Copper–Nickel Tandem Catalysts for Selective Reduction of Carbon Dioxide to Ethylene by Stabilization of Cu⁺ via Tannic Acid

Electrochemical carbon dioxide reduction reaction (CO 2 RR) provides an effective method to convert CO 2 into valuable C 2+ products (e.g., C 2 H 4 ) while mitigating atmospheric CO 2 emissions. However, the C 2+ performance is severely restricted by the sluggish CC coupling step during CO 2 RR. To this end, a tandem catalyst (namely Ni–NC/CuTA [TA = tannic acid]) comprising Ni, N‐doped carbon (Ni–NC), and TA‐modified copper‐based component (CuTA) is developed. Ni–NC component is primarily responsible for reduction of CO 2 to CO intermediates, which facilitate CO dimerization through improving the local CO coverage. CuTA component mainly executes CC coupling to boost C 2 H 4 production in which Cu + species stabilized by TA molecules synergize with Cu 0 species to expediate CC coupling during CO 2 RR. The optimal Ni–NC/CuTA catalyst produces C 2 H 4 in a Faraday efficiency (FEC 2 H 4 ) of 38.9% at −1.0 V (vs RHE, RHE = reversible hydrogen electrode) in a flow cell, surpassing the non‐tandem counterpart of CuTA (FEC 2 H 4 of 23.9%) and XC‐72/CuTA (FEC 2 H 4 of 19.9%), as well as the TA‐free Ni–NC/Cu catalyst (FEC 2 H 4 of 27.6%). This work showcases that integration of tandem catalysis with Cu + /Cu 0 synergism offers an efficient approach to accelerate CC coupling toward C 2+ products.