Cobalt and Nitrogen Co-Doped Graphene-Carbon Nanotube Aerogel as an Efficient Bifunctional Electrocatalyst for Oxygen Reduction and Evolution Reactions

• Published in: Catalysts Vol. 8; no. 7; p. 275
• Main Authors: Qiao, Xiaochang, Jin, Jutao, Fan, Hongbo, Cui, Lifeng, Ji, Shan, Li, Yingwei, Liao, Shijun
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 07.07.2018
• Subjects: Aerogels; Carbon; Carbon nanotubes; Catalysts; Chemical reactions; Cobalt; cobalt and nitrogen co-doped; Current density; Electrocatalysts; Electrolytes; Energy conversion; Energy storage; Graphene; graphene-carbon nanotube aerogel; Nitrogen; Noble metals; oxygen evolution reaction; Oxygen evolution reactions; oxygen reduction reaction; Oxygen reduction reactions; Structural hierarchy; Voltammetry
• ISSN: 2073-4344; 2073-4344
• DOI: 10.3390/catal8070275

In this study, a low-cost and environmentally friendly method is developed to synthesize cobalt and nitrogen co-doped graphene-carbon nanotube aerogel (Co-N-GCA) as a bifunctional electrocatalyst for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER). The as-prepared Co-N-GCA has a hierarchical meso- and macroporous structure with a high N doping level (8.92 at. %) and a large specific surface area (456 m2 g−1). In an alkaline medium, the catalyst exhibits superior ORR electrocatalytic activity with an onset potential 15 mV more positive than Pt/C, and its diffusion-limiting current density is 29% higher than that of commercial Pt/C. The obtained Co-N-GCA is also highly active toward the OER, with a small overpotential of 408 mV at a current density of 10 mA cm−2. Its overall oxygen electrode activity parameter (ΔE) is 0.821 V, which is comparable to most of the best nonprecious-metal catalysts reported previously. Furthermore, Co-N-GCA demonstrates superior durability in both the ORR and the OER, making it a promising noble-metal-free bifunctional catalyst in practical applications for energy conversion and storage.