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A hierarchical structure alumina with high surface area was synthesized using a sol-gel method assisted by propylene oxide (PO), which was subsequently converted into alumina exhibiting different transitional phases (γ, δ, θ) through varying calcination temperatures. These aluminas were employed as substrates for the active copper phase in the RWGS catalyst, facilitating a systematic exploration of how the alumina phase influences catalyst performance. The characterized catalysts underwent assessments using techniques such as N 2 adsorption-desorption, XRD, H 2 -TPR, CO 2 -TPD, FESEM, and HRTEM. An examination of the impact of copper loading (ranging from 5.0 to 20.0 wt%) in the Cu/γ-Al 2 O 3 catalyst on RWGS performance revealed that the catalyst containing 15.0 wt% Cu exhibited the highest CO 2 conversion rate, achieving 8% at 300 °C under a 1CO 2 :1H 2 ratio at atmospheric pressure. This specific catalyst demonstrated 100% selectivity for CO. Evaluating the extended stability of Cu catalysts supported by γ-, δ-, and θ-Al 2 O 3 phases, all loaded with the same amount of Cu (15.0 wt%), was carried out at 450 °C. The δ- and θ-Al 2 O 3 -supported catalysts were able to maintain approximately 100% of their initial catalytic activities after 72 h, whereas the activity of the catalyst supported by γ-Al 2 O 3 decreased. The examination of the crystalline phases of the catalyst support and stability testing demonstrated the significant impact of porosity on mass transfer and the diffusion processes of reactants and production on the structure of the catalyst. This study revealed how adjusting the macropore size and porosity within various crystalline phases can optimize the filling degree and achieve an ideal balance between reaction and mass transfer rates. [Display omitted] • Catalyst support with the highest surface area was prepared via a sol-gel method. • Effect of hierarchical alumina as catalyst support was investigated in RWGS reaction. • 15 wt% Cu/γ-Al 2 O 3 catalyst exhibited the highest CO 2 conversion of 8% at 300 °C. • CO selectivity was 100% over 15 wt% Cu/γ-, δ-, and θ-Al 2 O 3 catalysts. [ABSTRACT FROM AUTHOR]

The discovery and development of efficient technologies that enable the use of CO2 as a starting material for chemical synthesis (at scale) is probably one of the biggest scientific challenges of our time. But a key question is if the cure will not be worse than the disease? In this work, the economic feasibility of the electrochemical reduction of CO2 to ethylene is assessed and it is demonstrated that from a Capital expenditure and Operational expenditure point of view the electrochemical production of ethylene from CO2 is not feasible under the current market conditions. Even in the case that the renewable electricity price would be zero, the feasibility is hampered by the state-of-the-art catalyst performance (selectivity) and the cost of the electrochemical reactor. Turning the installation on and off, if this would be even practically possible, is not interesting because our study shows that because of the high Capital expenditure, the payback time of the process would become unacceptably high. Finally, because of the high electricity requirement, this Carbon Capture and Utilization process has a lower CO2 avoidance potential than the substitution of gray electricity by green electricity. This means that today the available green electricity would best be used to close coal and gas based power plants instead of powering the electrochemical conversion of CO2 to ethylene. [ABSTRACT FROM AUTHOR]

The development of copper nanoparticle (CuNP)-based catalysts for the electrochemical reduction of carbon dioxide (ECO2-R) offers a promising approach to enhance its transformation into other industrially significant compounds. This study reports ECO2-R at -1.3 V vs RHE using CuNPs and catalytic inks composed of CuNPs and ionic liquids (ILs), observing significant differences in the selectivity of each catalyst. Specifically, CuNPs alone show a preference for producing ethylene and aqueous products, such as formic acid, ethanol, and formaldehyde. In contrast, the addition of ILs to the catalytic system redirects selectivity toward gaseous products, with methane being the main product. These findings highlight the potential to optimize catalyst composition to tailor the selectivity of CO2 conversion processes. ILs modify the catalytic environment and influence reaction pathways, enabling the selection of specific products. [ABSTRACT FROM AUTHOR]

A modified Metal‐Organic Framework UiO‐66‐NH2‐based photocathode in a zero‐gap gas phase photoelectrolyzer was applied for CO2 reduction. Four types of porous carbon fiber layers with different wettability were employed to tailor the local environment of the cathodic surface reactions, optimizing activity and selectivity towards formate, methanol, and ethanol. Results are explained by mass transport through the different type and arrangement of carbon fiber support layers in the photocathodes and the resulting local environment at the UiO‐66‐NH2 catalyst. The highest energy‐to‐fuel conversion efficiency of 1.06 % towards hydrocarbons was achieved with the most hydrophobic carbon fiber (H23C2). The results are a step further in understanding how the design and composition of the photoelectrodes in photoelectrochemical electrolyzers can impact the CO2 reduction efficiency and selectivity. [ABSTRACT FROM AUTHOR]

Plasma‐based CO2 conversion has attracted increasing interest. However, to understand the impact of plasma operation on post‐plasma processes, we studied the effect of adding N2, N2/CH4 and N2/CH4/H2O to a CO2 gliding arc plasmatron (GAP) to obtain valuable insights into their impact on exhaust stream composition and temperature, which will serve as feed gas and heat for post‐plasma catalysis (PPC). Adding N2 improves the CO2 conversion from 4 % to 13 %, and CH4 addition further promotes it to 44 %, and even to 61 % at lower gas flow rate (6 L/min), allowing a higher yield of CO and hydrogen for PPC. The addition of H2O, however, reduces the CO2 conversion from 55 % to 22 %, but it also lowers the energy cost, from 5.8 to 3 kJ/L. Regarding the temperature at 4.9 cm post‐plasma, N2 addition increases the temperature, while the CO2/CH4 ratio has no significant effect on temperature. We also calculated the temperature distribution with computational fluid dynamics simulations. The obtained temperature profiles (both experimental and calculated) show a decreasing trend with distance to the exhaust and provide insights in where to position a PPC bed. [ABSTRACT FROM AUTHOR]

The reforming reactions of greenhouse gases require catalysts with high reactivity, coking resistance, and structural stability for efficient and durable use. Among the possible strategies, exsolution has been shown to demonstrate the requirements needed to produce appropriate catalysts for the dry reforming of methane, the conversion of which strongly depends on the choice of active species, its interaction with the support, and the catalyst size and dispersion properties. Here, we exploit the exsolution approach, known to produce stable and highly active nanoparticle-supported catalysts, to develop iridium-nanoparticle-decorated perovskites and apply them as catalysts for the dry reforming of methane. By studying the effect of several parameters, we tune the degree of exsolution, and consequently the catalytic activity, thereby identifying the most efficient sample, 0.5 atomic % Ir-BaTiO3, which showed 82% and 86% conversion of CO2 and CH4, respectively. By comparison with standard impregnated catalysts (e.g., Ir/Al2O3), we benchmark the activity and stability of our exsolved systems. We find almost identical conversion and syngas rates of formation but observe no carbon deposition for the exsolved samples after catalytic testing; such deposition was significant for the traditionally prepared impregnated Ir/Al2O3, with almost 30 mgC/gsample measured, compared to 0 mgC/gsample detected for the exsolved system. These findings highlight the possibility of achieving in a single step the mutual interaction of the parameters enhancing the catalytic efficiency, leading to a promising pathway for the design of catalysts for reforming reactions. [ABSTRACT FROM AUTHOR]

