Engineering external Ni via spatially-selective Ga alloying for coke-resistant dry reforming of methane

2D-Ga 2 O 3 nanosheets sterically hinder pore entry for targeted Ga distribution. • NiGaSi shows superior activity and drastically reduced carbon deposition. • In-situ DRIFTS identifies carbonyls as key reactive intermediates. • Ga promotes CH 4 activation and inhibits coke formation via isolation effect. Dry reforming of methane (DRM) over Ni-based catalysts suffers from severe coking. We propose a spatially-selective Ga alloying strategy using trace 2D-Ga 2 O 3 to modify external Ni sites. The 2D-Ga 2 O 3 nanosheets, fabricated by air bubbling, are geometrically hindered from entering catalyst pores, enabling targeted surface distribution. After reduction, NiGa alloy forms and dilutes surface Ni ensembles to suppress carbon formation. NiGaSi achieves ∼54% CO 2 and ∼40% CH 4 conversions at 700°C, with only 14.8 wt% coke after 10 h versus 69.8 wt% for NiSi. In-situ DRIFTS identifies carbonyls as reactive intermediates with CH 4 cleavage as the rate-limiting step, while Ga donation promotes CH 4 activation. This morphology-enabled spatial design strategy offers a route for precise catalyst engineering.