The adsorption of anionic [Ptx(CO)y]n− clusters on an Au(111) electrode and its oxidative conversion to an atomic Pt adlayer

Abstract Fabricating platinum film can be a promising approach to remedy the high-cost and scarcity of Pt, and opens up an avenue for studying the electrochemical property of a unique Pt entity. The current report describes Pt-carbonyl cluster denoted as [Ptx(CO)y]n− adsorbed onto an ordered Au(111) substrate from an aqueous PtCl62− solution saturated with carbon monoxide (CO). This Pt+CO cluster was converted into CO-capped metallic Pt adlayer by exposing to O2 and N2. This transformation manifested in the drastic changes of the Au(111) surface structure, where the striped and honeycomb structures were converted into (√7  ×  √7)R19.1° and (2 × 2) - CO structures, as revealed by in situ scanning tunneling microscope (STM). The chemical composition of the Au(111)-supported Pt-carbonyl cluster was characterized by X-ray photoelectron spectroscopy (XPS) and cyclic voltammetry (CV), which resulted in a 47/73 (Pt/CO) ratio. This Pt-carbonyl cluster was accompanied with counter cations La3+, indicating that it was anionic. The XPS and stripping voltammetry results indicate a [Pt47(CO)73]5- cluster, whose CO molecules could be stripped off to produce an ordered smooth Pt metallic adlayer, making it possible to study the electrocatalytic properties of a well-organized Pt thin film.