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

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–FeOx SACs in real reactions boosting reverse water-gas shift (rWGS) reactivity. Besides providing single active sites, Pd SAs surprisingly promote the dynamic carburization of FeOx surface over a long-term reaction, leading to outstanding rWGS activity (42.0 mmolCO·gcat−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 FeOx encapsulation. This work reveals the multiple roles of single atoms in real reactions, indicating the wider application of SACs.