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This work suggests an engineering methodology for catalytic 2D materials to achieve more efficient catalytic systems. Zinc gallate (ZnG), a Lewis acidic material with a thin 2D morphology, can easily form aggregates through layer–layer packing. Inner parts of ZnG aggregates would have difficulty in interacting with substrates. By coating hollow microporous organic polymer (H-MOP) supports with ZnG, the catalytic performance of ZnG can be enhanced due to facilitated contact of substrates with Zn species in shells. H-MOP@ZnG-2 with an optimal ZnG coating showed a much enhanced catalytic performance for the reductive carbon dioxide fixation with amines to formamides compared with ZnG. Various amines can be utilized in the reductive carbon dioxide fixation to formamides. In addition, H-MOP@ZnG-2 showed recyclability, maintaining its catalytic performance for five successive reactions. [ABSTRACT FROM AUTHOR]

Addressing the pressing and significant issue of reducing greenhouse gas emissions in our society, it is crucial to develop environmentally sustainable materials for carbon dioxide adsorption. In this work, we propose a straightforward and effective method, that is, in situ growth of covalent organic frameworks (COFs) on a polyacrylonitrile (PAN) nanofiber substrate using a reversible polycondensation termination technique and successfully prepare flexible COF nanofiber membranes (PANm@BTCA-TPB and APANm@BTCA-TPB COF) for highly efficient capture of CO2. The resulting composite of PAN@COFs comprises numerous nanofibers enveloped by well-defined porous COFs spheres (∼500 nm) that possess a stable crystal structure, abundant functional groups, and excellent stability. Additionally, these composites demonstrate promising capabilities in efficient carbon dioxide capture and have potential for the separation of carbon dioxide and methane. The proposed approach of in situ growth of COFs on nanofibrous membranes is not only applicable to other COF materials derived from Schiff bases but also provides an effective strategy for constructing flexible COF-based membranes that can meet the requirements of various application scenarios. [ABSTRACT FROM AUTHOR]

Carbon mitigation is one challenging issue that the world is facing. To tackle the deleterious impacts of CO2, processes emerged, including chemisorption from amine-based solvents and, more recently, physisorption in nanoporous solids. Physisorption in metal–organic frameworks (MOFs) is currently attracting considerable attention; however, the selection of the optimum sorbent is still challenging. While CO2 adsorption by MOFs has been widely explored from a thermodynamics standpoint, dynamical aspects remain less explored. CALF-20-(Zn) MOF was recently proposed as a promising alternative to the commercially used CO2 13X zeolite sorbents; however, an in-depth understanding of the nanoscopic mechanisms originating its good performance still has to be achieved. To do so, we deliver some insights into the adsorption and diffusion of CO2, H2O, and mixtures in CALF-20 through atomistic simulations. CALF-20-(Zn) was revealed to exhibit unconventional guest–host behaviors that give rise to abnormal guest thermodynamics and dynamics. The hydrophobic nature of the nanoporous solid leads to a low water adsorption enthalpy at low loading, followed by a continuous increase, driven by strong water hydrogen bonds, found to arrange as quasi 1D molecular wires in MOF nanoporosity, recalling water behavior in small-diameter carbon nanotubes. While no superdiffusion was found in the CALF-20-(Zn) as compared to carbon nanotubes, this behavior was shown to impact the guest-loading diffusion coefficient profile, with the presence of a minimum that correlates with the inflection point in the adsorption isotherm corresponding to the H2O wires formation. Interestingly, the diffusion coefficients of CO2 and H2O were also found to be of the same order of magnitude, with similar nonlinear profiles as a function of the guest loading. We further demonstrated that the diffusion coefficient for CO2 in the presence of water decreases with increasing water loading. [ABSTRACT FROM AUTHOR]

