Synthesis Of Chalcogenide Nano-Materials By Chemical Solution Methods And Their Electrochemical Performances

In this dissertation, a facile and ultrafast microwave-assisted heating process has been developed to synthesize pure phaseα-MnO2 nanorods based on the redox reaction of KMnO4 and ascorbic acid; A microwave-assisted heating process has been developed to synthesize a-MnO2 nanowires based on the decomposed reaction of KMnO4 in ionic liquid([BMIM][PF6]) aqueous solution; Nanoflakes(with an average thickness of 5 nm) constructed 8-MnO2 flower-like nanospheres with a diameter of about 500 nm were prepared in water bath at 60℃usingβ-CD as a capping reagent; Nanoflakes(with an average thickness of 15 nm) constructed CuS hollow nanospheres with a diameter of about 500 nm were successfully prepared by a simple and efficient way with the aid of CTAB. The products were characterized by X-ray diffraction (XRD), X-ray spectra (EDX), Field emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET), Barrett-Joyner-Halenda (BJH), Thermo-gravimetric (TG), Cyclicvoltammetry (CV), Charging-discharging (CD), Linear sweep voltammtry (LSV), Chronopotentiometric (CP), Tafel techniques. The main points can be summarized as followed:1. We get the uniform pure phase a-MnO2 nanorods from potassium permanganate (KMnO4) and ascorbic acid (Vitamin C) with microwave irradiation heating at 160℃for 30 min in 0.5 M dilute sulfuric acid. The average diameter of theα-MnO2 nanorods is about 50 nm and length over 3μm. The reaction temperature and time were found to play important roles in formation of a-MnO2 nanorods. The product was characterized by TG, CV and CD curves. The results show that a-MnO2 nanorods exhibit excellent electrochemical characteristics. It's possible that the a-MnO2 nanorods can be used as a cathode material in supercapacity. 2. By combing the advantages of both RTILs and microwave heating, a-MnO2 nanowires have been successfully synthesized. The results showed that the as-prepared a-MnO2 nanowires have a diameter of about 15 nm and a length of 2μm. Its length-diameter ratio is 130:1. A plausible four-step mechanism was proposed to explain the formation of a-MnO2 nanowires. The product was characterized by electrochemical methods. The results show thatα-MnO2 nanowires have similar electrochemical catalytic property as commercial Pt electrodeideal in alkaline solution. It's possible that the a-MnO2 nanowires can be used as a catalyst in fuel cells.3. Water bath method is a popular method to prepare nanometer powders. Nanoflakes(with an average thickness of 5 nm) constructed 5-MnO2 flower-like nanospheres with a diameter of about 500 nm were prepared in water bath at 60℃usingβ-CD as a capping reagent. The results show that (3-CD plays a key role. The electrochemical properties of the as-prepared samples were utilized by cyclicvoltammetry curves in 0.5 M Na2SO4 neutral solution. The results show that a-MnO2 nanowires exhibited excellent electrochemical characteristics.4. CuS hollow nanospheres have been synthesized via liquid phase reduction method in the presence of cupric sulphate anhydrous (CuSO4·5H2O) with thioacetamide (TAA) in ethylene glycol (EG) under the assistance of cetyltrimethylammonium bromide (CTAB). The hollow nanospheres are composed of nanoflaks with a diameter about 15 nm. A possible growth mechanism of the CuS hollow nanospheres was proposed. The product was characterized by XRD, FESEM, BET, CV, LSV and CP. The results show that the porous CuS hollow nanospheres with special high BET surface area (99.77 m2 g-1) exhibited high electrochemical catalytic properties.