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) molecu...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 e V(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.展开更多
Graphene,a rapidly rising star on the horizon of material science,has a unique two-dimensional nanostructure as well as exceptional mechanical and electronic properties.Despite its short history,graphene has exhibited...Graphene,a rapidly rising star on the horizon of material science,has a unique two-dimensional nanostructure as well as exceptional mechanical and electronic properties.Despite its short history,graphene has exhibited great potential in various applications.In order to implement the potential applications,functionalization of graphene is necessary to obtain uniform dispersions for good processability.Two kinds are dominant for functionalization such as covalent and non-covalent methods.The former is based on the formation of covalent bonds,and the latter the interaction among molecules.In this review,we summarized briefly the recent progress of functionalized graphene sheets (FGs) in different fields,such as optoelectronic materials,sensors,energy storage materials,catalytic,reinforcing components and so on,and also prospected the development trend of FGs in the future.展开更多
Band gap, which can be tuned by changing the size of quantum dots (QDs) based on the quantum confinement effect, plays a fundamental role in electrical and optical properties of QDs. However, the tuning of the band ga...Band gap, which can be tuned by changing the size of quantum dots (QDs) based on the quantum confinement effect, plays a fundamental role in electrical and optical properties of QDs. However, the tuning of the band gap by changing the size results in a series of intrinsic problems, such as the instability of the extremely small QDs, negative combination with biomolecules because of the large size of QDs, etc. Recently, several new methods have been developed to further study and improve the tuning of the band gap. In this paper, we summarized the recent progress in the fields of tuning the band gap of QDs, including alloyed QDs, core-shell QDs and doped QDs. The review has also prospected the development trend of tuning the band gap as well as their applications.展开更多
基金supported by the National Natural Science Funds for Distinguished Young Scholars(Grant No.51425306)the National Natural Science Foundation of China(Grant Nos.51273144,51373116,51573215&51411140036)+1 种基金the Natural Science Foundation of Tianjin City(Grant No.14JCZDJC37900)the Program for New Century Excellent Talents in University(Grant No.NCET-13-0403)
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 e V(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.
基金supported by the National Natural Science Foundation of China(Grant Nos.50873074,51011140072)the National Basic Research Program of China("973"Project)(Grant No.2010CB934700)the Natural Science Foundation of Tianjin City(Grant No.10JCZDJC22400)
文摘Graphene,a rapidly rising star on the horizon of material science,has a unique two-dimensional nanostructure as well as exceptional mechanical and electronic properties.Despite its short history,graphene has exhibited great potential in various applications.In order to implement the potential applications,functionalization of graphene is necessary to obtain uniform dispersions for good processability.Two kinds are dominant for functionalization such as covalent and non-covalent methods.The former is based on the formation of covalent bonds,and the latter the interaction among molecules.In this review,we summarized briefly the recent progress of functionalized graphene sheets (FGs) in different fields,such as optoelectronic materials,sensors,energy storage materials,catalytic,reinforcing components and so on,and also prospected the development trend of FGs in the future.
基金supported by the National Natural Science Foundation of China (Grant Nos. 51073115, 51003072, 51173127, 51011140072)the National Basic Research Program of China ("973" Program) (Grant No. 2010CB934700)the Natural Science Foundation of Tianjin City (Grant No. 10JCZDJC22400)
文摘Band gap, which can be tuned by changing the size of quantum dots (QDs) based on the quantum confinement effect, plays a fundamental role in electrical and optical properties of QDs. However, the tuning of the band gap by changing the size results in a series of intrinsic problems, such as the instability of the extremely small QDs, negative combination with biomolecules because of the large size of QDs, etc. Recently, several new methods have been developed to further study and improve the tuning of the band gap. In this paper, we summarized the recent progress in the fields of tuning the band gap of QDs, including alloyed QDs, core-shell QDs and doped QDs. The review has also prospected the development trend of tuning the band gap as well as their applications.
