N, P-Codoped Graphene Dots Supported on N-Doped 3D Graphene as Metal-Free Catalysts for Oxygen Reduction

Abstract

Nitrogen and phosphorus-codoped graphene dots supported on nitrogen-doped three-dimensional graphene (N, P-GDs/N-3DG) have been synthesized by a facile freeze-annealing process. On the surface of the 3D interconnected porous structure, the N, P-GDs are uniformly dispersed. The as-prepared N, P-GDs/ N-3DG material served as a metal-free catalyst for oxygen reduction reaction (ORR) in an alkaline medium and evaluated by a rotating ring-disk electrode. The N, P-GDs/N-3DG catalyst exhibits excellent ORR activity, which is comparable to that of the commercial Pt/C catalyst. Furthermore, it exhibits a higher tolerance to methanol and better stability than the Pt/C. This enhanced electrochemical catalytic performance can be ascribed to the presence of abundant functional groups and edge defects. This study indicates that P−N bonded structures play a vital role as the active sites in ORR.

Phosphorus-Doped Graphene Electrocatalysts for Oxygen Reduction Reaction

“…Among these elements, nitrogen is by far the most studied dopant because of its similar atomic size to carbon and slightly higher electronegativity than carbon. The ORR performance can be remarkably enhanced in nitrogen-doped graphene (N-graphene), which has been demonstrated and reviewed in previous works [ 27 , 28 , 29 ]. Besides, many previous articles reviewed the synthesis methods and the application of different heteroatoms-doped graphene (X-graphene) [ 25 , 30 , 31 ].…”

“…Last but not least, the building of the multiple doped structures or the composites will play a more important role. For example, we have recently synthesized P, N-graphene dots/N-3D-graphene [ 27 ]. We found that P–N bonded structures can serve as ORR active sites.…”

Synthesis of Doped/Hybrid Carbon Dots and Their Biomedical Application

“…NCDs were used as the stabilizer in three different compositions of HA particles accommodate 1% to 5% NCDs [ 89 ]. Adding P and N did not improve the fluorescence properties of N/P-co-doped CDs, although their aqueous dispersibility increases significantly [ 90 ]. The purpose of S-doping in CDs is typically to enhance metal ion (Fe 3+ ions, other heavy metal ion) detection sensitivity by 0–500 µM [ 91 ].…”

Rational design of large flat nitrogen-doped graphene oxide quantum dots with green-luminescence suitable for biomedical applications

“…Doping of GOQDs generates local defects in the graphene layer and thus delocalized charge. 55 This charge can be a key factor determining cytotoxicity, cellular uptake, and intracellular trafficking of the nanoparticles. 56 Among the different dopants, nitrogen-doped GOQDs (N-GOQDs) have garnered the most interest due to enhanced photoemission and tunable optical properties rendered by the three possible types of N-doping, including pyridinic N, pyrrolic N, and quaternary.…”