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The coupling reaction of carbon dioxide (CO2) and epoxides is one of the most efficient pathways to achieve the carbon balance. However, to accomplish it under the mild conditions, especially under the atmospheric pressure, is still a perplexing problem. Three novel ionic liquids (ILs), [DMAPBrPC][TMGH], [DMAPBrPC][DBUH], and [DMAPBrPC][BTMA], are designed and synthesized. All of them display the excellent catalytic activity for the title reaction achieving the yield over 96.6% under the atmospheric CO2 pressure at 60 °C. Interestingly, [DMAPBrPC][BTMA] with the inert hydrogen atom in cation exhibits the superior catalytic activity as compared to other two ILs with the protic hydrogen atom in cation along with the same anion. The active hydrogen atom in [DMAPBrPC][TMGH] and [DMAPBrPC][DBUH] would impede the –COO− group to absorb CO2, which is an unfavorable item for the reaction. Moreover, the strong hydrogen bond in [DMAPBrPC][TMGH] and [DMAPBrPC][DBUH] would lessen the nucleophilic ability of Br− anion resulting in the inferior catalytic performance, which is further confirmed by the density functional theory (DFT) calculations. The cation without the active hydrogen atom could also be employed to design the ILs with the excellent catalytic feature when it is combined with the suitable anion.

Abstract Developing metal‐nitrogen‐carbon (M‐N‐C)‐based single‐atom electrocatalysts for carbon dioxide reduction reaction (CO2RR) have captured widespread interest because of their outstanding activity and selectivity. Yet, the loss of nitrogen sources during the synthetic process hinders their further development. Herein, an effective strategy using 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIM][BF4]) as a liquid nitrogen source to construct a nickel single‐atom electrocatalyst (Ni‐SA) with well‐defined Ni‐N4 sites on a carbon support (denoted as Ni‐SA‐BB/C) is reported. This is shown to deliver a carbon monoxide faradaic efficiency of >95% over a potential of −0.7 to −1.1 V (vs reversible hydrogen electrode) with excellent durability. Furthermore, the obtained Ni‐SA‐BB/C catalyst possesses higher nitrogen content than the Ni‐SA catalyst prepared by conventional nitrogen sources. Importantly, only thimbleful Ni nanoparticles (Ni‐NP) are contained in the large‐scale‐prepared Ni‐SA‐BB/C catalyst without acid leaching, and with only a slight decrease in the catalytic activity. Density functional theory calculations indicate a salient difference between Ni‐SA and Ni‐NP in the catalytic performance toward CO2RR. This work introduces a simple and amenable manufacturing strategy to large‐scale fabrication of nickel single‐atom electrocatalysts for CO2‐to‐CO conversion.

The coupling reaction of carbon dioxide (CO2) and epoxides is one of the most efficient pathways to achieve the carbon balance. However, to accomplish it under the mild conditions, especially under the atmospheric pressure, is still a perplexing problem. Three novel ionic liquids (ILs), [DMAPBrPC][TMGH], [DMAPBrPC][DBUH], and [DMAPBrPC][BTMA], are designed and synthesized. All of them display the excellent catalytic activity for the title reaction achieving the yield over 96.6% under the atmospheric CO2 pressure at 60 °C. Interestingly, [DMAPBrPC] [BTMA] with the inert hydrogen atom in cation exhibits the superior catalytic activity as compared to other two ILs with the protic hydrogen atom in cation along with the same anion. The active hydrogen atom in [DMAPBrPC] [TMGH] and [DMAPBrPC][DBUH] would impede the --COO- group to absorb CO2, which is an unfavorable item for the reaction. Moreover, the strong hydrogen bond in [DMAPBrPC][TMGH] and [DMAPBrPC][DBUH] would lessen the nucleophilic ability of Br- anion resulting in the inferior catalytic performance, which is further confirmed by the density functional theory (DFT) calculations. The cation without the active hydrogen atom could also be employed to design the ILs with the excellent catalytic feature when it is combined with the suitable anion. [ABSTRACT FROM AUTHOR]