Thermodynamic Aspects of the Electrochemical Conversion of Biomass and CO 2 to Sustainable Chemicals

Boosting CO2 Conversion with Terminal Alkynes by Molecular Architecture of Graphene Oxide-Supported Ag Nanoparticles

Liquid fuel synthesis via CO2 hydrogenation by coupling homogeneous and heterogeneous catalysis

Alcohol Production from Carbon Dioxide: Methanol as a Fuel and Chemical Feedstock

Electrochemical CO2 reduction reaction (eCO2RR) offers a promising solution to produce valuable chemical building blocks especially when coupled with renewable energy sources. However, its practical application faces significant challenges including low production selectivity due to competing hydrogen evolution reactions (HER). As both reactions are highly sensitive to the chemical environment formulated around active sites within electrochemical double layer (EDL), a comprehensive understanding is required on the role of electrolyte components, such as cation, anion, local pH, and water molecules, in tailoring chemical environment and thereby determining selectivity between eCO2RR and HER kinetics on the same catalyst surface.In this context, recent studies have shown that electrolyte engineering can largely control eCO2RR/HER selectivity.[2,3] For instance, different alkali cations have been shown to largely determine CO2 conversion kinetics due to their different hydrated structure within EDL structures.[4] Moreover, an increased cation population within EDL can promote effective eCO2RR over HER even under highly acidic conditions through charge screening effect.[5] Nevertheless, a lack of dynamic information from conventional experimental approaches (e.g. gas chromatography-mass spectrometry) is largely limiting our efforts to comprehensively understand electrolyte engineering effects. To advance our knowledge in electrolyte engineering for high eCO2RR selectivity, it is essential to investigate the functional correlation between electrolyte properties and eCO2RR/HER competition occurring at the electrochemical interface in operando manner.[6,7] In this work, we utilized in situ Differential Electrochemical Mass Spectrometry (DEMS) to monitor the effects of various electrolyte engineering on eCO2RR/HER selectivity in a dynamic manner. Based on the online collection of product molecules and CO2 from Au catalyst surface, in situ DEMS can provide detailed information on both reaction competition between eCO2RR and HER and local CO2 concentration on catalyst surface on electrified catalyst surface. Based on the strength of in situ DEMS analysis, the critical role of electrolyte components will be addressed in terms of eCO2RR/HER kinetics and the local chemical environment. Overall, this work will highlight importance of understanding specific role of electrolyte engineering toward designing efficient eCO2RR systems for carbon-neutral energy technology.[1] A. Wagner, C. D. Sahm, and E. Reisner, Nat. Catal. 2020, 3, 775–786.[2] J. C. Bui, C. Kim, A. J. King, O. Romiluyi, A. Kusoglu, A. Z. Weber, and A. T. Bell, Acc. Chem. Res. 2022, 55, 484-494.[3] G. Marcandalli, M. C. O. Monteiro, A. Goyal, and M. T. M. Koper, Acc. Chem. Res. 2022, 55,1900-1911.[4] M. C. O. Monteiro, F. Dattila, B. Hagedoorn, R. Garcia-Muelas, N. Lopez, and M. T. M. Koper, Nat. Catal. 2021, 4, 654-662.[5] J. Gu, S. Liu, W. Ni, W. Ren, S. Haussener, and X. Hu, Nat. Catal. 2022, 5, 268-276.[6] A. Goyal, G. Marcandalli, V. A. Mints, and M. T. M. Koper, J. Am. Chem. Soc. 2020, 142, 4154-4161[7] E. L. Clark and A. T. Bell, J. Am. Chem. Soc. 2018, 140, 7012-7020.

Recent progress in dual-atoms catalysts for carbon dioxide reduction

Toward abiotic sugar synthesis from CO2 electrolysis

Efficient Electrocatalytic CO2 Reduction to C2+ Alcohols at Defect-Site-Rich Cu Surface

HI-Light: A Glass-Waveguide-Based "Shell-and-Tube" Photothermal Reactor Platform for Converting CO2 to Fuels.

