Enhanced Carbon Dioxide Research Articles

Stabilized Cu0 -Cu1+ dual sites in a cyanamide framework for selective CO2 electroreduction to ethylene

Electrochemical reduction of carbon dioxide to produce high-value ethylene is often limited by poor selectivity and yield of multi-carbon products. To address this, we propose a cyanamide-coordinated isolated copper framework with both metallic copper (Cu0) and charged copper (Cu1+) sites as an efficient electrocatalyst for the reduction of carbon dioxide to ethylene. Our operando electrochemical characterizations and theoretical calculations reveal that copper atoms in the Cuδ+NCN complex enhance carbon dioxide activation by improving surface carbon monoxide adsorption, while delocalized electrons around copper sites facilitate carbon-carbon coupling by reducing the Gibbs free energy for *CHC formation. This leads to high selectivity for ethylene production. The Cuδ+NCN catalyst achieves 77.7% selectivity for carbon dioxide to ethylene conversion at a partial current density of 400 milliamperes per square centimeter and demonstrates long-term stability over 80 hours in membrane electrode assembly-based electrolysers. This study provides a strategic approach for designing catalysts for the electrosynthesis of value-added chemicals from carbon dioxide.

Evaluation of Na2CO3-doped MCM-48-Li4SiO4 adsorbent for CO2 capture: Performance and DFT mechanism

Efficient CO2 adsorbents are crucial for addressing the global climate crisis. In this study the novel adsorbents were synthesized using an impregnation precipitation method with MCM-48 as the silica source and Li2CO3 as the lithium source. By doping alkali metal carbonate (Na2CO3), the ML-Na2CO3 adsorbent was created for high-temperature CO2 capture. The results showed that the maximum adsorption capacity of 35.63 wt% was achieved at 600℃ in the mixture (15 vol% CO2, the balance being N2)when the adsorbent contained 15 wt% Na2CO3, representing a 4.49 wt% increase compared to the undoped ML adsorbent. The adsorption kinetics analysis confirmed a good fit with the biexponential model. Density Functional Theory (DFT) simulations revealed that the adsorption energy increased by an average of 0.1035 eV and Oslab exhibited high activity in chemisorbing CO2, forming CO32−. Na2CO3 doping modified the electronic structure of Oslab and Lislab, resulting in increased high-energy electrons, reflective activity, and improved CO2 adsorption energy. Overall, incorporating Na2CO3 enhanced carbon dioxide adsorption performance by 114.42 %, indicating a promising potential for real flue gas CO2 adsorption applications.

Enhanced carbon dioxide reduction in microbial electrosynthesis using amine-functionalized metal-organic framework catalyst

Microbial electrosynthesis (MES) is a promising technology that can reduce carbon dioxide (CO2) into valuable platform chemicals using microbial biocatalytic action. However, inefficient microbe-electrode interactions greatly reduce the current uptake by microbes, ultimately hampering the CO2 reduction reaction. Therefore, this study aimed to enhance microbe-electrode interaction using amine-functionalized metal-organic framework (MOF) catalysts such as NH2-UiO-66(Zr) and NH2-UiO-66(Zr/Ni) on the cathode. Both abiotic and biotic cyclic voltammetry (CV) revealed the highest reduction current response from the NH2-UiO-66(Zr/Ni)-modified cathode among the tested cathodes, such as NH2-UiO-66, Pt-C, and unmodified cathode (control). Thus, the MES using the NH2-UiO-66(Zr/Ni) cathode could achieve an acetic acid production rate of 1166 ± 31 mg/L·d at a coulombic efficiency of 76 ± 2 %, which was higher than the MES operations with NH2-UiO-66(Zr) and without catalyst with corresponding values of 912 ± 12 mg/L·d and 67 ± 3 %, and 428 ± 13 mg/L·d and 56 ± 4 %, respectively. Biofilm analyses using scanning electron microscopy and confocal microscopy showed thick biofilm development on the NH2-UiO-66(Zr/Ni) cathode with abundant live bacteria. The results suggest that the amine-functionalized MOF can enhance the interaction of microbes with the cathode, resulting in efficient and high-rate bioelectrochemical CO2 reduction to valuable organic chemicals.