The escalating threat of anthropogenic climate change has spurred an urgent quest for innovative CO2 capture and utilization (CCU) technologies. Metal–organic frameworks (MOFs) have emerged as prominent candidates in CO2 capture and conversion due to their large specific surface area, well-defined porous structure, and tunable chemical properties. This review unveils the latest advancements in MOF-based materials specifically designed for superior CO2 adsorption, precise separation, advanced photocatalytic and electrocatalytic CO2 reduction, progressive CO2 hydrogenation, and dual functionalities. We explore the strategies that enhance MOF efficiency and examine the challenges of and opportunities afforded by transitioning from laboratory research to industrial application. Looking ahead, this review offers a visionary perspective on harnessing MOFs for the sustainable capture and conversion of CO2. [ABSTRACT FROM AUTHOR]

In this study, imidazolium‐based multifunctional ionic polymer (IP 1–IP 3) series, co‐incorporated with phenolic hydroxyl groups as hydrogen bond donors (HBDs) and Cl− as nucleophiles, are synthesized by a facile quaternization method. The physicochemical characterizations of these IPs are systematically examined by using FTIR, XPS, BET, TGA, CO2‐TPD, SEM with elemental mapping and TEM methods. Their catalytic activities are evaluated toward the conversion of carbon dioxide (CO2) and epoxides into cyclic carbonates under solvent‐ and additive‐free environments. Apart from the synergy effect between HBDs and Cl−, it is found that the types of the spacer linking the two imidazole units in the diimidazole precursors (L1–L3) also play an important role in the catalytic activity. And IP 2, with a pyridine spacer as a Lewis base site, exhibits the best catalytic performance under solvent‐free mild conditions i. e., atmospheric pressure CO2, 80 °C, and 5 h. Notably, the catalyst demonstrates a good substrate applicability. Furthermore, IP 2 exhibited good reusability, stability, and it can be recycled for ten successive runs with stable and potential catalytic activity. This study provides an alternative route to construct IPs with efficient activity for CO2 catalytic conversion and fixation under mild‐conditions. [ABSTRACT FROM AUTHOR]

In recent years, the in situ resource utilization of CO 2 in the Martian atmosphere by low-temperature plasma technology has garnered significant attention. However, numerical simulation is extremely time-consuming for modeling the complex CO 2 plasma, involving tens of species and hundreds of reactions, especially under Martian pressure. In this study, a deep neural network (DNN) with multiple hidden layers is introduced to investigate the CO 2 conversion in radio-frequency (RF) discharges at a given power density under Martian pressure in almost real time. After training on the dataset obtained from the fluid model or experimental measurements, the DNN shows the ability to accurately and efficiently predict the various discharge characteristics and plasma chemistry of RF CO 2 discharge even in seconds. Compared with conventional fluid models, the computational efficiency of the DNN is improved by nearly 10 6 times; thus, a real-time calculation of RF CO 2 discharge can almost be achieved. The DNN can provide an enormous amount of data to enhance the simulation results due to the very high computational efficiency. The numerical data also suggest that the CO 2 conversion increases with driving frequency at a fixed power density. This study shows the ability of the DNN-based approach to investigate CO 2 conversion in RF discharges for various applications, providing a promising tool for the modeling of complex non-thermal plasmas. [ABSTRACT FROM AUTHOR]

This work proposes a methodology to increase the open‐circuit voltage of perovskite solar cells via modulating the buried interface using π‐conjugated molecules, featuring a push‐pull electronic structure configuration. In the planar perovskite solar cells using tin oxide nanocrystal as an electron transport layer, the 2‐methyl‐1‐aminobenzene derivatives with 4‐(Heptafluoropropan)‐2‐methylaniline notable not only reduce the interfacial energy barrier but also passivate the defects at the buried interface. This modulation enhances the open circuit voltage of Cs0.05(FA0.85MA0.15)0.95Pb(I0.85Br0.15)3 (bandgap ≈1.60 eV) perovskite solar cell to a high value of 1.241 V and thus the power conversion efficiency to 24.16% under standard testing condition. An even higher efficiency of 25.11% can be achieved when employing in the Cs0.05MA0.05FA0.9PbI3 (bandgap ≈1.54 eV) perovskite solar cell. The open circuit voltage (1.241 V) is among the highest in triple‐cation perovskite solar cells which reaches 95% Shockley–Queisser limit. A solar‐to‐CO conversion efficiency of 11.76% can be achieved in the fabricated perovskite solar minimodule driven carbon dioxide electrolyzer. This demonstrates the potential of utilizing perovskite solar cells for CO2 conversion as a clean and green energy environment. [ABSTRACT FROM AUTHOR]

A major impediment to the development of the efficient use of artificial photosynthesis is the lack of highly selective and efficient photocatalysts toward the conversion of CO2 by sunlight energy at room temperature and ambient pressure. After many years of hard work, we finally completed the synthesis of graphdiyne-based palladium quantum dot catalysts containing high-density metal atom steps for selective artificial photosynthesis. The well-designed interface structure of the catalyst is composed of electron-donor and acceptor groups, resulting in the obvious incomplete charge-transfer phenomenon between graphdiyne and plasmonic metal nanostructures on the interface. These intrinsic characteristics are the origin of the high performance of the catalyst. Studies on its mechanism reveal that the synergism between 'hot electron' from local surface plasmon resonance and rapid photogenerated carrier separation at the ohmic contact interface accelerates the multi-electron reaction kinetics. The catalyst can selectively synthesize CH4 directly from CO2 and H2O with selectivity of near 100% at room temperature and pressure, and exhibits transformative performance, with an average CH4 yield of 26.2 μmol g−1 h−1 and remarkable long-term stability. [ABSTRACT FROM AUTHOR]

As a result of electrochemical conversion of carbon dioxide (CO2), value-added chemicals like as synthetic fuels and chemical feedstocks can be produced. In the current state of the art, copper-based materials are most widely used being the most effective catalysts for this reaction. It is still necessary to improve the reaction rate and product selectivity of CuOx for electrochemical CO2 reduction reaction (CO2RR). The main objective of this work was synthesized and evaluate the copper oxide electrocatalyst combined with silver (CuO 70% Ag 30%) for the conversion of carbon dioxide into synthetic fuels. The catalysts have been prepared by the oxalate method and assessed in a flow cell system. The results of electrochemical experiments were carried out at room temperature and at different potentials (-1.05 V–0.75 V vs. RHE in presence of 0.1 M KHCO3) and gas and liquid chromatographic analysis are summarized. The CuOx-based electrodes demonstrated the selective of ~ 25% at -0.55 V for formic acid (HCOOH) and over CuO -Ag and selective of ethylene at ~ 20% over CuOx at -1.05 V. Other products were formed as ethylene, ethanol, and propanol (C2H4, EtOH, PrOH) at more positive potentials. On the other hand, carbon monoxide, acetate, ethylene glycol, propinaldehyde, glycoaldehyde and glyoxal (CO, CH3COO, C2H6O2, C3H6O, C2H4O2, C2H2O2) have been formed and detected. Based on the results of these studies, it appears that the formation of synthetic fuels from CO2 at room temperature in alkaline environment can be very promising. [ABSTRACT FROM AUTHOR]

