Hydrothermal Embedding of Pd Single Atoms Into SnO ₂ for Efficient CO Oxidation

ABSTRACT This work employs a hydrothermal embedding strategy to fabricate a highly efficient and stable Pd/SnO ₂ catalyst for CO oxidation. With only 0.15 wt.% Pd, the hydrothermally treated catalyst (Pd/SnO ₂ ‐H) exhibits a reaction rate three times that of the fresh counterpart (Pd/SnO ₂ ‐F). Combined experimental and theoretical evidence reveals that hydrothermal treatment redistributes Pd species and partially incorporates Pd atoms into the SnO ₂ lattice, generating single‐atom Pd sites (Pd ₁ ). These lattice‐incorporated Pd ₁ sites strengthen the Pd‐SnO ₂ interaction, which weakens the Pd─O bond, thereby promoting the formation of oxygen vacancies and, more importantly, facilitating the subsequent rate‐determining O ₂ activation step. This enables a low‐barrier Mars–van Krevelen pathway, in contrast to the higher‐energy Langmuir–Hinshelwood route operating on PdO clusters in Pd/SnO ₂ ‐F, thereby explaining the high intrinsic activity of Pd/SnO ₂ ‐H. Furthermore, Pd lattice doping modulates the d ‐electron distribution of Pd and weakens CO adsorption, effectively alleviating the CO poisoning typically observed on conventional Pd nanoparticles. Together, these results establish a new design principle for high‐performance single‐atom catalysts, demonstrating that lattice‑embedding of the active metal into a reducible oxide support can simultaneously enhance redox kinetics and suppress poisoning.