Facile synthesis of hybrid graphene and carbon nanotubes as a metal-free electrocatalyst with active dual interfaces for efficient oxygen reduction reaction

Abstract

We report metal-free electrocatalysts to enhance utilization of dissolved and gaseous oxygen during oxygen reduction reaction (ORR).Proper balance between hydrophobicity and hydrophilicity is achieved using reduced graphene oxide (rGO) and polyelectrolyte functionalized multiwalled carbon nanotubes (pMWNTs). In this unique architecture, both two-and three-phase reactions in ORR can be maximized with a quasi-four-electron pathway.

Copolymer‐Induced Intermolecular Charge Transfer: Enhancing the Activity of Metal‐Free Catalysts for Oxygen Reduction

“…Compared with the spectrum of the pure EDC electrolyte, the XPS spectrum of N 1s for CNT‐EDC exhibits the disappearance of tertiary N and the low‐binding‐energy shift of quaternary N (at 403.2 eV), indicating that the electron on the CNT had been transferred to the wrapped EDC chains . As for the CNT‐EDC sample, the XPS of the C 1s curve deconvolution (Figure b) yielded four peaks for the C=C, C−C, C−N, and O=C−O species (at 285.0, 285.5, 286.2, and 287.1 eV, respectively), demonstrating that the EDC electrolyte was successfully wrapped onto CNT . Additionally, the content of O species for EDC (29.73 at.…”

“…Compared to the heteroatom‐doping methods, the noncovalent‐induced charge delocalization without pyrolysis treatment serves as a desirable and controllable strategy, which can avoid the damage to carbon lattices, ensure electron conductivities, and keep atomically precise regulation. In this regard, several advances in choosing pristine carbonaceous materials (e.g., carbon nanotubes and graphene) and designing the competitive polyelectrolyte or other electron acceptors (e.g., poly(diallyldimethylammonium chloride), nitrobenzene, and graphene quantum dots) have been demonstrated to tune the electron delocalization on carbonaceous materials for good ORR activity . Nevertheless, the task of comparable or boosted activity is not trivial considering the inferior intrinsic activity of pristine carbonaceous materials.…”

“…In this regard, several advances in choosing pristinec arbonaceousm aterials( e.g.,c arbon nanotubes and graphene) and designing the competitive polyelectrolyte or other electron acceptors (e.g.,p oly(diallyldimethylammonium chloride), nitrobenzene, and graphene quantum dots) have been demonstrated to tune the electron delocalization on carbonaceous materials for good ORR activity. [21][22][23] Nevertheless, the task of compa-rable or boosted activity is not trivial considering the inferior intrinsic activity of pristine carbonaceousmaterials.…”

“…[19] As for the CNT-EDC sample, the XPS of the C1sc urve deconvolution (Figure 2b)y ieldedf our peaks for the C=C, CÀC, CÀN, and O=CÀO species(at 285.0, 285.5, 286.2,and 287.1 eV,r espectively), demonstratingt hat the EDC electrolyte was successfully wrapped onto CNT. [21,27] Additionally,t he content of Os peciesf or EDC (29.73 at. %) is highert han the theoretical value because of its strong tendency to absorb water in air.T he CNT-EDC sample showedamuch higherc ontent of the element O( 14.11at.…”

Three-Dimensional Heteroatom-Doped Nanocarbon for Metal-Free Oxygen Reduction Electrocatalysis: A Review

“…To restrain the stacking interaction, which may bury active sites for ORR, between 2D heteroatomdoped graphene sheets, researchers tactfully incorporated 1D structured CNTs between graphene sheets [119][120][121][122][123][124]. The resulting CNTs/graphene hybrid exhibited good ORR activity comparable to and/or better than the commercial Pt/C catalysts under alkaline conditions.…”