Photoreaction of Graphene Oxide Nanosheets in Water

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• 作者：Yasumichi Matsumoto ; Michio Koinuma ; Shintaro Ida ; Shinya Hayami ; Takaaki Taniguchi ; Kazuto Hatakeyama ; Hikaru Tateishi ; Yusuke Watanabe ; Satoru Amano
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：October 6, 2011
• 年：2011
• 卷：115
• 期：39
• 页码：19280-19286
• 全文大小：948K
• 年卷期：v.115,no.39(October 6, 2011)
• ISSN：1932-7455

文摘

Graphene oxide (GO) nanosheets have many semiconducting 蟺-conjugated sp² domains of various sizes within an oxygenated sp³ domain. The chemical and physical properties, therefore, can be widely tuned by adjusting the degree of oxidation through photoreaction, because the semiconducting domains act as a semiconducting photocatalyst when irradiated with light of energy exceeding the band gap of the domains. In this paper, we report new photoreactions similar to photocatalytic reactions in which H₂ and CO₂ are evolved from an aqueous suspension of GO nanosheets under UV irradiation; these reactions are based on the photoreactions of oxygen-containing functional groups and carbon. As a result, reduced GO (rGO) nanosheets with many holes and defects were produced. We conjecture that some carbons in the holes belong to zigzag edges, CH bonds, or both and that the rGO nanosheets therefore have ferromagnetic properties. In photoelectrochemical measurements of a GO nanosheet electrode, a large anodic photocurrent was generated by the CO₂ evolution reaction and a small cathodic photocurrent was generated by reduction of oxygen-containing functional groups and the H₂ evolution reaction. The mechanism of the photoreaction between GO nanosheets and water is discussed in terms of band energy levels estimated from experimental results.