Titanium Dioxide Induced Immobilization of Small Platinum Nanoparticles on Carbon Spherogels: A Strategy Towards Stable and Efficient Electrocatalysts for the Hydrogen Evolution Reaction

ABSTRACT This study introduces a new strategy to electrocatalyst synthesis by immobilizing platinum nanoparticles (Pt‐NPs) on carbon spherogels—nanoporous, monodisperse carbon hollow spheres with diameters of 170–240 nm and surface areas of up to 800 m ² g ⁻¹ with or without incorporated titanium‐dioxide (TiO ₂ ) sublayers, using supercritical deposition. The resulting materials feature precisely tunable Pt‐loadings (2–11 wt%), narrow Pt‐NP size distributions, low interparticle distances (4.4–8.2 nm), and high Pt‐NP dispersion (Pt‐NP mean diameter 2.2–3.5 nm). The presence of TiO ₂ sublayers enhances both catalytic activity and durability in the hydrogen evolution reaction compared to a commercial Pt/C benchmark with similar Pt content. TiO ₂ containing electrocatalysts exhibit Pt‐NPs in the inner part of spheres and outstanding stability, demonstrated by (a) minimal potential shifts (1–4 mV) after accelerated stability tests, (b) suppression of Pt‐NP growth and detachment, and (c) structural integrity retention after 70 h under harsh conditions. These findings highlight the potential of spherogels as advanced catalyst supports and offer a scalable synthesis route without requirement for hazardous templating agents. Thanks to the tunable support morphology, precise Pt‐NP deposition, and remarkable long‐term performance, this approach emerges as a strong candidate for designing next generation electrocatalysts.