Revealing Microscopic Mechanism of Antipoisoning Nanocatalysts at Single-Molecule, Single-Particle Level

Developing Pt-based nanocatalysts with high resistance to CO poisoning is critical, yet the microscopic mechanisms remain elusive. Herein, we investigate the catalytic dynamics of monodispersed Pt-Pd alloy nanoparticles for resazurin reduction with single-molecule fluorescence microscopy. It reveals a volcano-shaped activity dependence on alloy composition, with equiatomic PtPd exhibiting optimal performance. Kinetic analysis based on a dual-site competitive Langmuir-Hinshelwood mechanism reveals that alloying weakens CO adsorption, adhering to the Sabatier principle. Furthermore, autocorrelation analysis uncovers a direct correlation between catalytic activity and surface structural dynamics. Surprisingly, unlike pure Pt, which exhibits a persistent "memory" of the CO-poisoned state, Pt-Pd alloys display rapid, stochastic surface reconstruction that erases such memory. These findings demonstrate that superior CO tolerance stems not only from static electronic effects but also from accelerated surface dynamics breaking the kinetic poisoning bottleneck. Ultimately, these insights establish a clear structure-function relationship for bimetallic antipoisoning nanocatalysts.