Carbon dioxide (CO2) conversion is a suite of chemical and biological processes that transform the carbon in CO2 into other forms, such as mineral carbonates, alcohols, hydrocarbons, polymers, or elemental carbon materials. Such processes allow CO2 to replace fossil fuels to enable sustainable production of chemicals and materials, and support durable storage of CO2 in long‐lived products, two underexamined aspects of addressing CO2 accumulation in the atmosphere. CO2 can, in principle, serve as a feedstock for any carbon‐based product, and is better suited to forming carbonates, other oxygenated products, or single‐carbon products that share similar properties to CO2. CO2 conversion requires new infrastructure for CO2 capture, clean energy, and product distribution, and may need CO2 transportation, clean hydrogen, and water resources. Infrastructure buildouts could benefit from clustered siting, integration of utilization infrastructure with other carbon management infrastructure, improved public engagement, and improved research on pipeline modeling and testing for safety from propagating brittle fractures. CO2 utilization is enabled by economic and noneconomic policies that develop the sector's value for sustainable product formation and long‐term carbon storage. Though CO2 conversion technologies are operating today in select markets at pilot, demonstration, and commercial scales, most areas of the product and process landscape require investment in research, development, and demonstration. The first1 and final2 reports of the National Academies of Sciences, Engineering, and Medicine (NASEM) Committee on Carbon Utilization Infrastructure, Markets, Research, and Development offer comprehensive assessments of the infrastructure, market, policy, and research needs to enable CO2 conversion to serve the needs of circular carbon economies and durable carbon storage.

The conversion of carbon dioxide into higher value chemicals is a viable way to support sustainability and net-zero economy goals. Of the different CO2 conversion routes, direct conversion offers a simplified process, lower reaction temperatures, and thus low energy input. Alcohols can be directly combined with CO2 to produce polycarbonates, e.g., DMC (dimethyl carbonate) formation from methanol and CO2. Recently CO2 and 1,6-hexanediol were shown to convert into poly(hexamethylene carbonate)diol using an atmospheric flow based process in single step. For these conversions, CeO2-based catalysts are widely used due to the abundance of oxygen vacancies that are believed to be the active sites for this reaction. Microwave (MW) heating is a unique approach that can provide selective volume-based heating and enhanced reaction rates and/or selectivities. For the current work, CO2 and diol conversion into polymers were investigated on different CeO2 catalysts under microwave heating and the performance was compared against conventional heating. The reaction products were analyzed using infrared spectroscopy (IR) and nuclear magnetic resonance (NMR) spectroscopy. Preliminary results showed microwaves irradiation produced faster rates of polycarbonate production as evidenced by IR data.

The use of redox-active organic molecules for aqueous electrochemical carbon dioxide capture is limited by their tendency to undergo reversible oxidation by oxygen. Here we show that a naphthoquinone derivative, when reduced in the presence of tetraalkylammonium countercations, displays enhanced stability toward oxygen while maintaining carbon dioxide binding ability. By combining structural modification with control of non-covalent interactions, we mitigate a previously observed trade-off between carbon dioxide capture performance and resistance to aerobic oxidation. In situ spectrophotometry and comparative voltammetry indicate that ion pairing stabilizes the reduced quinone both by shifting its redox potential and by promoting carbon dioxide adduct formation. Among the cations tested, tetraethylammonium provides the most favorable balance, supporting efficient capture and release cycle with 87 % Coulombic efficiency and an energy cost of 157 kilojoules per mole of carbon dioxide from a gas mixture containing carbon dioxide, oxygen, and nitrogen. These findings illustrate how molecular design combined with electrolyte engineering can improve the durability of aqueous quinone-based electrochemical carbon capture systems and may inform the development of more robust and energy-efficient approaches for sustainable carbon management.

MXene - A frontier exploiter in carbon dioxide conversion: Synthesis and adsorption

Carbon dioxide (CO2) conversion has attracted much interest recently owing to its importance in both scientific research and practical applications, but still faces a bottleneck in selectivity control and mechanism understanding owing to diversified active sites. Single-atom catalysts (SACs) featuring isolated and well-defined active centers are proved to not only exhibit unparalleled performances in various processes of CO2 conversion but also provide excellent research paradigms by circumventing the heterogeneity of active sites. Herein, we will not only critically review recent progress on the application of SACs in chemical CO2 conversion based on previous comprehension of general thermodynamics and kinetics, but also try to offer a multi-level understanding of SACs from a molecular point of view in terms of the central atom, coordination environment, support effect and synergy with other active centers. Meanwhile, crucial scientific issues of research methods will be also identified and highlighted, followed by a future outlook that is expected to present potential aspects of further developments.