Revolutionizing Rice: The Synthesis of Nature's Evolution and Biotechnology in C4 Rice

Agriculture plays a fundamental role in meeting the essential needs of humanity, yet numerous factors continuously influence agricultural production and productivity. Over time, evolving agricultural practices have significantly increased yields of staple food crops, thereby enhancing global food security. However, as the world's population continues to grow, there is a pressing need to further augment crop yields. Historically, increases in yield were achieved by expanding cultivated land, but rapid industrialization and urbanization have diminished available agricultural land and depleted natural resources essential for farming. In response to these challenges, enhancing crop photosynthetic efficiency has emerged as a pivotal strategy. Photosynthesis, the process by which plants convert sunlight into energy, has been optimized in various crops through evolutionary and biotechnological approaches. One such innovation is the adaptation of the C4 photosynthetic pathway into C3 rice, a staple food for billions worldwide. The C4 pathway, found in several efficient crops like maize and sugarcane, enhances carbon dioxide uptake and reduces photorespiration, leading to improved water and nitrogen use efficiency. This review explores the integration of nature’s evolutionary principles with cutting-edge biotechnological advancements in the development of C4 rice. By introducing the C4 pathway into rice—a traditionally C3 plant—scientists aim to dramatically increase its productivity and resilience to environmental stressors. This transformative approach not only holds promise for meeting future food demands sustainably but also addresses the challenges posed by climate change and resource scarcity. Moreover, the review examines the scientific basis, technological innovations, and potential agricultural implications of implementing C4 rice. It highlights the collaborative efforts of researchers, agronomists, and biotechnologists worldwide in reimagining rice cultivation to secure global food supplies while minimizing environmental impact. Ultimately, the integration of C4 photosynthesis into rice represents a significant step forward in agricultural innovation, poised to redefine food production capabilities and enhance global food security in the face of escalating population growth and environmental change.

Enhanced carbon dioxide drainage observed in digital rock under intermediate wetting conditions

Carbon dioxide (CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document}) trapping in capillary networks of reservoir rocks is a pathway to long-term geological storage. At pore scale, CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document} drainage displacement depends on injection pressure, temperature, and the rock’s interaction with the surrounding fluids. Modeling this interaction requires adequate representations of both capillary volume and surface. For the lack of scalable representations, however, the prediction of a rock’s CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document} storage potential has been challenging. Here, we report how to represent a rock’s pore space by statistically sampled capillary networks (ssCN) that preserve morphological rock characteristics. We have used the ssCN method to simulate CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document} drainage within a representative sandstone sample at reservoir pressures and temperatures, exploring intermediate- and CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document}-wet conditions. This wetting regime is often neglected, despite evidence of plausibility. By raising pressure and temperature we observe increasing CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document} penetration within the capillary network. For contact angles approaching 90∘\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^\\circ$$\\end{document}, the CO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_2$$\\end{document} saturation exhibits a pronounced maximum reaching 80%\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\%$$\\end{document} of the accessible pore volume. This is about twice as high as the saturation values reported previously. For enabling validation of our results and a broader application of our methodology, we have made available the rock tomography data, the digital rock computational workflows, and the ssCN models used in this study.

Enhanced carbon dioxide adsorption performance of UiO-66-SO3H with a mixed ligand strategy

In this work, a sulfonated UiO-66 was synthesized and modified with a mixed ligand strategy using 2-amino terephthalic acid as a second linker. The X-ray diffraction (XRD) diffractogram shows a transition from an amorphous to a crystalline pattern with the addition of a second linker. The Fourier transforms infrared spectroscopy spectra show the presence of new peaks at 1255, 1382, and 1426 cm−1, which refer to N-H and C-N stretching. All the mixed ligand samples showed stable thermal stability as the pristine UiO-66-SO3H sample. The field emission scanning electron microscopy analysis also showed a morphological change from a round-like shape (UiO-66-SO3H) to a triangular-based pyramid shape (UiO-66-SO3H-NH2-0.85). The nitrogen physisorption analyses showed a significant increase in the BET surface area of UiO-66-SO3H-NH2-0.85 (706 m2/g) from UiO-66-SO3H (16 m2/g). The CO2-TPD results demonstrated that the greater formation of medium basic sites (monodentate carbonate and bidentate carbonate species) is due to the increase in the amount of the second linker. Furthermore, the UiO-66-SO3H-NH2-0.85 showed CO2 adsorption of 2.17 mmol/g, five times higher than UiO-66-SO3H (0.43 mmol/g). Both samples also showed excellent recyclability up to ten cycles. After being reused for ten cycles, the sample preserved the characteristics of the XRD pattern and crystallinity, functional groups, and thermal stability. For the water and pH stability studies, UiO-66-SO3H and UiO-66-SO3H-NH2-0.85 maintained the original XRD patterns, a high BET surface area, and good CO2 adsorption in water and acid environments.

