Large-Scale Production of Edge-Selectively Functionalized Graphene Nanoplatelets via Ball Milling and Their Use as Metal-Free Electrocatalysts for Oxygen Reduction Reaction

Abstract

Edge-selectively functionalized graphene nanoplatelets (EFGnPs) with different functional groups were efficiently prepared simply by dry ball milling graphite in the presence of hydrogen, carbon dioxide, sulfur trioxide, or carbon dioxide/sulfur trioxide mixture. Upon exposure to air moisture, the resultant hydrogen- (HGnP), carboxylic acid- (CGnP), sulfonic acid- (SGnP), and carboxylic acid/sulfonic acid- (CSGnP) functionalized GnPs readily dispersed into various polar solvents, including neutral water. The resultant EFGnPs were then used as electrocatalysts for oxygen reduction reaction (ORR) in an alkaline electrolyte. It was found that the edge polar nature of the newly prepared EFGnPs without heteroatom doping into their basal plane played an important role in regulating the ORR efficiency with the electrocatalytic activity in the order of SGnP > CSGnP > CGnP > HGnP > pristine graphite. More importantly, the sulfur-containing SGnP and CSGnP were found to have a superior ORR performance to commercially available platinum-based electrocatalyst.

Facile production of ultrathin graphitic carbon nitride nanoplatelets for efficient visible-light water splitting

“…Samples of bulk GCN were first prepared by using melamine as the precursors, and UGCNPs were synthesized by a facile ball-milling process. Ball milling can effectively induce the cleavage of C-C bonds, while simultaneously causing doping and exfoliation in graphene [29][30][31][32]. Hence it is reasonable to infer that ball milling can be employed to cut and exfoliate GCN, which has a similar 2D layered structure, except that the neighboring layers are held by hydrogen bonding rather than the weak van der Waals force [24,33,34].…”

Earth‐Abundant Nanomaterials for Oxygen Reduction

“…H, COOH, SO 3 H, COOH/SO 3 H) at selected edge sites. [213] The ORR results show graphene functionalized with -SO 3 H groups provides the highest performance.Similarly,s elective doping of edge sites with sulfur has also been achieved recently by using as imple dry ball milling of graphite with S 8 . [214] Note that S 8 -graphene does not show any considerable enhancement because attachment of S 8 cannot improve the local electronic structure of the graphene.However,S-doped into graphene induces charges that create the active centers for enhanced ORR performance.T his has been further demonstrated by recent interesting examples on the reuse of S-doped graphene,produced from lithium-sulfur batteries, for enhancing ORR.…”

Sulfur–Graphene Nanostructured Cathodes via Ball-Milling for High-Performance Lithium–Sulfur Batteries

“…We have recently developed a simple low-cost, but effective and eco-friendly, ball-milling method for large-scale production of various graphene nanoplatelets (GnPs) edge-functionalized with different moieties without the basal plane damage, and hence good electrical/thermal conductivity [39][40][41][42] . Through the one-step ball-milling of graphite in the presence of sulfur (Fig.…”

“…S4b) for 0.7S-0.3GnP-700C -1M HCl clearly indicate that a considerable amount (3.8 at%, Table S2) of S-dopants have been strongly bonded into the carbon network through C-S (164.5 eV and 165.9 eV) and C-SO3 (168.3 eV) bonds, apart from those physically adsorbed sulfur. [39][40][41][42] . For all the S-GnPs, the intensity of the D band is higher than that of the G band due to the presence of defects induced by S-doping.…”