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Electrochemical CO2 reduction reaction (eCO2RR) is a promising strategy to achieve carbon cycling by converting CO2 into value‐added products under mild reaction conditions. Recently, single‐atom catalysts (SACs) have shown enormous potential in eCO2RR due to their high utilization of metal atoms and flexible coordination structures. In this work, the recent progress in SACs for eCO2RR is outlined, with detailed discussions on the interaction between active sites and CO2, especially the adsorption/activation behavior of CO2 and the effects of the electronic structure of SACs on eCO2RR. Three perspectives form the starting point: 1) Important factors of SACs for eCO2RR; 2) Typical SACs for eCO2RR; 3) eCO2RR toward valuable products. First, how different modification strategies can change the electronic structure of SACs to improve catalytic performance is discussed; Second, SACs with diverse supports and how supports assist active sites to undergo catalytic reaction are introduced; Finally, according to various valuable products from eCO2RR, the reaction mechanism and measures which can be taken to improve the selectivity of eCO2RR are discussed. Hopefully, this work can provide a comprehensive understanding of SACs for eCO2RR and spark innovative design and modification ideas to develop highly efficient SACs for CO2 conversion to various valuable fuels/chemicals. [ABSTRACT FROM AUTHOR]

CO2 electroreduction into liquid fuels is of broad interest and benefits reducing the energy crisis and environment burdens. CuS has been reported to be a desirable candidate for CO2 electroreduction into formate; however, its formate selectivity and stability are still far from the demands of practical application. Herein, we report CuS nanoparticles exhibiting good Faradaic efficiency of formate (about 98 %) in CO2 electroreduction and its deactivation mechanism during the reaction. The deactivation of CuS was found to be associated with the reconstruction and S loss of CuS, which deteriorates the Faradaic efficiency of formate. Combined with ionic and gas analyses, the S atom in CuS was lost in the form of H2S, SO2, and SO42−, followed by the reconstruction of CuS into copper oxides. Such a catalyst reconstruction facilitates electroreductions of CO2 and H2O, respectively, into CO and H2, etc., resulting in the degradation of catalytical performance of CO2 electroreduction into formate. This work reveals the important role of S loss and reconstruction of metal sulfide catalysts during the electroreduction reaction, which may benefit the further development of CuS‐based electro‐catalyst for CO2 electroreduction. [ABSTRACT FROM AUTHOR]

Polymeric carbon nitride (PCN) has initiated another wave of studies on its properties and behavior since the discovery of its photocatalytic ability. However, pristine PCN is unable to cope with the growing varieties of applications. Making PCN more adaptive to evolving conditions is one of the greatest challenges. Molecular engineering strategy proves to be a powerful tool to modify PCN with specified purpose, revealing that what is really appealing on PCN is its structural and electronic adjustability. By tuning the molecular structure of PCN, the in‐plane electronic environment is accordingly changed, hence improving its photocatalytic activity. Herein, to further understand the relationship between the molecular structure of PCN and its photocatalytic performance, a comprehensive review on the recent progress of molecular engineering on PCN photocatalysts is presented. After introducing the fundamental properties of PCN and typical molecular engineering methodologies, the effects of different approaches of molecular structure modifications on the electronic structure of PCN are discussed in detail to unveil the role of molecular structures in electronic configuration regulation and the resultant photocatalytic performance. Finally, design principles of efficient PCN photocatalysts based on molecular engineering are provided, facilitating the understanding of its photocatalysis mechanism on the electronic level. [ABSTRACT FROM AUTHOR]

The emerging metal single‐atom catalyst has aroused extensive attention in multiple fields, such as clean energy, environmental protection, and biomedicine. Unfortunately, though it has been shown to be highly active, the origins of the activity of the single‐atom sites remain unrevealed to date owing to the lack of deep insight on electronic level. Now, partially oxidized Ni single‐atom sites were constructed in polymeric carbon nitride (CN), which elevates the photocatalytic performance by over 30‐fold. The 3d orbital of the partially oxidized Ni single‐atom sites is filled with unpaired d‐electrons, which are ready to be excited under irradiation. Such an electron configuration results in elevated light response, conductivity, charge separation, and mobility of the photocatalyst concurrently, thus largely augmenting the photocatalytic performance. [ABSTRACT FROM AUTHOR]