Sacrificial Agent-Controlled Photodeposition: Revealing Pt-Photodeposition Key Features of Pt-Nanoparticle Co-catalysts for Maximized Photocatalytic H₂ Evolution

Photocatalytic H2 production from TiO2 substrates (and many other common semiconductors) relies on the use of a suitable co-catalyst. The most widely used co-catalyst is Pt that is typically photodeposited as metallic Pt0 nanoparticles (NPs) on various titania structures. In this Pt photodeposition process, parameters such as the Pt concentration in the solution or the nature of the sacrificial agents strongly affect the NP deposition amount, the particle size, and its distribution. Despite considerable investigations, unifying concepts that connect Pt-deposit features with H2 evolution efficiency focus mainly on a critical Pt loading amount but are often inconclusive. In the present work, we use thin-film sputter-deposited anatase layers as well-defined photoabsorbers for Pt deposition under a wide range of conditions, characterize the NPs, and measure photocatalytic H2 evolution. From the results, we find that a unifying criterion for achieving a maximized co-catalytic efficiency of Pt deposits is to overcome a critical Pt particle density, independent of the detailed particle features of Pt deposition conditions.