CO₂ is an important C1 source in organic synthesis due to its abundant, non-toxic and low-cost properties. There- fore, it is of great significance to use CO₂ as a C1 source to synthesize compounds with high added value. This review focuses on the recent progress in the carboxylation of organic compounds using CO₂ as an electrophile under electrochemical conditions. The electrochemical carboxylation of non-activated organic halides, unsaturated alkene compounds and some special compounds are mainly introduced. And the use of sacrificial anodes and non-sacrificial anodes is classified in detail. The reaction mechanisms of these reactions are also discussed. This review provides a reference for the application of such reactions in organic synthesis in the future.

Carbon dioxide (CO₂) exerts a significant influence on climate change as a potent greenhouse gas. From a chemical standpoint, CO₂ serves as an abundant and cost-effective “carbon one (C1)” resource with non-toxicity, renewability, and easy obtainability. The utilization of CO₂ for synthesizing high-value-added chemicals represents an important avenue for addressing national strategic requirements and aligning with China’s objectives of peaking carbon emissions by 2030 and achieving carbon neutrality by 2060. Organic photocatalysis can harness light energy to induce electron transfer in organic chemical reactions, facilitating bond cleavage and recombination processes. This approach offers advantages such as mild reaction conditions, environmental friendliness and exceptional selectivity. By integrating CO₂ resource utilization with organic photocatalysis, novel opportunities arise for enriching carboxylation reactions. Two distinct types of photocatalytic carboxylation reactions, those involving carbon anions as pivotal intermediates and those featuring CO₂ radical anions as key intermediates, are systematically elucidated.

Reducing carbon dioxide emission and converting carbon dioxide from the air have always been a hot topic for researchers. Carbon dioxide is an ideal raw material for synthesizing organic compounds because of its good physical properties such as non-toxicity, abundance and easy availability. In recent years, hydrosilylation reaction has become an effective method to convert carbon dioxide into formate, formaldehyde, methanol, methane and other valuable chemical products under moderate conditions, which greatly promotes the conversion and utilization of carbon dioxide. The research progress on the design, synthesis and catalytic performance of catalytic systems used to catalyze the hydrosilylation for reduction of carbon dioxide is summarized and discussed. The reaction mechanism of hydrosilylation reduction of carbon dioxide is discussed, and the advantages and disadvantages of various catalyst systems are also analyzed. At last, the future research directions in this field are prospected.

Porous organic polymers (POPs) are a new class of porous materials that connect organic structural units by covalent bonds, having the features of various synthetic methods, adjustable pore properties, stable pore structures, low relative density and large specific surface areas. POPs have been applied in fields of gas adsorptions, separations and storage, optoelectronic devices, sensing and heterogeneous catalysis, showing the important application value. Carbon capture, utilization and storage (CCUS) technology is the unique way to significantly reduce carbon dioxide (CO₂) emissions from fossil fuels, and catalytic conversion of CO₂ into valuable fuels or industrial value-added products is an effective and potential strategy to solve the utilization of renewable energy and realize the development of green chemistry. In this review, the synthesis and properties of covalent-organic frameworks (COFs), covalent triazine frameworks (CTFs), hypercrosslinked polymers (HCPs), conjugated microporous polymers (CMPs) and polymer of intrinsic microporosity (PIMs) and their progress of chemical fixation of CO₂ in recent years, is reviewed, and the application prospects of POPs in CO₂ catalysis are prospected.

As a class of common and important compounds, carboxylic acids are widely used in areas of medicine, pesticides and polymers. Therefore, development of facile and efficient methods for the synthesis of carboxylic acids is of great significance. Electrochemical synthesis of carboxylic acids has attracted widespread attentions due to its environmentally friendly and mild conditions. This article mainly reviews the relevant research in electrochemical synthesis of carboxylic acids in recent years from two aspects: electrochemical oxidation for carboxylation and electrochemical reduction of carbon dioxide for carboxylation.

The bidentate N-heterocyclic carbene (NHC)-pyridine nitrogen manganese complex catalyzed coupling reaction of epoxides with CO₂ was developed. The binary system resulting from the manganese complex Mn-2 in combination with tetrabutylammonium iodide (TBAI) exhibits the high activity for the synthesis of cyclic carbonate from epoxides and CO₂. The binary catalytic system is suitable for a broad range of substrates scope, such as terminal epoxides and sterically hindered internal epoxides. A possible catalytic pathway was elaborated by UV-vis, FT-IR and HRMS method.

