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In this study, we report highly stable photoactive quaternary metal chalcogenide Cu2ZnSnS4 nanocrystals synthesis from low cost, ecofriendly, non-toxic and earth-abundant elements for photovoltaic devices. Their electro-optical properties such as, tunable band gap, high-absorption coefficient and wide absorption window make them highly suitable materials to be utilized as absorber layer and counter electrode in various types of solar cells. For this purpose, first we synthesized Cu2ZnSnS4 nanocrystals by colloidal, co-precipitation, wet chemical and hydrothermal methods using stabilizing agents under variable reaction conditions. Afterwards, hydrothermal method was employed to synthesize nanocrystals of Cu2CoSnS4, Cu2FeSnS4, Cu2SrSnS4 and Cu2NiSnS4 by replacing Zn with Co, Fe, Sr and Ni metals. The UV–Vis absorption spectra indicate the nanocrystals can absorb entire visible region of electromagnetic radiation and their band gaps range from 1.5 to 1.7 eV. The X-ray diffraction (XRD) patterns confirm the formation of kieserite phase of all nanocrystals with a crystallite size of approximately 6–10 nm. These nanocrystals are coated on surface of the synthesized ZnO nanoparticles to study their application as absorbing layer in quantum dots-sensitized solar cells (QDSSCs). Moreover, they were adsorbed on ITO substrate to study their utilization as counter electrode of dye-sensitized solar cells (DSSCs). The solar cells exhibit efficiencies of 1.2–1.8%, which prove the synthesized nanocrystals can perform excellent role as light absorber and counter electrode in any kind of solar cell device. [ABSTRACT FROM AUTHOR]

Flexible supercapacitors (SCs) have shown great potential for portable electronic devices due to ultra-long lifetime and high power characteristics. However, low energy densities of SCs hinder their practical applications. Herein, mesoporous C60 fullerene micro-particles (mCF) are prepared using Krätschmer-Huffman method, followed by solvent extraction and column chromatography for purification. The as-prepared mCF is characterized by XRD, EIMS, XPS, EDX, SEM, Raman spectroscopy and BET analysis, respectively. The mCF supported on carbon cloth (mCF@CC) is used as the electrode to study charge storage properties. The mCF@CC exhibits excellent capacitance of 440 F/g at 2 A/g, good rate capability of 84.85% at high current density of 12 A/g and stable life up to 10000 cycles. Additionally, the mCF@CC electrode possesses good flexible characteristics and presents almost same performance after 1000 bending cycles. Thus, mesoporous C60 fullerene micro-particles can be employed as negative electrode material for the flexible next generation supercapacitors. [ABSTRACT FROM AUTHOR]

Calcium-doped lanthanum chromates La1−xCaxCrO3 (0 ≤ x ≤ 0.4) are successfully synthesized using sol-gel method. The La1−xCaxCrO3 powders were characterized using X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy and Ultraviolet-Visible spectroscopy. To determine appropriate calcination temperature, the thermal decomposition process of La0.8Ca0.2CrO3 precursor is investigated via thermogravimetric and differential scanning calorimetry, X-ray diffraction and Fourier Transform Infrared spectroscopy analyses. The highest crystallization in La0.8Ca0.2CrO3 can be obtained while calcining at 800 °C. The microstructural analyses demonstrate that the La1−xCaxCrO3 nanoperovskite powders with a diameter of ~ Ø20 nm are nearly spherical, whereas the grain sizes decrease with increasing the doping concentration of calcium. The substantial formation of Cr6+ ions after Ca-doping decrease the band gap energy of powders achieved during the formation of impurity energy level, which can contribute in potential optical applications. [ABSTRACT FROM AUTHOR]