The CO2 reduction into carbon-contained fuel via solar energy offers the powerful tools to realize the zero-emission carbon cycle. Owing to the intriguing features of the two-dimensional (2D) heterostructures, it is susceptible to modulate the electronic structure as well as the surface geometry for optimizing the photocatalytic CO2 reactivity. From this perspective, we surveyed the fundamental insights of 2D semiconductor heterostructures, involving the fabrication strategies and classification of the 2D semiconductor heterostructure. Also, we have detailly discussed the overview of 2D semiconductor heterostructure for optimizing CO2 photocatalytic influenced factors, including the solar energy utilization, photogenerated carriers separation, and redox reaction kinetics. Afterwards, we showed the significant advantages of 2D heterostructures in elevating CO2 photoreduction performance, focusing on activity, selectivity and photostability. By analyzing the limitations and developments, we ended by putting forward insights into the further researches about the CO2 photocatalysts and reactor design, even industrial applications. [ABSTRACT FROM AUTHOR]

Defect engineering is an emerging technology for tailoring nanomaterials' characteristics and catalytic performance in various applications. Recently, defect‐engineered nanoparticles have emerged as highly researched materials in catalytic applications because of their exceptional redox reaction capabilities and physicochemical and optical properties. The properties of nanomaterials can be readily adjusted by controlling the nature and concentration of defects within the nanoparticles, avoiding the need for intricate design strategies. This review investigates defect engineering in nanocatalysts, including the design, fabrication, and applications. Initially, the various categories and strategies of nanomaterial defects and their impacts on the nanocatalysts' electronic and surface properties, catalytic activity, selectivity, and stability are summarized. Then, the catalytic processes and their uses, including gas sensing, hydrogen (H2) evolutions, water splitting, reductions of carbon dioxide (CO2) and nitrogen to value‐aided products, pollutant degradation, and biomedical (oncotherapy, antibacterial and wound healing, and biomolecular sensing) applications are discussed. Finally, the limitations in defect engineering and the prospective paths for allowing the logical design and optimization of nanocatalytic materials for long‐term and efficient applications are also examined. This comprehensive review gives unique insights into the current state of defect engineering in nanocatalysts and inspires future research on exploiting shortcomings to improve and customize catalytic performance. [ABSTRACT FROM AUTHOR]

Converting carbon dioxide into valuable chemicals requires suitable catalysts to perform efficiently under severe reaction conditions. Developing suitable supported copper catalysts can potentially improve catalytic performance for CO 2 reduction by interacting with copper active components. Herein, we investigate Cu/ZrO 2 catalysts, synthesized by wet-impregnation (WI) method with various copper contents, for the reverse water-gas shift (RWGS) reaction. It is anticipated that metal-support interaction, surface defects, and oxygen vacancies in oxide catalysts play critical roles in defining catalytic activity. To understand this, various ZrO 2 -supported catalysts with different crystallite sizes were prepared by altering the calcination temperature and assessing their catalytic performance. The results showed that 2 wt%Cu/ZrO 2 catalyst calcined at 800 °C had the highest CO 2 conversion to CO of ∼37 % at 600 °C, with less than 0.25 % coke formation. Kinetics studies showed that the redox model agreed better with experimental data when considering equilibrium conditions. [Display omitted] • Volcano correlations in CO 2 conversion curves with peaks at 2 wt%Cu and 800 °C. • Better reducibility, high dispersion, and stronger MSI in 2 wt%Cu/ZrO 2 -800 sample. • ZrO 2 phase change from monoclinic to tetragonal by raising calcination temperature. • 37 % conversion at 600 °C with 2 wt%Cu/ZrO 2 -800 catalyst, stable for 72 h TOS. • Redox mechanism of the 2 wt%Cu/ZrO 2 -800 catalyst in RWGS, based on kinetic studies. [ABSTRACT FROM AUTHOR]

While the mild production of syngas (a mixture of H2 and CO) from CO2 and H2O is a promising alternative to the coal‐based chemical engineering technologies, the inert nature of CO2 molecules, unfavorable splitting pathways of H2O and unsatisfactory catalysts lead to the challenge in the difficult integration of high CO2 conversion efficiency with produced syngas with controllable H2/CO ratios in a wide range. Herein, we report an efficient plasma‐driven catalytic system for mild production of pure syngas over porous metal–organic framework (MOF) catalysts with rich confined H2O molecules, where their syngas production capacity is regulated by the in situ evolved ligand defects and the plasma‐activated intermediate species of CO2 molecules. Specially, the Cu‐based catalyst system achieves 61.9 % of CO2 conversion and the production of pure syngas with wide H2/CO ratios of 0.05 : 1–4.3 : 1. As revealed by the experimental and theoretical calculation results, the in situ dynamic structure evolution of Cu‐containing MOF catalysts favors the generation of coordinatively unsaturated metal active sites with optimized geometric and electronic characteristics, the adsorption of reactants, and the reduced energy barriers of syngas‐production potential‐determining steps of the hydrogenation of CO2 to *COOH and the protonation of H2O to *H. [ABSTRACT FROM AUTHOR]

The urgent need to address global carbon emissions and promote sustainable energy solutions has led to a growing interest in carbon dioxide (CO2) conversion technologies. Among these, the transformation of CO2 into methanol (MeOH) has gained prominence as an effective mitigation strategy. This review paper provides a comprehensive exploration of recent advances and applications in the direct utilization of CO2 for the synthesis of MeOH, encompassing various aspects from catalysts to market analysis, environmental impact, and future prospects. We begin by introducing the current state of CO2 mitigation strategies, highlighting the significance of carbon recycling through MeOH production. The paper delves into the chemistry and technology behind the conversion of CO2 into MeOH, encompassing key themes such as feedstock selection, material and energy supply, and the various conversion processes, including chemical, electrochemical, photochemical, and photoelectrochemical pathways. An in-depth analysis of heterogeneous and homogeneous catalysts for MeOH synthesis is provided, shedding light on the advantages and drawbacks of each. Furthermore, we explore diverse routes for CO2 hydrogenation into MeOH, emphasizing the technological advances and production processes associated with this sustainable transformation. As MeOH holds a pivotal role in a wide range of chemical applications and emerges as a promising transportation fuel, the paper explores its various chemical uses, transportation, storage, and distribution, as well as the evolving MeOH market. The environmental and energy implications of CO2 conversion to MeOH are discussed, including a thermodynamic analysis of the process and cost and energy evaluations for large-scale catalytic hydrogenation. [ABSTRACT FROM AUTHOR]

