Substrate Curvature Enhances Molecular Electrocatalysts for the Efficient Production of Hydrogen Peroxide

The two-electron oxygen reduction reaction (2e^- ORR) offers a green alternative to the anthraquinone process but demands efficient catalysts. Here, we demonstrate substrate curvature as an independent design lever for 2e^- ORR catalysis. Cobalt phthalocyanine (CoPc) was immobilized on carbon supports of distinct geometries, i.e., planar graphene and carbon nanotubes with different diameters, to isolate the curvature effects. In alkaline flow cells, CoPc on 15 nm CNTs delivers a >15-fold higher turnover frequency than CoPc on graphene does and a maximum productivity of 73.9 mol g_cat^-1 h^-1. <i>In situ</i> spectroscopy and density functional theory revealed curvature-induced strengthening of *OOH adsorption, lowering the barriers for H₂O₂ formation. When integrated into a 10 cm × 10 cm porous solid-electrolyte reactor, the optimal catalyst achieves >70% selectivity at 10 A and stable operation for more than 10 h. This validation positions curvature engineering as a predictable, tunable strategy for designing high-performance electrocatalysts.