Hybrid Cu⁰ and Cu^{x +} as Atomic Interfaces Promote High-Selectivity Conversion of CO₂ to C₂ H₅ OH at Low Potential

The mixing of charge states of metal copper catalysts may lead to a much improved reactivity and selectivity toward multicarbon products for CO₂ reduction. Here, an electrocatalyst model composed of copper clusters supported on graphitic carbon nitride (g-C₃ N₄ ) is proposed; the connecting Cu atoms with g-C₃ N₄ can be oxidized to Cu^{x +} due to substantial charge transfer from Cu to N atoms, while others stay as Cu⁰ . It is revealed that CO₂ can be captured and reduced into *CO on the Cu_t ⁰ site, owing to its zero oxidation state. More importantly, C-C coupling reaction of two *CHO species on the Cu_t ⁰ -Cu_b ^{x +} atomic interface can occur with a rather low kinetic barrier of 0.57 eV, leading to the formation of the final C₂ product, namely, C₂ H₅ OH. During the whole process, the limiting potential is just 0.68 V. These findings may open a new avenue for CO₂ reduction into high-value fuels and chemicals.