Carbon dioxide electrochemical reduction (CO2ER) presents numerous advantages in mitigating greenhouse gas emissions by converting CO2 into value-added chemicals and can be integrated with renewable energy sources such as solar and wind. Nevertheless, establishing an electrochemically stable catalytic system that can effectively decrease the overpotential while maintaining high current density and faradaic efficiency is challenging. The precise mechanisms causing the reactions and the specific functions of the electrode with electrolytes are still not fully understood. Hence, a significant increase in attention has been paid to using ionic liquids (ILs) as electrolytes for CO2ER. This phenomenon is attributed to the unique capabilities of ILs to reduce overpotential, increase current density, and improve electrochemical stability. Therefore, this study evaluated the effect of incorporating ILs into electrolytes to comprehend the cation and anion influences on CO2ER reactions. Linear sweep voltammetry (LSV) and chronoamperometry (CA) were employed to examine the reduction peaks and current density values for different electrolytes, respectively. Consequently, a 0.1 M NBu4PF6 acetonitrile solution containing 1-ethyl-3-methylimidazolium tetrafluoroborate [EMIM][BF4] demonstrated a significantly lower onset potential of the reduction by 320 mV. A reduced CO2ER efficiency involving ILs with long alkyl chains was also observed. Meanwhile, a novel hypothesis concerning molecular orbitals for the CO2ER reaction mechanism was discussed. Overall, various performance variables (reduction stability, applied potential, and current density) of CO2ER were improved using cations with short alkyl chains, anions with high highest occupied molecular orbital (HOMO) levels, and appropriate solvation media. These findings can serve as selection criteria to aid in choosing appropriate ionic liquids for CO2 electrochemical reduction (CO2ER). [ABSTRACT FROM AUTHOR]

An artificial neural network (ANN) was applied to construct the relationship between the CO2 photocatalyst variables. A total of 147 data points from 38 research publications related to photocatalytic CO2 reduction via bismuth-based photocatalysts were used to develop, validate and test the developed model. The most important variable for the yield of the obtained product is irradiation time. The longer irradiation time the higher obtained product yield. Whereas the type of main product and band gap energy had the strongest effect on product yield in the positive and negative directions, respectively, in the Pearson correlation analysis. The ANN model was successfully tested to predict other literature datasets. The ANN model can then be used to estimate the yield of the obtained product, which reflects the CO2 photocatalytic reduction efficiency.

[Display omitted] • Novel carbon nitride catalysts prepared with cost-effective, low-temperature methods. • The materials show enhanced properties, higher surface areas and abundant basic sites. • Their catalytic activity is superior to conventional carbon nitride. • Threefold increase in CO 2 cycloaddition efficiency and stable catalytic activity. • This advancement has potential for converting CO 2 into valuable chemicals. The interest in using carbon nitrides (CN) for CO 2 conversion has stimulated extensive research on CN synthesis. Herein, we report the synthesis of two novel CN materials using low-cost commercially available precursors at low temperatures in a short duration of time. Two CN materials, one derived from 5-amino tetrazole (named 4NZ-CN) and the other derived from 3, 5-diamino-1, 2, 4-triazole (named 3NZ-CN) precursors, are prepared by refluxing these precursors for 2 h at 100 °C. 4NZ-CN and 3NZ-CN catalysts show higher surface areas (55.80 and 52.00 m2 g-1) and more basic sites (10.05 and 5.65 mmol g−1) than the conventional graphitic carbon nitride (g-C 3 N 4) derived from melamine, for which the corresponding values are 9.20 m2 g-1 and 0.62 mmol g−1, respectively. In addition, both CN exhibit a 3-fold higher catalytic activity for CO 2 cycloaddition to epoxides than g-C 3 N 4. The structure−activity relationship was ascertained using a combination of experimental and computational studies, and a catalytic mechanism was proposed. This work provides a facile strategy for the synthesis of novel CN materials at relatively low temperatures, and the developed catalysts show remarkable performance in the conversion of CO 2 to value-added chemicals. [ABSTRACT FROM AUTHOR]

Abstract As a result of electrochemical conversion of carbon dioxide (CO2), value-added chemicals like as synthetic fuels and chemical feedstocks can be produced. In the current state of the art, copper-based materials are most widely used being the most effective catalysts for this reaction. It is still necessary to improve the reaction rate and product selectivity of CuOx for electrochemical CO2 reduction reaction (CO2RR). The main objective of this work was synthesized and evaluate the copper oxide electrocatalyst combined with silver (CuO 70% Ag 30%) for the conversion of carbon dioxide into synthetic fuels. The catalysts have been prepared by the oxalate method and assessed in a flow cell system. The results of electrochemical experiments were carried out at room temperature and at different potentials (-1.05 V–0.75 V vs. RHE in presence of 0.1 M KHCO3) and gas and liquid chromatographic analysis are summarized. The CuOx-based electrodes demonstrated the selective of ~ 25% at -0.55 V for formic acid (HCOOH) and over CuO -Ag and selective of ethylene at ~ 20% over CuOx at -1.05 V. Other products were formed as ethylene, ethanol, and propanol (C2H4, EtOH, PrOH) at more positive potentials. On the other hand, carbon monoxide, acetate, ethylene glycol, propinaldehyde, glycoaldehyde and glyoxal (CO, CH3COO, C2H6O2, C3H6O, C2H4O2, C2H2O2) have been formed and detected. Based on the results of these studies, it appears that the formation of synthetic fuels from CO2 at room temperature in alkaline environment can be very promising.

China is the world’s largest CO2 emitter and coal consumer, and its coal dominated energy structure is difficult to be changed in the short term. In the context of carbon peaking and carbon neutrality, the capture and storage or conversion of carbon dioxide into renewable fuels and chemicals can reduce dependence on fossil fuels and at the same time reduce CO2 emissions, providing key technical support for the green transition of coal-fired power plants and energy chemicals. Electrocatalysis and microbial conversion are important ways to produce renewable fuels and chemicals from carbon dioxide. The reaction rate of electrocatalytic reduction of CO2 is high, but the products are mostly limited to C1 and C2 products. Microbial CO2 fixation has the advantages of high selectivity and variety of products. However, the low electron transfer and energy supply lead to a long reaction period in the microbial CO2 fixation. Integration of electrocatalysis and microbial conversion can play their advantages to efficiently produce the value-added multi-carbon products. In this paper, firstly, the reaction principles, typical products of electrocatalysis and microbial CO2 fixation under a single technical route were introduced respectively. The catalyst and reactor of electrocatalytic CO2 reduction were discussed, and the microbial species and biological metabolic pathways of microbial fixation of CO2 were summarized. Secondly, two methods of the integration of electrocatalysis and microbial conversion was reviewed, and the system structure, working principle, electrode materials and value-added products were analyzed. Finally, the technology readiness level of different coupling methods was compared, and the future prospects were highlighted from four aspects: the catalysts for electrocatalytic CO2 reduction, the engineered microbial strains, the design and integration of coupling systems and the linkage between academic research and industry.

