Carbon Dot-Polyaniline Covalent Nanocomposites for Supercapacitors and Conductive Coatings

The potential of a simple yet previously unachieved chemical transformation between carbon dot (CD), a nanoparticle, and aniline, a subnanometer-sized molecule, is demonstrated through the synthesis of a CD-polyaniline (CD-PANI) nanocomposite. Contrary to the traditional grafting of carbon nanomaterials onto preformed PANI chains, CDs were first covalently conjugated with aniline through amidation between the −COOH groups of CDs and the −NH2 groups of aniline, which served as molecular seeds for the in situ oxidative polymerization of aniline. The nanocomposite uses CD as a covalent cross-linking core, from which PANI chains grow directionally to form a branched network. This structure prevents PANI aggregation and enhances mechanical stability, thereby improving electron and ion transport. The CD-PANI nanocomposite exhibits high electrical conductivity, remarkable structural integrity, and enhanced charge storage capacity, delivering a specific capacitance of 656 Fg–1 at 0.5 Ag–1 and retaining 286 Fg–1 at 5 Ag–1, with 91% capacitance retention after 5000 cycles, enabled by efficient ion diffusion and low charge-transfer resistance. Electrochemical studies confirm its superior supercapacitor performance compared to other nanocarbon/PANI composites. This improvement is attributed to the covalent nature of the CD-PANI interface and the synergistic interaction between CD and the polymer matrix, which ensures long-term cycling stability and addresses key limitations of conventional PANI-based electrode materials. The straightforward, scalable, and environmentally sustainable synthesis of this nanocomposite makes it a strong candidate not only for high-performance supercapacitors but also for the development of low-cost, metal-free conductive paints, bridging new material platforms and nanostructured design with practical applications in energy storage and flexible electronics.