High Yield Au Nanorods Synthesis: Investigation of the Synthesis Parameters Tunability by Statistical Methods

Gold nanorods are well-known for their localized surface plasmon resonance (LSPR) properties, which are sensitive to both their size and morphology. This LSPR effect, combined with their absorption ranging from the visible to the infrared portion of light, makes them particularly suitable for applications in fields such as photocatalysis, photovoltaics, biosensing, and medical imaging. Traditionally, their synthesis has been based on a seed-mediated method with the use of ascorbic acid as a mild reducing agent. In this work, hydroquinone is used as a reducing agent to achieve nearly quantitative yield in terms of gold consumption. Using a customized design of experiment, the present study explores the influence of seed, silver nitrate, cetyltrimethylammonium bromide (CTAB), hydroquinone, and gold precursor concentrations on the second LSPR wavelength value, linked to the rod aspect ratio (AR). Statistical analysis of the results revealed multiple significant quadratic effects and interactions, notably between CTAB and silver nitrate, indicating the formation of a complex between these two components that results in anisotropic growth. The predictive power of the developed model was investigated and validated by its accuracy in predicting, for new conditions, the plasmonic properties of nanorods with a well-controlled AR. This comprehensive understanding of the tunability and mechanism of the process provides valuable insights into optimizing the production of gold nanorods with desired properties for various applications. To this end, a web application was developed to enable any researcher to freely access the model designed in this work and choose the optimal experimental conditions for synthesis.