Journal: Nature Communications

Article Title: High figure-of-merit for ZnO nanostructures by interfacing lowly-oxidized graphene quantum dots

doi: 10.1038/s41467-024-46182-2

Figure Lengend Snippet: a Illustration of graphene quantum dots (GQDs)-decorated 3D ZnO (3D GQD@ZnO) obtained by dipping the 3D ZnO into GQD solution. b Schematic of energy filtering and phonon scattering effect at grain boundaries and GQD/ZnO interfaces in the 3D GQD@ZnO. c Transmission electron microscopy (TEM) image showing decoration of GQDs in 3D ZnO. Yellow circles of Fast Fourier-Transform (FFT) patterns indicate a hexagonal pattern of GQD, and white circles show an atomic plane of wurtzite ZnO structure. The inset of c indicates a high-resolution (HR)-TEM image of GQD coated on 3D ZnO. Temperature-dependent d Seebeck coefficient, e thermal conductivity, and f Figure-of-merit ( zT ) for 3D ZnO with varying grain sizes and its heterostructure with GQDs (3D GQD@ZnO). Filled circles are measured values, and open circles indicate the estimated values obtained using a modified Debye-Callaway model. Error bars shown in the Fig. 1 represent the standard deviation (SD).

Article Snippet: The temperature-dependent electrical conductivity ( σ ) and Seebeck coefficient ( S ) of the 3D ZnO and 3D GQD@ZnO were measured using a Linseis (LSR-3) system under a He atmosphere. σ was calculated using the following formula ( ): \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{{{{\rm{\sigma }}}}}}=\frac{l}{A\cdot R}$$\end{document} σ = l A ⋅ R Here, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R$$\end{document} R , and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A$$\end{document} A are the resistance and cross-sectional area of the sample, respectively, and the distance between the two probes is represented by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$l$$\end{document} l (Supplementary Fig. ).

Techniques: Transmission Assay, Electron Microscopy, Modification, Standard Deviation

Journal: Nature Communications

Article Title: High figure-of-merit for ZnO nanostructures by interfacing lowly-oxidized graphene quantum dots

doi: 10.1038/s41467-024-46182-2

Figure Lengend Snippet: a Photograph of 3D ZnO film on the sapphire substrate. b Cross-section of scanning electron microscopy (SEM) image of 3D ZnO. c TEM image of 3D ZnO. d , e Energy dispersive spectrometer (EDS) elemental mapping images corresponding to TEM image of c . f – h TEM images of 3D ZnO samples based on annealing temperature. The insets of f – h indicate the distribution of 2D plate-like grain sizes on the surface of thin-shell ZnO corresponding to the TEM images of f – h .

Article Snippet: The temperature-dependent electrical conductivity ( σ ) and Seebeck coefficient ( S ) of the 3D ZnO and 3D GQD@ZnO were measured using a Linseis (LSR-3) system under a He atmosphere. σ was calculated using the following formula ( ): \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{{{{\rm{\sigma }}}}}}=\frac{l}{A\cdot R}$$\end{document} σ = l A ⋅ R Here, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R$$\end{document} R , and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A$$\end{document} A are the resistance and cross-sectional area of the sample, respectively, and the distance between the two probes is represented by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$l$$\end{document} l (Supplementary Fig. ).

Techniques: Electron Microscopy

Journal: Nature Communications

Article Title: High figure-of-merit for ZnO nanostructures by interfacing lowly-oxidized graphene quantum dots

doi: 10.1038/s41467-024-46182-2

Figure Lengend Snippet: Temperature-dependent a Seebeck coefficient, b electrical conductivity, and c power factor of 3D ZnO with varying grain sizes. d Optical microscopy (OM) and digital (inset) images of 3D ZnO film transferred onto a microfabricated thermoelectric measurement platform (MTMP). e Comparison of thermal conductivities of 3D ZnO samples measured on MTMP as a function of temperature. Filled circles are measured values, and open circles indicate estimated values obtained using a modified Debye-Callaway model. f Comparison of zT values of 3D ZnO samples. Error bars shown in Fig. 3 represent the SD.

