Author
Yuan-Ron Ma
Other affiliations: University of Nottingham
Bio: Yuan-Ron Ma is an academic researcher from National Dong Hwa University. The author has contributed to research in topics: Nanorod & Materials science. The author has an hindex of 21, co-authored 51 publications receiving 2134 citations. Previous affiliations of Yuan-Ron Ma include University of Nottingham.
Papers
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TL;DR: A comprehensive review of recent developments in novel synthesis, exceptional characteristics, and prominent applications of one-dimensional nanostructures of tungsten oxides, molybdenum oxide, tantalum oxides and tin oxides is provided in this article.
Abstract: 1D metal-oxide nanostructures have attracted much attention because metal oxides are the most fascinating functional materials. The 1D morphologies can easily enhance the unique properties of the metal-oxide nanostructures, which make them suitable for a wide variety of applications, including gas sensors, electrochromic devices, light-emitting diodes, field emitters, supercapacitors, nanoelectronics, and nanogenerators. Therefore, much effort has been made to synthesize and characterize 1D metal-oxide nanostructures in the forms of nanorods, nanowires, nanotubes, nanobelts, etc. Various physical and chemical deposition techniques and growth mechanisms are exploited and developed to control the morphology, identical shape, uniform size, perfect crystalline structure, defects, and homogenous stoichiometry of the 1D metal-oxide nanostructures. Here a comprehensive review of recent developments in novel synthesis, exceptional characteristics, and prominent applications of one-dimensional nanostructures of tungsten oxides, molybdenum oxides, tantalum oxides, vanadium oxides, niobium oxides, titanium oxides, nickel oxides, zinc oxides, bismuth oxides, and tin oxides is provided.
695 citations
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TL;DR: In this article, the synthesis of nanostructured ruthenium (Ru) doped copper oxide (CuO) thin films by colloidal solution method and ionic liquid is presented.
140 citations
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TL;DR: In this article, the structural, dielectric, and electrical transport properties of CFEO were investigated in detail, which revealed the formation of spherical, elongated grains with stoichiometric presence of Co, Fe, Er, and O. The relaxation time and spread factor obtained from e′ dispersion are ∼10−3 s and ∼0.50 (± 0.10), respectively.
Abstract: Erbium (Er3+) substituted nanocrystalline, cobalt-rich ferrites, which can be represented chemically as Co1.1Fe1.9–xErxO4 (CFEO; x = 0.0–0.2), were synthesized by the sol–gel autocombustion method. The structural, dielectric, and electrical transport properties of CFEO were investigated in detail. CFEO materials crystallize in a spinel cubic structure for x ≤ 0.10; formation of orthoferrite (ErFeO3) secondary phase was noted for x ≥ 0.15. Microstructural and compositional studies revealed the formation of spherical, elongated grains with stoichiometric presence of Co, Fe, Er, and O. The dielectric constant (e′) dispersion fits to the Debye’s function for all CFEO ceramics. The relaxation time and spread factor obtained from e′ dispersion are ∼10–3 s and ∼0.50 (±0.10), respectively. The complex impedance analyses confirm a grain-interior mechanism contributing to the dielectric properties. Semiconducting behavior and small polaron conduction mechanism were evident in electrical transport properties of CFEO...
137 citations
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TL;DR: A broadband visible photoluminescence is observed in the wavelength region 500-900 nm, also indicating the extension of luminescence into the near-infrared region and the existence of broadband visible emission can be attributed to the exist of defect/impurity states induced by oxygen vacancies.
Abstract: We report the synthesis of one-dimensional (1D) Bi2O3 nanohooks by the oxidative metal vapor phase deposition technique. Surface morphology observations confirm the formation of 1D nanohooks with nanoparticles at their tips. Structural analysis by x-ray diffraction (XRD) and transmission electron microscopy (TEM) reveals the crystalline nature of the 1D nanostructure. Elemental analysis confirms that the 1D nanohooks consist of only elements Bi and O. The XRD study suggests that the synthesized product is of two phases (α- and β-Bi2O3) with monoclinic and tetragonal crystal structures respectively. The phonon vibration modes corresponding to Bi2O3 are determined by Raman scattering. A broadband visible photoluminescence (PL) is observed in the wavelength region 500–900 nm, also indicating the extension of luminescence into the near-infrared region. The existence of broadband visible emission can be attributed to the existence of defect/impurity states induced by oxygen vacancies.
130 citations
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TL;DR: One-dimensional (1D) MoO2 nanorods in the form of a large-area array and nanobranched structure were prepared by hot-filament metal?oxide vapour deposition at low and high pressures in atmospheric argon flows respectively as discussed by the authors.
