Shape Changes of Pt Nanoparticles Induced by Deposition on Mesoporous Silica

Abstract Polyvinylpyrollidone (PVP)‐capped platinum nanoparticles (NPs) are found to change shape from spherical to flat when deposited on mesoporous silica substrates (SBA‐15). Transmission electron microscopy (TEM), small‐angle X‐ray scattering (SAXS), and extended X‐ray absorption fine structure (EXAFS) analyses are used in these studies. The SAXS results indicate that, after deposition, the 2 nm NPs have an average gyration radius 22% larger than in solution, while the EXAFS measurements indicate a decrease in first neighbor co‐ordination number from 9.3 to 7.4. The deformation of these small capped NPs is attributed to interactions with the surface of the SBA‐15 support, as evidenced by X‐ray absorption near‐edge structure (XANES).