Durable Equilibrium-Level Dry Reforming of Methane over Strain Regulated Oligo-Ni/Y2O3

Precise control of catalytic active centers and their interfacial strain is central to accelerating heterogeneous reactions, yet systematic regulation of strain at subnanometer metal–oxide interfaces remains challenging. Here, we report a class of 3d metal/heavy rare-earth metal oxide oligoatomic catalysts, in which finite metal ensembles are anchored on oxide surfaces to form nuclearity-dependent, strain-coupled metal–oxide interfaces. By varying the metal species, oxide support, and, most critically, the average number of metal atoms in each ensemble, we show that interfacial strain can be systematically tuned across diverse 3d metal/oxide combinations. In the Ni/Y2O3 system, an optimal nuclearity range of approximately 4–6 Ni atoms maximizes both compressive Ni–Ni strain and tensile Y–O distortion, creating a strained Ni–O–Y interface that balances CH4 oxidation and CO2 reduction during dry reforming of CH4. The resulting catalyst sustains near-equilibrium CH4 and CO2 conversion for over 1200 h without coke accumulation or detectable active-site collapse and remains stable under natural-gas reforming conditions. Theory and in situ spectroscopy reveal that nuclearity-regulated interfacial strain redirects carbon-containing intermediates away from deep dehydrogenation and toward continuous oxidation, thereby establishing a dynamic carbon balance. These findings position oligoatomic catalysts within the structural regime situated between single-/dual-atom and nanoparticle catalysts and highlight ensemble nuclearity as a tunable parameter for modulating interfacial strain in demanding catalytic reactions.