Azobenzene/graphene hybrid for high-density solar thermal storage by optimizing molecular structure

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• 作者：Man Li ; YiYu Feng ; EnZuo Liu ; ChengQun Qin…
• 关键词：solar thermal energy storage ; azobenzene ; graphene ; hydrogen bonds ; density functional theory
• 刊名：SCIENCE CHINA Technological Sciences
• 出版年：2016
• 出版时间：September 2016
• 年：2016
• 卷：59
• 期：9
• 页码：1383-1390
• 全文大小：1,301 KB
• 刊物类别：Engineering
• 刊物主题：Chinese Library of Science
  Engineering, general
  
• 出版者：Science China Press, co-published with Springer
• ISSN：1869-1900
• 卷排序：59

文摘

A large capacity storing solar energy as latent heat in a close-cycle is essentially important for solar thermal fuels. This paper presents a solar thermal molecule model of a photo-isomerizable azobenzene (Azo) molecule covalently bound to graphene. The storage capacity of the Azo depending on isomerization enthalpy (ΔH) is calculated based on density functional theory. The result indicates that the ΔH of Azo molecules on the graphene can be tuned by electronic interaction, steric hindrance and molecular hydrogen bonds (H-bonds). Azo with the withdrawing group on the ortho-position of the free benzene shows a relatively high ΔH due to resonance effect. Moreover, the H-bonds on the trans-isomer largely increase ΔH because they stabilize the trans-isomer at a low energy. 2-hydroxy-4-carboxyl-2′,6′,-dimethylamino-Azo/graphene shows the maximum ΔH up to 1.871 eV (107.14 Wh kg-1), which is 125.4% higher than Azo without functional groups. The Azo/graphene model can be used for developing high-density solar thermal storage materials by controlling molecular interaction.