Metal-Assisted Chemical etching for the direct synthesis of bimetallic Cu-Pd nanoparticles on silicon

An original study is presented for the synthesis of Cu100-xPdx nanoparticles directly on silicon by Metal Assisted Chemical Etching (MACE). CuPd is chosen as a representative bimetallic system on account of its interest and potential applications in catalysis and electrocatalysis, among others. The proposed methodology allows precise control of the nanoparticle bimetallic composition and structure. Thus, we demonstrate that Cu100-xPdx solid solutions and phase-separated nanoparticles can be synthesized at will by simply changing the deposition conditions. In-depth physical characterization of the synthesized material (structure, morphology, composition, oxidation state and d-band center position) is carried out by XRD, SEM-EDX and XPS. Finally, band bending simulations at the nanoscale in combination with electrochemical measurements help to interpret some of the peculiarities of the Pd, Cu and Cu100-xPdx deposits. The new method can be easily implemented, used for various silicon substrate geometries and extended to any bimetallic system whose metals are suitable for MACE of silicon.