One-pot synthesis of Pt@TiO₂ core-shell nanoparticles for stable hydrogen evolution reaction in acidic and alkaline media

Noble-metal nanomaterials such as Pt, Ru, and Ir are commonly used as electrocatalysts for the hydrogen evolution reaction (HER) via efficient water splitting, but the degradation in their activity over time limits their use. To maintain the stability of the metal surface, core-shell nanoparticles composed of a TiO₂ shell domain and coral-like Pt core were synthesized in a one-pot synthesis requiring only the metal precursors. The Pt@TiO₂ core-shell nanoparticles are uniformly formed within 10 min by the spontaneous inter-cation redox reaction (ICR) between Pt²⁺ and Ti³⁺ ionic species. This synthetic strategy is environmentally friendly as it requires no additional reductants, surfactants, or organic compounds. The Pt@TiO₂ core-shell nanoparticles exhibited HER activity in both acidic and alkaline media comparable to that of the Pt/C control; the former was also more durable. The TiO₂ shell enhanced the hydrophilicity of the Pt@TiO₂ surface, ensuring that a large number of active sites were available for sufficient HER performance.