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In recent years, single‐atom catalysts (SACs) have received increasing attention in the field of electrochemical CO2RR with their efficient atom utilization efficiency and excellent catalytic performance. However, their low metal loading and the presence of linear relationships for single active sites with simple structures possibly restrict their activity and practical applications. Active site tailoring at the atomic level is a visionary approach to break the existing limitations of SACs. This paper first briefly introduces the synthesis strategies of SACs and DACs. Then, combining previous experimental and theoretical studies, this paper introduces four optimization strategies, namely spin‐state tuning engineering, axial functionalization engineering, ligand engineering, and substrate tuning engineering, for improving the catalytic performance of SACs in the electrochemical CO2RR process by combining previous experimental and theoretical studies. Then it is introduced that DACs exhibit significant advantages over SACs in increasing metal atom loading, promoting the adsorption and activation of CO2 molecules, modulating intermediate adsorption, and promoting C−C coupling. At the end of this paper, we briefly and succinctly summarize the main challenges and application prospects of SACs and DACs in the field of electrochemical CO2RR at present. [ABSTRACT FROM AUTHOR]

Excess CO2 can be effectively converted into valuable fuels and chemicals by electrochemical CO2 reduction, which can help establish a low‐carbon emission economy and solve the current energy crisis. In recent years, metal‐organic frameworks (MOFs), as an emerging multifunctional material with porous structure, high chemical tunability and large specific surface area, has received increasing attention in the field of electrochemical CO2RR. In this paper, we present a comprehensive overview of various MOFs and their derivatives as CO2RR electrocatalysts and analyze their roles in the catalytic process from physical and chemical aspects. In addition, combining experiments and theory, this article also offers a personal view on the electronic structure modulation strategies to improve electrocatalytic performance. The article concludes with an analysis of the challenges in realizing MOFs and their derivatives for electrocatalytic CO2RR applications. [ABSTRACT FROM AUTHOR]

In this paper, CaxZn10‐xFe20 catalysts were prepared by the co‐precipitation method and applied to CO2 hydrogenation. The experimental results show that the CO2 conversion of the catalyst Ca1Zn9Fe20 at a Ca doping amount of 1 mmol can reach 57.91 %, which is 13.5 % more than the CO2 conversion of the catalyst Zn10Fe20. Moreover, the catalyst Ca1Zn9Fe20 has the lowest selectivity for both CO and CH4, with 7.40 % and 6.99 %, respectively. The catalysts were characterized by XRD, N2 adsorption‐desorption, CO2‐TPD, H2‐TPR, and XPS. The results demonstrate that the doping of Ca increases the basic sites on the catalyst surface and thus allows the catalyst to adsorb more CO2 to promote the reaction. Besides, the Ca doping amount of 1 mmol can suppress the formation of graphitic carbon on the catalyst surface and prevent the excess graphitic carbon from covering the active site Fe5C2. [ABSTRACT FROM AUTHOR]

Recent years have seen a growing interest in metal‐free CO2 activation by silylenes, silylones, and silanones. However, compared to mononuclear silicon species, CO2 reduction mediated by dinuclear silicon compounds, especially disilynes, has been less explored. We have carried out extensive computational investigations to explore the mechanistic avenues in CO2 reduction to CO by donor‐stabilized disilyne bisphosphine adduct (R1M) and phosphonium silaylide (R2) using density functional theory calculations. Theoretical calculations suggest that R1M exhibits donor‐stabilized bis(silylene) bonding features with unusual Si−Si multiple bonding. Various modes of CO2 coordination to R1M have been investigated and the coordination of CO2 by the carbon center to R1M is found to be kinetically more facile than that by oxygen involving only one or both the silicon centers. Both the theoretically predicted reaction mechanisms of R1M and R2‐mediated CO2 reduction reveal the crucial role of silicon‐centered lone pairs in CO2 activations and generation of key intermediates possessing enormous strain in the Si−C−O ring, which plays the pivotal role in CO extrusion. [ABSTRACT FROM AUTHOR]

