Recent advances in metallic core–shell nanoparticles for electrocatalysis: synthesis, characterization, and applications

Metallic core–shell nanoparticles (MCSNs) have attracted significant research interest in electrochemical energy conversion owing to their distinctive microstructures and superior catalytic performances. By rationally designing a metallic core with a specific surface (shell), synergistic interactions between the core and the shell, benefiting from the intrinsic strain, ligand, geometric, and ensemble effects, can endow multi-metallic CSNs with highly enhanced activity, selectivity, and stability in electrocatalytic reactions, compared to their monometallic counterparts. In this review, we outline the key breakthroughs—especially in the past 5 years—of MCSNs, focusing on their precise design/synthesis, intrinsic effects arising from core–shell interactions, state-of-the-art characterization techniques, and exceptional performance in critical electrochemical reactions, including water splitting, oxygen reduction reaction (ORR), CO₂ reduction reaction (CO₂RR), N₂/NO₃⁻ reduction reaction (N₂RR/NO₃RR), and small organic molecule electrooxidations. We further discuss the ongoing challenges and opportunities for MCSNs, particularly in achieving computationally guided design/atomic-precision synthesis, enabling scalable production, and advancing in situ or operando characterization methods. We hope that the present review will inspire chemists working in this field to develop new MCSNs for sustainable energy applications.