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• An mn single-atom catalyst (SAC) with a coordination structure of Mn-O 4 anchored in nitrogen-doped graphitic carbon was developed for the first time. • The prepared catalyst exhibits a high CO faradic efficiency (FE) of 98.5 % and CO partial current density (j CO) of ∼9.77 mA cm−2 at a low overpotential of 0.32 V with 0.5 M KHCO 3 aqueous as the electrolyte in an H-type electrolytic cell, which outperforms current state-of-the-art nitrogen-coordinated mn SACs. • The nitrogen-free coordination environment significantly alters the electronic state and catalytic ability of the single mn site, which leads to the remarkable performance of CO 2 electroreduction. • Density functional theory (DFT) calculations reveal that the Mn-O 4 site significantly lowers the free energy of the COOH* formation compared to the conventional n atoms coordinated mn SACs, and thus facilitates the CO 2 -to-CO conversion. • A higher current density of 27.8 mA cm−2 with a FE CO of 93.8 % at 0.51 V overpotential is achieved in an ionic liquid (IL) electrolyte. Modulating the ordinary nitrogen coordination environment of single-atom catalysts (SACs) is a promising strategy for customizing their activity and selectivity in electrochemical reduction of CO 2 (CO 2 RR). However, less attention has been paid to developing Mn-SACs with nitrogen-free coordination environment for CO 2 electroreduction. Herein, we construct a Mn SAC with a coordination structure of Mn-O 4 anchored in nitrogen-doped graphitic carbon, which exhibits a 98.5 % of CO faradic efficiency (FE CO) with a high CO partial current density (j CO) of ∼9.77 mA cm−2 at a low overpotential of 0.32 V in an H-type electrolytic cell. Furthermore, a higher current density of 27.8 mA cm−2 with a FE CO of 93.8 % at 0.51 V overpotential was achieved in an ionic liquid (IL) electrolyte. Density functional theory (DFT) calculations reveal that the Mn-O 4 site significantly lowers the free energy of the COOH* formation compared to the conventional N atoms coordinated Mn SACs, and thus facilitates the CO 2 -to-CO conversion. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • The low-cost Cu 2 O/g-C 3 N 4 heterojunction is constructed by simple hydrothermal method. • Cu 2 O/g-C 3 N 4 exhibited synergistic effects of thermalcatalysis and photocatalysis. • The overpotential reduce by 0.34 V in ILs than KHCO 3 electrolyte. • We provided strategy of CO 2 reduction to ethanol assisted by ILs under thermal field. Photocatalytic CO 2 reduction is a potential way to address simultaneously environmental pollution and energy shortage. However, the difficulties of CO 2 activation and C C coupling lead to quite low conversion efficiency of CO 2 to C2 products. In this study, we constructed Cu 2 O/g-C 3 N 4 heterojunction for photocatalytic CO 2 reduction to ethanol by coupling thermal field and ionic liquids (ILs). The ethanol rate reached 0.71 mmol·g−1·h−1 over Cu 2 O/g-C 3 N 4 under photothermalcatalysis, which is 1.89 times that of photocatalysis and 7.05 times that of thermal catalysis. The temperature enhanced thermal motion of the radical, which promotes the formation of ethanol through the ·CH 3 dimerization. The 1-aminopropyl-3-methylimidazolium bromide ILs shows superior CO 2 reduction performance with a high current density (21.3 mA·cm−2) than KHCO 3 electrolyte (12.8 mA·cm−2). The overpotential is reduced by 0.34 V, which accelerates CO 2 reduction by reducing polarization. It is found that the ILs played a key role in suppressing H 2 O reduction and increasing ethanol yield in this photothermalcatalytic strategy. [ABSTRACT FROM AUTHOR]

Schematic PTCR conversion of CO 2 to ethanol via the AuCu/g-C 3 N 4 to achieve carbon cycle. • AuCu/g-C 3 N 4 composite was constructed with the aid of seed crystal mediated method. • Ultrathin porous g-C 3 N 4 nanosheets promotes rivet of AuCu NPs and accelerates carrier migration. • AuCu can quicken charge separation, and synergistic effect promote C-C coupling to ethanol. • Thermal accelerates the movement of *CO and promotes the formation of ethanol by C-C coupled process. • We provide efficient method of converting CO 2 to ethanol by combination of AuCu alloy and g-C 3 N 4. Here, we report ultrathin porous g-C 3 N 4 nanosheets modified with AuCu alloy NPs for photothermalcatalytic CO 2 reduction to ethanol. The positive charge on the Au surface improves the adsorption of CO 2 molecules and the charge transfer from Au to Cu in the alloy enriches Cu with excessive negative charges, promoting the formation of intermediates CO 2 ·- and *CO on the surface of Cu. The strong interaction between the metal and g-C 3 N 4 accelerates the migration of photogenerated charges. The increase of temperature leads to the enhancement of the thermal motion of the molecules, resulting in the synergy of photocatalysis and thermal catalysis, which promotes the formation of C-C coupling by *CO polymerization, so that the yield of CH 3 CH 2 OH was increased. At 120 ℃, the yield and selectivity of ethanol are 0.89 mmol·g−1·h−1 and 93.1% for 1.0 wt% AuCu/g-C 3 N 4 , which are 4.2 times that of photocatalysis and 7.6 times that of thermal catalysis. [ABSTRACT FROM AUTHOR]