The term "covalent organic framework" (COF) refers to a class of porous organic polymeric materials made from organic building blocks that have been covalently bonded. The preplanned and predetermined bonding of the monomer linkers allow them to demonstrate directional flexibility in two‐ or three‐dimensional spaces. COFs are modern materials, and the discovery of new synthesis and linking techniques has made it possible to prepare them with a variety of favorable features and use them in a range of applications. Additionally, they can be post‐synthetically altered or transformed into other materials of particular interest to produce compounds with enhanced chemical and physical properties. Because of its tunability in different chemical and physical states, post‐synthetic modifications, high stability, functionality, high porosity and ordered geometry, COFs are regarded as one of the most promising materials for catalysis and environmental applications. This study highlights the basic advancements in establishing the stable COFs structures and various post‐synthetic modification approaches. Further, the photocatalytic applications, such as organic transformations, degradation of emerging pollutants and removal of heavy metals, production of hydrogen and Conversion of carbon dioxide (CO2) to useful products have also been presented. Finally, the future research directions and probable outcomes have also been summarized, by focusing their promises for specialists in a variety of research fields. [ABSTRACT FROM AUTHOR]

Bi‐based electrocatalysts have been widely investigated in the CO2 reduction reaction (CO2RR) for the formation of formate. However, it remains a challenge to achieve high Faradaic efficiency (FE) and industrial current densities at low overpotentials for obtaining both high formate productivity and energy efficiency (EE). Herein, we report an Ag−Bi2O3 hybrid nanofiber (Ag−Bi2O3) for highly efficient electrochemical reduction of CO2 to formate. Ag−Bi2O3 exhibits a formate FE of >90% for current densities from −10 to −250 mA ⋅ cm−2 and attains a yield rate of 11.7 mmol ⋅ s−1 ⋅ m−2 at −250 mA ⋅ cm−2. Moreover, Ag−Bi2O3 increased the EE (52.7%) by nearly 10% compared to a Bi2O3 only counterpart. Structural characterization and in‐situ Raman results suggest that the presence of Ag induced the conversion of Bi2O3 from a monoclinic phase (α‐Bi2O3) to a metastable tetragonal phase (β‐Bi2O3) and accelerated the formation of active metallic Bi at low overpotentials (at > −0.3 V), which together contributes to the highly efficient formate formation. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) is an abundant, inexpensive, renewable C1 resource and the main component of greenhouse gas, thereby the research for its sustainable and efficient conversion has received notable attention in recent years. Electrochemical organic synthesis, as a green and efficient synthetic method, is convinced to be an ideal approach for CO2 utilization. In this review, recent advances in electrocarboxylation with CO2 were summarized through different reaction types, which would disclose the great potential of electrocarboxylation in green organic synthesis. [ABSTRACT FROM AUTHOR]

We investigated the CO2 adsorption and electrochemical conversion behavior of triazole‐based C3N5 nanorods as a single matrix for consecutive CO2 capture and conversion. The pore size, basicity, and binding energy were tailored to identify critical factors for consecutive CO2 capture and conversion over carbon nitrides. Temperature‐programmed desorption (TPD) analysis of CO2 demonstrates that triazole‐based C3N5 shows higher basicity and stronger CO2 binding energy than g‐C3N4. Triazole‐based C3N5 nanorods with 6.1 nm mesopore channels exhibit better CO2 adsorption than nanorods with 3.5 and 5.4 nm mesopore channels. C3N5 nanorods with wider mesopore channels are effective in increasing the current density as an electrocatalyst during the CO2 reduction reaction. Triazole‐based C3N5 nanorods with tailored pore sizes exhibit CO2 adsorption abilities of 5.6–9.1 mmol/g at 0 °C and 30 bar. Their Faraday efficiencies for reducing CO2 to CO are 14–38% at a potential of −0.8 V vs. RHE. [ABSTRACT FROM AUTHOR]

To overcome the challenges of global warming and environmental pollution, it is necessary to reduce the concentration of carbon dioxide (CO2) in the atmosphere, which is mainly accumulated in the air through the burning of fossil fuels. Therefore, the development of environmentally friendly strategies to capture carbon dioxide and convert it into value‐added products offers a promising way forward for reducing carbon dioxide concentration in the atmosphere. In this context, POPs (porous organic polymers) have shown great potential as CO2 selective adsorbents due to their high specific surface area, chemical stability, nanoscale porosity and structural diversity, as well as POPs based heterogeneous catalysts for CO2 conversion. This review provides a concise account of preparation methods of various POPs, challenges and current development trends of POPs in photocatalytic CO2 reduction, electrocatalytic CO2 reduction and chemical CO2 conversion. [ABSTRACT FROM AUTHOR]