Construction of Co,N-Coordinated Carbon Dots for Efficient Oxygen Reduction Reaction

Abstract

For the sake of the oxygen reduction reaction (ORR) catalytic performance, carbon dots (CDs) doped with metal atoms have accelerated their local electron flow for the past few years. However, the influence of CDs doped with metal atoms on binding sites and formation mechanisms is still uncertain. Herein, Co,N-doped CDs were facilely prepared by the low-temperature polymerization–solvent extraction strategy from EDTA-Co. The influence of Co doping on the catalytic performance of Co-CDs was explored, mainly in the following aspects: first, the pyridinic N atom content of Co-CDs significantly increased from 4.2 to 11.27 at% compared with the CDs, which indicates that the Co element in the precursor is advantageous in forming more pyridinic-N-active sites for boosting the ORR performance. Second, Co-CDs are uniformly distributed on the surface of carbon black (CB) to form Co-CDs@CB by the facile hydrothermal route, which can expose more active sites than the aggregation status. Third, the highest graphite N content of Co-CDs@CB was found, by limiting the current density of the catalyst towards the ORR. Composite nanomaterials formed by Co and CB are also used as air electrodes to manufacture high-performance zinc–air batteries. The battery has good cycle stability and realizes stable charges and discharges under different current densities. The outstanding catalytic activity of Co-CDs@CB is attributed to the Co,N synergistic effect induced by Co doping, which pioneer a new metal doping mechanism for gaining high-performance electrocatalysts.

Carbon Dots: Synthesis, Characterizations, and Recent Advancements in Biomedical, Optoelectronics, Sensing, and Catalysis Applications

“…This unique metal doping technique opens up new possibilities for the production of high-performance electrocatalysts. 239 For the first time, Ndoped lignin-based carbon nanodots (NL-CNDs), made using Under visible area (λ > 420 nm), this reaction occurs at normal pressure and without the need for a sacrificial agent. This value is 27.5-times greater than that of pure C 3 N 4 .…”

Nanozyme Inhibited Sensor Array for Biothiol Detection and Disease Discrimination Based on Metal Ion-Doped Carbon Dots

“…Recently, CDs have attracted widespread attention due to their merits of facile preparation, chemical inertness, excellent photostability, easy surface modification, as well as negligible cytotoxicity and good biocompatibility. − Since the first synthesis of CDs by Scrivens et al in 2004, great efforts have been made to improve their photoluminescent quantum yield and endow CDs with more applications. − Owing to the large atomic radius, unoccupied orbitals, and extensive free electrons of metal ions, metal ion-doping is an effective approach to tune the physicochemical properties of CDs. − M-CDs facilely integrate the advantages of metal ions and CDs and have been taken as versatile nanoplatforms for various applications, such as antibacterial testing, therapy, magnetic resonance imaging, nanozyme-based chemo/biosensing, and so on. − …”

Fabrication of Orange Fluorescent Boron-Doped Graphene Quantum Dots for Al3+ Ion Detection

“…Graphene quantum dots represent a new type of fluorescent nanomaterial with excellent optical properties and low toxicity, which has successfully become an ideal substitute for traditional fluorescent materials [ 7 , 8 ]. Graphene quantum dots possess tunable optical properties due to their unique electronic structure, stable and durable fluorescence, controllable emission wavelengths, and wide excitation wavelength range, which have been applied in photocatalysis, sensors, solar light sources, organic LEDs, photodetectors, and in other fields/applications [ 9 , 10 , 11 ]. In addition, graphene quantum dots have simple functions; excellent thermal, mechanical, and electrochemical luminescence properties; low toxicity and high environmental safety; and good biocompatibility, and have been successfully applied in ion detection, organic detection, biological imaging, drug delivery, and other fields [ 12 , 13 , 14 ].…”