Article Snippet: The temperature-dependent electrical conductivity ( σ ) and Seebeck coefficient ( S ) of the 3D ZnO and 3D GQD@ZnO were measured using a Linseis (LSR-3) system under a He atmosphere. σ was calculated using the following formula ( ): \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{{{{\rm{\sigma }}}}}}=\frac{l}{A\cdot R}$$\end{document} σ = l A ⋅ R Here, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R$$\end{document} R , and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A$$\end{document} A are the resistance and cross-sectional area of the sample, respectively, and the distance between the two probes is represented by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$l$$\end{document} l (Supplementary Fig. ).

Techniques: Microscopy, Comparison, Modification

Journal: Nature Communications

Article Title: High figure-of-merit for ZnO nanostructures by interfacing lowly-oxidized graphene quantum dots

doi: 10.1038/s41467-024-46182-2

Figure Lengend Snippet: a Digital image of bare 3D ZnO (before decorating with GQDs) and 3D GQD@ZnO (after decorating with GQDs via the solution process). b TEM image for a fragment of 3D GQD@ZnO. c , d Magnifications of b . The inset in d shows the size distribution of GQD. e Magnification of d indicating the hexagonal arrangement of GQD with a d-spacing of 0.21 nm. f FFT patterns of e . Yellow circles are hexagonal FFT patterns of GQD. g UV–Vis absorption spectra of ZnO film and GQDs. The inset shows their Tauc plots. h Low and high-binding energies of ZnO film and GQDs, respectively, obtained from ultraviolet photoelectron spectroscopy (UPS) spectra. i Schematics of energy filtering and phonon scattering at GQD/ZnO interface based on the calculated energy-band structure.

Article Snippet: The temperature-dependent electrical conductivity ( σ ) and Seebeck coefficient ( S ) of the 3D ZnO and 3D GQD@ZnO were measured using a Linseis (LSR-3) system under a He atmosphere. σ was calculated using the following formula ( ): \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{{{{\rm{\sigma }}}}}}=\frac{l}{A\cdot R}$$\end{document} σ = l A ⋅ R Here, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R$$\end{document} R , and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A$$\end{document} A are the resistance and cross-sectional area of the sample, respectively, and the distance between the two probes is represented by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$l$$\end{document} l (Supplementary Fig. ).

Techniques: Binding Assay, Spectroscopy

Journal: Nature Communications

Article Title: High figure-of-merit for ZnO nanostructures by interfacing lowly-oxidized graphene quantum dots

doi: 10.1038/s41467-024-46182-2

Figure Lengend Snippet: Temperature-dependent a Seebeck coefficient, b thermal conductivity, and c zT of 3D ZnO (small grain) and 3D GQD x @ZnO ( x \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$=$$\end{document} = 1, 2, 3, and 4). Filled circles are measured values and open circles are estimated values. d Comparison of previously reported non-nanostructuring and nanostructuring approaches to the thermal conductivity of ZnO as a function of temperature. Filled star is measured values and open stars are estimated values. e Temperature-dependent zT values of previously reported nanostructured ZnO-based thermoelectric materials. Error bars shown in the Fig. 5 represent the SD.

Article Snippet: The temperature-dependent electrical conductivity ( σ ) and Seebeck coefficient ( S ) of the 3D ZnO and 3D GQD@ZnO were measured using a Linseis (LSR-3) system under a He atmosphere. σ was calculated using the following formula ( ): \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{{{{\rm{\sigma }}}}}}=\frac{l}{A\cdot R}$$\end{document} σ = l A ⋅ R Here, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R$$\end{document} R , and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$A$$\end{document} A are the resistance and cross-sectional area of the sample, respectively, and the distance between the two probes is represented by \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$l$$\end{document} l (Supplementary Fig. ).

Techniques: Comparison