High‐rate electrochemical CO2‐to‐CO conversion provides a favorable strategy for carbon neutrality. Molecular catalysts, especially those with isolated metal active centers, are known to be the efficient CO2‐to‐CO electrocatalysts due to their high selectivity and outstanding instinct activity; however, the controllable scale‐up synthesis and durable utilization at industrial current densities still remain a challenge. Here, it is developed a molecularly dispersed cobalt phthalocyanine loaded on carbon nanotube for high‐current long‐term CO2‐to‐CO electrolysis. The resultant catalyst exhibits a high CO selectivity with a maximum Faradaic efficiency of 97% and performs a current density of −200 mA cm−2 in a flow cell with a TOF of 83.9 s−1, which is among the best of CO‐selective electrocatalysts. With a series of impregnation loading experiments, the process of molecular‐dispersion or aggregation is investigated. In addition, the application of selective and durable electrolysis at a current of 0.25 A is realized up to 38.5 h in a scale‐up MEA configuration. Subsequent characterization shows robust durability closely related to the dispersion of CoPc. This study provides a triumph to catalyze commercial‐scale CO production using molecularly dispersed phthalocyanine electrocatalysts.

Although various chemicals and fuels have been successfully synthesized via the electrocatalytic CO 2 reduction reaction (CO 2 RR), the selective reduction of CO 2 to CO is widely recognized as one of the most economically viable reactions due to its simplicity and needing the least electrons transfer to form the product. [2] Among the reported CO 2 RR electrocatalysts, metallic Ag ones have demonstrated high catalytic selectivity toward CO, however, requiring high cathodic potentials (e.g., ≥0.9 V vs RHE). [3] Various approaches have been attempted to improve the CO 2 RR performance of Ag electrocatalysts. For instance, Kim and co-workers immobilized small Ag NPs (≈5 nm) on carbon support to achieve a high faradic efficiency (FE CO ) of 84.4% at −0.75 V versus RHE. [4] Luo and co-workers reported the use of the dominant Ag (100) facet exposed at the active edge of the triangular Ag nanoplates to attain a high FE CO of 96.8% at −0.855 V versus RHE. [5] Recently, the same team investigated the structure sensitivity of Ag nanocubes toward CO 2 RR and unveiled that the Ag nanocubes enclosed by {100} facets with the edge lengths below 25 nm can achieve a superb FE CO of 99.0% at −0.856 V versus RHE. [6] They attributed the superb FE CO to the increased percentage of edge active sites. These approaches utilize the edge active sites of Ag nanocrystals to improve CO 2 RR performance, however, such highly active edge sites areThe electrocatalytic CO 2 RR to produce value-added chemicals and fuels has been recognized as a promising means to reduce the reliance on fossil resources; it is, however, hindered due to the lack of high-performance electrocatalysts. The effectiveness of sculpturing metal/metal oxides (MMO) heterostructures to enhance electrocatalytic performance toward CO 2 RR has been well documented, nonetheless, the precise synergistic mechanism of MMO remains elusive. Herein, an in operando electrochemically synthesized Cr 2 O 3 -Ag heterostructure electrocatalyst (Cr 2 O 3 @Ag) is reported for efficient electrocatalytic reduction of CO 2 to CO. The obtained Cr 2 O 3 @Ag can readily achieve a superb FE CO of 99.6% at −0.8 V (vs RHE) with a high J CO of 19.0 mA cm −2 . These studies also confirm that the operando synthesized Cr 2 O 3 @Ag possesses high operational stability. Notably, operando Raman spectroscopy studies reveal that the markedly enhanced performance is attributable to the synergistic Cr 2 O 3 -Ag heterostructure induced stabilization of CO 2 •−/*COOH intermediates. DFT calculations unveil that the metallic-Ag-catalyzed CO 2 reduction to CO requires a 1.45 eV energy input to proceed, which is 0.93 eV higher than that of the MMO-structured Cr 2 O 3 @Ag. The exemplified approaches in this work would be adoptable for design and development of high-performance electrocatalysts for other important reactions.

Practical electrochemical CO2-to-CO conversion requires a non-precious catalyst to react at high selectivity and high rate. Atomically dispersed, coordinatively unsaturated metal-nitrogen sites have shown great performance in CO2 electroreduction; however, their controllable and large-scale fabrication still remains a challenge. Herein, we report a general method to fabricate coordinatively unsaturated metal-nitrogen sites doped within carbon nanotubes, among which cobalt single-atom catalysts can mediate efficient CO2-to-CO formation in a membrane flow configuration, achieving a current density of 200 mA cm−2 with CO selectivity of 95.4% and high full-cell energy efficiency of 54.1%, outperforming most of CO2-to-CO conversion electrolyzers. By expanding the cell area to 100 cm2, this catalyst sustains a high-current electrolysis at 10 A with 86.8% CO selectivity and the single-pass conversion can reach 40.4% at a high CO2 flow rate of 150 sccm. This fabrication method can be scaled up with negligible decay in CO2-to-CO activity. In situ spectroscopy and theoretical results reveal the crucial role of coordinatively unsaturated metal-nitrogen sites, which facilitate CO2 adsorption and key *COOH intermediate formation.

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Electrochemical CO2‐to‐CO conversion offers an attractive and efficient route to recycle CO2 greenhouse gas. Molecular catalysts, like CoPc, are proved to be possible replacement for precious metal‐based catalysts. These molecules, a combination of metal center and organic ligand molecule, may evolve into single atom structure for enhanced performance; besides, the manipulation of molecules’ behavior also plays an important role in mechanism research. Here, in this work, the structure evolution of CoPc molecules is investigated via electrochemical‐induced activation process. After numbers of cyclic voltammetry scanning, CoPc molecular crystals become cracked and crumbled, meanwhile the released CoPc molecules migrate to the conductive substrate. Atomic‐scale HAADF‐STEM proves the migration of CoPc molecules, which is the main reason for the enhancement in CO2‐to‐CO performance. The as‐activated CoPc exhibits a maximum FECO of 99% in an H‐type cell and affords a long‐term durability at 100 mA cm−2 for 29.3 h in a membrane electrode assembly reactor. Density‐functional theory (DFT) calculation also demonstrates a favorable CO2 activation energy with such an activated CoPc structure. This work provides a different perspective for understanding molecular catalysts as well as a reliable and universal method for practical utilization.