The production of water‐dispersed graphene with low defects remains a challenge. The dry ball milling of graphite with additives produces edge‐selectively functionalized graphene. However, the “inert” additives require a long milling time and cause inevitable in‐plane defects. Here, the mechanochemical reaction of graphite with persulfate solved the above drawback and produced edge‐selectively hydroxylated graphene (EHG) nanosheets through a 2 h ball‐milling and a subsequent 0.5 h sonication. The mechanochemical cleavage of persulfate yielded SO4⋅− to spontaneously oxidize graphite to form the carbon radical cations selectively at edges, followed by hydroxylation with water of moisture. Because the O−O bond dissociation energy of persulfate is 20 % of the graphitic C−C bond, the rather low milling energy allowed the hydroxylation of graphite at edges with nearly no in‐plane defects. The obtained EHG showed high water‐dispersibility and excellent photothermal and electrochemical properties, thereby opening up a new door to fabricate graphene‐based composites.
Copper- and nitrogen-codoped reduced graphene oxide material (Cu/N-rGO) was prepared with a hydrothermal method. Its versatile catalytic performances were demonstrated toward the oxidative degradation of rhodamine B (RhB) and oxygen reduction reaction (ORR). The Cu and N codoping of graphene enhanced not only its activation ability toward H2O2, but also its electrocatalytic ability for ORR. It was observed that the use of 3%Cu/N-rGO together with 40 mmol·L−1 H2O2 and 4 mmol·L−1 Na2CO3 could remove more than 94% of the added RhB (30 mg·L−1) in 20 min through a catalytic Fenton-like degradation. Quenching experiments and electron paramagnetic resonance (EPR) measurements indicated that the main reactive species generated in the catalytic oxidation process were surface-bound •OH. The modified graphene also showed good electrocatalytic activity for ORR reaction in alkaline media through a four-electron mechanism. On the electrode of Cu/N-rGO, the ORR reaction exhibited an onset potential of −0.1 V and a half-wave potential of −0.248 V, which were correspondingly close to those on a Pt/C electrode. In comparison with a Pt/C electrode, the 3%Cu/N-rGO electrode showed much greater tolerance to methanol. Such outstanding catalytic properties are attributed to the abundant active sites and the synergism between Cu and N in Cu/N-rGO.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.