Enhancing carbon dioxide foam flooding for Egyptian oil recovery: the role of Arabic gum nanocomposites in foam stability and interfacial properties

In response to the growing demand for environmentally sustainable solutions in the oil and gas sector. In this study, three nanocomposites, namely Arabic gum silica oxide (ASO), Arabic gum iron oxide (AIO), and Arabic gum iron silica oxide (AIS), were synthesized. Spectroscopic analyses confirmed the chemical composition of these nanomaterials, while visual inspection and dynamic light scattering (DLS) analysis were employed to evaluate their particle size distribution and stability. It was found that ASO demonstrated a significant 26.8% increase in oil recovery compared to pure Arabic gum (15.6%) when applied at a concentration of 5 wt.% during CO2 foam flooding. This enhancement can be attributed to the high foam volume (134.1 mL) and prolonged drainage half-life (3562.5 s) at 30 °C. Furthermore, ASO displayed favorable interfacial tension (32.21 mN/m) and a superior storage modulus (10−27 mN/m) compared to pure Arabic gum (10−28 mN/m and 46.13 mN/m, respectively), indicating enhanced elasticity and improved stability of bubble-lamellae, ultimately resulting in enhanced oil recovery. Conversely, AIO nanocomposite exhibited a negative impact on recovered oil (4.8%), attributed to its low stability (zeta potential: −3.6 mV). These findings underscore the potential of ASO as a promising foaming agent for efficient oil recovery processes.

Enhancing carbon dioxide uptake in biochar derived from husk biomasses: Optimizing biomass particle size and steam activation conditions

This research focuses on developing activated biochars for CO2 adsorption, evaluating the impact of particle size and steam activation conditions on almond shells (AS), pistachio shells (PS), and nut shells (NS), three crops that are grown worldwide. A literature review was carried out on the characteristic parameters that a biomass must have to produce a biochar of an acceptable quality to capture CO2. Initially, a physicochemical characterization of the selected biomasses was conducted, revealing high levels of volatiles (78–84 wt%), carbon (41–53 wt%), and inherent metals (Ca, K, Mg and Na). This process involved pyrolysis and activation under pre-established conditions, followed by CO2 adsorption analysis using thermogravimetry. Interestingly, intermediate-sized biochars (ranging from 2 to 1.4 mm) exhibited higher CO2 uptake. Once the optimal particle size was determined, steam activation conditions were further optimized by varying temperature. In this regard, these conditions were established at 900 °C for 30 min, at a steam flow rate of 0.15 mL/min and a pressure of 1 bar. This study highlighted biomass heterogeneity, resulting in distinct biochar morphologies (microporous PS activated biochars, and mesoporous NS and AS biochars) and higher carbon content compared to raw materials. However, the O/C and H/C ratios fell as severity rose. On researching steam activation holding times at a constant temperature of 900 °C, similar trends were observed, with high carbon content in the biochars. Finally, based on CO2 adsorption results, 2.81, 2.12 and 1.76 mmol/g for PS, AS and NS activated biochars, respectively, optimal shorter activation times (15 min) were selected for AS and NS biochars.

Analysis of Hyperosmotic Tolerance Mechanisms in Gracilariopsis lemaneiformis Based on Weighted Co-Expression Network Analysis.

We conducted transcriptome sequencing on salt-tolerant mutants X5 and X3, and a control (Ctr) strain of Gracilariopsis lemaneiformis after treatment with artificial seawater at varying salinities (30‱, 45‱, and 60‱) for 3 weeks. Differentially expressed genes were identified and a weighted co-expression network analysis was conducted. The blue, red, and tan modules were most closely associated with salinity, while the black, cyan, light cyan, and yellow modules showed a close correlation with strain attributes. KEGG enrichment of genes from the aforementioned modules revealed that the key enrichment pathways for salinity attributes included the proteasome and carbon fixation in photosynthesis, whereas the key pathways for strain attributes consisted of lipid metabolism, oxidative phosphorylation, soluble N-ethylmaleimide-sensitive factor-activating protein receptor (SNARE) interactions in vesicular transport, and porphyrin and chlorophyll metabolism. Gene expression for the proteasome and carbon fixation in photosynthesis was higher in all strains at 60‱. In addition, gene expression in the proteasome pathway was higher in the X5-60 than Ctr-60 and X3-60. Based on the above data and relevant literature, we speculated that mutant X5 likely copes with high salt stress by upregulating genes related to lysosome and carbon fixation in photosynthesis. The proteasome may be reset to adjust the organism's proteome composition to adapt to high-salt environments, while carbon fixation may aid in maintaining material and energy metabolism for normal life activities by enhancing carbon dioxide uptake via photosynthesis. The differences between the X5-30 and Ctr-30 expression of genes involved in the synthesis of secondary metabolites, oxidative phosphorylation, and SNARE interactions in vesicular transport suggested that the X5-30 may differ from Ctr-30 in lipid metabolism, energy metabolism, and vesicular transport. Finally, among the key pathways with good correlation with salinity and strain traits, the key genes with significant correlation with salinity and strain traits were identified by correlation analysis.