Abstract Metallurgical slag such as solid waste generated in the steel industry carries environmental pollution risks, but it is rich in nutrients required by microalgae. Metallurgical slag used for carbon capture and biomass energy conversion has multiple benefits: (i) reduction and harmless treatment of metallurgical solid waste, (ii) assisting in carbon neutrality by efficient carbon fixation, and (iii) production of biodiesel from CO2. In this study, AOD, BOF, BFS, HVS, and VTS slag were applied to culture Chlorella pyrenoidosa (C. pyrenoidosa) with the regulation of growth, carbon fixation, and lipid synthesis. An excellent fixed amount of CO2 with 94.59 mg is obtained from C. pyrenoidosa biomass at BOF slag added (mass ratio of CO2 captured/microalgae/slag with 1.99/1.00/10.53) since high Ca/Mg mass ratio of 419 (8.38 mg/L Ca and 0.02 mg/L Mg), no Cr and low concentration of Al (0.04 mg/L) contribute to regulating antioxidant enzyme activity (SOD and POD) to resist ROS and improving PEPC activity to reduce carbon flux toward lipid to promote biomass synthesis. Both metal concentrations from Ca (5.86 mg/L), Mg (0.05 mg/L), Al (0.42 mg/L), and Cr (0.006 mg/L) and suitable pH (10.53) in AOD leaching solution at solid/liquid ratio of 0.5 g/L change carbon flow toward efficient lipid synthesis (47.07 wt%) by continuously providing raw materials and energy by regulating ACC, ME, and PEPC activities. High value‐added biodiesel with high concentrations of C16 and C18 methyl esters from lipid of C. pyrenoidosa is achieved, following other ecological and economic benefits including 197 mg CO2 captured and 2198 mg AOD applied with harmless. In this study, C. pyrenoidosa is cultured with elements from metallurgical slag solid waste, which promotes C. pyrenoidosa efficient carbon fixation to assist in carbon neutrality, and provides guidance for CO2 conversion to high‐value‐added products with low cost.

Near‐infrared light‐driven photocatalytic CO2 reduction (NIR‐CO2PR) holds tremendous promise for the production of valuable commodity chemicals and fuels. However, designing photocatalysts capable of reducing CO2 with low energy NIR photons remains challenging. Herein, a novel NIR‐driven photocatalyst comprising an anionic Ru complex intercalated between NiAl‐layered double hydroxide nanosheets (NiAl‐Ru‐LDH) is shown to deliver efficient CO2 photoreduction (0.887 μmol h−1) with CO selectivity of 84.81 % under 1200 nm illumination and excellent stability over 50 testing cycles. This remarkable performance results from the intercalated Ru complex lowering the LDH band gap (0.98 eV) via a compression‐related charge redistribution phenomenon. Furthermore, transient absorption spectroscopy data verified light‐induced electron transfer from the Ru complex towards the LDH sheets, increasing the availability of electrons to drive CO2PR. The presence of hydroxyl defects in the LDH sheets promotes the adsorption of CO2 molecules and lowers the energy barriers for NIR‐CO2PR to CO. To our knowledge, this is one of the first reports of NIR‐CO2PR at wavelengths up to 1200 nm in LDH‐based photocatalyst systems. [ABSTRACT FROM AUTHOR]

Photocatalytic CO2 conversion towards C2+ fuels is a promising technology for simultaneously achieving carbon neutrality and alleviating the energy crisis. However, this strategy is inefficient due to the difficulty of both multi-electron transfer and C-C coupling during C2+ formation. In this work, CuInS2/MXene heterostructure with Cu vacancy is rationally designed by in situ hydrothermal synthesis. The VCu--CuInS2/MXene heterostructure has a suitable band structure and tight interface contact. Catalytic performances under different testing conditions, in situ spectroscopy, and COMSOL simulation reveal that LSPR-activated MXene promotes the formation of crucial intermediate CH2* and triggers the C--C coupling process under near-infrared light, as the key to acetate. Moreover, in situ XPS analysis, DFT calculations, and photoelectrochemical characterizations unveil that copper vacancy can promote charge transfer from CuInS2 to MXene and boost local electron aggregation on the MXene, further enhancing the photocatalytic efficiency and selectivity of C2 products. Contributing to the synergistic effect of copper vacancy and plasmonic MXene, VCu--CuInS2/MXene achieved excellent CO2RR activity with an acetate evolution rate of 250.0 μmol/h/g and a selectivity of 97.5% under the full spectrum irradiation, which is 38.8 and 3.3 times higher than that of VCu--CuInS2/MXene, respectively. [ABSTRACT FROM AUTHOR]

The conversion of CO2‐H2 mixtures on Ni‐based catalysts can proceed through either the reverse water gas shift reaction (RWGS) path to produce CO or the CO2 methanation path to produce CH4. The balance between these competing reactions depends on both the reaction conditions and catalyst structure. In this study, using surface‐sensitive infrared and ambient pressure X‐ray photoelectron spectroscopies, we investigate the effect of reaction conditions on the interaction between CO2 and H2 on a Ni(111) model catalyst. Our findings highlight the occurrence of RWGS, involving direct dissociation of CO2 to CO and atomic oxygen, followed by oxygen reacting with hydrogen to form H2O, and CO and H2O desorption. Hydrogen affects the distribution of CO between hollow and top sites by displacing oxygen from the energetically preferred hollow sites. The overall balance between oxygen production from CO2 dissociation and oxygen removal by hydrogen governs the oxygen coverage and consequently the distribution of CO between top and hollow sites. This balance is significantly influenced by the reaction temperature and the H2/CO2 partial pressures. [ABSTRACT FROM AUTHOR]

This study explores photocatalytic conversion of CO2 using TiO2−Cu heterojunctions with different Cu contents and investigates influence of different reaction media on the process efficiency. The use of KOH favored liquid products, especially ethanol. An analysis of H2 production as the main competitive reaction was done. Sodium oxalate led to an increase in H2 evolution by approximately 600 μmol g‐1 compared to pure water, in the presence of CO2 in the reaction medium, but the blank test (without CO2) indicates a lower H2 yield (~136 μmol g−1), which suggests that the competitive reaction with CO2 also plays a role in H2 production. This role was related to the decrease of the initial pH from approximately 8.5 to 5.2, stabilizing at 5.5 at the end of the 6 h reaction. In an environment saturated with N2, the pH increases to 9 and stabilizes at 7.8 at the end of the process. In the presence of acetic acid, both CO and H2 production were suppressed, with a significant increase in the selectivity for methane via cleavage of the acid's carbon bond. The findings underscore the importance of optimizing reaction conditions to achieve higher yields of desired products in the photocatalytic conversion of CO2. [ABSTRACT FROM AUTHOR]

Solid solutions are garnering substantial attention in the realm of solar energy utilization due to their tunable electronic properties, encompassing band edge positions and charge‐carrier mobilities. In this study, we designed and synthesized Co1‐xZnxFe2xGa2–2xO4 (0

