Mesoporous Core–Shell Pd@Pt Nanospheres as Oxidase Mimics with Superhigh Catalytic Efficiency at Room Temperature

Mesoporous Pt–Pd bimetallic core–shell nanospheres (mPd@Pt NSs) with palladium-rich cores and platinum-rich shells were synthesized via a simple, two-step, wet chemical strategy mediated by nitrogen-doped carbon dots. The BET surface area of mPd@Pt NSs was found to be 210.4 m2·g–1, which is significantly higher than the currently reported unsupported Pt-based nanomaterials. Because of the large active surface area, the as-prepared mPd@Pt NSs show superhigh oxidase activity and exhibit excellent oxidase-like catalytic efficiency with a catalytic constant (Kcat) as high as 2.1 × 103 s–1 at room temperature, which is of the same order of magnitude as the natural horseradish peroxidase (HRP) (Kcat = 4.3 × 103 s–1) at 37 °C and five-fold greater than the reported Kcat values of oxidase-like nanozyme obtained at 30 °C.