Short-Term Annealing Effect on Hydrogen Evolution Activity of Amorphous Al₈₇Y₄Gd₁Ni₄Fe₄

Area of Science:

• Materials Science
• Electrochemistry
• Catalysis

Background:

• Amorphous metal alloys (AMA) offer unique properties but require optimization for catalytic applications.
• The hydrogen evolution reaction (HER) is crucial for sustainable energy, particularly in alkaline media.

Purpose of the Study:

• To investigate the structural evolution of Al87Y4Gd1Ni4Fe4 AMA upon annealing.
• To evaluate the impact of annealing on the electrocatalytic activity for HER in 1 M KOH.
• To understand the relationship between structural changes and HER kinetics.

Main Methods:

• Controlled nanocrystallization via short-term annealing at 647 ± 2 K.
• Structural characterization using X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), and High-Resolution Transmission Electron Microscopy (HRTEM).
• Electrochemical evaluation including potentiostatic tests and electrochemical impedance spectroscopy (EIS).
• Surface analysis using Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM/EDS).

Main Results:

• Annealing induced uniform dispersion of AlFe2Ni, GdFe2, and Al(X) nanophases within the amorphous matrix.
• Nanodomain formation decreased charge transfer barriers and created new active sites for H* adsorption.
• Electrocatalytic activity for HER significantly improved, with current density increasing, exchange current density (i0) rising by 2-3 orders of magnitude, and charge transfer resistance (Rct) decreasing.
• Volumetric hydrogen evolution rates increased from 35.1 to 106.0 mL/(g·min) initially and up to 217.9 mL/(g·min) upon reuse.
• Surface reconstruction and Ni enrichment were observed after HER, accelerating H* recombination.

Conclusions:

• Controlled nanocrystallization of AMA through annealing is an effective strategy to enhance HER performance.
• The synergistic effect between the amorphous matrix and nanophases provides high catalytic activity and stability.
• Annealed AMA presents a promising, cost-effective catalyst for alkaline hydrogen evolution.