Reactive deposition of Pt single-atoms on g-C₃N₄: effect of Pt-precursors

Anchoring Pt single atoms (SAs) as co-catalysts on g-C₃N₄ has emerged as a promising approach to enhance the hydrogen production performance of this photocatalytic system. Particularly, by so-called reactive deposition, a maximum hydrogen evolution reaction performance can be achieved using a minimum amount of Pt loading. In this study, we explore the effects of different platinum (Pt) precursors on the reactive deposition of SAs onto g-C₃N₄, aiming to optimize the performance in photocatalytic hydrogen production. By examining a variety of Pt precursor types, we highlight critical parameters influencing deposition, including precursor charge, solution pH, ionic strength, and ligand properties. Our results reveal that precursors bearing anionic charges are distinctly more effective than cationic precursors for depositing highly active Pt SAs. Crucially, we find that the surface deposition reaction strongly depends on the ligand involved, with chloride-based complexes enabling more efficient Pt attachment compared to bromide-based complexes. Notably, variations in the oxidation state of platinum (Pt⁴⁺versus Pt²⁺) did not significantly influence deposition outcomes. Among all precursors studied, (NH₄)₂[PtCl₆] achieved the highest catalytic activity, with optimal Pt loading (∼0.026 wt%) and superior hydrogen evolution rates surpassing the widely utilized H₂[PtCl₆] precursor. Furthermore, adjustments to solution conditions, such as significant pH changes due to increased ionic strength, were found to negatively impact deposition and catalytic effectiveness. These insights underscore the importance of precursor selection and solution chemistry control, providing a robust basis for the development of efficient and cost-effective single-atom photocatalysts formed by adsorption-reaction treatments.