Galvanic replacement of liquid metal galinstan with Pt for the synthesis of electrocatalytically active nanomaterials

Abstract

The galvanic replacement reaction is a verstile method for the fabrication of bimetallic nanomaterials which is usually limited to solid precursors. Here we report on the galvanic replacement of liquid metal galinstan with Pt which predominantly results in the formation of a Pt₅Ga₁ material. During the galvanic replacement process an interesting phenomenon was observed whereby a plume of nanomaterial is ejected upwards from the centre of the liquid metal droplet into solution which is due to surface tension gradients on the liquid metal surface that induces surface convection. It was also found that hydrogen gas was liberated during the process facilitated by the formation of the Pt rich nanomaterial which is a highly effective catalyst for the hydrogen evolution reaction (HER). The material was characterised by scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and dynamic light scattering measurements. It was found that Pt₅Ga₁ was highly effective for the electrochemical oxidation of methanol and ethanol and outperformed a commercial Pt/C catalyst. Density functional theory calculations confirmed that the increased activity is due to the anti poisoning properties of the surface towards CO upon the incorporation of Ga atoms into a Pt catalyst. The use of liquid metals and galvanic replacement offers a simple approach to fabricating Ga based alloy nanomaterials that may have use in many other types of applications.