Microtextural Characteristics of Ultramafic Rock-Forming Minerals and Their Effects on Carbon Sequestration

Ultramafic rocks are promising candidates for carbon sequestration by enhanced carbon dioxide (CO2) mineralization strategies due to their highly CO2-reactive mineral composition and their abundant availability. This study reports the mineralogy and microtextures of a representative ultramafic rock from the Ma-Hin Creek in northern Thailand and provides evidence of CO2 mineralization occurring through the interaction between CO2 and the rock in the presence of water under ambient conditions. After sample collection, rock description was determined by optical petrographic analysis. The rock petrography revealed a cumulated wehrlite comprising over 50% olivine and minor amounts of clinopyroxene, plagioclase, and chromian spinel. Approximately 25% of the wehrlite had altered to serpentine and chlorite. A series of CO2 batch experiments were conducted on six different rock sizes at a temperature of 40 °C and pressure of 1 atm over five consecutive days. The post-experimental products were dried, weighed, and geochemically analyzed to detect changes in mineral species. Experimental results showed that product weight and the presence of calcite increased with reducing grain size. Additionally, the modal mineralogy of the wehrlite theoretically suggests potential CO2 uptake of up to 53%, which is higher than the average uptake values of mafic rocks. These findings support the rock investigation approach used and the preliminary assessment of carbon mineralization potential, contributing to enhanced rock weathering techniques for CO2 removal that could be adopted by mining and rock supplier industries.

Enhancing carbon sequestration: Innovative models for wettability dynamics in CO2-brine-mineral systems

This study investigates the application of machine learning techniques—specifically convolutional neural networks, multilayer perceptrons and cascaded forward neural networks —to understand the wettability of the CO2/brine/rock system, a critical factor in carbon dioxide (CO2) capture, utilization, and storage in deep saline aquifers. Understanding wettability is essential for improving the efficacy of CO2 storage. The study incorporates variables such as salinity, mineral types, measurement methods, pressure, and temperature into the machine learning models. Using a dataset of 876 samples from existing literature, the proposed models were trained and optimized using the Adam optimizer, Levenberg-Marquardt algorithm, and particle swarm optimization respectively.The performance of these models was evaluated through plot analysis, statistical indicators, and the Taylor diagram, demonstrating a high level of accuracy compared to experimental data. The specifically convolutional neural networks model showed exceptional accuracy in predicting CO2 wettability in brine, with a root mean square error of 0.9612 and coefficient of determination value of 0.9982. The minimal presence of outliers in the specifically convolutional neural networks model further confirms its robustness.This research highlights the effectiveness of deep learning in modeling complex wettability behaviors in CO2-brine-mineral systems, offering substantial insights for enhancing carbon dioxide (CO2) capture, utilization, and storage strategies. The novelty of this work lies in its comprehensive integration of multiple variables and the use of advanced machine learning optimization techniques, going beyond previous efforts by achieving higher predictive accuracy and providing a more detailed understanding of wettability dynamics.

Mitigating CO2 emissions through an industrial symbiosis approach: Leveraging cork ash carbonation

This study explores for the first time the potential use of carbonation as a method for managing cork ash, a byproduct of biomass waste incineration. Additionally, the cork ash was combined with fly ash from municipal solid waste incineration to leverage the carbonation reaction's ability to stabilize heavy metals. The findings suggest that subjecting biomass ash to carbonation can lead to the formation of mineral carbonates, effectively capturing CO2 and reducing its release into the atmosphere. The combination of various alkaline wastes and the stabilization of leachable heavy metals through carbonation reactions also opens opportunities for synergies between different industrial sectors. Finally, the study proposes a route for the obtained materials valorisation via ‘end of waste’: the reuse of the resulting materials as substitutes for natural resources, particularly in applications like building materials and polymer composites, can further enhance carbon dioxide savings.