The conversion of carbon dioxide (CO2) into carbon-neutral fuels using solar energy is crucial for achieving energy sustainability. However, the high carrier charge recombination and low CO2 adsorption capacity of the photocatalysts present significant challenges. In this paper, a TAPB-COF@ZnIn2S4-30 (TAPB-COFZ-30) heterojunction photocatalyst was constructed by in situ growth of ZnIn2S4 (ZIS) on a hollow covalent organic framework (HCOF) with a hollow core-shell structure for CO2 to CO conversion. Both experimental studies and theoretical calculations indicate that the construction of heterojunctions improves the efficiency of carrier separation and utilisation in photocatalysis. The yield of photoreduction of CO2 to CO by the TAPB-COFZ-30 heterojunction photocatalyst reached 2895.94 μmol g-1 with high selectivity (95.75%). This study provides a feasible strategy for constructing highly active core-shell composite photocatalysts to optimize CO2 reduction.

Rapidly increasing levels of atmospheric carbon dioxide and their damaging impact on the global climate system raise doubts about the sustainability of the fossil resource based energy system. Meanwhile, raising living standards and increasing global population lead to an ever growing need for energy. Renewable energy sources are believed to present a solution to these problems with the sheer abundance of solar energy showing particular promise to fulfill the world's energy needs. However, for large scale application of solar energy to be possible, the problem of its storage has to be addressed. The insufficient flexibility of present-day storage technologies has led to the quest for producing solar fuels, centering on hydrogen as a fuel in a prospective hydrogen economy. Nevertheless, the gaseous state, low volumetric energy density and explosive nature of hydrogen makes it a challenging fuel for practical applications. Using solar energy to produce carbon-based liquid fuels solves these challenges, closes the anthropogenic carbon cycle and allows for the continued utilization of existing infrastructures. A promising method for the production of such fuels consists in the photoelectrochemical and electrochemical conversion of carbon dioxide. In this thesis, both methods are investigated using molecular homogeneous catalysts and heterogeneous systems. The photoelectrochemical reduction of carbon dioxide on TiO2-protected Cu2O photocathodes was investigated using a rhenium bipyridyl catalyst in solution. Important charge transport limitations were encountered, which could be overcome by the addition of protic additives to the electrolyte. Improving on this result, the molecular catalyst was covalently immobilized on the TiO2 surface of the photocathode by modifying the bipyridyl ligand with a phosphonate binding group. A nanostructure of TiO2 was needed to support sufficient catalyst to sustain the photocurrent generated by the Cu2O photoelectrode. The complete device showed photocurrents exceeding 2.5 mA cm-2 and large faradaic efficiency for the production of CO. Moving toward heterogeneous catalysis, the promotion of the CO2 to CO conversion reaction on silver surfaces by imidazolium cations was investigated. Replacing the imidazolium C2 proton with a phenyl substituent led to an enhancement of the co-catalytic effect. Replacing the C4 and C5 protons with methyl groups, however, suppressed the catalysis-promoting effect of the imidazolium salt for different C2 substituents and led to new insights into the role of imidazolium. The unassisted solar-driven splitting of CO2 into CO and O2 was demonstrated using water as electron source. This was achieved by the use of a porous gold cathode and an IrO2 anode, driven by three methylammonium lead iodide perovskite solar cells in series. Extended operation over 18 h was shown, achieving a solar to CO efficiency exceeding 6.5 %. Atomic layer deposition (ALD) modification of CuO nanowire cathodes with SnO2 was investigated, leading to striking impacts on the catalytic selectivity of this system. In an aqueous electrolyte, bare CuO led to the production of a wide spectrum of products, which was modified to the production of CO with high selectivity upon ALD modification. By exploiting the oxygen evolving activity of SnO2-coated CuO, a low cost bifunctional system was constructed, achieving sustained solar-driven production of CO with up to 13.4% efficiency.