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Ethylene is an ideal CO2 product in an electrocatalytic CO2 reduction reaction (CO2RR) with high economic value. This paper synthesised Al-doped octahedral Cu2O (Al–Cu2O) nanocrystal by a simple wet chemical method. The selectivity of CO2RR products was improved by doping Al onto the surface of octahedral Cu2O. The Al–Cu2O was used as an efficient electrocatalyst for CO2RR with selective ethylene production. The Al–Cu2O exhibited a high % Faradic efficiency (FEC2H4) of 44.9% at −1.23 V (vs. RHE) in CO2 saturated 0.1 M KHCO3 electrolyte. Charge transfer from the Al atom to the Cu atom occurs after Al doping in Cu2O, optimizing the electronic structure and facilitating CO2RR to ethylene production. The DFT calculation showed that the Al–Cu2O catalyst could effectively reduce the adsorption energy of the *CHCOH intermediate and promote the mass transfer of charges, thus improving the FEC2H4. After Al doping into Cu2O, the center of d orbitals shift positively, which makes the d–band closer to the Fermi level. Furthermore, the density of electronic states increases due to the interaction between Cu atoms and intermediates, thus accelerating the electrochemical CO2 reduction process. This work proved that the metal doping strategy can effectively improve the catalytic properties of Cu2O, thus providing a useful way for CO2 cycling and green production of C2H4. [ABSTRACT FROM AUTHOR]

Electrochemical CO2 reduction (CO2RR) to produce high value-added chemicals or fuels is a promising technology to address the greenhouse effect and energy challenges. Formate is a desirable product of CO2RR with great economic value. Here, nitrogen-doped bismuth nanosheets (N-BiNSs) were prepared by a facile one-step method. The N-BiNSs were used as efficient electrocatalysts for CO2RR with selective formate production. The N-BiNSs exhibited a high formate Faradic efficiency (FEformate) of 95.25% at −0.95 V (vs. RHE) with a stable current density of 33.63 mA cm−2 in 0.5 M KHCO3. Moreover, the N-BiNSs for CO2RR yielded a large current density (300 mA cm−2) for formate production in a flow-cell measurement, achieving the commercial requirement. The FEformate of 90% can maintain stability for 14 h of electrolysis. Nitrogen doping could induce charge transfer from the N atom to the Bi atom, thus modulating the electronic structure of N-Bi nanosheets. DFT results demonstrated the N-BiNSs reduced the adsorption energy of the *OCHO intermediate and promoted the mass transfer of charges, thereby improving the CO2RR with high FEformate. This study provides a valuable strategy to enhance the catalytic performance of bismuth-based catalysts for CO2RR by using a nitrogen-doping strategy. [ABSTRACT FROM AUTHOR]

The electrocatalytic reduction of CO2 using electricity produced from renewable resources is a strategy for achieving CO2 emission reduction and sustainable energy development. Further, the reaction has a large number of industrial practical applications, since CO2 can be converted to fuels via downstream chemical processing of the CO product. Herein, we successfully synthesized a low Mn-content single-atom catalyst (SAC) with Mn–N2O2 sites, covalently integrated into carbon nanosheets (Mn–NO/CNs) using a one-pot synthesis method. The Mn–NO/CN catalyst displays efficient electrocatalytic performance for the CO2 reduction reaction (CO2RR). Using an H-type electrolytic cell, the maximum CO Faraday efficiency (FE) at −0.460 V (V vs. RHE) reaches 96.0% in 0.5 M KHCO3 electrolyte. In the flow cell measurements, Mn–NO/CNs exhibits a current density of 28 mA cm−2 at a very low potential of −0.425 V (V vs. RHE) for the CO2RR with 1.0 M KOH as the mobile phase. The FECO remains above 80% even after 70 h, demonstrating the excellent durability of the catalyst even at a very low potential. The X-ray absorption spectra (XAS) and DFT calculations show that the Mn–N2O2 site is the active catalytic center, which facilitates the adsorption of CO2 and significantly lowers the free energy barrier leading to the formation of the critical intermediate *COOH. The presence of dual N and O coordinated to the single atom metal sites embedded in the 2D carbon nanosheet significantly improves catalytic activity for the reduction of CO2. Therefore, the catalytic performance of the single atom metal catalyst can be enhanced by adjusting the coordination environment. [ABSTRACT FROM AUTHOR]

Electrocatalytic reduction of CO 2 into valuable fuels and chemical feedstocks in a sustainable and environmentally friendly manner is an ideal way to mitigate climate change and environmental problems. Here, we fabricated a series of self-supporting Bi-Sb bimetallic nanoleaves on carbon paper (CP) by a facile electrodeposition method. The synergistic effect of Bi and Sb components and the change of the electronic structure lead to high formate selectivity and excellent stability in the electrochemical CO 2 reduction reaction (CO 2 RR). Specifically, the Bi-Sb/CP bimetallic electrode achieved a high Faradic efficiency (FE formate , 88.30%) at -0.9 V (vs RHE). The FE of formate remained above 80% in a broad potential range of -0.9 to -1.3 V (vs RHE), while FE CO was suppressed below 6%. Density functional theory calculations showed that Bi(012)-Sb reduced the adsorption energy of the *OCHO intermediate and promoted the mass transfer of charges. The optimally adsorbed *OCHO intermediate promoted formate production while inhibiting the CO product pathway, thereby enhancing the selectivity to formate synthesis. Moreover, the CO 2 RR performance was also investigated in a flow-cell system to evaluate its potential for industrial applications. The bimetallic Bi-Sb catalyst can maintain a steady current density of 160 mA/cm 2 at -1.2 V (vs RHE) for 25 h continuous electrolysis. Such excellent stability for formate generation in flow cells has rarely been reported in previous studies. This work offers new insights into the development of bimetallic self-supporting electrodes for CO 2 reduction.