Effect of surface engineering of nanofillers using plasma-treated water for carbon dioxide capture in mixed matrix membranes: Experimental and molecular dynamics

This work introduces an innovative approach to enhance carbon dioxide (CO2) capture performance in mixed-matrix membranes (MMMs) by incorporating plasma-treated ceria (CeO2) nanoparticles into a polyurethane (PU)-based membrane. Functionalization of CeO2 by means of plasma aimed at improving interfacial interactions with both polymer matrix and CO2 gas molecules, with the consequent enhancement of CeO2 nanoparticles dispersion within the matrix and improvement of gas separation performance. Based on the results of the gas separation tests, the PU membrane containing 5 wt% plasma-treated CeO2 exhibited a CO2 permeability of 51.2 barrer and a CO2/N2 ideal selectivity of approximately 76.5, demonstrating a 26.1% increase in CO2/N2 ideal selectivity compared to the pristine PU membrane. However, a further increase in filler content to 10 wt% led to nanoparticle agglomeration, resulting in a decrease in selectivity due to the formation of non-selective pathways through the membrane. Molecular dynamics (MD) simulations corroborated these experimental findings, providing additional insights into the interaction mechanisms between the polymer matrix and the functionalized nanoparticles.

Nitrided copper-iron composite oxides derived from layered double hydroxides for enhanced carbon dioxide electroreduction to methane and formic acid

The reduction of carbon dioxide into valuable chemical products is a promising solution to address carbon balance and energy issues. Herein, amorphous nitrided copper-iron oxides are prepared by gas-phase nitriding of CuFe-layered double hydroxide precursors with urea as a nitrogen source. The obtained materials show high activity for CO2 electroreduction to methane and formic acid, achieving a total Faraday efficiency of 74.7% at −0.7 V vs. RHE and exhibiting continuous 10 h durability in the H-cell. The uniformly distributed Cu+ sites act as active sites by losing electrons to activate CO2. During the CO2 electroreduction, CO2 is converted to *COOH via proton-electron coupling; *COOH combines directly with a proton in solution to produce the HCOOH product; and the other part of *COOH undergoes a protonated dehydration process to form the *CHO intermediate, which dehydrates again to form CH4. This study provides a new approach for designing CO2 electroreduction catalysts.

Weak Bimetal Coupling-Assisted MN4 Catalyst for Enhanced Carbon Dioxide Reduction Reaction.

The design of multimetal catalysts holds immense significance for efficient CO2 capture and its conversion into economically valuable chemicals. Herein, heterobimetallic catalysts (MiMo)L were exploited for the CO2 reduction reactions (CO2RR) using relativistic density functional theory (DFT). The octadentate Pacman-like polypyrrolic ligand (H4L) accommodates two metal ions (Mo, W, Nd, and U) inside (Mi) and outside (Mo) its month, rendering a weak bimetal coupling-assisted MN4 catalytically active site. Adsorption reactions have access to energetically stable coordination modes of -OCO, -OOC, and -(OCO)2, where the donor atom(s) are marked in bold. Among all of the species, (UiMoo)L releases the most energy. Along CO2RR, it favors to produce CO. The high-efficiency CO2 reduction is attributed to the size matching of U with the ligand mouth and the effective manipulation of the electron density of both ligand and bimetals. The mechanism in which heterobimetals synergetically capture and reduce CO2 has been postulated. This establishes a reference in elaborating on the complicated heterogeneous catalysis.

Enhanced carbon dioxide sequestration and Cr detoxification: Direct carbonation of AOD slag with additives under ambient conditions

This study focused on AOD stainless steel slag (AOD slag), utilizing a direct wet carbonation process at ambient temperature and pressure to effectively capture CO2. We first evaluated the impact of four distinct additives such as NaCl (Simulated seawater concentration, 2.43 mol/L), NaOH (Simulated cold rolling wastewater, 0.01 mol/L), NH4Cl (0.5 mol/L) and CH3COONH4 (0.5 mol/L) on the carbonation of AOD slag, ultimately selecting CH3COONH4 for its superior performance. Within the “AOD slag + CH3COONH4” system, we conducted a comprehensive examination of carbonation parameters, including additive concentration, particle size, solid-liquid ratio, temperature and time, with a focus on optimizing carbonation efficiency (ηc) and carbonation capacity (Cc). Additionally, we provided an in-depth exploration of the simultaneous efficient carbonation and detoxification mechanisms pertaining to the stainless steel slag. Under standard conditions (293 K, 1 atm), the system achieved an impressive ηc of 80.02%, and Cc of 386.62 kg CO2/ton slag, higher than those previously reported. Furthermore, after five experimental cycles, the system maintained a 70% original efficiency, with Cr leaching concentrations significantly below the national standard requirement of 1.5 mg/L.