The CO2 adsorption performance of nanoporous graphene depends on the pore size and type of nitrogen-containing functional groups (N-groups) introduced into the graphene structure. In this study, N-groups, such as amine, cyanide, and pyridine, were introduced into graphene with three different pore sizes to assess their CO2 adsorption performance. In particular, N-containing graphene with a pore size of 8.26 Å exhibited a high adsorption performance, which was attributed to the formation of additional hydrogen bonds between CO2 molecules and hydrogen atoms on the inner edges of the pore. Additionally, Lewis acid–base interactions between the nitrogen atom of the N-groups and carbon atoms of CO2 also contributed to the enhanced adsorption. The CO2 adsorption performance decreased in the order cyanide > amine > pyridine in this structure. The adsorption performances of the N-groups were different because the cyanide group lacked steric hindrance, while the amine and pyridine groups were affected by steric hindrance owing to the hydrogen atoms on the inner edge. CO2 adsorption performance decreased with increasing pore size. Additionally, adsorption approached that of the N-groups introduced on the outer edge because of the decreased effect of pores on CO2 adsorption and the morphological similarities of hydrogen atoms between the inner and outer edges. The findings of this study underscore the importance of introducing N-groups into the inner edges of nanoporous graphene with appropriately sized pores for effective CO2 adsorption and offer valuable insights into the development of efficient systems for capturing and storing CO2 using nanoporous graphene. [ABSTRACT FROM AUTHOR]

Here, we demonstrate how temporally controlled pulses of current can control the physical properties of multiwalled carbon nanotubes (MWCNTs) synthesized from the electrolysis of air-captured carbon dioxide. Our findings demonstrate that a transient 1 min 7.5-fold rate increase of current or carbonate reduction during nucleation of MWCNTs leads to 2.5 times smaller average MWCNT diameters, a higher degree of graphitization in the walls, and an overall 10% lower energy consumption over the full growth duration. Conversely, when identical transient current pulses are applied after MWCNT nucleation in the middle of CNT growth, our findings indicate the deposition of noncatalytic onionlike carbons on the surface of the MWCNTs to form hybrid nanostructured materials, but no changes are observed to MWCNT diameters, energy consumption, or wall graphitization of the MWCNTs. A detailed study of this system by three-electrode cyclic voltammetry, imaging, X-ray diffraction (XRD), and Raman spectroscopy supports the mechanistic role of current pulses in nucleation to facilitate rapid catalyst reduction and minimize coarsening to sustain catalysts with high activity. This work demonstrates how temporally controlled electrochemical current density, and hence carbon flux, in molten carbonate electrolysis is a powerful tool to engineer the production of carbon nanostructures with tailored physical properties and a total energy consumption footprint. [ABSTRACT FROM AUTHOR]

Taking carbon dioxide (CO2) as a significant C1 source and converting it into value-added chemicals presents a promising strategy for addressing the energy and environmental issues arising from excessive anthropogenic emissions. Nevertheless, catalytic CO2 conversion, particularly under moderate conditions, remains a formidable challenge. Herein, a composite of Aza-COF-immobilized silver nanoparticles (Ag NPs), Ag/Aza-COF, was successfully fabricated by taking the nitrogen-rich COF, Aza-COF, as the porous carrier. Catalytic experiments revealed that with the presence of Ag/Aza-COF, 100% conversion of 2-methylbut-3-yn-2-ol to the corresponding alkylene cyclic carbonate was achieved after 9 h of reaction at ambient temperature and pressure using CH3CN as the solvent. Further studies revealed that the Ag/Aza-COF exhibits very high catalytic activity and effective recyclability in CO2 fixation with alkynyl alcohol and alkynyl amine at moderate conditions, surpassing the performance of surfactant-protected Ag NPs. X-ray photoelectron spectroscopy and Raman spectral analyses elucidated that strong interactions resulting from the coordination between the nitrogen atoms in the Aza-COF and Ag atoms in Ag NPs prevents their further aggregation and thereby preserving the high activity and recyclability of the composite. This finding demonstrates that the judicious selection of appropriate porous materials to restrict the aggregation of metal particles can yield efficient nanocatalyst composites. [ABSTRACT FROM AUTHOR]

