CO2 Production Research Articles

Geoenergy in the Styrian Basin

The Styrian Basin (SB) is the westernmost basin within the Pannonian Basin Complex and is located in SE Austria, where the crustal thickness decreases from more than 40 km to less than 30 km. It can be divided into the West and East Styrian Basin. The pre-Neogene basement includes Penninic and crystalline rocks overlain by Paleozoic rocks. The age of the basin fill ranges from the early to late Miocene. Despite a long hydrocarbon exploration history, only a single sub-economic gas field has been discovered. The lack of commercial deposits is probably due to limited source-rock quality and an unfavourable heat-flow history. In contrast, a significant number of geothermal wells with a cumulative length of >54 km have been drilled in the East SB. The main geothermal reservoirs are fractured Paleozoic carbonates and Miocene (Badenian) sandstones. Geothermal gradients in the SB are typically above 4°C/100 m. The hottest geothermal well (Frutura GT1) produces water with a temperature of 125°C (bottom hole temperature 138°C) from a depth of ∼3.3 km. Utilization of geothermal energy in the SB includes balneology, district and greenhouse heating, production of medical salt, CO 2 and electricity.

Engineering single-atomic Ni sites stabilized with adjacent spinel nanoparticles to boost CO2 electroreduction

Single-atom catalysts show great potential in the electrochemical CO2 reduction reaction (CO2RR), but face significant challenges in accelerating reaction kinetics. Herein, we develop a three-dimensional heterostructured MgAl2O4/Ni-N-C catalyst via a facile pyrolysis strategy, featuring abundant atomically dispersed Ni sites and ∼14 nm MgAl2O4 nanoparticles. The MgAl2O4 with rich oxygen vacancies is crucial for stabilizing Ni atoms and promoting CO2 activation, thereby contributing to an excellent selectivity of nearly 100 % and good stability for CO production. The CO Faraday efficiency remains > 90 % within a large potential window (−0.57 to −0.97 V vs. RHE), and achieves the maximum of 98.7 % at −0.82 V. Theoretical calculations reveal that MgAl2O4 introduction can modulate the electron structure of Ni atoms, and accelerate the formation of *COOH intermediate, thus boosting CO2RR performance. This research provides a novel approach for the design of high-efficiency single-atom catalysts for CO2 conversion.

Investigation on CO2 capture performance of low-viscosity diamine non-aqueous absorbents with N-methyldiethanolamine regulation

In recent years, non-aqueous absorbents have attracted increasing attention due to their ability of significantly reducing sensible and latent heats in regeneration processes compared to conventional organic amine aqueous solution. But high viscosity of non-aqueous absorbents after CO2 absorption saturation became an obstacle to their industrial application. Here, a novel low-viscosity diamine non-aqueous absorbent for high-efficiency CO2 capture was proposed, in which N-methyldiethanolamine (MDEA) with steric hindrance effect was introduced as a regulator and dimethyl sulfoxide (DMSO) as a cosolvent. The effects of MDEA on CO2 capture performance of various non-aqueous absorbents and its regulation mechanism on CO2 absorbent viscosity were investigated systematically. Experimental results showed that when 25 wt% 2-(2-aminoethylamino)ethanol (AEEA) was screened as main CO2 absorption component, AEEA/MDEA/DMSO non-aqueous absorbent exhibited a high CO2 absorption capacity of 2.55 mol/kg and a fast CO2 absorption rate. Based on further mass fraction optimisation, it was found that the lowest viscosity of non-aqueous absorbents after CO2 absorption was 13.12 mPa s and the highest CO2 regeneration reached 93.5 % with AEEA and MDEA were 17.5 wt% and 12.5 wt%, respectively. 13C NMR tests showed that two characteristic peaks of carboxylated carbon appeared in CO2 products, which indicated that both amino groups on AEEA molecule were involved in CO2 absorption reaction. DFT calculations indicated that hydrogen bonding strength between MDEA and CO2 products was relatively lower than that of AEEA and CO2 products, which favored reducing absorbent saturation viscosity significantly. Thermodynamic analysis revealed that total regeneration energy consumption for 17.5 wt% AEEA/12.5 wt% MDEA/70 wt% DMSO non-aqueous absorbent was 1.72 GJ/t CO2, which was 53 % lower than that of MEA aqueous solution.

