Ion-Sieve-Confined Synthesis of Size-Tunable Ru for Electrochemical Hydrogen Evolution

The controllable and low-cost synthesis of nanometal particles is highly desired in scientific and industrial research. Herein, size-tunable Ru nanoparticles were synthesized by using a novel ion-sieve-confined reduction method. The H₂TiO₃ ion-sieve was used to adsorb Ru³⁺ into the hydroxyl-enriched porous [TiO₃]^2- layers. The confined environment of the interlayer space facilitates Ru-Ru collision and bonding during annealing, achieving a precise reduction from Ru³⁺ to Ru⁰ without additional reductants. Owing to the confinement effect, Ru⁰ nanoparticles are uniformly embedded in the pores on the surface of the postannealed TiO₂ matrix (Ru@TiO₂). Ru@TiO₂ exhibited a lower overpotential than Pt/C (57 vs 87 mV at 10 mA cm^-2) for the HER in 0.1 M KOH solution. The confinement-induced reduction of metal ions was also preliminarily proved in ion-exchanged zeolites, which provides facile and abundant approaches for the size-controllable synthesis of nanometal catalysts with high catalytic activity.