Abstract

Supported Pt catalysts are highly active for the selective catalytic oxidation of ammonia (NH3-SCO), but their practical use is limited by poor N2 selectivity and insufficient hydrothermal durability under high-temperature exhaust conditions. Herein, we report a composition-regulated high-entropy oxide interface strategy to stabilize Pt–Cu dual sites and steer NH3 oxidation toward selective N2 formation. A series of fluorite-type Ce-based high-entropy oxides, including CeZrLaPrYOx, CeSmLaPrYOx, and CeSnLaPrYOx, were constructed as thermally robust supports for Pt and Cu loading. Among them, PtCu/HEO-Zr calcined at 1000 °C exhibits the best NH3-SCO performance, achieving 90% NH3 conversion at 260 °C while maintaining N2 selectivity above 80% over a broad temperature window of 100–300 °C under a high weight hourly space velocity of 100,000 mL·g−1·h−1. More importantly, after harsh hydrothermal aging at 800 °C with 10 vol% H2O for 12 h, the catalyst shows negligible activity loss and nearly unchanged N2 selectivity, demonstrating exceptional structural and catalytic robustness. Structural and surface analyses reveal that Zr incorporation optimizes the fluorite high-entropy lattice, increases oxygen vacancy concentration, promotes lattice oxygen mobility, strengthens surface acidity, and enriches active Cu2+ species, thereby enhancing the interfacial cooperation between NH3 activation and oxygen-assisted intermediate conversion. In situ DRIFTS further reveals that PtCu/HEO-Zr favors an Olat-assisted internal selective catalytic reduction pathway, in which adsorbed NH3 is activated to -NH2 species and subsequently reacts with lattice oxygen-derived intermediates to form N2O22−-like species that decompose into N2 and H2O. Meanwhile, the formation of nonselective NOx and N2O products is suppressed. This work highlights high-entropy oxide-supported Pt–Cu interfaces as a promising platform for designing hydrothermally durable and N2-selective NH3-SCO catalysts.

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