LAUSR

Electrocatalytic CO2 reduction reaction (CO2RR) offers a promising strategy to lower CO2 emission while producing value‐added chemicals. A great challenge facing CO2RR is how to improve energy efficiency by reducing overpotentials. Herein, partially nitrided Ni nanoclusters (NiNx) immobilized on N‐doped carbon nanotubes (NCNT) for CO2RR are reported, which achieves the lowest onset overpotential of 16 mV for CO2‐to‐CO and the highest cathode energy efficiency of 86.9% with CO Faraday efficiency >99.0% to date. Interestingly, NiNx/NCNT affords a CO generation rate of 43.0 mol g−1 h−1 at a low potential of −0.572 V (vs RHE). DFT calculations reveal that the NiNx nanoclusters favor *COOH formation with lower Gibbs free energy than isolated Ni single‐atom, hence lowering CO2RR overpotential. As NiNx/NCNT is applied to a membrane electrode assembly system coupled with oxygen evolution reaction, a cell voltage of only 2.13 V is required to reach 100 mA cm−2, with total energy efficiency of 62.2%.