Three dimensional (3D) hierarchical NiCo2O4 nanosheet arrays (NSAs)@ZnWO4 nanoflakes (NFs) core-shell structures have been successfully grown on a carbon cloth (CC) using two-step hydrothermal approach, following a heat treatment route. Compared with the pure CC@NiCo2O4 NSAs electrode, the binder-free CC@NiCo2O4@ZnWO4 hybrid system gives rise to a higher specific capacitance of 872.0 Fg−1 at a low current density of 1 Ag−1 and 791.1 Fg−1 at a quite high current density of 20 Ag−1, and retains ~ 92.9% of the initial capacitance even after 5000 cycles of charge and discharge. The excellent electrochemical performance of CC@NiCo2O4@ZnWO4 electrode is attributed to its high specific surface area of the 3D structures, fast electron transport property of NiCo2O4 material as the skeleton, and the synergistic effect between NiCo2O4 and ZnWO4 materials, demonstrating that CC supported NiCo2O4 NSAs@ZnWO4 NFs composite as the high-performance electrode materials are highly desirable for the application of flexible supercapacitors. [ABSTRACT FROM AUTHOR]

Ag-doped NiO porous network structure grown on Ni foam has been synthesized through a facile hydrothermal method. Then network structure is assembled by numerous interconnected superfine nanowires, and Ag is uniformly distributed in the body of NiO network. The unique porous network structure doped by conductive Ag and the direct integration of electrode materials on Ni foam current collector provide efficient pathways for electron transport and electrolyte ions diffusion. The electrochemical results demonstrate that the Ag-doped NiO electrode exhibits a specific capacitance of 570.7 F g and excellent cycling stability. The Ag-doped NiO electrode with relatively high electrochemical performance is a promising candidate for the supercapacitor electrodes. These results can also provide strategies to develop advanced electrode materials supercapacitor applications. [ABSTRACT FROM AUTHOR]

Nest-like hollow structure of MnO was synthesized via a simple and facile hydrothermal procedure without using any template or surfactant. The morphology of MnO nanostructures can be easily controlled by altering the reaction time. The architectural feature of hollow nest-like MnO was investigated by using field emission scanning electron microscopy, transmission electron microscopy, and high-resolution transmission electron microscopy. This nest-like hollow nanosphere of MnO exhibits prominent electrochemical properties, such as the considerable specific capacitance of 211.1 F g at 1 A g, excellent voltammograms property and the remarkable long-term cycling stability with 93.6 % surplus of capacitance after 1000 cycles. From the above, this nest-like hollow nanostructured MnO is a promising electrode material for supercapacitor. [ABSTRACT FROM AUTHOR]

Cr-doped MnO nanostructure has been fabricated via a facile hydrothermal method and its morphology and electrochemical properties was discussed systematically. In this process, flower-like MnO transforms into the self-assembled orchid structure under the influence of Cr-doped. Moreover, electrochemical behaviors of the Cr-doped MnO nanostructure electrode were clarified by cyclic voltammograms, galvanostatic charge/discharge tests and electrochemical impedance spectroscopy, which shows a high specific capacitance of 202.5 F g and superior cycling stability (6.8 % capacitance decay after 1000 cycling test). These remarkable and excellent results prove it has a great potential of application in future energy storage device. [ABSTRACT FROM AUTHOR]

Nanocrystalline CeO and ZnCeO materials are prepared using solution-combustion synthesis annealed at temperature of 350 °C. The architectural changes of crystal structure of pure and doped materials are characterized thorough corresponding XRD, SEM and TEM analysis. The surface activities are investigation and optical analyses of CeO2 and ZnCeO2 materials are characterized by atomic force microscopy, and UV-Vis spectroscopy. Blue-shift in PL spectrum indicated the presence of Zn on CeO. The bond confirmation of Ce-O and Zn-O were perceived using IR and Raman spectra. The as-prepared nanostructures were exposed to ethanol for gas-sensing properties. [ABSTRACT FROM AUTHOR]

In this paper, chrysanthemum-like tungsten disulfide (WS) nanostructure was synthesized by a facile hydrothermal solution route with the assistance of cetyltrimethyl ammonium bromide and Pluronic (F-127). The as-prepared products were characterized by X-ray powder diffraction, scanning electron microscopy and ultraviolet-visible spectrometer. The experimental results indicated the polymer-surfactant complexes have significant effects on the morphology of the as-prepared products. A possible formation mechanism has also been investigated based on the interaction behavior of polymer-surfactant complexes in aqueous solution. The chrysanthemum-like WS nanostructures have good optical absorption property. This well-controlled synthesis approach may be extended to fabricate complex structures of other transition metal sulfide materials. [ABSTRACT FROM AUTHOR]