Insight into synergistic effects of oxygen and nitrogen dual-dopants in carbon catalysts on selective catalytic reduction of NO_x with NH₃: A combined computational and experimental verification

Heteroatom doping in carbon catalysts has been shown to enhance the low-temperature selective catalytic reduction of NO_x with NH₃ (NH₃-SCR); however, precise identification of active structure and activity origin remains challenging as various heteroatoms co-existence. Here, we provide a new insight into the synergistic effects of oxygen and nitrogen dual-dopants on carbon-catalyzed NH₃-SCR. Density functional theory calculations reveal a new reaction pathway that the quaternary N enhances O₂ activation and NO oxidation, and carboxyl as Bronsted acid site coupling H₂O as H mediator decreases energy barriers of intermediate NH₂NO evolution by enhancing H transfer, which was further experimentally verified by model activated cokes with controllable doping patterns. The dual-doped activated coke delivers superior NO conversion (∼90 %) and N₂ selectivity (above 90 %) with H₂O presence and corresponding kinetic and in-situ characterizations evidence the reaction pathway on dual-doped carbon. This work guides the design of high-performance heteroatom doped carbon catalysts for NH₃-SCR.