Locking Ni Atoms in Ordered PtNi for Durable Hydrogen Production: From Electrocatalyst Design to Practical AEMWE Stack Validation

Abstract

To advance the performance of anion exchange membrane water electrolyzers (AEMWE), the development of highly active and durable electrocatalysts is crucial to overcome the sluggish kinetics compared to acidic conditions. Alloying Ni atoms is an effective strategy because it can weaken the hydrogen adsorption strength on Pt to maximize its activity based on Sabatier's principle with the volcano plot. However, Ni often faces durability challenges such as chemical leaching and structural deformation under alkaline conditions. In this study, intermetallic PtNi nanostructures were designed to improve hydrogen evolution reaction (HER) performance through theoretical insights from density functional theory (DFT). DFT reveals that the intermetallic nanostructure increases dissolution potentials, leading to higher intrinsic structural durability compared to disordered PtNi. Theoretical catalytic activity was also analyzed through Gibbs free energy diagrams and electronic structure calculations by Ni introduction. To validate these predictions, intermetallic PtNi/C catalysts were synthesized, and their structure was confirmed using physicochemical techniques. Electrochemical tests, from half-cell to single-cell and practical-scale AEMWE stack systems, demonstrated improved HER performance. A 3-cell stack showed excellent-maintained performance with less than 2% degradation during 3,000 h. These findings highlight effective strategies of atomic ordering engineering for low Platinum group metal electrocatalysts with high activity and durability in practical AEMWE systems.