Boosted Solar Thermochemical Low-Temperature CO2 Splitting On Pt/CeO2 by Interface Catalysis.

Solar thermochemical CO2 splitting using metal oxides is considered as a promising approach to produce solar fuels since it is capable to tap abundant sunlight directly and store solar energy in the renewable fuel. It remains a grand challenge to achieve highly efficient CO2 splitting at low temperature (<800 °C) due to insufficient activation of metal oxides for CO2. Herein, the introduction of a small amount of Pt was found to be able to greatly increase the performance of CO2 splitting with the highest peak CO production rate of about 65 mL min-1 g-1, CO productivity of about 53 mL g-1, nearly 100 % CO2 conversion and long-term stability for 0.5Pt/CeO2, which exceeded most of the state-of-the-art transition metals-based oxides even at lower temperature (700 °C). This could be attributed to the addition of Pt leading to the formation of an interface (Pt0-Ov-Ce3+) after CH4 reduction, which improved CO2 activation and dissociation due to beneficial breakage of C=O bond by the cooperation of Pt0 and oxygen vacancies in the interface.

Biochemical and microbial characterization of a forest litter-based bio-fertilizer produced in batch culture by fermentation under different initial oxygen concentrations.

This work focused on the physico-chemical, biochemical and microbiological characterization of a new organic fertilizer based on fermented forest litter (FFL) mixed with agro-industrial by-products, on the culture realized in airtight glass bottle. Under strict anaerobiosis (0% initial oxygen concentration (IOC)), after a 16-day batch culture, the bottle-headspace analysis showed that the specific CO2 production rate was low (0.014 mL/h.g dry matter) compared to those reached under aerobic conditions (e.g. 0.464 mL/h.g dm at 21% IOC). Moreover, the culture displayed a slight fermented fruity odour, mainly due to ethanol and ethyl acetate detected in the headspace (335 µL and 58.6 µL accumulated, respectively). The FFL organic matter degradation followed by infrared spectroscopy and catabolic potential and diversity characterized by BIOLOG® EcoPlates were poor and pH dropped to 4.54. The microbiome's metabolism was oriented toward lactic fermentation with medium acidification, enrichment in lactic acid bacteria (LAB), depletion in fungi and absence of pathogens. By increasing IOC from 0 to 21%, the respirometric activity, and the catabolic potential and diversity increased. However, some enterobacteria were detected above 5% IOC. Ethanol and ethyl acetate decreased strongly with IOC, and aromatics and proteins contained in the solid matrix remained in the culture. This study showed the importance of oxygen on the final product. A 2% IOC was found to ensure an optimal balance between LAB development, preservation of functional catabolic diversity and bio-product free of microbial pathogens.

Photocatalysis of Adsorbed Catechol on Degussa P25 TiO2 at the Air-Solid Interface.

Semiconductor photocatalysis with commercial TiO2 (Degussa P25) has shown significant potential in water treatment of organic pollutants. However, the photoinduced reactions of adsorbed catechol, a phenolic air pollutant from biomass burning and combustion emissions, at the air-solid interface of TiO2 remain unexplored. Herein we examine the photocatalytic decay of catechol in the presence of water vapor, which acts as an electron acceptor. Experiments under variable cut-off wavelengths of irradiation (λcut-off ≥ 320, 400, and 515 nm) distinguish the mechanistic contribution of a ligand-to-metal charge-transfer (LMCT) complex of surface chemisorbed catechol on TiO2. The LMCT complex injects electrons into the conduction band of TiO2 from the highest occupied molecular orbital of catechol by visible light (≥2.11 eV) excitation. The deconvolution of diffuse reflectance UV-visible spectral bands from LMCT complexes of TiO2 with catechol, o-semiquinone radical, and quinone and the quantification of the evolving gaseous products follow a consecutive kinetic model. CO2(g) and CO(g) final oxidation products are monitored by gas chromatography and Fourier-transform infrared spectroscopy. The apparent quantum efficiency at variable λcut-off are determined for reactant loss (Φ- TiO2/catechol = 0.79 ± 0.19) and product growth ΦCO2 = 0.76 ± 0.08). Spectroscopic and electrochemical measurements reveal the energy band diagram for the LMCT of TiO2/catechol. Two photocatalytic mechanisms are analyzed based on chemical transformations and environmental relevance.

