AuPt nanostructures with a high hydrogen evolution reaction activity through a halide-mediated microwave assisted route

Abstract

In light of the escalating scarcity and rising costs of platinum, it is imperative to take a strategic approach to its rational utilization as an electrocatalyst for the hydrogen evolution reaction (HER). In this study, we present a novel microwave (MW)-assisted synthesis route combined with the addition of halide ions, specifically chloride, for the synthesis of AuPt nanostructured electrocatalysts. By adjusting the Au : Pt ratio in solution, as well as the halide concentration, we achieve control over the composition, size, shape, and structure of the nanocrystals (NCs). Comparative analysis of the HER electrocatalytic activity revealed that samples produced in the presence of chloride exhibit reduced overpotentials and increased mass activities. Notably, when using a 1 : 4 Au : Pt ratio and 0.12 mmol of HCl, NCs display lower overpotential and Tafel slope values compared to commercial platinum carbon (Pt/C) catalyst (24 mV @ 10 mA cm⁻² and 13 mV dec⁻¹ compared to 31 mV @ 10 mA cm⁻² and 30 mV dec⁻¹ respectively). Moreover, this nanostructure exhibits a 6.9 fold higher mass activity compared to Pt/C (13.8 A mg_Pt⁻¹ and 2.0 A mg_Pt⁻¹, respectively). We attribute the enhancement in electrocatalytic performance to the formation of an Au-rich core supporting a Pt shell structure, which maximizes the exposure of Pt atoms. This synthesis route offers a pathway to produce Pt-based catalysts with superior electrocatalytic performance for HER, contributing to the rational use of Pt in green hydrogen production.