The increasing anthropogenic emissions of greenhouse gases (GHG) is encouraging extensive research in CO 2 utilisation. Dry reforming of methane (DRM) depicts a viable strategy to convert both CO 2 and CH 4 into syngas, a worthwhile chemical intermediate. Among the different active phases for DRM, the use of nickel as catalyst is economically favourable, but typically deactivates due to sintering and carbon deposition. The stabilisation of Ni at different loadings in cerium zirconate inorganic complex structures is investigated in this work as strategy to develop robust Ni-based DRM catalysts. XRD and TPR-H 2 analyses confirmed the existence of different phases according to the Ni loading in these materials. Besides, superficial Ni is observed as well as the existence of a CeNiO 3 perovskite structure. The catalytic activity was tested, proving that 10 wt.% Ni loading is the optimum which maximises conversion. This catalyst was also tested in long-term stability experiments at 600 and 800°C in order to study the potential deactivation issues at two different temperatures. At 600°C, carbon formation is the main cause of catalytic deactivation, whereas a robust stability is shown at 800°C, observing no sintering of the active phase evidencing the success of this strategy rendering a new family of economically appealing CO 2 and biogas mixtures upgrading catalysts. [Display omitted] [ABSTRACT FROM AUTHOR]

The quest for efficient and sustainable methods to mitigate carbon dioxide (CO2) emissions is a pressing global challenge. This study delves into the crucial role of polymers in tailoring the performance of titanium dioxide (TiO2) nanofibers for CO2 conversion reactions. By systematically comparing the influence of different polymers, specifically polyvinyl pyrrolidone (PVP) and polyvinylidene fluoride (PVDF), on the CO2 conversion activity of TiO2-NFs, we shed light on the remarkable potential of polymeric selection to fine-tune catalyst properties. The paper uses advanced experimental techniques to analyze the structural and morphological properties of PVP-TiO2-NFs and PVDF- TiO2-NFs demonstrating their various morphologies. The investigation involves SEM, XRD, BET, Raman, and UV-Vis spectroscopy to better understand the charge separation and recombination processes involved in both materials' CO2 conversion. The results show considerable differences, the choice of polymer significantly impacts the CO2 conversion performance of TiO2-NFs. PVP-based NFs exhibit enhanced surface area and porosity, resulting in superior catalytic activity, while PVDF-based NFs demonstrate remarkable stability. These findings pave the way for innovative approaches to tackle climate change and develop a more environmentally friendly future by advancing energy-efficient and long-lasting photocatalytic technology. [ABSTRACT FROM AUTHOR]

Carbon dioxide (CO2) utilization technologies have emerged as a promising approach to address the direct and indirect consequences of climate change and the need for sustainable resource management. Those innovative technologies aim to capture and utilize CO2 by converting it into valuable products or directly using it as a chemical feedstock in various industries, thus, avoiding their release into the atmosphere. In this study, different CO2 utilization pathways including CO2 to chemicals and fuels, CO2 to building materials, CO2 to enhanced oil recovery (EOR), and CO2 to bio‐products are discussed in terms of their status – economic, environmental and technology readiness level performances. Moreover, various CO2 utilization pathways are comparatively analyzed considering their advantages and drawbacks, CO2 uptake potentials, and overall climate benefits. According to the comparison results, photocatalytic and electrochemical reduction of CO2 along with the bio‐fixation of CO2 are gaining more attention in the recent research and investigations, from the energy intensity and environmental point of view, whereas EOR remains dominant in terms of the scalability, maturity and economic benefits. However, limitations of EOR related to the capacity, life cycle and different geolocations, as well as the complexities of other mature approaches make room for emerging technologies to be more energy‐effective and environmentally friendly. Overall, most of the promising CO2 utilization techniques are either technologically immature or limited in scale to deploy globally. One of the main barriers to reusing CO2 is associated with the high cost of CO2‐based production and the low value of the CO2 market. © 2024 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

The design of molecular scaffolds bearing multiple functional groups for the activation and ring‐opening of epoxides is a crucial challenge for the synthesis of efficient homogeneous and heterogeneous catalysts that are used for the cycloaddition reaction of CO2 to epoxides. Traditional approaches to prepare such multifunctional catalysts often imply multistep synthetic procedures and expensive building blocks. In this work we show that bifunctional catalysts for the cycloaddition of CO2 to epoxides bearing a Lewis acid metal and a quaternary ammonium halide group can be prepared in just two steps starting from an opportunely designed epoxide precursor by using inexpensive substrates. Such a readily accessible catalyst was applied for the cycloaddition of CO2 to a series of epoxides under atmospheric conditions generally leading to quantitative substrate conversion and high carbonate selectivities. Importantly, we also show that the epoxide‐driven concept developed for the preparation of the molecular catalyst, could be applied to prepare recyclable heterogeneous systems for the target cycloaddition reaction. [ABSTRACT FROM AUTHOR]

The cycloaddition of CO2 to epoxides to afford versatile and useful cyclic carbonate compounds is a highly investigated method for the nonreductive upcycling of CO2. One of the main focuses of the current research in this area is the discovery of readily available, sustainable, and inexpensive catalysts, and of catalytic methodologies that allow their seamless solvent-free recycling. Water, often regarded as an undesirable pollutant in the cycloaddition process, is progressively emerging as a helpful reaction component. On the one hand, it serves as an inexpensive hydrogen bond donor (HBD) to enhance the performance of ionic compounds; on the other hand, aqueous media allow the development of diverse catalytic protocols that can boost catalytic performance or ease the recycling of molecular catalysts. An overview of the advances in the use of aqueous and biphasic aqueous systems for the cycloaddition of CO2 to epoxides is provided in this work along with recommendations for possible future developments. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel 2D-COF (CuABD) realizes efficient charge transfer within the framework. • The HCOOH production rate over CuABD can reach 1.26 mmol g−1 h−1. • The π-conjugated skeleton propelled electronic delocalization and carrier transport. Sunlight-driven CO 2 reduction to value-added chemicals is an effective strategy to promote carbon recycling. The exploration of catalysts with efficient charge separation is crucially important for highly efficient CO 2 photoreduction. In this work, the preparation of metal-cluster-based covalent organic framework (CuABD) integrated features from both metal organic frameworks (MOFs) and covalent organic frameworks (COFs) through the condensation of diamines and functionalized trinuclear copper clusters demonstrate a thoughtful design strategy. The reported yield of 1.3 mmol g−1 h−1 for formic acid (HCOOH) under simulated solar irradiation is impressive, surpassing the performance of many COF- and MOF-based catalysts previously reported. Compared to its isomorphic metal-free structure (named BDFTD) and bare trinuclear Cu cluster which present extremely poor catalytic activities, CuABD displays remarkably enhanced CO 2 reduction activity. Experimental and theoretical investigations reveal that the efficient charge transfer between diamine monomer and cyclic trinuclear copper (I) units, and the electron delocalization of the π-conjugated framework are responsible for the appealing catalytic performance. In summary, the work presents a well-structured and scientifically sound exploration of a metal-cluster-based covalent organic framework for efficient CO 2 reduction under sunlight. [ABSTRACT FROM AUTHOR]