Fabrication of a Partial Encapsulation Architecture on S-Scheme Heterojunctions toward Durable Selective Photocatalytic CO2 Reduction.

It remains a challenging issue to achieve durably stable photocatalytic CO2 reduction over heterojunctions owing to their inherent structural assembly features. Herein, a unique partial encapsulation architecture is fabricated on the 3D/2D CoWO4/C3N5 heterojunction by embedding CoWO4 microspheres on C3N5 nanosheets, which achieves efficient, durable, stable, and selective photocatalytic CO2 reduction. For the optimal 5%-CoWO4/C3N5 heterojunction, the yield of selective CO2 reduction to CO is 7.70 and 3.82 times higher than those of CoWO4 and C3N5 in 4 h, respectively, and it maintains a stable CO generation rate within 20 cycles over 80 h. A series of characterization experiments and density functional theory calculations reveal that the structural stability is reinforced significantly via strong interfacial interaction owing to the unique partial encapsulation architecture fabricated on the 3D/2D CoWO4/C3N5 heterojunction, the separation efficiency of photogenerated carriers is improved by inducing a built-in electric field and triggering the S-scheme charge-transport path, and the high CO product selectivity is attributed to the much lower free energy required for the generation path of CO compared to that for CH4.

New insights into the spatial variability of microbial diversity and density in peatlands exposed to various electron acceptors with an emphasis on methanogenesis and CO2 fluxes.

Peatlands are vital in the global carbon cycle, acting as significant sinks for carbon and releasing methane (CH4) and carbon dioxide (CO2) into the atmosphere. However, the complex interactions between environmental factors and the microbial communities responsible for these greenhouse gas emissions remain insufficiently understood. To address this knowledge gap, a pilot-scale mesocosm study was conducted to assess the impact of different terminal electron acceptors (TEAs), including sulfate (SO4 2-), humic acid (HA), and goethite, on CH4 and CO2 emissions and microbial community structures in peatlands. Our results revealed that the addition of TEAs significantly altered the CH4 and CO2 emissions. Specifically, the addition of SO4 2- nearly doubled CO2 production while substantially inhibiting CH4 emissions. The combined addition of SO4 2- and HA, as well as HA alone, followed a similar pattern, albeit with less pronounced effects on CH4. Goethite addition resulted in the highest inhibition of CH4 among all treatments but did not significantly increase CO2 production. Community composition and network analysis indicated that TEAs primarily determined the structure of microbial communities, with each treatment exhibiting distinct taxa networks. Proteobacteria, Acidobacteria, Chloroflexi, and Bacteroidetes were the most abundant phyla across all mesocosms. The presence of methanotrophs, including Methylomirabilales and Methylococcales, was linked to the inhibition of CH4 emissions in these mesocosms. This study provides novel insights into the spatial variability of microbial diversity and density in peatlands under various TEAs, emphasizing the role of methanogenesis and CO2 fluxes in carbon cycling. Our findings enhance the understanding of carbon cycling in microbe-rich environments exposed to TEAs and highlight the potential for future studies to investigate the long-term effects of TEAs on microbial communities, enzymes, and carbon storage.

Anion Effect in Electrochemical CO2 Reduction: From Spectators to Orchestrators.

