Fabrication of semi‐flexible carbon quantum dots‐reinforced polypyrrole ( PPy / CQDs ) composite electrodes by hybrid electrospray deposition for high‐performance energy storage device

Abstract

Summary A carbon quantum dots‐reinforced polypyrrole (PPy/CQDs) composite electrodes were prepared via the hybrid electrospray method. PPy/CQDs composite shows superior electrochemical performance with a specific capacity (Qg) of 174.21 C g−1 at 1 A g−1 in 3 M KOH aqueous electrolyte. An all‐solid‐state asymmetric supercapacitor (ASC) is composed of PPy/CQDs as a positive electrode and rGO as a negative electrode with PVA/KOH gel electrolyte, which exhibited the specific capacity (Qg) of 79.25 C g−1 at the current density of 1.5 A g−1 with an energy and power density of 26.44 Wh kg−1 and 18 090.82 W kg−1, respectively. An assembled PPy/CQDs//rGO device offers cyclic retention of about 76.8% at 15 A g−1 after 10 000 cycles. The above results confirmed that the as‐prepared PPy/CQDs composite electrode is more suitable for high‐performance‐based semi‐flexible supercapacitor application.

Zero‐Dimensional Carbon Nanomaterials for Electrochemical Energy Storage

“…[208] The share of GQDs or CQDs in composite materials used in supercapacitors is explained by their easy surface modification, fast electron transfer, rich heteroatom doping, and their large specific surface area, [209] which facilitates high electrochemical capacity. Components interacting with GQDs or CQDs bring even greater benefits in the area of energy storage including conductive polymers, [183][184][185][186][187][188][210][211][212] metal oxides, [170][171][172][173][174][175][176]213,214] hydroxides [179] and sulfides, [177,178,215] spinels, [181][182][183] and other carbon nanostructures of various dimensionality. [189,191,216,217] Examples of composites of this type with an indication of their utility in the construction of SCs are summarized in Table 5.…”

“…CQDs-reinforced PPy composite electrodes constructed by Dhandapani et al were, in turn, tested for use in high-performance semi-flexible supercapacitors. [212] For this purpose, the authors created an asymmetric device containing CQDs/PPy as the positive electrode and rGO as the negative electrode separated by a PVA/KOH gel electrolyte (Figure 31). Electrochemical measurements of the assembled CQDs/PPy//rGO device (Figure 31) confirmed an excellent electrochemical performance as well as high specific capacitance (174.21 C g À 1 at 1 A g À 1 ) with a cyclic retention after 10,000 cycles of about 76.8 %.…”

“…CQDs‐reinforced PPy composite electrodes constructed by Dhandapani et al . were, in turn, tested for use in high‐performance semi‐flexible supercapacitors [212] . For this purpose, the authors created an asymmetric device containing CQDs/PPy as the positive electrode and rGO as the negative electrode separated by a PVA/KOH gel electrolyte (Figure 31).…”

“… (a) Scheme of the asymmetric device based on CQDs/PPy composite and rGO, (b) CV curves of electrode materials at a scan rate of 10 mV s −1 , (c) CV curves of the asymmetric device tested for various potential ranges at a scan rate of 60 mV s −1 , and (d) GCD curves of the asymmetric device at different potentials (current density 8 A g −1 ). Reproduced with permission [212] . Copyright (2022) Wiley.…”

pH-Sensitive Fluorescence Emission of Boron/Nitrogen Co-Doped Carbon Quantum Dots

“…For the last two decades, carbon quantum dots (CQDs) as a zero-dimensional carbon nanomaterial, which have sizes lower than 10 nm have gained intense interest due to their impressive advantages, including their widespread source of precursors, small sizes, strong photoluminescence (PL), high biocompatibility and photostability, low cytotoxicity and, flexible surface structures [1][2][3][4]. With their unique properties, CQDs have been employed in various applications such as chemical sensing, biosensing, photocatalysts, energy storage, and biomedical applications [5][6][7][8][9]. Unlike other carbon-based nanomaterials, CQDs possess a graphitic core composed of sp 2 /sp 3 hybrid with numerous functional groups, which consist of primarily oxygen-related groups and post-modified chemical groups on the surface [10][11][12].…”