synchronously, Figure S4a (Supporting Information) shows that the prime NiCo 2 O 4 also contains trace amount of carbon, which may come from the residual carboneous product of urea pyrolysis.…”

“…For instance, Chen and co‐workers have designed a nanocomposite of CDs and NiO nanorods to couple the Faradaic pseudocapacitance of NiO and the excellent electrical conductivity of CDs, delivering a high specific capacitance of 1858 F g −1 at 1 A g −1 and excellent cycling stability . Moreover, the CDs have been reported to act as a structure‐directing agent to improve the surface area of electrode materials . In our previous work, we found that CDs have played an important role in improving supercapacitance behavior of a ternary composite of graphene oxide/carbon dots/polypyrrole, where the CDs between GO film and polypyrrole (PPy) layer can increase electron transportation and thus reduce the resistance of the electrodes .…”

Morphology‐dependent electrochemical performance of nitrogen‐doped carbon dots@polyaniline hybrids for supercapacitors

“…Hence, the addition of N‐CDs improved the hydrophilic ability of binary hybrids and facilitated the contact of electrolyte with binary hybrids. By contrasting the redox peak positions of CV curves, the redox peaks shifted positively with the increase of the N‐CDs, indicating that the main contribution of pseudocapacitance was the redox reaction between H 2 SO 4 electrolyte and binary hybrids …”