Experimental Study on Photocatalytic Activity of Cu 2 O/Cu Nanocomposites Under Visible Light
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Experimental Study on Photocatalytic Activity of Cu2O/Cu Nanocomposites Under Visible Light Bo Zhou Æ Zhiguo Liu Æ Hongxia Wang Æ Yanqiang Yang Æ Wenhui Su
Received: 16 January 2009 / Accepted: 5 June 2009 / Published online: 18 June 2009 Ó Springer Science+Business Media, LLC 2009
Abstract Cu2O/Cu nanocomposites (NCs) are synthesized using a two-step hydrothermal method, their different phase compositions are obtained by adjusting the reaction time, and then, they are used as photocatalysts to degrade dye Procion Red MX-5B (PR), methylene blue (MB) and methyl orange (MO) under visible-light. Experimental results indicate Cu2O/Cu NCs exhibit a much higher photocatalytic activity than pure Cu2O, they remain almost unchanged in their phase compositions in the long photocatalytic reaction process, except for partial oxidation of particle surface. They still exhibit a high photocatalytic activity even at the end of four photocatalytic reaction cycles. It can therefore be concluded that Cu2O/Cu nanocomposites are good candidates for processing of pollutant water. Keywords Cu2O/Cu Nanocomposites Hydrothermal method Photocatalyst
B. Zhou Z. Liu (&) Y. Yang W. Su Department of Physics, Center for Condensed Matter Science and Technology, Harbin Institute of Technology, 150080 Harbin, China e-mail: [email protected] B. Zhou e-mail: [email protected] H. Wang College of Chemistry and Chemical Engineering, Harbin Normal University, 150025 Harbin, China W. Su International Center for Materials Physics, Academia Sinica, 110015 Shenyang, China
1 Introduction It is increasingly important nowadays to find possible solutions to environmental pollution problems. Photo-degradation is one of the ways to treat polluted water and air. Semiconductor-based photocatalysts have attracted much attention from the research community because of their low cost and availability, TiO2 and ZnO are the most commonly used ones. However, the broad band gap (3.0–3.2 eV) of TiO2 or ZnO-based photocatalysts limits their applications because they can be activated by ultraviolet (UV) light only [1–4]. The maximum irradiation of sunlight lies in the visible range, and so, only photocatalysts with corresponding band gap can make full use of the solar energy. Cuprous oxide (Cu2O) has a direct band gap of ca. 2.2 eV, and it is therefore widely used for solar energy conversion [5–7], photocatalytic degradation of organic pollutants [8, 9] and decomposition of water into O2 and H2 [10, 11]. Another important quality of photocatalysts is quantum efficiency. Due to the easy recombination between photoelectrons and holes, pure semiconductors exhibit a very low quantum efficiency. The quantum efficiency can be improved by adding noble metal (e.g., Ag, Au, Cu, Pt) into photocatalysts to quickly transfer photogenerated electrons, and prevent the recombination, so that the metal/semiconductor heterostructure exhibits an excellent photocatalytic activity [11–17]. However, to the best of our knowledge, not much work has been done so far on the synthesis
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