Electronic structure and oxygen vacancy modulation in PdMo₂O_x/CeO₂ catalyst for enhanced propane combustion and water resistance

Catalytic total oxidation of light alkanes remains a significant challenge in environmental catalysis due to the chemical inertness of C-H bonds. In this study, a series of transition metal (W, Mo, Cr) modified PdM₂O_x/CeO₂ catalysts were synthesized and evaluated for propane combustion. Among them, the Mo-promoted catalyst (PdMo₂O_x/CeO₂) exhibited the most exceptional catalytic activity, achieving T ₉₀ at approximately 270 °C, and displaying a 5-fold higher reaction rate (2.05 ×10⁻⁷ mol·g⁻¹·s⁻¹ vs 0.41 ×10⁻⁷ mol·g⁻¹·s⁻¹) with exceptional long-term stability and robust resistance against water vapor. whereas the W-modified counterpart showed a detrimental effect on performance. Comprehensive characterizations and DFT calculations reveal that Mo promotion significantly increases the concentration of both Lewis/Brønsted acid sites and surface oxygen vacancies by the enhanced oxygen mobility and facilitating the oxygen vacancy formation energy ( E _Ov = −1.26 eV), while simultaneously tailoring the electronic structure of Pd to a state favoring reactant adsorption. In situ DRIFTS further confirms that the synergistic acid-redox effect enables the rapid decomposition of inhibitory carboxylate intermediates, preventing their accumulation. This work provides a comprehensive understanding of the synergistic interplay between acidity and redox properties, offering a promising strategy for designing advanced catalysts for light alkane abatement.