Synthesis of highly dispersed Nb₂O₅–graphene heterojunction composites using ethylene diamine tetraacetic acid and boron-functionalized graphene quantum dots for symmetrical flexible supercapacitors with ultrahigh energy density

Abstract

Nb2O5 is a promising metal oxide electrode material for supercapacitors because of outstanding structural stability and wide electrochemical window, but low inherent conductivity hinders its many applications. The paper reports...

Diverse Morphologies of Nb2O5 Nanomaterials: A Comparative Study for the Growth Optimization of Elongated Spiky Nb2O5 and Carbon Nanosphere Composite

“…The CV curves exhibit different oxidation and reduction peaks in the measured potential window range corresponding to the redox nature of suNb 2 O 5 . [ 49,50 ] In addition, the CV current rises with increasing scan rate, demonstrating the fast diffusion of ions. CV graphs of the suNb 2 O 5 , CNS, and suNb 2 O 5 ‐CNS composite at a scan rate of 10 mV s −1 are shown in Figure 6h.…”

Engineering functionalization and properties of graphene quantum dots (GQDs) with controllable synthesis for energy and display applications

“…In another recent paper, Xiaoyue et al demonstrated a strategy for forming PN junctions and Schottky heterojunctions in a composite material using B-doped GQDs, which are electron-deficient elements. 155 In this study, B-GQDs acted as P-type semiconductors, creating PN junctions with Nb 2 O 5 /B-GQD and Schottky heterojunctions with Graphene/B-GQD, significantly improving the intrinsic conductivity of Nb 2 O 5 .…”

“…192 B-doping also induces hole formation in the graphene structure of GQDs, making them behave as p-type semiconductors. 155 B-doped GQDs (B-GQDs) can be synthesized by adding borax or boric acid (H 3 BO 3 ) as the B dopant to carbon sources such as glucose or 1,3,6-trinitropyrene (TNP) and subjecting them to hydrothermal treatment. Among the various B-C bonding structures present in B-GQDs, the graphite-like BC 3 structure plays a crucial role in enhancing the electrical conductivity of B-GQDs.…”

“…154 The ethylene diamine located at the edge of GQDs acts as a highly reactive amino group, making it easier to introduce additional functional groups through subsequent modifications. 155 Additionally, diamine-functionalized GQDs synthesized from GO using 2,2′-(ethylenedioxy)bis(ethylamine) and H 2 O 2 emitted green-yellow PL with a relatively high QY of 22% and exhibited chelating properties for capturing radicals and cations. 156 Moreover, GQDs functionalized with octadecylamine (ODA), which is primarily used for the surface modification of various carbon nanomaterials, have also been reported.…”

Advances in Structural Modifications and Properties of Graphene Quantum Dots for Biomedical Applications

“…Other key attributes of GQDs are that they are mostly water-soluble or dispersible, are generally biocompatible with human neural cells, have good photostability, and have low cytotoxicity. − The photophysical properties of GQDs include but are not limited to nanosecond luminescence lifetimes and room temperature phosphorescence or white emission . GQDs are amenable to grafting onto other molecules, dyes, metal complexes, or polymers. , This rich chemistry of GQDs is exploited for the design and fabrication of nanodevices for electrocatalysis, electronics, light-emitting diodes, solar cells, , supercapacitors, − and fuel cells. , They also have a high potential for biomedical applications involving diagnosis, drug delivery, gene delivery, − bioimaging, and biosensing . Accordingly, this article focuses on the synthesis, modification, characterization, and biomedical applications of GQDs of size 20 nm or less …”