Single-atom-driven dynamic carburization over Pd1–FeOx catalyst boosting CO2 conversion

Abstract

<h2>Summary</h2> Single-atom catalysts (SACs) are featured as an emerging type of heterogeneous catalysts due to their distinct reaction mechanisms. Beyond the conventional understanding, here, we report a dual effect of Pd₁–FeO_x SACs in real reactions boosting reverse water-gas shift (rWGS) reactivity. Besides providing single active sites, Pd SAs surprisingly promote the dynamic carburization of FeO_x surface over a long-term reaction, leading to outstanding rWGS activity (42.0 mmol_CO·g_cat⁻¹·h⁻¹) and CO selectivity (>98%) beyond that of other reported Fe-based catalysts. Utilizing state-of-the-art characterization techniques, we reveal that this dynamic carburization yields a highly active Fe₅C₂ phase with the lowest activation barrier of 27.7 kJ/mol for the atmospheric rWGS reaction. The dual effect of SACs results in catalytic performance superior to that of Pd nanoparticles, over which carburization is inhibited by a rapid FeO_x encapsulation. This work reveals the multiple roles of single atoms in real reactions, indicating the wider application of SACs.