The electrochemical CO2 reduction reaction (eCO2RR) offers a pathway to produce valuable chemical fuels from CO2. However, its efficiency in aqueous electrolytes is hindered by the concurrent H2 evolution reaction (HER), which takes place at similar potentials. While the influence of cations on this process has been extensively studied, the influence of anions remains largely unexplored. In this work, we study how eCO2RR selectivity and activity on a gold catalyst are affected by a wide range of inorganic and carboxylate anions. We utilize in situ differential electrochemical mass spectrometry (DEMS) for real-time product monitoring coupled with molecular dynamics (MD) simulations. We show that anions significantly impact eCO2RR kinetics and eCO2RR selectivity. MD simulations reveal a new descriptor─free energy of anion physisorption─where weakly adsorbing anions enable favorable CO2 reduction kinetics, despite the negative charge carried by the electrode surface. By leveraging these fundamental insights, we identify propionate as the most promising anion, achieving nearly 100% Faradaic efficiency while showing high CO production rates that are comparable to those in bicarbonate. These insights underscore the vital role of anion selection in achieving a highly efficient eCO2RR in aqueous electrolytes.

Processes of Metal Oxides Catalyst on Conversion of Spent Coffee Grounds into Rich-Synthesis Gas by Gasification

Spent coffee grounds (SCGs), a waste product of the coffee industry, present a significant untapped resource for fuel production. This study aims to optimize the gasification of SCG using various metal catalysts (NiO, MnO2, Al2O3, and Fe2O3) to maximize syngas yield. SCG samples were gasified at different temperatures (800 °C, 900 °C, 1000 °C) and analyzed using Scanning Electron Microscopy (SEM), Thermogravimetric Analysis (TG-DTA), and Fourier Transform Infrared (FTIR) spectroscopy to evaluate catalyst performance and reaction mechanisms. The findings indicated that utilizing mixing techniques for physical contact to introduce catalysts led to a uniform distribution of catalyst particles throughout the sample. The decomposition rate of the gasification experiment after adding the catalyst was 24% faster than that of the pure SCGs. In the gasification experiment, the MnO2 catalyst showed the highest CO production, which was 71% higher than that of NiO under the same conditions. At this temperature, MnO2 generated around 171% more CO than at 800 °C, surpassing the yields observed with other catalysts. The study concludes that Mn emerged as the most promising catalyst, significantly improving both CO and CH4 yields. Selecting the appropriate metal catalyst and optimizing operational temperatures are crucial for enhancing the efficiency of SCG gasification.

Selective Photocatalytic Benzene Oxidation Using Iron‐Carbon Nitride Fragments Functionalized with Cyamelurate‐Like Groups

Carbon nitrides have emerged as promising supports for catalytically active metals in various chemical reactions. Among these, the selective oxidation of benzene to phenol stands out as particularly challenging within the chemical industry due to its traditionally low yields and complex reaction pathways. In our current investigation, we have focused on the synthesis of ionic carbon nitride fragments via a straightforward alkaline hydrolysis method. These fragments demonstrate a remarkable ability to stabilize iron cations within the carbon nitride structure (Frag‐Fe), resulting in a highly efficient photocatalyst for benzene oxidation. Employing hydrogen peroxide as the oxidant in a single‐step reaction, we achieved an impressive 47% yield of phenol using Frag‐Fe at 12 hours, with negligible production of CO2 as a byproduct. This compelling outcome underscores the effectiveness of our alkaline synthesis approach in generating carbon nitride‐based photocatalysts with exceptional activity for C‐H oxidation reactions. Our findings not only contribute to the advancement of carbon nitride‐based catalysis, but also hold significant promise for the development of more sustainable and efficient chemical processes in the future.

