Recent progress in Pt-based electrocatalysts: A comprehensive review of supported and support-free systems for oxygen reduction

In recent years, there has been notable progress in developing advanced catalyst materials and improving the performance of Pt-based catalysts for the oxygen reduction reaction (ORR). ORR is pivotal for achieving high energy conversion efficiency in fuel cells and metal-air batteries. Despite extensive research, balancing the activity and stability of electrocatalysts remains challenging. Due to the high cost and limited availability of Pt, there's a focus on developing Pt alloys, hybrid catalysts, and nanostructured materials with enhanced catalytic activity and utilization using cost-effective methods. Hybridizing multiple active components with Pt shows promise for achieving synergistic effects and meeting high-performance targets set by the U.S. Department of Energy for 2025. This review aims to present recent advances and assess the significance of supported and support-free Pt-based electrocatalysts for ORR. It focuses on carbon, inorganic, and hybrid support materials, as well as support-free metal nanostructures, highlighting their key features and catalytic potential. This offers valuable insights into developing novel Pt-based hybrid electrocatalysts for superior ORR performance in energy conversion and storage applications.