Crystal Facet Effect in Chiral PdPt₃ Hollow Nanocages as Nanozymes for Use in Enantiomer Recognition

Understanding the crystal facet effect in chiral enantiomer recognition plays an important role in designing and fabricating chiral nanozymes for biosensing and biodetection applications. Herein, we design an ideal platform to study the crystal facet effect in chiral enantiomer recognition using cubic and icosahedral PdPt₃ hollow nanocages (NCs) as peroxidase mimics via surface ligand decoration of l/d-cysteine (l/d-Cys). The two PdPt₃ NCs have the same structure of surface ligand, particle size, wall thickness, surface area, and elemental composition, with the only difference of exposed crystal facets, i.e., {100} for cubic PdPt₃ NC-l/d-Cys and {111} for icosahedral PdPt₃ NC-l/d-Cys. The cubic PdPt₃ {100} facet demonstrates 2.2-fold higher peroxidase-like catalytic activity than the icosahedral PdPt₃ {111} facet, which also leads to the better enantiomer recognition performance of discerning 3,4-dihydroxy-l/d-phenylalanine. Our work provides the concept of crystal facet tuning for designing chiral nanozymes with high stereoselective properties.