Impacts of anthropogenic resuspension on sediment organic matter: An experimental approach

Globally coastal sediments are frequently disturbed by a wide range of physical anthropogenic processes (e.g. bottom trawling) which causes resuspension of sediment organic matter (OM) into the overlaying water column. In this study we present experimental results showing that anthropogenic sediment resuspension decreases the organic carbon (14x) and nitrogen (3x) content in the sediment material resuspended to the water column, while no measurable response was found for organic phosphorus. Our findings furthermore show that the OM bioavailability decreased and the Carbon:Nitrogen:Phosphorus stoichiometry was changed suggesting that anthropogenic resuspension changes the chemical composition, and/or production and degradation pathways of the OM pool. The detected changes in OM biogeochemistry could affect nutrient release, fuel oxygen consumption and at the same time increase CO2 production in coastal waters.

Efficiency Assessment of the Production of Alternative Fuels of High Usable Quality within the Circular Economy: An Example from the Cement Sector

This article aims to present the mechanisms regulating the waste management system of one of the European countries that affect the cement industry. This publication analyses the possibility of using selected fractions of municipal and industrial waste as alternative fuels, including an analysis of ecological costs and benefits. The methodology includes the analysis of production data and the calculation of savings resulting from the use of alternative fuels. On this basis, ecological aspects were also indicated that should be taken into account when analyzing the profitability of the investment. Production data from an example Polish cement plant were used to analyze the research problem. Based on the guidelines of environmental standards and technical specifications, the parameters that PASr alternative fuels should meet were calculated in the company laboratory. This fuel type was then calculated in terms of emission intensity and production efficiency. The research results obtained in this paper study emphasize that the change in cement clinker production technology toward the use of waste raw materials and secondary fuels does not lead to an increase in heavy metal emissions to the extent that would justify qualifying cement as a material requiring systematic control of its harmful impacts on humans and the natural environment. The conclusions show that the use of alternative fuels reduces CO2 emissions and production costs, without negatively affecting the efficiency and production volume. The average energy requirement for the production of 1 ton of cement is approximately 3.3 GJ, which corresponds to 120 kg of coal with a calorific value of 27.5 MJ per kg. Energy costs account for 30–40% of the total cement production costs. Replacing alternative fuels with fossil fuels will help reduce energy costs, providing a competitive advantage for cement plants that use it as an energy source. The presented considerations can provide an answer to all interested parties, including representatives of the executive and legislative authorities, on what path the sector should follow to fit into the idea of sustainable building materials and the circular economy.

N-doped carbon-coated CoSe2/ZnIn2S4 Z-scheme heterojunction for enhanced visible-light photocatalytic performances

N-doped carbon (NC)/CoSe2/ZnIn2S4 Z-scheme heterojunction was constructed by growing ZnIn2S4 on N-doped carbon-coated CoSe2 derived from the metal-organic framework (ZIF-67) via the self-sacrificing template method and hydrothermal method. X-ray photoelectron spectroscopy, electron paramagnetic resonance, and density-functional theory (DFT) calculations demonstrate that NC/CoSe2/ZnIn2S4 (NSZ) Z-scheme heterojunction was constructed with CoSe2 as an electron mediator. The optimal 5NSZ composite achieved 97.3% in photocatalytic degradation efficiency of tetracycline hydrochloride (TCH) within 30 min, and H2O2 production of 645.3 μM under visible light for 60 min. Moreover, the top-flight photocatalytic hydrogen evolution (PHE) rate of 6772.9 μmol g−1 h−1 is 19.1 folds and 2.2 folds higher than pure ZnIn2S4 and Pt–ZnIn2S4, respectively. The photoreduction CO2 gas produces rates of CO (53.7 μmol g−1 h−1), C2H4 (7.0 μmol g−1 h−1), and C2H6 (6.4 μmol g−1 h−1) products were obtained within 10 h under visible light. This work provides an effective strategy for designing unique noble-metal-free Z-scheme heterojunction photocatalysts to purify the environment and produce clean energy.

