Dynamic yttria–NiCo interfaces enable coke-resistant and sintering-free dry reforming of methane via enhanced CO₂ activation

Dry reforming of methane (DRM) presents a sustainable route for converting greenhouse gases (CH₄ and CO₂) into syngas (H₂ and CO). However, catalyst deactivation due to coking and sintering remains a critical challenge. In this study, we observe that yttria-modified NiCo-MgAl₂O₄ (YO_x-NiCo) catalysts exhibit significantly enhanced activity, stability, and coke resistance compared to the unmodified NiCo counterpart. The YO_x-NiCo-MgAl₂O₄ catalysts achieve higher CH₄ and CO₂ conversions across the temperature range of 650–800 °C, with remarkably low activation energies–107.5 kJ/mol for CH₄ and 59.4 kJ/mol for CO₂–the latter being among the lowest reported for DRM catalysts. Combined density functional theory (DFT) and microkinetic modeling reveal that the yttria-NiCo interface plays a critical role in the reaction mechanism. CO₂ first adsorbs on yttria as carbonate-like intermediates, which migrate to the YOx-NiCo interfacial sites. At these interfaces, the activated intermediates generate reactive oxygen species, thereby enhancing CO₂ conversion, sustaining continuous carbon gasification, and suppressing coke accumulation. The improved stability of the YO_x-NiCo-MgAl₂O₄ catalyst is further attributed to reversible exsolution-redispersion of NiCo, confirmed through H₂-TPR and CO₂ titration cycles, which demonstrate dynamic regeneration of active sites under both reducing and oxidizing conditions. The increase in both metal dispersion and surface area of YO_x-NiCo-MgAl₂O₄ compared to NiCo-MgAl₂O₄ counterparts contributes to the higher dispersion of active metal sites, which leads to its superior performance. These combined computational and experimental insights demonstrate that engineering a dynamic yttria-NiCo interface fundamentally enhances oxygen mobility, surface reactivity, structural stability. This work represents a significant advancement in DRM catalyst design, positioning YO_x-NiCo-MgAl₂O₄ as a highly promising candidate for long-term industrial applications.