Browsing by Author "Aamir, Muhammad"
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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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- In this study, a facile and potentially scalable synthesis of AgBiS2 (schapbachite) using melts of metal xanthates is presented; AgBiS2 is both a significant mineral and a technologically important material. This ternary material was synthesized by a novel and low-cost solventless route using simple ethyl xanthate complexes of silver and bismuth. p-XRD analysis indicates that the synthesized ternary material is highly crystalline and belongs to the cubic phase (schapbachite). The electrochemical properties of the material were tested; the potential of the synthesized material for application in charge storage shows a high specific capacitance of 460 F g−1 at 2 mV s−1. A capacitance retention of 83% with a 100% coulombic efficiency was observed after 3000 cycles. The charge storage potential, analysed by fabricating actual symmetrical devices, shows a specific capacitance of 14 F g−1 at 2 mV s−1. An energy density of 26 W h kg−1 and a power density of 3.6 kW kg−1 were observed. Besides, the potential for the oxygen evolution reaction was also studied. An overpotential of 414 mV and a Tafel slope of 134 mV dec−1 were obtained for water oxidation. The fabrication of an electrolyzer cell using the synthesized material as the cathode indicates that a current of 10 mA cm−2 can be achieved at a potential of 1.63 V.
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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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- 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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