Solvothermal-Assisted Hybridization between Reduced Graphene Oxide and Lithium Metal Oxides: A Facile Route to Graphene-Based Composite Materials

• Published in: Journal of physical chemistry. C Vol. 116; no. 13; pp. 7269 - 7279
• Main Authors: Han, Song Yi, Kim, In Young, Jo, Kyung Yeon, Hwang, Seong-Ju
• Format: Journal Article
• Language: English
• Published: Columbus, OH American Chemical Society 05.04.2012
• Subjects: Chemical synthesis methods; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Fullerenes and related materials; diamonds, graphite; Materials science; Methods of nanofabrication; Nanoscale materials: clusters, nanoparticles, nanotubes, and nanocrystals; Physics; Specific materials; Structure of solids and liquids; crystallography; Raman spectra; Nanosheet; Photoluminescence; Solvothermal synthesis; Electron transfer; Hybridization; Reflection spectrum; Carbon carbon bond; Chemical bonds; Crystal morphology; Nanomaterial synthesis; Crystal structure; Nanoplate; Ethanol; Diffuse reflection; Photocatalysis; Ultraviolet spectra; Titanates; Photocurrents; Raman spectroscopy; Carbon; Composite materials; Nanocomposites; Graphene; Graphite; Lithium oxide; Photoconductivity; Catalyst activity; X-ray photoelectron spectra
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp301508k

Hybridization between lithium metal oxide and reduced graphene oxide, or RGO, can be achieved by the solvothermal treatment of the water/ethanol-based suspension of graphite oxide, or GO, nanosheets containing powdery lithium metal oxide. The solvothermal treatment for the mixture suspension of GO and Li4Ti5O12 gives rise not only to the reduction of GO to RGO but also to the attachment of the Li4Ti5O12 particles to the flat surface of RGO 2D nanosheets. The crystal structure and crystal morphology of the Li4Ti5O12 particles remain intact after the composite formation with the RGO nanosheets. The formation of chemical bonds and internal electron transfer between the RGO and Li4Ti5O12 components is evidenced by micro-Raman and X-ray photoelectron spectroscopy, showing the weakening of the carbon–carbon bonds and the formation of carbon–oxygen bonds. In comparison with the pristine Li4Ti5O12 material, the Li4Ti5O12–RGO nanocomposites display better anode performance with a larger discharge capacity of ∼175 mAhg–1, underscoring the merit of RGO hybridization in improving the electrode performance of bulk metal oxide. Diffuse reflectance UV–vis and photoluminescence spectroscopic analyses reveal a strong electrical connection between lithium titanate and RGO, which is mainly responsible for the observed improvement of the electrode performance upon the composite formation. In addition to the electrode performance, the photocatalytic activity of the lithium titanate for the generation of photocurrent can be remarkably enhanced by the coupling with RGO, confirming the usefulness of the present synthetic method in optimizing the photoinduced functionality of metal oxides. The solvothermal strategy presented here is also applicable for the synthesis of LiMn2O4–RGO nanocomposite showing much superior electrode performance over the pristine LiMn2O4. The experimental findings underscore that the present synthetic method can provide a universal way to not only immobilize multicomponent metal oxides on the surface of RGO nanosheets with a strong electrical connection but also improve the electrode and photocatalytic activity of these metal oxides.