Pd nanorods have demonstrated many useful applications in multiple fields of science and engineering. This has encouraged further investigation into Pd nanorod synthesis in recent years. Current methods of metal nanostructure synthesis are not environmentally friendly or sustainable due to the use of harmful chemicals such as ethylene glycol and energy intensive reactions. This study examines two possible green alternatives for Pd nanorod synthesis that includes the use of both green reducing agents and solvents, or application of rod-shape virus-like-particles (VLPs) as biotemplate. A literature review on Pd nanorod synthesis using aforementioned sustainable methods as well as its application in different fields was conducted.

For first approach, different reducing agents were tried, and ascorbic acid was chosen for further study as a suitable reducing agent for sustainable synthesis of Pd nanorods by reducing a Pd precursor salt. Continuous-flow millifluidic reactors were employed to enhance yield of synthesized Pd nanorods with better size and morphology control. Compartmentalized flow of the reaction solution was achieved by conducting experiment at boiling point of aqueous solvent that led to uniform liquid plugs of the solution being transported by vaporized solvent and contributed to enhanced Pd nanostructure synthesis via better heat transfer and reactant mixing. Parametric study examined the effect of different factors such as reactant concentrations on size and morphology of synthesized Pd nanorods using Transmission Electron Microscopy (TEM). A kinetic study was performed to examine correlation of reduction rate to the formation of desired seeds, and its effect on the yield of Pd nanorods using Ultraviolet-Visible (UV-Vis) spectroscopy. For second approach, Tobacco Mosaic Virus (TMV) VLPs were used as a rod-shape viral biotemplate for palladium nanorod synthesis in an aqueous solution without addition of external reducing agent. Functional groups present on TMV VLP capsid protein are capable of reducing Pd precursor salt to achieve a coating of mineralized Pd metal. TMV VLPs were obtained through expression in Escherichia coli (E-coli) bacterial medium. Pd mineralization on the outer-wall of capsid protein of TMV VLPs was attempted using batch synthesis method.