Harnessing Self-Organizing Element Reduction−Segregation to Steer the Surface States of NiCo Catalyst for Methane Dry Reforming

Abstract NiCo alloys alleviate deactivation in Ni-based methane dry reforming (DRM) catalysts via element segregation, but the evolution of chemical states during reduction-segregation remains unclear. Herein, precise activation temperature (AT) tuning affords AT-NiCo-S2-ENdr catalysts with NiCo alloys confined in SiO2nanowires. In situ characterizations reveal that inert CoO with inward segregation converts to active Co0 (still segregating inward) above 700 °C AT, whereas inert Nix+ (Ni−O−Si coordination) persistently segregates to the surface, even with partial reduction to Ni0. Leveraging this temperature-controlled self-organization, 700-NiCo-S2-ENdr strikes an optimal balance between NiCo reduction and segregation, maximizing the number of surface Ni−Ov−Si and Co0 active sites. Furthermore, surface Co0 lowers the CO2 activation energy, while surface Ov binding enhances CH2* oxidation to suppress carbon deposition. Notably, 700-NiCo-S2-ENdr approaches state-of-the-art performance among non-noble catalysts (580−960 μmolCH4 gcat−1 s−1 at 650−800 °C, carbon-free stability over 100h). This work provides a paradigm for designing high-performance alloy catalysts through controlled self-organization.