A research team from Harbin Institute of Technology has recently published a comprehensive review in Catal titled “Platinum-based intermetallics for oxygen reduction catalysis: From binary to high-entropy.” The paper systematically summarizes the latest progress in platinum-based intermetallic compounds for the oxygen reduction reaction (ORR) in fuel cells.

Background

The ORR is a key half-reaction in proton exchange membrane fuel cells (PEMFCs), but its sluggish kinetics remain a major bottleneck for fuel cell development. Conventional Pt-based alloy catalysts face challenges such as metal dissolution and insufficient durability. In contrast, intermetallic compounds with long-range ordered structures offer a promising route to enhance catalytic performance by tuning electronic structures and improving stability.

Key Highlights

• Advantages of Intermetallic Compounds: Compared with disordered alloys, intermetallics feature long-range ordered crystal structures and precise stoichiometry. These properties enable geometric and ligand effects to optimize Pt’s electronic structure, weaken excessive adsorption of oxygen intermediates, and boost intrinsic activity. Stronger Pt–M bonding and higher formation energy also suppress metal leaching and particle sintering, significantly improving durability.

• Binary Systems: Traditional high-temperature annealing for ordering often causes nanoparticle sintering. Strategies such as strong metal–support interactions and low-temperature ordering synthesis can overcome this issue. Core–shell structures and anisotropic morphology control further enhance activity and stability.

• Ternary Systems: Introducing a third element with atomic size differences induces lattice strain, optimizing Pt’s d-band center and adsorption energy. Some elements strengthen covalent bonding through strong p–d orbital hybridization, improving resistance to dissolution. Low-melting-point metals can also promote atomic diffusion, reducing ordering temperatures and enabling highly ordered nanocrystals.

• High-Entropy Systems: High-entropy intermetallics incorporate five or more elements, combining ordered structures with high configurational entropy. This synergy allows precise electronic tuning and multiple active sites. Their unique sluggish diffusion and entropy stabilization effects confer exceptional structural stability, pushing intermetallic catalysts to new heights.

• Performance Summary: Across binary, ternary, and high-entropy systems, Pt-based intermetallics exhibit mass and specific activities far exceeding commercial Pt/C catalysts, with minimal degradation after tens of thousands of accelerated durability cycles. This demonstrates that structural ordering and compositional diversification are effective strategies to simultaneously overcome activity and stability bottlenecks.

• Future Outlook: Research will focus on scalable, precise synthesis methods; advanced characterization to reveal dynamic evolution of active sites; machine learning-assisted design; entropy-mediated catalytic mechanisms; and integration into practical membrane electrodes and industrial-scale validation—key steps toward commercialization.

Significance

This review outlines the evolution of Pt-based intermetallics from binary to high-entropy systems, revealing universal strategies for tuning electronic structures and strengthening atomic bonding through structural ordering and compositional diversity. It provides insights into current challenges and future directions for designing next-generation high-performance catalysts.

Authors & Institutions
• Changlin Li, Xiaoyue An, Yajing Qi, Xinyu Wang, Tongbo Zhang, Yu Liu, Lin He, Fengyu Wu, Weiwei Yang
Corresponding Authors: Menggang Li, Yongsheng Yu
School of Chemistry and Chemical Engineering, Harbin Institute of Technology, Harbin, China
Corresponding Authors & Emails
• Menggang Li – mengg.li@hit.edu.cn
• Yongsheng Yu – ysyu@hit.edu.cn