Selective Phase Exposure Induces Ni-Ce Interfacial Redox Reconstruction for CO2 Activation

Abstract

Efficient catalytic activation of CO2 remains a central challenge in heterogeneous catalysis because of the thermodynamic stability and kinetic inertness of the CO2 molecule. Metal-oxide interfaces are widely recognized as key catalytic environments where cooperative redox processes enable CO2 dissociation and catalyst regeneration, yet their catalytic functionality is often limited by incomplete exposure of metal-oxide interfacial sites. Here we report a selective phase exposure strategy to reconstruct redox-active Ni-Ce interfacial environments in Ni-Ce-Al catalysts. Ni-Ce-Al oxide microspheres were synthesized by spray pyrolysis followed by controlled alkaline leaching. This treatment selectively removes γ-Al2O3 while preserving NiAl2O4 and CeO2 phases, exposing buried Ni-Ce interfacial domains and suppressing CeAlO3 formation. As a result, CeO2 species are stabilized adjacent to Ni sites, promoting oxygen vacancy formation and enhancing oxygen mobility at the metal-oxide interface. Moderate leaching maximizes the exposure of metallic Ni and defect-rich CeO2 at Ni-Ce interfaces, whereas excessive leaching disrupts the reconstructed interfacial redox environment and reduces oxygen-vacancy density. Operando DRIFTS measurements reveal stabilized CO2-derived intermediates associated with the reconstructed interface. The catalysts were evaluated for the synergistic coupling of dry reforming of methane (CH4 + CO2 ↔ 2CO + 2H2) and the reverse water-gas shift reaction (CO2 + H2 → CO + H2O). The optimally leached catalyst exhibits the highest activity and the lowest apparent activation energy for CO2 conversion, revealing how controlled exposure of Ni-Ce interfacial domains governs oxygen-vacancy-mediated CO2 activation under CO2-rich reforming conditions.