Hydrosilylation of carbon dioxide (CO₂) is one of the most significant sustainable approaches for utilizing CO₂ as a C1 feedstock. This approach enables the conversion of CO₂ to value-added chemicals at various oxidation levels, such as formate, formaldehyde, methanol, or methane. Additionally, the formylation and/or alkylation of the N—H bonds of amines can also be achieved in certain catalytic systems with CO₂ and hydrosilanes. Currently, remarkable progress has been made in the field of CO₂ hydrosilylation. This focused review mainly describes advances in the design and catalytic performance of leading catalytic systems reported in the past three years, including noble transition metal catalysis, nonprecious transition metal catalysis, rare-earth metal catalysis, main-group metal catalysis, and metal-free catalysis. Moreover, current bottlenecks and perspectives of this field are also discussed.

An efficient visible light-facilitated decarbon-carboxylation of activated alkenes has been successfully developed. Compared with traditional alkene carboxylation, this method features mild conditions, up to 96% yield and good compatibility with a variety of functional groups. It provides a new method for the synthesis of phenylacetic acid and its derivatives. The mechanism study shows that the reaction realizes the synthesis of the corresponding carboxylic acid with constant apparent carbon number by substituting the carbon-carbon double bond of alkene.

The pursuit of cleanliness, energy efficiency, and resource preservation through photochemical reactions has led to the emergence of novel pathways and methodologies in synthetic chemistry, rendering it one of the most dynamic research domains within modern organic synthesis. Carbon dioxide (CO₂), owing to its non-toxic, cost-effective, abundant, and recyclable attributes, serves as an optimal C1 precursor in synthetic chemistry. Recent years have witnessed rapid advancements in the photochemical conversion of CO₂ into carboxylic acid compounds, offering a gentle and highly efficient synthetic approach for their production. An overview of the research progress on the synthesis methodologies of carboxylic acid compounds through photochemical CO₂ conversion is provided, while certain associated reaction mechanisms are also elucidated.

Carbon dioxide (CO₂) is the attractive green and renewable C1 resource, and its direct participation in organic synthesis reactions as a reaction feedstock or promoter, which is a research direction advocated by green chemistry. On the other hand, the three-component coupling reaction is considered to be one of the most attractive strategies in synthetic chemistry, which is capable of synthesizing complex molecules directly from simple and readily available raw materials. Based on this, this paper reviews the three-component coupling reaction systems involving CO₂ as a raw material or promoter, categorizes them according to the types of products generated: carboxyl, ester, carbonyl, haloalkyl, and cyano compounds as well as CO₂ as a promoter. An outlook on the development of such reactions is also given.

Carbazole moiety exhibits excellent electron transfer ability due to its rigid planar structure and large conjugate system. The N atom and aromatic ring of carbazole can be easily modified, and carbazole-based ligands and polymers have attracted significant amounts of interests in the fields of catalysis and material sciences. Important progress has been achieved in both homogeneous and heterogeneous catalysis promoted by catalysts containing carbazole as the backbone or linker. The catalytic conversion of carbon dioxide can provide an important technology support for realization of carbon neutrality goals. In this paper, the recent progresses on the use of carbazole-based ligands, carbazole-based complexes or carbazole-based heterogeneous materials in catalytic transformation of CO₂ are reviewed, including the methods of catalyst preparation, the different types of reactions in homogeneous and heterogeneous catalysis. This review will provide systematic information for further understanding the important role of carbazole units in catalysis and designing more efficient carbazole-based materials.

Two new phenolic resin porous organic polymers PRP-1, PRP-2 were obtained by one-step polymerization of phenolic resin reaction using functionalized pillar[n]arene and 1,4-bis(4-formylphenyl)benzene as polymerization monomers. The pore characters of PRP-1 and PRP-2 were evaluated by solid-state nuclear magnetic carbon spectroscopy (¹³C CP/MAS NMR), fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (PXRD), scanning electron microscopy (SEM), nitrogen and carbon dioxide adsorption and desorption, and thermogravimetric analysis (TG). The results showed that mutilid-hydroxyl groups on the aromatic macrocycles of pillar[5]arene significantly affect the polymer structure, and the specific surface area of PRP-2 with a higher number of hydroxyl groups is more than 10 times higher than that of PRP-1. Polymers PRP-1 and PRP-2 can be used for non-homogeneous catalytic carbon dioxide (CO₂) conversion, and PRP-2 exhibits higher conversion. This work shows that the functionalized pillar[n]arene has a potential application in organic porous polymers.

