Core-passivation: A concept for stable core-shell nanoparticles in aqueous electrocatalysis

The stability of nanoparticles is a major challenge in thermal and electrocatalysis. This is especially true for core-shell nanoparticles where only a few monolayers of noble metal protect the usually non-noble core material. In this work, we utilize the practical nobility concept to engineer stable core-shell nanoparticles with a self-passivating core material. Specifically, tantalum carbide as core material in combination with a 1-3 monolayer thick platinum shell exhibits exceptional stability in aqueous media. The core-shell catalyst shows no sign of structural changes after 10,000 degradation cycles up to 1.0 V-RHE. Due to the efficient passivation of tantalum carbide at the solid/liquid interface, the dissolution reduces by a factor of eight compared to bare Pt. Our findings confirm that passivating core materials are highly beneficial for the stabilization of core-shell nanomaterials in aqueous media. They open up new ways for the rational design of cost-efficient but stable non-noble core - platinum shell nanoparticles where harsh, oxidizing conditions are employed.