Ordered Hollow Sphere Array Nanoreactors for Direct Electroreduction of Diluted CO ₂ Into Ethylene

Direct electroreduction of industrially diluted CO 2 into C 2 H 4 represents a promising route for sustainable energy conversion, yet the selectivity and current density of this process are fundamentally constrained by the insufficient reactant concentration and generation of *CO intermediates. Herein, we addressed this issue by designing an ordered hollow sphere array nanoreactor with Cu nanoparticle and Ni single atom as the tandem catalytic sites (Cu‐NP/Ni‐NC OHSpA) using a unique reverse templating protocol. Mechanistic studies demonstrate that *CO can be generated on Ni site and undergoes spillover to the neighboring Cu particle. Significantly, the ordered hollow sphere array serves as effective CO reservoir to enhance the *CO coverage and thereby promote the C‐C coupling to form C 2 H 4 . As a consequence, Cu‐NP/Ni‐NC OHSpA exhibits excellent electrocatalytic performance toward the conversion of diluted CO 2 (i.e., 15% CO 2 /Ar), affording a C 2 H 4 Faradaic efficiency (FE C2H4 ) of 57.5% with a partial current density (J C2H4 ) of 110 mA cm −2 .