The Selection of Stable Pt Single-Atom Catalysts Supported on 3d–5d Transition Metal Carbides

The low loading of platinum (Pt) group metals (PGMs) is attractive to designing cost-effective catalysts. Among PGMs, Pt is one of the most widely used metals in catalytic applications. Single-atom catalyst (SAC) configurations allow efficient utilization of precious metals such as Pt in designing low PGM content catalysts. The thermodynamic and kinetic stability of SACs is a preliminary requirement for their long-term application in catalysis. Here, we combine density functional theory (DFT) calculations and Cs-corrected scanning transmission electron microscopy (STEM) with a high-angle annular dark-field (HAADF) detector to reveal the atomic resolution and chemical contrast of Pt SAC configurations on transition metal carbide (TMC) supports. Our DFT-based thermodynamic, activation energy, and characteristic diffusion time calculations performed over a large set (∼250) of Pt SAC configurations show that Pt strongly binds on polar surfaces of some common TMCs such as NbC, TaC, WC, VC, HfC, CoC, and MoC, and these Pt-bound systems show enhanced stability/durability. The theoretical predictions were further verified experimentally using a case study of Pt SAC supported on HfC. Images collected before and after a postannealing treatment and DFT calculations demonstrate the kinetic stability of Pt SACs supported on HfC. Therefore, the results from the current study provide a key guidance principle for the selection of stable Pt SACs supported on TMCs for catalytic applications.