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

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 m² g^-1 with or without incorporated titanium-dioxide (TiO₂) 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 TiO₂ sublayers enhances both catalytic activity and durability in the hydrogen evolution reaction compared to a commercial Pt/C benchmark with similar Pt content. TiO₂ 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.