In-situ atmosphere thermal pyrolysis of spindle-like Ce(OH)CO₃ to fabricate Pt/CeO₂ catalysts: Enhancing Pt-O-Ce bond intensity and boosting toluene degradation

In this work, a series of spindle-like CeO₂ supports with different contents of surface oxygen vacancies were fabricated by an in-situ atmosphere thermal pyrolysis method. Due to the unique surface physicochemical properties of the modified CeO₂ supports, the interaction between Pt and CeO₂ can be regulated during the synthesis of the Pt/CeO₂ catalyst. The abundant oxygen vacancies on the CeO₂ support could preferentially trap Pt²⁺ ions in solution during the Pt impregnation process and enhance the Pt-CeO₂ interaction in the subsequent reduction process, which results in the strongest Pt-O-Ce bonds formed on the PCH catalysts successfully (0.6% Pt loading on the CH support, which generated by thermal pyrolysis of Ce(OH)CO₃ under H₂ atmosphere). The strong Pt-O-Ce bond would trigger abundant surface oxygen species generated and enhanced the lattice oxygen species transfer from CeO₂ supports to Pt nanoparticles. It was crucial to boosting the toluene catalytic activity. Therefore, the PCH catalyst exhibits the highest activity for toluene oxidation (T₁₀ = 120 °C, T₅₀ = 138 °C, and T₉₀ = 150 °C with WHSV = 60,000 mL g^-1 h^-1) and remarkable durability and water resistance among all catalysts. We also conclude that the Pt-O-Ce bond may be the active site for toluene oxidation by calculating the turnover frequencies (TOF_Pt-O-Ce) value for all Pt/CeO₂ catalysts. Moreover, the DFT calculation indicates that the Pt/CeO₂ catalyst with a strong Pt-O-Ce bond possesses the lowest oxygen absorption energy and higher CO tolerance ability, which leads to excellent catalytic performance for toluene and CO catalytic oxidation.