Abstract: One-dimensional (1D) MoO2 nanorods in the form of a large-area array and nanobranched structure were prepared by hot-filament metal?oxide vapour deposition at low and high pressures in atmospheric argon flows respectively. The x-ray diffraction (XRD) patterns of both as-synthesized samples show that the 1D MoO2 nanorods are monoclinic crystals in space group P 21/c. The Raman spectrum of the large-area array of 1D MoO2 nanorods appears to be the same as that of a two-dimensional (2D) MoO2 thin film. The Raman spectrum of the nanobranched structure of 1D MoO2 nanorods showed a downshift and asymmetric broadening of the Raman first-order TO peak when compared with the bulk (q = 0) mode. The Raman shift and broadening were attributed to phonon confinement effect in the 1D nanorods. The in?situ Raman spectra of laser-induced oxidation of the nanobranched structure of 1D MoO2 nanorods demonstrate that they can be oxidized easily and more strongly than the 3D bulk MoO2 powder.
129 citations
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2,643 citations
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TL;DR: The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature, and challenges in producing high-performing electrolytes are analyzed.
Abstract: Electrolytes have been identified as some of the most influential components in the performance of electrochemical supercapacitors (ESs), which include: electrical double-layer capacitors, pseudocapacitors and hybrid supercapacitors. This paper reviews recent progress in the research and development of ES electrolytes. The electrolytes are classified into several categories, including: aqueous, organic, ionic liquids, solid-state or quasi-solid-state, as well as redox-active electrolytes. Effects of electrolyte properties on ES performance are discussed in detail. The principles and methods of designing and optimizing electrolytes for ES performance and application are highlighted through a comprehensive analysis of the literature. Interaction among the electrolytes, electro-active materials and inactive components (current collectors, binders, and separators) is discussed. The challenges in producing high-performing electrolytes are analyzed. Several possible research directions to overcome these challenges are proposed for future efforts, with the main aim of improving ESs' energy density without sacrificing existing advantages (e.g., a high power density and a long cycle-life) (507 references).
2,480 citations
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TL;DR: The exciting successes in taming molecular-level movement thus far are outlined, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion are highlighted.
Abstract: The widespread use of controlled molecular-level motion in key natural processes suggests that great rewards could come from bridging the gap between the present generation of synthetic molecular systems, which by and large rely upon electronic and chemical effects to carry out their functions, and the machines of the macroscopic world, which utilize the synchronized movements of smaller parts to perform specific tasks. This is a scientific area of great contemporary interest and extraordinary recent growth, yet the notion of molecular-level machines dates back to a time when the ideas surrounding the statistical nature of matter and the laws of thermodynamics were first being formulated. Here we outline the exciting successes in taming molecular-level movement thus far, the underlying principles that all experimental designs must follow, and the early progress made towards utilizing synthetic molecular structures to perform tasks using mechanical motion. We also highlight some of the issues and challenges that still need to be overcome.
2,301 citations
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TL;DR: The constituent, the structure and the properties of the carbon-metal oxide composites, including the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability are described.
Abstract: This paper presents a review of the research progress in the carbon–metal oxide composites for supercapacitor electrodes. In the past decade, various carbon–metal oxide composite electrodes have been developed by integrating metal oxides into different carbon nanostructures including zero-dimensional carbon nanoparticles, one-dimensional nanostructures (carbon nanotubes and carbon nanofibers), two-dimensional nanosheets (graphene and reduced graphene oxides) as well as three-dimensional porous carbon nano-architectures. This paper has described the constituent, the structure and the properties of the carbon–metal oxide composites. An emphasis is placed on the synergistic effects of the composite on the performance of supercapacitors in terms of specific capacitance, energy density, power density, rate capability and cyclic stability. This paper has also discussed the physico-chemical processes such as charge transport, ion diffusion and redox reactions involved in supercapacitors.
1,800 citations
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TL;DR: In this paper, the authors reviewed several key issues for improving the energy densities of supercapacitors and some mutual relationships among various effecting parameters, and challenges and perspectives in this exciting field are discussed.
Abstract: In recent years, tremendous research effort has been aimed at increasing the energy density of supercapacitors without sacrificing high power capability so that they reach the levels achieved in batteries and at lowering fabrication costs For this purpose, two important problems have to be solved: first, it is critical to develop ways to design high performance electrode materials for supercapacitors; second, it is necessary to achieve controllably assembled supercapacitor types (such as symmetric capacitors including double-layer and pseudo-capacitors, asymmetric capacitors, and Li-ion capacitors) The explosive growth of research in this field makes this review timely Recent progress in the research and development of high performance electrode materials and high-energy supercapacitors is summarized Several key issues for improving the energy densities of supercapacitors and some mutual relationships among various effecting parameters are reviewed, and challenges and perspectives in this exciting field are also discussed This provides fundamental insight into supercapacitors and offers an important guideline for future design of advanced next-generation supercapacitors for industrial and consumer applications
1,761 citations