Steering the Product Selectivity of CO₂ Electroreduction by Single Atom Switching in Isostructural Copper Nanocluster Catalysts

Even single atom manipulation can cause drastic changes in catalytic activity and selectivity, especially in atomic-level catalysts. However, it is challenging to accurately elucidate the influence of specific atoms on performance due to the intertwined factors in catalysts. Atomically precise isostructural nanoclusters (NCs) can serve as ideal platforms to uncover the impact of individual atoms on catalytic properties. Herein, a pair of isostructural Cu NCs ([Cu₁₃(SC₆H₃F₂)₃(P(PhF)₃)₇H₁₀]⁰ and [Cu₁₄(SC₆H₃F₂)₃(P(PhF)₃)₈H₁₀]⁺ namely as Cu₁₃ and Cu₁₄) were synthesized. In the electrochemical CO₂ reduction reaction, Cu₁₃ shows barely any activity toward only 2e product CO with a maximum 13% FE at -1.1 V. In contrast, Cu₁₄ can promote CO₂ deep reduction to hydrocarbons (CH₄ and C₂H₄) with maximum FE of 54.3% at -1.2 V. Based on the crystallographic and computational analyses, the extra Cu at the top in Cu₁₄ squeezes the H connected with three core Cu into the center of the same plane, optimizing the electronic structure and thereby promoting CO₂ activation and H₂O dissociation, which is further confirmed by comprehensive in situ characterizations, kinetic experiments, and theoretical calculations. This work provides a unique isostructural NCs system to gain fundamental insights into switching catalytic reactivity by single-atom manipulation.