Preparation of binary metal oxides derived from coordination polymers for supercapacitor and catalysis applications

With the spread of portable electronics and electric vehicles, storage of electrical energy has become more important. Supercapacitors are devices that can store electrochemically electrical energy. Supercapacitors with high energy density can be prepared with transition metals oxides containing redox active metal ions. In this thesis, metal oxides are prepared from coordination polymers containing two different metal ions and their electrochemical properties are investigated in detail. In this thesis, coordination polymers containing two different metal ions by using {K2[Cu(pydc)2]·3H2O}n (pydc = pyridine-2,3-dicarboxylate) and Co(Ace)2.4H2O or Ni(Ace)2.4H2O (Ace = acetate) were synthesized at room temperature, hydrothermal, microwave and ultrasonic assisted synthesis methods in various morphologies and formulas. Metal oxides containing two different metal ions were prepared by calcination of coordination polymers at 400 °C in a static air atmosphere. Metal oxides are determined as CuCo2O4/CuO and NiO/CuO composites in various compositions and morphologies. Supercapacitor properties of metal oxides were investigated by electrochemical methods. According to CV tests, the reversibility of redox reactions was found to be high in binary metal oxides. Specific capacitance values of metal oxides are calculated by using discharge curves. The highest capacitance value among CoCuOx materials was achieved with CoCuOx-HT (629 F/g), which was prepared by hydrothermal method. Similarly, NiCuOx-HT reached the highest capacitance among the NiCuOx with 367 F/g. In cycle stability tests, the most stable metal oxides was determined as 79% for CoCuOx-MW and 99% for NiCuOx-RTP. Asymmetric device was designed using CoCuOx-HT and activated carbon, and the capacitance of the device was determined as 36.11 F/g at 1 A/g, while the power density was 38.87 kW/kg and the energy density was 42.65 Wh/kg. Nitrophenol and its derivatives, which can be found in industrial and agricultural wastewater, are considered to be an organic pollutant and their treatment is very costly. Nitrophenols can be reduced by using metal oxide nanocatalysts in the presence of NaBH4 and converted to aminophenols which is a starting material of some drugs and various compounds. The catalytic activities of some metal oxides were tested with the model reaction of nitrophenol reduction. When NiCuOx-RTP used as a catalyst the reaction took place with 100% conversion and it was determined that the rate constant for the catalytic reaction was 1.3963 min-1.