Carbon dioxide radical anion ($\mathrm{CO}_{2}^{-\cdot}$) is an active chemical intermediate with strong reduction ability, which is used widely as C1-building block and single electron reducing reagent in organic synthesis. CO₂ and formic acid or formate salts are common source of $\mathrm{CO}_{2}^{-\cdot}$. $\mathrm{CO}_{2}^{-\cdot}$ can be generated by either direct reduction of CO₂ or hydrogen atom transfer (HAT) of formate salts. The production, characterization methods and application of $\mathrm{CO}_{2}^{-\cdot}$ are summarized, and the insights are provided into the prospects in this field.

Carbon dioxide (CO₂) is a green and renewable C1 synthon, and the direct carboxylation of inert chemical bonds with CO₂ could afford high value-added carboxylic acid derivatives from simple molecules, which feature both atomic and step economies. Organic electrosynthesis is a green synthesis technology using electrons as "reagents", and the development of electrochemical carboxylation of inert bonds with CO₂ has become a hot research topic in recent years. The recent progress on the electroreductive carboxylation of inert bonds with CO₂ is summarized, including C—H, C—C, C—O, and C—F single bonds. The mechanism and application of these reactions are emphatically discussed, and the challenges and development trends in this field are also covered.

Carbon dioxide (CO₂) serves as a sustainable carbon source for building biomass, fossil fuels, and organic chemicals. Converting CO₂ into value-added chemicals or fuels is an ideal approach to achieve carbon cycling. The reduction and conversion of CO₂, a pivotal aspect of C1 chemistry, have long been a subject of intense research interest. Previous studies have demonstrated that through transition metal catalysis, hydrogen, boranes, and silanes (E—H, E=H, B or Si) act as effective reducing agents to transform CO₂ into a range of C1 chemicals, such as formate, formaldehyde, and methanol. Over the past decade, research focus in this field has shifted towards utilizing cost-effective metals as catalysts for selective CO₂ reduction. A comprehensive review of homogeneous iron-catalyzed CO₂ reduction using E—H is presented, emphasizing reaction mechanisms and selectivity.

Dearomative carboxylation of aromatic compounds with carbon dioxide (CO₂) could be utilized for the synthesis of cyclic carboxylative frameworks. The dearomative carboxylation exhibits advantages such as reconstitution molecular spatial structure, environmental friendliness, mild conditions, high yield, and high selectivity, and is of significant importance in pharmaceutical synthesis and natural product chemistry. The recent advancements in the dearomative carboxylation of aromatics with CO₂ are summarized, including elucidation of the reaction characteristics and the scope of substrates via transition-metal catalysis, photoredox catalysis, and electropromoted chemistry.

The cyclic carbonate is a crucial chemical product extensively employed in battery electrolytes, cosmetics, paints, and various other industries. Additionally, it serves as an eco-friendly solvent and reaction precursor for organic synthesis. As the commercial products via CO₂ conversion, cyclic carbonates were mainly prepared through the cycloaddition reaction of epoxides with CO₂. By far, the production of cyclic carbonates still relies on the thermal catalytic cycloaddition reactions, in which high temperature is always required due to the high energy barrier for the ring-opening of epoxides and CO₂ activation. In recent years, novel catalytic pathways have been proposed accompanied with the emergence of new catalytic materials. Especially the light/electricity-driven cycloaddition reactions render the synthesis of cyclic carbonates under room tem- perature. In addition, achievements have also been made on electron-induced cyclic carbonate synthesis from olefins or vicinal diols and CO₂. The present review provides a comprehensive overview of the photocatalytic/electrocatalytic synthesis of cyclic carbonates from CO₂, aiming to offer novel insights into the design of innovative reaction pathways and catalytic materials by incorporating material engineering and catalytic mechanisms.

