Although Faraday efficiency (FE) for CO production of single-atom catalysts immobilized on nitrogen-doped carbon supports (M-N/C) for CO2 electrocatalytic reduction reaction (CO2RR) is generally over 90%, M-N/C catalysts demonstrate a...

process, desired products can be easily adjusted by changing the type of electrocatalysts and the applied potentials. [3] Unfortunately, there are still many challenges for CO 2 electroreduction due to the highly stable chemical bound of CO 2 molecule and high energy barrier of proton-coupled multielectron transfer process. [4] Thus, it is critical to develop efficient and stable catalyst materials for CO 2 electroreduction.At present, many catalysts have been reported, including metal, metal oxide, MXenes (transition-metal carbides, nitrides, and carbonitrides), carbon-based materials (e.g., graphene, carbon nanotube (CNT), and carbon quantum dots (CQD)). [5] The ideal heterogeneous catalyst of CO 2 electroreduction should contain highly dispersed active species and sufficient accessible surface to prevent the problem of the mass transfer. [6] Recently, single atom catalysts (SACs) have drawn much attention for CO 2 RR, with advantages of unique electronic structure, unsaturated coordination configuration of active centers, maximum atom-utilization efficiency, quantum size effect, strong interactions between metal and support as well as foreign atom effect. [7] SACs materials afford high selectivity and stability toward desired products, exhibiting great potential to bridge the gap between the homogeneous and heterogeneous catalysis.To date, researchers have successfully developed efficient M-N-C-based (M = Ni, Fe, Co, Mn, Zn, Sn) electrocatalysts with Construction of single atom catalysts (SACs) with high activity toward electroreduction of CO 2 still remains a great challenge. A very simple and truly cost-effective synthetic strategy is proposed to prepare SACs via a impregnation-pyrolysis method, through one-step pyrolysis of graphene oxide aerogel. Compared with other traditional methods, this process is fast and free of repeated acid etching, and thus it has great potential for facile operation and large-scale manufacturing. Both X-ray absorption fine structure and high-angle annular dark-field scanning transmission electron microscopy images confirm the presence of isolated nickel atoms, with a high Ni loading of ≈2.6 wt%. The obtained 3D porous Ni-and N-codoped graphene aerogel exhibits excellent activity toward electroreduction of CO 2 to CO, in particular exhibiting a remarkable CO Faradaic efficiency of 90.2%. Density functional theory calculations reveal that free energies for the formation of intermediate *COOH on coordinatively unsaturated NiN sites are significantly lower than that on NiN 4 site, suggesting the outstanding activities of CO 2 electroreduction originate from coordinatively unsaturated NiN sites in catalysts.

Engineering electronic structure to enhance the binding energies of reaction intermediates in order to achieve a high partial current density can lead to increased yield of target products. Herein, amino‐functionalized carbon is used to regulate the electronic structure of tin‐based catalysts to enhance activity of CO2 electroreduction. The hollow nanotubes composed of SnS (stannous sulfide) nanosheets are modified with amino‐functionalized carbon layers, achieving a highest formate Faraday efficiency of 92.6% and a remarkable formate partial current density of 41.1 mA cm−2 (a total current density of 52.1 mA cm−2) at a moderate overpotential of 0.9 V versus reversible hydrogen electrode, as well as a good stability. Density functional theory calculations demonstrate that the superior activity is attributed to the synergistic effect among SnS and Aminated‐C in increasing the adsorption energies of the key intermediates and accelerating the charge transfer rate.