Surface enhanced vibrational spectroscopy and first-principles study of l-cysteine adsorption on noble trimetallic Au/Pt[at]Rh clusters

The Rh shell of the Au/Pt/Rh trimetallic nanoparticles induces a wide variety of interesting surface reactions by allowing the adsorption of amino acids like l-cysteine (l-Cys). We present a snapshot of theoretical and experimental investigation of l-Cys adsorption on the surface of noble trimetallic Au/Pt[at]Rh colloidal nanocomposites. Density functional theoretical (DFT) investigations of l-Cys interaction with the Rhodium (Rh) shell of a trimetallic Au/Pt[at]Rh cluster in terms of geometry, binding energy (E sub(B)), binding site, energy gap (E sub(g)), electronic and spectral properties have been performed. l-Cys establishes a strong interaction with the Rh shell. It binds to Rh by the S sub(1)-site, which makes a stable l-Cys-Rh surface complex. DFT can be taken as a valuable tool to assign the vibrational spectra of the adsorption of l-Cys on trimetallic Au/Pt[at]Rh colloidal nanocomposites and mono-metallic Rh nanoparticles. Surface-enhanced infrared spectroscopy (SEIRS) with l-Cys on a Rh sub(6) cluster surface has been simulated for the first time. Experimental information on the l-Cys-Rh surface complex is included to examine the interaction. The experimental spectral observations are in good agreement with the simulated DFT results. Characterization of the synthesized trimetallic Au/Pt[at]Rh colloidal nanocomposites has been done by high-resolution transmission electron microscopy (HR-TEM) with selected area electron diffraction (SAED) pattern, energy dispersive X-ray (EDX) spectroscopy, dynamic light scattering (DLS) measurements, zeta potential, zeta deviation analysis and UV-visible (UV-Vis) spectroscopic studies.