Synthesis of carbon dots from sodium polyacrylate and metal oxides for electrochemical applications

Various carbon-based materials and metal oxides have been used to improve the performance of electrochemical applications. However, there are both advantages and disadvantages to each kind of these electrode material. Hence, the use of multi-component electrode materials is a distinguished approach to magnifying energy storage performances by taking advantage of each component's unique functionality and synergetic effects. Noticeably, in these multi-component electrode materials, metal oxides show great potential as redox-active materials whereas carbon-based materials can increase the effective utilization of active materials and improve the electrical conductivity and structural integrity of the composite electrodes. Among several carbon-based materials, carbon dots (CDs) are a remarkable class of unique carbon nanomaterials that recently emerged as an option in electrochemical applications, owing to their excellent electron-transfer efficiency, high surface area, and unique electronic properties, low environmental hazard, and especially their notable semiconductor nanostructures. In addition to CDs, the metal oxides used in this work are TiO2 and CuO-NiO because both of them are abundant, inexpensive with low toxicity, and have simple preparation. Most prominently, they are novel materials with promising properties for electrochemical applications. Herein, we presented two projects within this thesis research based on a simple route to prepare CDs that combine with each metal oxide to study synergetic effects. In this work, CDs were synthesized from sodium polyacrylate via a one-step pyrolysis method. Sodium polyacrylate, which is a polymer widely used in diapers, cosmetics, and superabsorbent material, can be turned into useful nanomaterials. This polymer is a suitable precursor because of its high aqueous solubility, readily available, and low cost. TiO2 has not been widely investigated despite its faradaic and semiconducting properties, high stability, and long‐term electrochemical stability. Besides, CuO and NiO are also outstanding metal oxide that has been applied in a variety of electrochemical applications because of their high theoretical capacitance, low cost, chemical stability, abundant resources, environmental compatibility, and pseudocapacitive properties. However, the CuO-NiO nanocomposite is rarely applied in a supercapacitor, suggesting a novel approach to developing advanced electrode material. Consequently, the composite of carbon dots and metal oxides obtained in this work was a novel strategy to achieve a high-performance and low-cost supercapacitor.