Functionalized LDH via intercalation of gluconate anion and surface assembly of ultrafine copper hydroxide for improving mechanical properties and the fire safety of epoxy resin

To impart epoxy resin (EP) with outstanding mechanical properties and fire safety, LDH was systematically functionalized through gluconate anion (GA) intercalation followed by surface assembly of ultrafine Cu(OH)2, resulting in the LDH-GA@Cu(OH)2 hybrid. Comprehensive characterizations confirmed the successful synthesis of the desired product, with a uniform distribution of ultrafine Cu(OH)2 nanoparticles on the GA-intercalated LDH surface. The findings revealed that LDH-GA@Cu(OH)2 improved the mechanical properties of EP due to the increased LDH layer spacing, facilitating EP chain insertion, and the hydrogen bonding between the –OH of GA and the EP matrix. Fire retardancy tests indicated that the EP composite containing 7.5 wt% LDH-GA@Cu(OH)2 achieved a limiting oxygen index (LOI) of 30.1%. Furthermore, compared to pure EP, the composite demonstrated significant reductions in the peak heat release rate (PHRR) and peak CO production rate (PCOP) by 47.4% and 60.5%, respectively, underscoring its superior flame-retardant and toxic smoke suppression capabilities. Mechanistic studies further indicated that ultrafine Cu(OH)2 enhanced char formation through catalytic charring at the interface, which promoted compact and cohesive char layers. Overall, this work proposes a promising functionalization strategy for LDH to endow EP with excellent comprehensive performance.

A multifunctional epoxy composites based on cellulose nanofiber/carbon nanotube aerogels: Simultaneously enhancing fire-safety, thermal conductive and photothermal performance

As 5G technology develops and electronic power density increases, preparing epoxy resin (EP) composites with excellent fire-safety, thermostability, and thermal conductivity remains challenging. Herein, hexaphenoxy cyclotriphosphazene and poly(piperazine methylphosphonic acid pentaerythritol ester) were used as synergistic flame retardants (FR) for EP. The cellulose nanofiber/carboxylated multiwalled carbon nanotubes aerogels (CCA80) were prepared and immersed into the EP and FR mixture to obtain EP/CCA80/FR composites. Compared with neat EP, the limiting oxygen index of EP/CCA80/6 wt% FR increased by 38.9 %, the total heat release and CO2 production rate decreased by 30.61 % and 39.47 %, respectively, achieving the UL-94 V-0 rating. Moreover, its thermal conductivity was 1.06 W · m−1·K−1, 457.9 % higher than neat EP, while maintaining excellent electrical insulation. Its surface temperature maintained at 94.5 °C under 1.0 kW·m−2 irradiation for 2 h, exhibiting good photothermal conversion capability and photobleaching resistance. A novel fabrication methodology of multifunctional EP composites for high-performance electronic component was proposed.

Establishing a Robust Nonlinear Targeted Switch for C1 Electroproduction in Atomic Alloy Cox/Pd Bimetallenes

Establishing a targeted switch for CO2 conversion under electric drive is essential for achieving carbon‐balance by enabling selective chemicals. However, engineering the topological assembly of active sites to precisely regulate the competing pathways for various intermediates has been plagued by unclear structure‐function relationships. To tailor the CO/formate pathways, herein we established a robust nonlinear targeted switch with tunable active Cox sites integrated into Pd metallene, which involves Co1/Pd single‐atom alloy (favoring CO) and Co2/Pd diatomic alloy (favoring formate). Transitioning from Co1/Pd to Co2/Pd atomic alloy bimetallenes resulted in a nonlinear, high‐contrast flip in selectivity, surpassing 94% for CO and formate productions in both H‐cell and flow cell. Furthermore, the superior selectivity and current efficiency for CO (&gt; 80 %) and formate (&gt; 88%) were consistently maintained at ‐150 mA cm‐2 over continuous 200 h. Theoretical simulations and in‐situ spectroscopy analyses unveiled that appropriate adjacent metal site combinations (Pd‐Pd, Pd‐Co and Co‐Co) lead to tunable dz2 band center and a nonlinear shift in preferred adsorption configurations of intermediates, dictating the C1 pathways. Our finding reveals a desired switch in C1 selectivity and robust stability within Cox/Pd system, providing a new perspective for fine‐tuning energy conversion processes through specific topological assembly.

