Electronically tailoring 3D flower-like graphene via alumina doping and incorporating Co as an efficient oxygen electrode catalyst in both alkaline and acid media

• Published in: Journal of power sources 2017-06, Vol.353, p.28-39
• Main Authors: Ma, Xiu-Xiu, He, Xing-Quan
• Format: Article
• Language: English
• Subjects: Alumina; Electronically tailor; Nitrogen-doped graphene; Oxygen evolution reaction; Oxygen reduction reaction
• ISSN: 0378-7753; 1873-2755
• DOI: 10.1016/j.jpowsour.2017.03.142

3D graphene-based electrode catalysts have intrigued tremendous research in energy conversion and storage systems not only for the intrinsic properties of graphene, but also due to its high active density for the oxygen electrode reaction with efficient mass and electron transports. In this work, we try to electronically tailor 3D nitrogen-doped graphene (NG) using alumina (Al), and obtain the flower-like structure with a high Brunauer–Emmett–Teller (BET) surface area and abundant active sites, as a result, pure cobalt nanoparticles are easily confined. Physical characterizations confirm that this natural tuning of graphene by Al causes the increasing of surface defects, as a result, the physicochemical stability of Al and graphene is improved, and vice versa, consequently, the co-modification of Al and Co induce outstanding oxygen reduction reaction (ORR) performance including distinct onset potential, large diffusion limiting current density, kinetic current density and good stability, which are comparable with those of 20 wt% Pt/C in both alkaline and acidic media; in addition, the fabricated composite also delivers prior oxygen evolution reaction activity, superior to the benchmark RuO2. This hybrid herein exhibits a combined ORR and OER potential gap of 0.745 V, rivaling state-of-the-art bifunctional oxygen electrode catalysts. An efficient bifunctional catalysts by incorporating Co into 3D flower-like graphene tailored by Al2O3 was proposed. [Display omitted] •The electron structure of graphene was successfully tailored by N and alumina.•The tuned Al2O3@NG-800 showed a flower-like structure with abundant defects.•A hierarchical structure was formed for the proposed Al2O3@Co/NG-800.•Co showed strong electron coupling with alumina.•Al2O3@Co/NG-800 exhibited outstanding bifunctional performance.