Realization of the dehydrogenation pathway of formic acid oxidation by ultra-small core–shell Au–Pt nanoparticles with discrete Pt shells

Abstract

In this work, ultra-small core–shell Au–Pt nanoparticles with discrete Pt shells (denoted as USCS_D Au–Pt NPs) were successfully prepared by Fe(II)-assisted one-pot co-reduction of Au(III) ions and an ultra-low concentration of Pt(II) ions in citrate solution. In the as-prepared USCS_D Au–Pt NPs, the Pt atoms on their outer surfaces are effectively isolated by Au atoms (denoted as a discrete shell, CS_D). Furthermore, the as-prepared USCS_D Au–Pt NPs are determined to be USCS_D Au_61.2@Au_27.3Pt_11.5 NPs with an average size of 2.3 nm using a number of characterization techniques, including transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDS), cyclic voltammetry (CV), CO stripping voltammetry and X-ray photoelectron spectroscopy (XPS). Moreover, the as-prepared USCS_D Au_61.2@Au_27.3Pt_11.5-NP/C catalysts towards the formic acid oxidation reaction (FAOR) proceed through the direct pathway (dehydrogenation). In addition, their mass activity and specific activity towards the FAOR are 6.91 A mg_Pt⁻¹ and 4.88 mA cm⁻², which are about 16.8 and 7.33 times higher than those (0.4 A mg_Pt⁻¹ and 0.67 mA cm⁻²) of commercial Pt/C catalysts, respectively.