For single atom (SA) based catalysis, it is urgent to understand the nature and dynamic evolution of SA active sites during the reactions. Herein, an example of Pt SA-Zn0.5 Cd0.5 S (Pt SA-ZCS) displays interesting phenomena when facing the Brownian collision of ions in aqueous photocatalysis. Via the synchrotron radiation, surface techniques, microscopy and theory calculations, results show that there exist two kinds of Pt sites: PtZn-sub -S3 (Pt substituting the Zn site) and Ptads -S2 (Pt adsorbing on the surface). In Na2 S, the S2- can coordinate with Pt atoms and peel them from the Ptads -S2 sites, but left more stable PtZn-sub -S3 sites, bringing a low but stable catalytic activity (19.40 mmol g-1 h-1 ). While in ascorbic acid, the ascorbic acid ions show less complex ability with Pt atoms, but can decrease the migration barrier of Ptads -S2 sites (67.18 down to 35.96 mmol g-1 h-1 , 52.03% drop after 6 h). Therefore, the Ptads -S2 sites gradually aggregate into nanoclusters, bringing a high but decayed catalytic activity. Moreover, a Pt SA-ZCS-Sulfur composite is designed mainly covered by PtZn-sub -S3 sites accordingly (max: 79.09 mmol g-1 h-1 , 5% drop after 6 h and QE: 14.0% at 420 nm), showing a beneficial strategy "from mechanism to design principle". This article is protected by copyright. All rights reserved.
Identification the Stable Pt Single Sites in the Environment of Ions: From Mechanism to Design Principle