As an effective way to utilize CO₂ resources, multiphase catalytic carbon fixation is of great significance to promote carbon neutrality and carbon peak. The exploration of this reaction is of guiding significance to the establishment of other catalytic systems. This paper reviews the recent progress in the synthesis of a series of carbon dioxide fixed carbonyl derivatives by heterogeneous catalysis in the fields of photocatalysis, electrocatalysis, thermal catalysis, and photothermal catalysis. The synthesis of carbonyl derivatives by different heterogeneous catalysis CO₂, including organic carbonates, carbamates and carboxylic acids, is introduced. The reaction mechanism of these reactions is discussed. This provides a reference for the design and realization of the polyphase catalytic fixed CO₂ reaction.

A series of N-arylpyrrolidines were synthesized by using carbon dioxide and N-arylpropylamine derivatives as substrates, N-heterocyclic carbene IPr as catalyst, 1,3,5,7-tetramethylcyclotetrasiloxane (TMCTS) as reducing agent, triethylenediamine as base at atmospheric pressure. The reaction features mild conditions, metal-free and good functional group tolerance.

Cerium-doped zirconium-based NH₂-UiO-66 nanoparticles were synthesized in ionic liquid 1-butyl-3-methyl- imidazolium acetate at room temperature. The crystal structure and morphology were studied using X-ray diffraction, infrared spectroscopy, scanning electron microscopy and transmission electron microscopy. The valence state and distribution of elements in the obtained materials were examined using X-ray photoelectron spectroscopy and energy-dispersive X-ray spectroscopy. Catalytic performance studies show that the cerium-doped NH₂-UiO-66 exhibits improved catalytic efficiency in the cycloaddition reaction of 1,2-butylene oxide and carbon dioxide than pure NH₂-UiO-66. Studies on the photoelectric properties indicate that the cerium-doped NH₂-UiO-66 catalyst possesses strong photocurrent response, low interfacial charge transfer resistance, narrow band gap, and low flat band potential. This work provides a new approach of synthesizing high-performance catalyst for photocatalytic CO₂ cycloaddition.

A photoredox-catalyzed cascade carbon/carboxylation of activated alkenes with malonates acetals and CO₂ has been achieved, leading to a range of functionalized 1,1,3-tricarboxylates in good efficiency under mild reaction conditions. This reaction provides a facile and sustainable method for the synthesis of tricarboxylates by using CO₂ as the carboxylic source.

Development of catalytic methods using CO₂/H₂ as methylating reagent for selective methylation of amines is highly attractive. Herein, the methylation of N—H bond via boron promoted activation of Co-formate intermediates is reported. This catalytic system showed excellent functional group tolerance with high catalytic activity, and a series of methylated products were acquired in moderate to excellent yields under mild conditions (e.g. 80 ℃ or 60 ℃). It was inferred that imine complex C was the crucial intermediate formed via dehydration of species B, providing efficient C—N coupling for the selective N-methylation of secondary aromatic amines with CO₂/H₂.

Synthesis of cyclic carbonates from carbon dioxide (CO₂) and epoxides is an effective pathway for the CO₂ utilization. Although various metal catalysts have been reported, it is highly desirable to develop a method for the reuse or recycling of catalysts. Herein, an N-heterocyclic carbene-pyridine molybdenum complex supported over SBA-15 (Mo@SBA- 15) was used as an efficient and recyclable catalyst for converting CO₂ and epoxides into cyclic carbonates. Mo@SBA-15 in combination with tetra-butylammonium bromide (TBAB) shows high catalytic activity in the synthesis of cyclic carbonates under 100 ℃ and 1 MPa CO₂ pressure. In addition, Mo@SBA-15 was reused seven times without any significant activity loss.

The use of CO₂ as monomer to synthesize polymer materials is an important and potential applications topic from the viewpoint of green and sustainable chemistry. A new kind of CO₂-based polyurea (PUa) was synthesized by polycondensation of CO₂ with 4,7,10-trioxa-1,13-tridecanediamine and tris(2-aminoethyl)amine (TAEA). TAEA was used as cross-link reagent. The mechanical properties of PUa were significantly improved by inserted the crosslink agent of TAEA. The formed slight cross-linked PUa exhibited excellent mechanical properties with tensile strength of 26.8 MPa, elongation at break of 34% and Young’s modulus of 351 MPa. Moreover, it could be remolded for 3 times without obvious change in the mechanical properties, which are ascribed to the hydrogen bonding interaction among the main chains and the slight cross-linked structure. In addition, the synthesized CO₂-based PUa is of outstanding thermal performance with an initial decomposition temperature above 300 ℃, besides it is tolerance for a variety of organic solvents.