Amalgamation-based AuHgPt nanochains as electrocatalysts for the hydrogen evolution reaction†

Abstract

Gold–mercury (AuHg) nanochains were successfully synthesized based on the tip effect of Au NRs. Chained gold–mercury–platinum (AuHgPt) nanoalloys were prepared by the galvanic replacement reaction (GRR) using AuHg nanochains as templates at room temperature and used to study the electrochemical properties in the hydrogen evolution reaction (HER). The morphologies, structures, compositions, and electronic effects of the AuHgPt nanochains were investigated, and the hydrogen evolution properties of the nanomaterials were electrochemically evaluated. The results of HER polarization curves in an alkaline solution showed that the overpotential required for the AuHgPt nanochains to reach a current density of 10 mA cm⁻² was only 23 mV and the Tafel slope was 47.72 mV dec⁻¹, both of which were lower than those of commercial Pt/C (27 mV, 54.11 mV dec⁻¹). Moreover, the loss of current density at a current density of 50 mA cm⁻² after a long period of 24 h was only 2.5 mV dec⁻¹. The loss of current density was only 2.8% after a long-duration test at 50 mA cm⁻². The synergistic interactions between the alloyed metals resulted in the nanochains exhibiting excellent HER electrocatalytic activity and stability. In addition, density functional theory (DFT) calculations were employed to analyze the Gibbs free energies related to water dissociation and H₂ desorption on different nanoalloys, along with the d-band center (ε_d) for these materials, which indicate that the enhanced water dissociation ability stems from an interaction between the intensified OH–Au and the diminished H–Pt bonds. This conclusion is supported by the observed increase in the average ε_d values of Au and Pt atoms within the AuHgPt nanoalloy.