Carbon Dot-Regulated 2D MXene Films with High Volumetric Capacitance

Abstract

The flexible and conductive carbon dots (CDs)/MXene films with zero-dimensional (0D)/two-dimensional (2D) dot-sheet motif architectures are successfully fabricated via the Coulombic interaction between negatively charged Ti3C2T x MXene nanosheets and positively charged CDs synthesized from biomass by a green and economic one-pot hydrothermal process. The interlayer spacing coupled with the type and content of doped heteroatoms of the hybrid films can be regulated by the selected CDs with various particle sizes and heteroatoms. These CDs/MXene films with enlarged interlayer spacing and doped heteroatoms accelerate the ion diffusion and charge transfer. The optimized freestanding film electrode from pomelo juice with suitable layer spacing and profuse heteroatom doping indicates a high volumetric capacitance of 984.5 F cm–3 at a scan rate of 2 mV s–1, and a excellent volumetric energy density of 19.42 Wh L–1 is obtained in the corresponding assembled asymmetric supercapacitor. This study sheds light on a facile self-assembly route to fabricate multitudinous low cost and high-performance flexible MXene-based electrode.

Supramolecular Chemistry of Carbon‐Based Dots Offers Widespread Opportunities

“…[52,99] Ionic bonds between carbon dots and charged inorganic nanomaterials is also an effective approach to prepare organicinorganic nanocomposites. For example, CDs could be combined with gold nanoclusters to achieve intracellular temperature detection, [100] with 2D transition metal carbides (MXenes) to prepare supercapacitors, [101] or with tungsten disulfide to prepare electrochemical sensors. [102]…”

Quantum Energy Storage in 2D Heterointerfaces

“…(Ti 3 C 2 O x (OH) y F z + δe − + δH + → Ti 3 C 2 O x −δ(OH) y + δF z ) (Figure 5h). [ 84 ] Liu's group has explained the chemical reactivity of phosphorization treatment in the 0D/2D Ni 5 P 4 Ni 2 P (Ni x P y ) structure. During an ion exchange reaction on the surface between PH 3 and OH − (Ni(OH) 2 ), the chemically converted Ni x P y nanosheets were decorated with nanoparticles, where OH − contributes to emergence of porous structure and PH 3 results in the producing of nanoparticles all across the nanosheets.…”

“…g) XPS spectra and h) CV curves of pure MXene and carbon dot/MXene hybrids. Reproduced with permission [84]. Copyright 2020, American Chemical Society.…”

Post-modified biomass derived carbon materials for energy storage supercapacitors: a review

“…Good conductivity, rich surface functional groups, adjustable hydrophilic/ hydrophobic properties and rich redox active reaction sites give MXenes excellent charge storage capacity. Li et al 134 used four kinds of renewable biomass (wheat straw, Enteromorpha prolifera, pomelo juice, and tribute chrysanthemum) derived hetero-atom-doped CDs as cheap conductive pads, and CDs/ MXene self-supporting thin lm electrodes with a unique 0D/ 2D dot-like structure were constructed by Coulomb selfassembly. Due to the synergistic effect of the unique structure and properties of a single component, NSPJCDs/M-5% shows excellent volume capacitance (984.5 F cm −3 ), volume energy density (19.42 W h L −1 ), symbolic rate capacity (79.80%) and long-term cycle stability (94.6% retention rate aer 10 000 cycles).…”