This review article by Bing et al. focuses on the development of nanostructured Pt-alloy electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. The authors discuss the current technological advancements, challenges, and strategies to improve the performance and stability of these catalysts. Key topics include: 1. **Current Status and Challenges**: - High cost of Pt-based catalysts, which contribute significantly to the total cost of PEM fuel cells. - Insufficient activity and low stability of current catalysts. - Strategies to reduce Pt loading while maintaining or improving performance. 2. **Catalyst Nanostructures**: - **Pt-alloy nanoparticles**: Spherical shape with low-index facets (e.g., Pt(100), Pt(111)) offer advantages in surface-to-volume ratio and catalytic activity. - **Pt-alloy nanotextures**: Pt-skins/monolayers on base metals (e.g., Pt on Ni, Co, Cr) improve activity and stability. - **Branched or anisotropic elongated Pt or Pt-alloy nanostructures**: Enhance catalytic activity and stability. 3. ** Effects of Composition, Structure, Morphology, and Particle Size**: - Composition: Alloys with specific base metals (e.g., Ni, Co, Fe) show improved ORR activity compared to pure Pt. - Post-treatments: Acid leaching and heat treatment can reduce base metal dissolution and improve stability. - Ordering: Ordered intermetallic compounds can enhance catalytic activity by optimizing geometric and electronic structures. - Synthetic methods: Controlling precursor concentrations, capping agents, and reaction conditions can influence morphology and stability. 4. ** Issues and Future Directions**: - Base metal dissolution and leaching are major concerns for catalyst stability. - Surface modification techniques, such as forming Pt-skins or textured surfaces, are promising solutions. - Theoretical studies and computational methods provide insights into the ORR mechanism and the role of electronic and geometric structures. The article highlights the importance of understanding and controlling the synthesis and properties of Pt-alloy catalysts to achieve more efficient and durable fuel cell performance.This review article by Bing et al. focuses on the development of nanostructured Pt-alloy electrocatalysts for the oxygen reduction reaction (ORR) in proton exchange membrane (PEM) fuel cells. The authors discuss the current technological advancements, challenges, and strategies to improve the performance and stability of these catalysts. Key topics include: 1. **Current Status and Challenges**: - High cost of Pt-based catalysts, which contribute significantly to the total cost of PEM fuel cells. - Insufficient activity and low stability of current catalysts. - Strategies to reduce Pt loading while maintaining or improving performance. 2. **Catalyst Nanostructures**: - **Pt-alloy nanoparticles**: Spherical shape with low-index facets (e.g., Pt(100), Pt(111)) offer advantages in surface-to-volume ratio and catalytic activity. - **Pt-alloy nanotextures**: Pt-skins/monolayers on base metals (e.g., Pt on Ni, Co, Cr) improve activity and stability. - **Branched or anisotropic elongated Pt or Pt-alloy nanostructures**: Enhance catalytic activity and stability. 3. ** Effects of Composition, Structure, Morphology, and Particle Size**: - Composition: Alloys with specific base metals (e.g., Ni, Co, Fe) show improved ORR activity compared to pure Pt. - Post-treatments: Acid leaching and heat treatment can reduce base metal dissolution and improve stability. - Ordering: Ordered intermetallic compounds can enhance catalytic activity by optimizing geometric and electronic structures. - Synthetic methods: Controlling precursor concentrations, capping agents, and reaction conditions can influence morphology and stability. 4. ** Issues and Future Directions**: - Base metal dissolution and leaching are major concerns for catalyst stability. - Surface modification techniques, such as forming Pt-skins or textured surfaces, are promising solutions. - Theoretical studies and computational methods provide insights into the ORR mechanism and the role of electronic and geometric structures. The article highlights the importance of understanding and controlling the synthesis and properties of Pt-alloy catalysts to achieve more efficient and durable fuel cell performance.