EUROPEAN CONGRESS AND EXHIBITION ON ADVANCED MATERIALS AND PROCESSES - EUROMAT 2021

As an efficient and sustainable alternative to fossil fuels Hydrogen gas (H2) has emerged to be of great importance for the future of energy generation and storage. However, H2 production from the electrocatalytic hydrogen evolution reaction (HER) still remains a challenge. Although platinum and its alloys have been the benchmark electrocatalysts for HER, the scarcity, substandard stability and expensiveness limit their usage. In this quest, nanoporous metals, built of 3D scaffolds of bi-continuous ligament-pore structure, have shown growing inclination owing to their large surface area to volume ratio and enhanced catalytic properties. This work focusses on Nanoporous Gold (NPG) as a promising candidate with its noble nature, high conductivity and large surface area. Instead of common precursors constituting various alloying metals and high Au concentration, a supersaturated solid solution of AuFe2 was selected – with cheap and abundant Fe and minimum possible Au concentration according to the parting limit. Long and homogeneous melt-spun ribbons were obtained by rapid solidification of the arc-melted precursor. The as-quenched ribbon was dealloyed chemically in 1 M HNO3 and 1 M HCl at 70 °C for different durations. The structural and compositional investigation was accomplished using XRD, SEM and EDS techniques. The as-dealloyed samples possessed nanoporosity both on surface and cross-section with high Au content. The samples with best nanoporous morphology and supreme Au-rich composition were tested as electrocatalysts for HER in 0.5 M H2SO4. One of these samples shows low values of onset potential and Tafel slope as -4 mV and 47 mV/dec respectively while high exchange current density of 0.12 mA cm-2. Thus, the sample demonstrates excellent electrocatalytic activity given that an inexpensive precursor and simple procedure were employed for the fabrication.