Probing structural relaxation in nanosized catalysts by combining EXAFS and reverse Monte Carlo methods

Strain-induced structure relaxation, large structural disorder and complex non-Gaussian shape of the interatomic distances distribution are characteristic even for the simplest monometallic nanocatalysts, and may have significant impact on many properties, including catalytic ones. Extended X-ray absorption fine structure (EXAFS) spectroscopy is able to provide unique information on the structure of nanosized catalysts due to its sensitivity to short-range order in the material. The EXAFS studies of disorder effects in small nanoparticles (with size 1–2 nm) are, however, challenging due to the assumption of quasi-Gaussian bond length distributions that is made in the conventional analysis. One possible solution shown in this study for bare gold nanoparticles is a novel advanced approach: EXAFS data modeling using reverse Monte Carlo and evolutionary algorithm methods. In addition, we use here classical molecular dynamics simulations to validate the obtained results.