The continuous rise in atmospheric CO2 concentration, overconsumption of energy resources, and release of extraordinary organic pollutants are challenging issues of the modern era. Catalytic technology offers a promising solution to tackle these energy and environmental challenges in parallel by facilitating highly effective and sustainable processes. Herein, we report the fabrication of a series of different nature polyarylimide (PAI)-based covalent–organic frameworks (COFs) via the polycondensation reaction by altering linkers, organic solvents, and other experimental conditions. To optimize their catalytic performance, the resultant PAI-COFs were further decorated with metal–organic frameworks (ZIF-67). The decoration of COF4 with ZIF-67 led to adjusted bandgaps, created an active site, enhanced charge separation and migration of photoexcited electron–hole (e–h) pairs, extended the light absorption to the visible region, and also facilitated the transferring of electrons between the COFs and MOFs via the photoelectron modulation approach. Based on our findings, it is confirmed that COF4 and ZIF-67 (MOFs) are the optimal catalysts compared to the other COFs (COF1, COF2, and COF3) and MOFs (ZIF-8). Interestingly, compared to the pristine COF4, the 5ZIF-67/COF4 nanohybrid revealed ∼8-fold and ∼5.3-fold for CO2 conversion, direct CO2 capturing, and photoelectrochemical CO2 conversion with a faradaic efficiency of 50%. Likewise, the as-fabricated catalyst also exhibits exceptional activities for photocatalytic hydrogen production and pollutant oxidation. Ultimately, this work will provide a roadmap for the design and fabrication of COF-based nanohybrids for energy and environmental applications. [ABSTRACT FROM AUTHOR]

Experimental and theoretical insights into robust PIL-Br@ZIF-8 hetero-frameworks for the selective conversion of CO 2 into cyclic carbonates under mild conditions. [Display omitted] • A novel strategy is developed for fabricating core–shell PILs@ZIF-8 composites. • PIL-Br@ZIF-8 enables simultaneous adsorption and activation of CO 2 and epoxide. • Low-concentration/low-pressure CO 2 conversion into cyclic carbonates was achieved. • PIL-Br@ZIF-8 is recyclable and exhibits good thermal and structural stability. • Valuable insight into the cycloaddition mechanism is theoretically elucidated. The present study, for the first time, reports the fabrication of core–shell poly(ionic liquids)@ZIF-8 nanocomposites through a facile in-situ polymerization strategy. These composites exhibited exceptional structural characteristics including high specific surface areas and the integration of high-density Lewis acid/base and nucleophilic active sites. The structure–activity relationship, reusability, and versatility of the poly(ionic liquids)@ZIF-8 composites were investigated for the cycloaddition reaction between CO 2 and epoxide. By optimizing the composites structures and their catalytic performance, PIL-Br@ZIF-8(2:1) was identified as an exciting catalyst that exhibits high activity and selectivity in the synthesis of various cyclic carbonates under mild or even atmospheric pressure or simulated flue gas conditions. Moreover, the catalyst demonstrated excellent structural stability while maintaining its catalytic activity throughout multiple usage cycles. By combining DFT calculations, we investigated the transition states and intermediate geometries of the cycloaddition reaction in different coordination microenvironments, thereby proposing a synergistic catalytic mechanism involving multiple active sites. [ABSTRACT FROM AUTHOR]

Atomically precise metal nanoclusters (NCs) have emerged as a new frontier in electrocatalysis, enabling the study of electrocatalytic reactions on well‐defined stable surfaces and rational electrocatalyst design based on atomic‐level tailoring. In this review, we focus on the recent applications of these NCs to energy conversion reactions, including those involved in water splitting (hydrogen and oxygen evolution reactions), fuel cell operation (oxygen reduction and hydrogen oxidation reactions), and electrochemical CO2 reduction. Emblematic examples are used to highlight the roles of different NC parts, for example, core metal and surrounding ligands, and the significance of the electrode substrate. Finally, we discuss the perspectives of the future development and implementation of NC‐based energy conversion systems. [ABSTRACT FROM AUTHOR]

Carbon-supported noble-metal-free single-atom catalysts (SACs) have aroused widespread interest due to their green chemistry aspects and excellent performances. Herein, we propose a "ligand regulation strategy" and achieve the successful fabrication of bifunctional SAC/MOF (MOF = metal–organic framework) nanocomposite (abbreviated NiSA/ZIF-300; ZIF = ZIF-8) with exceptional catalytic performance and robustness. The designed NiSA/ZIF-300 has a planar interfacial structure with the Ni atom, involving one S and three N atoms bonded to Ni(II), fabricated by controllable pyrolysis of volatile Ni-S fragments. For CO2 cycloaddition to styrene epoxide, NiSA/ZIF-300 exhibits ultrahigh activity (turnover number (TON) = 1.18 × 105; turnover frequency (TOF) = 9830 molSC·molNi−1·h−1; SC = styrene carbonate) and durability at 70 °C under 1 atm CO2 pressure, which is much superior to Ni complex/ZIF, NiNP/ZIF-300, and most reported catalysts. This study offers a simple method of bifunctional SAC/MOF nanocomposite fabrication and usage, and provides guidance for the precise design of additional original SACs with unique catalytic properties. [ABSTRACT FROM AUTHOR]

Metallurgical slag such as solid waste generated in the steel industry carries environmental pollution risks, but it is rich in nutrients required by microalgae. Metallurgical slag used for carbon capture and biomass energy conversion has multiple benefits: (i) reduction and harmless treatment of metallurgical solid waste, (ii) assisting in carbon neutrality by efficient carbon fixation, and (iii) production of biodiesel from CO2. In this study, AOD, BOF, BFS, HVS, and VTS slag were applied to culture Chlorella pyrenoidosa (C. pyrenoidosa) with the regulation of growth, carbon fixation, and lipid synthesis. An excellent fixed amount of CO2 with 94.59 mg is obtained from C. pyrenoidosa biomass at BOF slag added (mass ratio of CO2 captured/microalgae/slag with 1.99/1.00/10.53) since high Ca/Mg mass ratio of 419 (8.38 mg/L Ca and 0.02 mg/L Mg), no Cr and low concentration of Al (0.04 mg/L) contribute to regulating antioxidant enzyme activity (SOD and POD) to resist ROS and improving PEPC activity to reduce carbon flux toward lipid to promote biomass synthesis. Both metal concentrations from Ca (5.86 mg/L), Mg (0.05 mg/L), Al (0.42 mg/L), and Cr (0.006 mg/L) and suitable pH (10.53) in AOD leaching solution at solid/liquid ratio of 0.5 g/L change carbon flow toward efficient lipid synthesis (47.07 wt%) by continuously providing raw materials and energy by regulating ACC, ME, and PEPC activities. High value‐added biodiesel with high concentrations of C16 and C18 methyl esters from lipid of C. pyrenoidosa is achieved, following other ecological and economic benefits including 197 mg CO2 captured and 2198 mg AOD applied with harmless. In this study, C. pyrenoidosa is cultured with elements from metallurgical slag solid waste, which promotes C. pyrenoidosa efficient carbon fixation to assist in carbon neutrality, and provides guidance for CO2 conversion to high‐value‐added products with low cost. [ABSTRACT FROM AUTHOR]

