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- Materials such as ternary MIMIIIE2 (where MI = Ag, Cu; MIII = In, Fe; E = S, Se) chalcopyrite-type nanocrystals have garnered interest recently because of their size- and composition-tunable electronic and optical properties. However, controlling the composition of multinary compounds is challenging due to the difference in reactivity of the involved components. Metal–organic precursors usually provide better control over stoichiometry due to preformed bonds. Herein, we have synthesized suitable sulfur-based (dihexyldithiocarbamato) and selenium-based (tetradiphenylimidodiselnodiphosphanate) metal-organic precursors of iron for the preparation of phase pure ternary CuFeS2 and CuFeSe2 nanocrystals, via hot injection route using oleylamine as solvent, decomposition initiator and capping agent. The nanomaterials were characterized by powder-X-ray diffraction (p-XRD), high resolution-transmission electron microscopy (HR-TEM), TEM, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and ultraviolet–visible (UV–Vis) analysis. The effect of temperature on synthesized nanoparticles was also investigated, showing that the size and morphology change from particles to sheet-like structures. The band gap of synthesized nanomaterials also showed variation along with the temperature change. The study shows a facile route for composition and morphologically controlled ternary chalcopyrite nanomaterials.
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- Different alkyl xanthate complexes of cobalt (alkyl = Ethyl, Hexyl, Octyl) were synthesized and used for the synthesis of nanoparticles by a solvent-less route. The p-XRD of the nanoparticles showed the formation of the CoS phase only from all precursors. The effect of size and surface capping on energy generation and energy storage applications was investigated. The electrocatalytic performance of the synthesized samples for hydrogen (HER) and oxygen evolution reaction (OER), indicates that CoS synthesized from the octyl xanthate complex (CoS-Oct) showed higher electrocatalytic performance. A lower over potential of 325 mV and 200 mV was observed for CoS-Oct, at a current density of 10 mA/cm2, for OER and HER, respectively. The charge storage performance was also investigated, where an inverse trend was observed i.e. the highest specific capacitance (1500 F/g, at scan rate 2 mV/s) was observed for the CoS sample synthesized from ethyl xanthate (CoS-ET). Similarly, the discharge time for CoS-ET was longer as compared to the other samples, suggesting better performance for the charge storage applications. The use of cobalt xanthate complexes for the preparation of CoS by melt method, and the effect of self-capped and uncapped surface of CoS on supercapacitance and OER/HER performance, has never been investigated before.
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- The development of cost-effective, functional materials that can be efficiently used for sustainable energy generation is highly desirable. Herein, a new molecular precursor of bismuth (tris(selenobenzoato)bismuth(III), [Bi(SeOCPh)3]), has been used to prepare selectively Bi or Bi2Se3 nanosheets via a colloidal route by the judicious control of the reaction parameters. The Bi formation mechanism was investigated, and it was observed that the trioctylphosphine (TOP) plays a crucial role in the formation of Bi. Employing the vapor deposition method resulted in the formation of exclusively Bi2Se3 films at different temperatures. The synthesized nanomaterials and films were characterized by p-XRD, TEM, Raman, SEM, EDX, AFM, XPS, and UV–vis spectroscopy. A minimum sheet thickness of 3.6 nm (i.e., a thickness of 8–9 layers) was observed for bismuth, whereas a thickness of 4 nm (i.e., a thickness of 4 layers) was observed for Bi2Se3 nanosheets. XPS showed surface oxidation of both materials and indicated an uncapped surface of Bi, whereas Bi2Se3 had a capping layer of oleylamine, resulting in reduced surface oxidation. The potential of Bi and Bi2Se3 nanosheets was tested for overall water-splitting application. The OER and HER catalytic performances of Bi2Se3 indicate overpotentials of 385 mV at 10 mA cm–2 and 220 mV, with Tafel slopes of 122 and 178 mV dec–1, respectively. In comparison, Bi showed a much lower OER activity (506 mV at 10 mA cm–2) but a slightly better HER (214 mV at 10 mA cm–2) performance. Similarly, Bi2Se3 nanosheets were observed to exhibit cathodic photocurrent in photoelectrocatalytic activity, which indicated their p-type behavior.
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- 2019| ElsevierNanomaterials synthesis using single source precursors is a fascinating development in material science. The shape and size dependent properties offer countless opportunities for interesting discoveries, but also poses challenges to the scientific community to control the shape and size of these materials. Selenocarboxylate complexes are difficult to synthesize, due to the instability of selenocarboxylic acids. In this study, we have developed an efficient one-pot synthesis of the selenobenzoate ligand and its three new metal complexes, tris(selenobenzoato)antimony(III), tris(selenobenzoato)bismuth(III) and bis(selenobenzoato)dibutyltin(IV). The complexes were used as single source precursors to synthesize Sb2Se3 nanorods, Bi2Se3 and SnSe nanosheets by colloidal thermolysis using the hot injection method. The as-synthesized nanomaterials were characterized by p-XRD, TEM, SAED and HRTEM techniques. The complexes were synthesized by a facile method with high yields and are stable at room temperature for period of several months, We believe that the selenobenzoate complexes with other metals can also be synthesized by using our method and those complexes can be useful precursors for metal selenide thin films or nanoparticles.
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- Herein, we report the synthesis of RGO-β-Bi2O3 nanocomposite for visible light driven efficient photocatalytic removal of wastewater pollutant. Improved oxidation of pristine graphite (PG) to graphene oxide (GO) was obtained by involving additional oxiding agent Na2S2O8 in Hummer’s method. The as-synthesized reduced graphene oxide (RGO) was decorated with β-bismuth oxide to develop RGO-β-Bi2O3 nanocomposite via in-situ wet processing method. The as-prepared na nocomposites were characterized by range of techniques. The photocatalytic activity of as-prepared RGO-β-Bi2O3 nanocomposite was investigated for the degradation of commercially available dye Direct Yellow-27 (DY-27), which is extensively used in the textile industries. The as syntesized RGO-β-Bi2O3 nanocomposite’s photocatalysis shows first order kinetic. Furthermore, effect of dye concentration, pH, catalyst loading and temperature were studied to optimize the photocatalytic performance. The enhanced photocatalytic efficiency of nanocomposite could be attributed to the greater surface area and reduction in recombination of excited electron and holes.
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