Establishing a Robust Nonlinear Targeted Switch for C1 Electroproduction in Atomic Alloy Cox/Pd Bimetallenes.

Establishing a targeted switch for CO2 conversion under electric drive is essential for achieving carbon-balance by enabling selective chemicals. However, engineering the topological assembly of active sites to precisely regulate the competing pathways for various intermediates has been plagued by unclear structure-function relationships. To tailor the CO/formate pathways, herein we established a robust nonlinear targeted switch with tunable active Cox sites integrated into Pd metallene, which involves Co1/Pd single-atom alloy (favoring CO) and Co2/Pd diatomic alloy (favoring formate). Transitioning from Co1/Pd to Co2/Pd atomic alloy bimetallenes resulted in a nonlinear, high-contrast flip in selectivity, surpassing 94% for CO and formate productions in both H-cell and flow cell. Furthermore, the superior selectivity and current efficiency for CO (> 80 %) and formate (> 88%) were consistently maintained at -150 mA cm-2 over continuous 200 h. Theoretical simulations and in-situ spectroscopy analyses unveiled that appropriate adjacent metal site combinations (Pd-Pd, Pd-Co and Co-Co) lead to tunable dz2 band center and a nonlinear shift in preferred adsorption configurations of intermediates, dictating the C1 pathways. Our finding reveals a desired switch in C1 selectivity and robust stability within Cox/Pd system, providing a new perspective for fine-tuning energy conversion processes through specific topological assembly.

Metal-organic framework-derived silver/copper-oxide catalyst for boosting the productivity of carbon dioxide electrocatalysis to ethylene

Electrochemical reduction of CO2 into valuable multi-carbon (C2) chemicals holds promise for mitigating CO2 emissions and enabling artificial carbon cycling. However, achieving high selectivity remains challenging due to the limited activity and active sites of CC coupling catalysts. Herein, we report an Ag-modified Cu-oxide catalyst (CuO/Ag@C) derived from metal-organic frameworks (MOF), capable of efficiently converting CO2 to C2H4. The MOF-derived porous carbon confines the size of metal nanoparticles, ensuring sufficient exposure of active sites. Remarkably, the CuO/Ag@C catalyst achieves an impressive Faradaic efficiency of 48.6% for C2H4 at −0.7 V vs. RHE, demonstrating excellent stability. Both experimental results and theoretical calculations indicate that Ag sites promote the production of CO, enhancing the coverage of *CO on Cu sites. Furthermore, the reconfiguration of charge density at the Cu-Ag interface optimizes the electronic states of the reaction sites, reducing the formation energy of the key intermediate *OCCHO, thereby favoring C2H4 production effectively. This work provides insight into structurally rational catalyst design for highly active and selective multiphase catalysts.

Assessing the net carbon removal potential by a combination of direct air capture and recycled concrete aggregates carbonation

Removing and storing CO2 from the atmosphere has an important role in combating climate change. This study assessed the CO2 removal potential of combining direct air capture with carbonation of recycled concrete aggregates (RCAs). An industrial-scale RCA carbonation process model quantified key parameters' impacts on carbonation duration and energy consumption. Furthermore, a lifecycle analysis evaluated scenarios of two cases: (i) using pure CO2 with transportation between DAC and carbonation, and (ii) onsite production of low-purity CO2. For 90 % carbonation of 1 tonne of RCA, the performance of case-i scenarios ranged from ∼13 kg net CO2 removal to ∼14 kg net CO2 emission, influenced by DAC technology, transport option, and electricity carbon intensity. In case-ii scenarios, 1 % CO2 feed purity achieved 70 % greater CO2 removal than using pure CO2. This work provides an initial indication of the potential of this scheme while revealing key factors to investigate in future experimental exploration.