An Electrochemical in Situ Infrared Spectroscopic Study of Graphene/Electrolyte Interface under Attenuated Total Reflection Configuration

详细信息    查看全文

• 作者：Yao Yao ; Wei Chen ; Yuanxin Du ; Zhuchen Tao ; Yanwu Zhu ; Yan-Xia Chen
• 刊名：Journal of Physical Chemistry C
• 出版年：2015
• 出版时间：October 1, 2015
• 年：2015
• 卷：119
• 期：39
• 页码：22452-22459
• 全文大小：641K
• ISSN：1932-7455

文摘

The interface of electrodes composed of 2, 3, or 5 monolayers (MLs) of graphene stacked on a Si prism in 0.1 M HClO₄ is examined by electrochemical in situ infrared spectroscopy under attenuated total reflection configuration (EC-ATR-FTIRS) combined with cyclic voltammetry in a wide potential window from 0 to 3. 0 V. At 5 MLs graphene, we observe significant oxidation current at E > 2.0 V in the first positive-going scan. This is accompanied by the appearance of three negative-pointing bands at 1230 cm^鈥? (C-O-C stretching), 1630 cm^鈥? (from both bending of water and C鈺怌 stretching), and 3300 cm^鈥? (O-H stretching of C-OH and water), suggesting the consumption of C-O-C, C鈺怌, C-OH, and water. The CVs for the second cycle are quite similar to what was observed for the first cycle, only that the current is ca. 10 times smaller. The general trends of the i鈥?i>E curves and IR spectral behavior at 2 MLs and 3 MLs graphene are also the same as those at 5 MLs graphene; only the current and band intensities at the corresponding potentials are much smaller than those at the latter. Our results suggest that the edge sites and the defects of graphene are probably the active sites for the oxidation of water at the graphene surface at E > 2.0 V, which can be easily destroyed through oxidation at such high potentials. Within the potential region of 0.05 V < E < 1.5 V, the high stability of the graphene layer makes it a promising support for nanocatalysts using EC-ATR-FTIRS.