Hybrid Organic-Inorganic Perovskites as Promising Substrates for Pt Single-Atom Catalysts

Single-atom catalysts (SACs) combine the best of two worlds by bridging heterogeneous and homogeneous catalysis. The superior catalytic properties of SACs, however, can hardly be exploited without a suitable substrate. Here, we explore the possibility of using hybrid organic-inorganic perovskites as supporting materials for single transition-metal atoms. By means of first-principles calculations, we predict that single Pt atoms can be incorporated into methylammonium lead iodide surfaces by replacing the methylammonium groups at the outermost layer. The iodide anions at the surface provide potentially uniform anchoring sites for the Pt atoms and donate electrons, generating negatively charged ${\mathrm{Pt}}_1^{\delta -}$ species that allow for preferential ${\mathrm{O}}_2$ adsorption in the presence of CO. Such Pt sites are able to catalyze CO oxidation and may also play a role in ${\mathrm{CO}}_2$ reduction. The fundamental understanding generated here will shed light on potential applications of hybrid perovskites in the field of (photo)catalysis.

Figure 1

Geometries of the ${\mathrm{Pt}}_1@(110)$ system before (left) and after (right) ${\mathrm{O}}_2$ adsorption. Purple and dark gray spheres indicate the iodine and lead atoms of the cage, and steel blue and red spheres represent the platinum and oxygen atoms. The MA group is displayed as a stick model with carbon, nitrogen, and hydrogen atoms depicted in light gray, blue, and white, respectively.

Figure 2

Reaction pathway and free-energy profile of CO oxidation at the ${\mathrm{Pt}}_1@(110)$ system with temperature and pressure for each gaseous reactant being 298 K and 1 atm, respectively (top). Configurations of the transition states (TS1-4) and intermediate states (bottom). A star represents an empty surface site or indicates an adsorbed species.