Fixing the greenhouse gas CO2 through epoxide helps to mitigate worldwide ecological troubles. The applications of metal‐free and solvent‐free catalysts remain a challenge for CO2 catalytic conversion. In this work, an array of quaternary ammonium salts derived from polyethyleneimine with hydroxyl groups ([PEI‐GDMAB‐Cn]Br) were constructed by the reaction of branched PEI with a molecular weight of 10000 and glycidyl alkyl dimethylammonium bromide. A range of experiments were designed to demonstrate that [PEI‐GDMAB‐Cn]Br can be considered as a valid metal‐free and solvent‐free homogeneous catalyst for the CO2‐epoxide cycloaddition reaction. Among of [PEI‐GDMAB‐Cn]Br, [PEI‐GDMAB‐C18]Br catalyzed the model reaction of CO2 and epichlorohydrin under optimized reaction conditions (T=80 °C, 1.0 atm CO2, catalyst 1 mol%, ECH 15 mmol, 16 h) and the conversion achieved at 97.5 %. Moreover, the catalyst exhibited stable reusability and broad substrate applicability, which was used in the following cycle succinctly, because of self‐separated properties by temperature control. The [PEI‐GDMAB‐C18]Br catalyzed reaction process was detected as a pseudo‐first‐order reaction after kinetic studies and an Ea was calculated to be 50.65 kJ/mol. A combinatorial catalytic mechanism of hydrogen bonding and bromide ions is suggested to explain the remarkable catalytic performance of this bifunctional catalyst. [ABSTRACT FROM AUTHOR]

Lead halide hybrids have shown great potentials in CO2 photoreduction, but challenging to afford C2+ reduced products, especially using H2O as the reductant. This is largely due to the trade‐off problem between instability of the benchmark 3D structures and low carrier mobility of quasi‐2D analogues. Herein, the lead halide dimensionality of robust coordination polymers (CP) was modulated by organic ligands differing in a single‐atom change (NH vs. CH2), in which the NH groups coordinate with interlamellar [PbI2] clusters to achieve the important 2D→3D transition. This first CP based on 3D cationic lead iodide sublattice possesses both high aqueous stability and a low exciton binding energy of 25 meV that is on the level of ambient thermal energy, achieving artificial photosynthesis of C2H5OH. Photophysical studies combined with theoretical calculations suggest the bridging [PbI2] clusters in the 3D structure not only results in enhanced carrier transport, but also promotes the intrinsic charge polarization to facilitate the C−C coupling. With trace loading of Rh cocatalyst, the apparent quantum efficiency of the 3D CP reaches 1.4 % at 400 nm with a high C2H5OH selectivity of 89.4 % (product basis), which presents one of the best photocatalysts for C2 products to date. [ABSTRACT FROM AUTHOR]

Since the initial introduction of porous C2N‐h2D materials by the Baek group in 2015, these materials have exhibited highly promising applications in fields such as semiconductor devices, heterogeneous catalysis, gas storage and separation, biomedicine, and more. However, much of the existing research on C2N materials has been based on theoretical calculations due to the challenges associated with their synthesis. In this study, an enhanced synthesis method for porous C2N materials has been successfully developed, involving the innovative and nonexplosive synthesis of hexaaminobenzene trihydrochloride (HAB·3HCl) as a crucial intermediate, as well as a time‐efficient synthesis of C2N. Rigorous structural characterizations have been conducted, including solid‐state NMR analysis, among others. The resultant C2N material has been effectively employed to improve the efficiency of CO2 conversion reactions. This straightforward protocol for synthesizing C2N materials is poised to stimulate further exploration and application of this promising 2D material in the near future. [ABSTRACT FROM AUTHOR]

Two new azo‐bridged hydroxyl‐rich porous organic polymers (POPs), named PPDA‐P5 and TB‐P5, were designed and successfully fabricated via azo‐coupling reaction with per‐hydroxylated pillar[5]arene macrocycle as the core and p‐phenylenediamine and Troger's base (TB) diamine as the linker, respectively. Owing to the abundant nitrogen and hydroxyl groups, both polymers exhibited excellent interaction affinity toward carbon dioxide (CO2) and then were applied as efficient heterogeneous catalysts for the transformation of CO2 to cyclic carbonates with high yield, even under mild conditions. Interestingly, TB‐P5 exhibited superior catalytic performance toward PPDA‐P5, indicating TB's positive role as an organic base. This design strategy and results provided new insight into the development of macrocycle‐based POPs in the field of heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Polyoxometalates can be tuned for specific catalytic property by substituting transition metal ions. We report the synthesis of hybrid materials of Cu2+, Co2+ and Ni2+ substituted phosphotungstates and poly(diallyldimethylammonium) chloride polymer (PDDA) for CO2 fixation. The in situ generated transition metal substituted polyoxometalates (TMS-POMs) are analyzed by FTIR, powder XRD, 31P NMR and SEM techniques. The hybrid TMS-POM materials are found to be good catalysts for converting epoxides to cyclic carbonates. Among these, PDDA-PWCo is the most efficient catalyst for cycloaddition of CO2 under solvent-free conditions at room temperature in shortest reaction time. Only 0.2 mol% of PDDA-PWCo is enough to deliver 100% conversion and selectivity to cyclic carbonates. This catalytic approach is employed for conversion of other cyclic, acyclic, and aromatic epoxides without using column purifications. Overall, the method of obtaining cyclic carbonates under green conditions using TMS-POMs-PDDA hybrid materials appears suitable for industrial applications. [ABSTRACT FROM AUTHOR]

Constructing stable nanochannels and nanoconfined environments for ionic liquids holds significant application value in gas separation, ion channels, and related fields. The functional polyionic liquid synthesized in this study exhibits a controllable assembly structure and demonstrates liquid crystal properties. Through heating and water treatment, the polyionic liquids crosslink to form multi-hierarchical nanopores, including sub-nanochannels with pore sizes similar to CO2, without the need for a catalyst. The specific surface area and pore size of the polyionic liquid network (PILC) were adjusted by regulating the self-assembly of polyionic liquids in water. The unique PILC, combining ionic liquid nanopores and liquid crystal structure properties, shows high CO2 adsorption performance and excellent CO2/N2 selectivities, surpassing commonly reported ionic liquid porous materials. Furthermore, PILC-2 exhibits good catalytic performance for CO2 cycloaddition, and its catalytic activity and selectivity did not significantly decrease after five cycles. This study successfully introduces hierarchical ionic liquid nanochannels into porous networks without involving any inorganic ordered nanomaterials. This provides a simple and effective approach for the highly selective adsorption and separation of CO2, as well as for the preparation of catalytic materials.

Poly(heptazine imide) (PHI), a carbon nitride polymer, is a highly efficient visible-light-driven photocatalytic material. We aimed to improve its photocatalytic performance for CO2 conversion. We prepared M-PHIs by encapsulating different metals (M = K, Li, Rb, and Na) and H-PHIs, in which the metal of each M-PHI was ion-exchanged with a proton. We evaluated their photocatalytic activities for CO2 conversion and found that Na-PHI and H-PHI, prepared from Na-PHI (H-PHI(NaCl)), showed more than twice the CO production efficiency of melon and other PHIs.The high CO production efficiency of Na-PHI and H-PHI(NaCl) was attributed to their extremely smaller particle size compared with those of the other PHIs. By closely examining the synthesis conditions of Na-PHI, we have identified a method to intentionally synthesize M-PHI with small particle size. These results provide a new strategy for highly efficient CO2 conversion using PHI.