Interstitial nitrogen-engineered square-planar Ni surfaces enabling efficient hydrogenation

Atomically precise engineering of nanocatalyst surfaces is critical for advancing heterogeneous catalysis, yet achieving both structural uniformity and electronic tunability remains challenging. Here, we report an interstitial atom-mediated strategy for constructing anti-perovskite Ni 3 CuN nanocatalysts featuring square-planar Ni surfaces coordinated by nitrogen. The resulting nanoparticles adopt cubic morphologies, undergoing nitrogen-driven facet reconstruction from high-index {210}/{110} planes to thermodynamically favored {100} facets. Atomic-resolution imaging and simulations reveal that these surfaces preferentially expose Ni-N arrangements on ( 1 ¯ 00) terminations, in contrast to Ni-Cu configurations on (100) facets. This well-defined surface architecture, characterized by expanded Ni-Ni distances and electron-deficient Ni sites, leads to a substantial enhancement in acetylene hydrogenation selectivity (from 25.5% to 80.1%), while maintaining or surpassing the intrinsic activity of pure Ni and exhibiting excellent stability over 110 hours of testing. These findings establish an interstitial atom-based strategy for tailoring catalytic nanostructures with precise control over surface geometry and electronic structure.