Single-Atom Catalysts on CN: Minimizing Single Atom Pt Loading for Maximized Photocatalytic Hydrogen Production Efficiency.

The use of metal single atoms (SAs) as co-catalysts on semiconductors has emerged as a promising technology to enhance their photocatalytic hydrogen production performance. In this study, we describe the deposition of very low amounts of Pt SAs (<0.1 at %) on exfoliated graphitic carbon nitride (CN) by a direct Pt-deposition approach from highly dilute chloroplatinic acid precursors. We find that - using this technique-a remarkably low loading of highly dispersed Pt SAs (0.03 wt %) on CN is sufficient to achieve a drastic decrease in the overall charge transfer resistance and a maximized photocatalytic efficiency. The resulting low-loaded Pt SAs/CN provides a H production rate of 1.66 m mol/h/mg Pt, with a remarkable stability against agglomeration; even during prolonged photocatalytic reactions no sign of light-induced Pt agglomerations can be observed. We ascribe the high performance and stability to the site-selective, stable coordination of Pt within the CN structure. Notably the H production rate of the low-loaded Pt SAs surpasses the activity of Pt SAs deposited by other techniques or nanoparticles at comparable or even higher loading - the optimized Pt SAs decorated CN show ≈5.9 times higher rate than Pt NP decorated CN.