Carbon Saturation Engineering of Intermetallic InNi Carbides for Enhanced CO 2 Hydrogenation

While conventional InNi alloy phases in supported Ni/In 2 O 3 catalysts show limited performance for CO 2 -to-methanol hydrogenation, we demonstrate that carbon incorporation into the InNi 3 gives rise to a distinct catalytic architecture. The saturated InNi 3 C 0.5 exhibits better catalytic stability and 40-fold enhanced methanol productivity compared with noncarburized alloys. Although the in situ carburization of InNi 3 in the CO 2 hydrogenation reaction produced the unsaturated InNi 3 C x, this catalyst had lower stability and activity compared to the saturated InNi 3 C 0.5 . Structural degradation mechanisms reveal atmosphere-dependent intermetallic carbon oxidation pathways in the InNi carbides. Furthermore, hierarchical engineering through an electrostatic assembly of the saturated InNi 3 C 0.5 hexagonal nanosheets on In 2 O 3 hollow nanotubes synergistically enhances both activity and durability. Density functional theory analysis unveils that carbon-induced electron redistribution creates Ni/C cooperation resembling uniform electron gas behavior, simultaneously optimizing hydrogenation capacity and oxygen vacancy dynamics on the oxide support. This work establishes intermetallic carbon saturation engineering as a general strategy for upgrading intermetallic catalysts in renewable fuel synthesis.