Tailored surface composition of Au/Pt nanocatalysts synthesized in microemulsions: a simulation study.

ABSTRACT

Au/Pt nanoparticles show an optimized catalytic activity when compared with Pt nanoparticles because Pt activity is improved by the presence of Au on the surface. It was checked whether a controllable surface composition can be achieved by the simple strategy of varying the Au Pt ratio. We present an in-depth kinetic simulation study on the influence of Au Pt ratio on the formation of Au/Pt nanoparticles synthesized in microemulsions. This study is able to explain the resulting nanoarrangement as a function of kinetic parameters such as Au Pt ratio and intermicellar exchange rate. The role of the micelles as a dosing pump of the Au precursor explains that a higher Au amount results in a Au reduction which takes place over a longer period of time. It implies that Au is deposited until longer stages of the synthesis, so Au is present at the nanoparticle surface. Micelles as reaction media produce a minor impact on Pt due to its slower reduction. These different kinetic behaviours of Au and Pt give rise to a surface composition which can be tailored by tuning the Au Pt ratio. Numerical results on surface composition successfully reproduce experimental data and further support the outcomes of the degree of atomic mixing under different Au Pt ratios.