Self-assembled Co 3 O 4 hexagonal plates by solvent engineering and their dramatically enhanced electrochemical performance

• Published in: Nanoscale 2017-01, Vol.9 (2), p.940-946
• Main Authors: Zhao, W, Zhou, X, Kim, I Jin, Kim, S
• Format: Article
• Language: English
• ISSN: 2040-3364; 2040-3372
• DOI: 10.1039/c6nr07871k

In this study, a facile two-phase solvothermal method was used to synthesize Co O nanocubes with high crystallinity and narrow size distribution (∼49 nm) for use in lithium-ion batteries. Here, oleylamine (OAm) was chosen as the solvent, surfactant, and reducing agent. After washing with the appropriate organic solvent, the Co O nanocubes self-assembled into hexagonal plates with a diameter and thickness of approximately 2.5 μm and 550 nm, respectively. Moreover, with the assistance of dipole-dipole and van der Waals interactions, the Co O nanocubes stacked along the [111] direction with their exposed facets attached, leading to their final exposed cross-sectional facet being (111). A possible assembling mechanism is proposed and explained in detail. Furthermore, the self-assembled (111) faceted Co O plates exhibited superior electrochemical capacity and stability to those original (001) faceted Co O nanocubes for Li ion storage. Therefore, the solvent engineered self-assembly into secondary structures has proven to be a potential strategy for energy applications.