Morphological and spectroscopic studies on enlargement of Pd nanoparticle in l-cysteine aqueous solution by AFM and XPS

► We have studied the enlargement mechanism of Pd nanoparticles (NPs) on SiO2/Si, when the l-cysteine adsorbs on the Pd NPs under water environment. ► The Pd NPs possess an interaction with the SiO2/Si surface. ► However, the interaction becomes small and the Pd NPs can be more easily migrated on the SiO2/Si surface due to the contributions of the H2O and/or the l-cysteine adsorbates. ► Because the Pd NPs aggregate each other, the enlargement of the Pd NPs occurs.