Probing electronic-structure pH-dependency of Au nanoparticles through X-ray Absorption Spectroscopy.

Research on gold nanoparticles (Au NPs) remains a field of intense activity due to their broad range of applications in diverse fields like catalysis, renewable energy, environmental science, and medicine. Herein, the morphological and electronic structures investigation of Au NPs prepared at different pH values is reported. The dependence of the localized surface plasmon resonance wavelength and electronic structure with size was determined by combining transmission electron microscopy, and various spectroscopic methods led by X-ray absorption spectroscopy. The X-ray absorption experiments evidenced that the citrate-stabilized Au NPs bulk electronic structure remains intact over a broad range of pHs, and changes were detected resulting from differences in NPs surface terminations.