Seeded Growth of Gold–Copper Janus Nanostructures as a Tandem Catalyst for Efficient Electroreduction of CO₂ to C₂₊ Products

Gold–copper (Au-Cu) Janus nanostructures (Au-Cu Janus NSs) are successfully prepared using N-oleyl-1,3-propanediamine as capping agent and Cu(acac)₂ as the precursor in a typical seeded growth strategy. By preferably depositing Cu atoms on one side of concave cubic Au seeds, the Cu part gradually grows larger as more Cu precursors are added, making the size tuning feasible in the range of 74–156 nm. When employed as an electrocatalyst for electrochemical CO₂ reduction (CO₂RR), the Au-Cu Janus NSs display superior performance to Au@Cu core-shell NSs and Cu NPs in terms of C₂₊ products selectivity (67%) and C₂₊ partial current density (−0.29 A cm^–2). Combined experimental verification and theoretical simulations reveal that CO spillover from Au sites to the nearby Cu counterparts would enhance CO coverage and thus promote C–C coupling, highlighting the unique structural advantages of the Au-Cu Janus NSs toward deep reduction of CO₂. The current work provides a facile strategy to fabricate tandem catalyst with a Janus structure and validates its structural advantages toward CO₂RR, which are of critical importance for the rational design of efficient CO₂RR catalyst.