Synthesis of silver nanowires for highly transparent conductive films and electrochemical reduction of carbon dioxide

Abstract

The traditional ITO-based transparent conductive films and electrodes have been widely applied in many fields and used in various electronics in the past decades. However, its brittle property and costly manufacturing process limit the development of ITO for next-generation electronic devices, which need the features of light weight, flexibility, and low cost. Silver nanowires have attracted considerable attention from researchers among many candidates due to their outstanding electrical, mechanical, and optical properties. Many synthesis methods of AgNWs have been demonstrated recently, but there are still some parameters that are unclear and need further investigations.

In this thesis, one-step solvothermal synthesis of AgNWs has been studied and explored. AgNWs with a high aspect ratio (~2000) were successfully obtained by using this method. The morphology of AgNWs was significantly affected when tuning the different factors, including the heating temperature of PVP dissolution, the molar ratio of PVP/AgNO3, the molecular rate of PVP, and the concentration of ionic assistants. Moreover, another latest modified polyol method, the Maillard reaction process, has also been introduced and researched in this thesis. The ultra-long AgNWs (~100 μm) were successfully generated through the Millard reaction method using ammonium chloride and glucose as reacting agents of MRPs. Effects of experimental parameters such as reaction time and pressure environment on the morphology of AgNWs have also been investigated. Besides, the extra salt additive (NaBr) was employed to see if the NW diameter would become thinner to achieve the high aspect ratio AgNWs. The NW diameter was greatly reduced when the molar ratio of NH4Cl/ NaBr was at 40:1; however, a large amount of Ag nanoparticles were generated, which could significantly affect the overall performance of AgNWs.

The AgNWs-based TCFs were fabricated in this project. With the help of annealing post-treatment, TCFs with low sheet resistance (~22 Ω/sq) and high transmittance (86%) were prepared using the high aspect ratio AgNWs. In addition, the AgNWs were applied to the electrochemical reduction of CO2 to syngas and showed the potential of syngas production. Nevertheless, more factors and studies need to be carried out to improve the Faradic efficiency of syngas production.