Can natural undisturbed revegetation restores soil organic carbon to levels under native climax vegetation under tropical semiarid climate?

AbstractLand‐use change has driven soil carbon stock losses in ecosystems worldwide. Implementing agricultural crops and exploiting forest resources trigger the breakdown of soil aggregates, thus exposing organic matter to microbial decomposition and enhancing carbon dioxide emissions, especially in biomes more susceptible to climate extremes as in the tropical semiarid regions. This study was based on the hypothesis that the undisturbed soil from the dry forest (Caatinga biome under natural revegetation in Brazilian semiarid) would have an improvement in the mass of macroaggregates and recover more than 50% of the soil C stock within 10 years. Thus, a field experiment was conducted to investigate soils from the Caatinga biome under native vegetation, “cowpea cropping” for over 30 years, and soil under natural revegetation for over 10 years, after conventional soil cultivation of maize and cowpea, to determine soil and soil‐aggregates carbon stocks and to estimate the recovery rate of these stocks. The proportional mass of aggregates of different sizes and the total stock of particulate organic carbon (POC) were also quantified. The results showed that soil under preserved native vegetation of dry forest Caatinga biome had higher total soil C stock (50.9 Mg ha−1) than that under cowpea cropping (23.2 Mg ha−1) and natural revegetation (45.1 Mg ha−1). The proportional mass of large macroaggregates was higher in soil under native vegetation for all depths. However, soil under cowpea cropping had lower C stocks in macroaggregates, and recovered roughly 63% of the original C stocks, while revegetation recovered 78% of the stock in 10 years. Although the conventional management system for cowpea monoculture aggravated losses in soil carbon stock by more than 50% of the original C stocks, dry forest under natural revegetation recovered 79% of this stock and almost 100% of POC stock in 10 years (~12 Mg ha−1). Furthermore, soil under undisturbed Caatinga dry forest achieved C stock levels equivalent to that of the global average range for semiarid tropical environments. The high recovery rate of C stock in forest soil under natural revegetation indicates the resilience potential of organisms responsible for structural protection of aggregates and the encapsulated soil organic matter content.

Enhancing carbon dioxide conversion in methane dry reforming multistep reactions through transformation of active species on catalyst surface

This study employed a novel one-pot method to encapsulate cerium species on the Ni–Al heterogeneous interface, aiming to achieve the capture and efficient utilization of greenhouse gas (CO2). Characterization results revealed that nickel species experienced various forms such as oxides and carbon-nickel compounds at the heterogeneous interface. The presence of cerium groups within the catalytic system induces the precipitation of nickel grain monomers on the support, decomposing the CH4–CO2 reforming process into a multistep reaction that breaks the thermodynamic barrier and kinetic limitation of the multicarbon coupling phenomenon, and greatly reduces the energy consumption of the reaction. Results showed that at a temperature of 800 °C and a Ni/Ce molar ratio of 0.2 in the catalyst, the activity was stable and the CO2 conversion reached 81.69 %, which was a 15.33 % enhancement compared to the base catalyst. Additionally, the mutual conversion of Ce3+/Ce4+ promoted the internal electron interaction process in the catalytic system, increasing the number of oxygen vacancies and reducing acidic sites, which facilitated reactant activation and carbon elimination. This work provides insights for the efficient utilization of greenhouse gases.

Coupling electrocatalytic redox-active sites in a three-dimensional bimetalloporphyrin-based covalent organic framework for enhancing carbon dioxide reduction and oxygen evolution

The 3D Co/Ni–TPNB-COF couples redox-active sites due to the charge redistribution between Ni(ii)-porphyrin and Co(ii)-porphyrin, and further simultaneously enhances its electrocatalytic carbon dioxide reduction and oxygen evolution performances.

Designing organic bridging linkers of metal–organic frameworks for enhanced carbon dioxide adsorption

The global rate of anthropogenic carbon dioxide (CO2) emission is rising, which urges the development of efficient carbon capture and storage (CCS) technologies.