Galvanic-Replacement-Assisted Pt Deposition on TiO₂ for Enhanced Photocatalytic Hydrogen Evolution (Supporting Information)

Considering that the simplicity of photodeposition and impregnation limits the controllable parameters during deposition, we investigate a deposition process utilizing galvanic replacement to achieve diverse deposition states of Pt cocatalysts. Various Pt nanoparticle morphologies are successfully obtained using Ag, Cu, and Bi as mediator metals. Among these, Pt nanoparticles loaded via Cu mediation exhibit high dispersion and demonstrate superior hydrogen evolution activity compared with those prepared by the conventional photodeposition method. Although using Ag and Bi results in the formation of byproducts such as AgCl and BiOCl, we demonstrate an effective deposition strategy to suppress or eliminate these byproducts. These findings suggest that the controlled deposition of diverse metal nanoparticles is beneficial for the hydrogen evolution reaction and offers considerable potential for broader applications in photocatalytic reactions, heterogeneous catalysis, and optical materials.