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%.
Copper-coordinated catalysts are reported to be effective for electrocatalytic CO 2 reduction reaction (CO 2 RR) to C 2 products but suffer from low selectivity. Herein a strategy was developed to tune the d-band structure of Cu II via coordinating with aromatic ligands to form Cu-based conjugated polymers for CO 2 RR to C 2 chemicals. The catalysts derived from copper chloride coordinating with tetraminobenzoquinone (TABQ) and with 1,2,4,5-benzenetetramine possessed high-density and compact Cu single-atom sites and displayed high activity for CO 2 RR to C 2 products. Especially, Cu-TABQ exhibited a maximum C 2 faradaic efficiency of 63.2 % with a current density of 423 mA cm À 2 at À 1.17 V (vs. reversible hydrogen electrode). Density functional theory calculations indicated that the TABQ linker possessing C=O groups significantly widened the d-band of coordinated Cu II , which facilitated binding of *CO intermediate on the catalyst and thus enhanced CÀ C coupling. This work provides mechanistic insight into the Cu II -coordinated polymers for CO 2 RR with high selectivity toward C 2 products.
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