The electrochemical fixation of carbon dioxide (CO2) into organic halides is one of the most prominent strategies for mitigating atmospheric CO2 emission, along with the difficulties associated with the toxic and carcinogenic halogenated compounds. Cu-based nanomaterials have been explored for numerous applications in nanotechnology, including electrocatalysis, organic catalytic transformations, and photocatalysis. In this work, we have designed and developed a Cu-embedded carbazole-derived porous organic polymer (Cu@Cz-POP) nanohybrid by utilizing the Friedel–Crafts alkylation approach and employing 1,4-dimethoxybenzene as the cross-linking agent comprising unique characteristic features of the extended π-conjugated system along with an active metal center with tunable electrochemical properties. The Brunauer–Emmett–Teller surface area of the conjugated Cz-POP is found to be 1060 m2 g–1. The X-ray photoelectron spectroscopy (XPS) study demonstrates the formation of CuO nanoparticles in the polymeric framework. X-ray absorption fine structure analysis (EXAFS) also reveals the existence of CuO with a smaller fraction of Cu in the polymeric framework, which is corroborated with the XPS analysis. The Cu@Cz-POP nanohybrid is fabricated by drop-casting over a Ni foam, showing promising electrocatalytic activity toward electrocarboxylation of benzyl bromide in 0.1 M TBA·BF4/CH3CN with saturated CO2 medium with a current density of 120 mA cm–2 delivering 65% yield of phenylacetic acid (PAA) as the primary product along with traces of benzyl 2-phenylacetate (BPA) and 1,2-diphenylethane (DPE), and the turnover frequency is found to be 8.556 × 10–7 s–1. Density functional theory calculations demonstrate that CuO is adsorbed more favorably at the N1 nitrogen atom of Cz-POP. An electron transfer from the N1 atom and the aromatic rings of Cz-POP to the CuO center is observed and confirmed by the overlap of alpha orbitals. [ABSTRACT FROM AUTHOR]

Sunlight irradiation significantly mediates plant litter's carbon dynamics and volatile carbon release in semi-arid and arid ecosystems. In this process, carbon loss is controlled by lignin, but the mechanisms of production of CO 2 and CH 4 during lignin photolysis are ambiguous. In this study, the photomineralization of plant litter and the lignocellulosic component collectively indicate that lignin is a major source of CO 2 and CH 4 emissions. Characterization and free radical analysis reveal that the production of CO 2 is due to the oxidation and ring-opening reaction of the coniferyl alcohol unit, with the subsequent decarboxylation of carboxylic acid as an oxidation product. This reaction involves o -quinone formation by the reactions between O 2 , superoxide radical (O 2 ·- ), and persistent free radicals (PFRs)-bearing lignin. Of this, O 2 ·- contributes to 43.2% of the photogenerated CO 2 , as a new pathway, derived from the electron transfer from PFRs to O 2 . Interestingly, photoinduced demethylation of the dimethoxybenzene-type compounds as the photolysis products of lignin results in a never-before-reported CH 4 formation chemical route independent of that of O 2 . This mechanistic insight into the role of lignin in volatile carbon production from the irradiative plant litter will contribute to a deeper understanding of carbon balance in water-limited ecosystems.

Although Africa contributes less than 5% to global greenhouse gas (GHG) emissions, its role in global climate action is pivotal. To date, 53 African countries have submitted their Nationally Determined Contributions (NDCs), and four have committed to a net-zero target. However, many of Africa's NDCs are vaguely expressed and without specific focus on explicit sectoral decarbonization targets. Furthermore, Africa's huge land-based carbon dioxide removal (CDR) potential remains unclear in the context of enabling net-zero (NZ) emissions within the continent. This study achieves two objectives: Under a NZ GHG emission trajectory in Africa, we uncover the implications of a targeted zero-emission electricity sector by 2030, on the energy landscape and other sustainability factors. This study also features the role of land-based biological removal methods─bioenergy carbon capture and storage (BECCS) and afforestation/reforestation (A/R)─in net zero actualization in Africa. Our results reveal a unified but disparate actualisation of the mid-century net zero emission goal across the continent, as all regions except North Africa achieve carbon neutrality. The industrial sector faces significant difficulties in transitioning and contributes substantially to positive emissions on the continent, with its share of total residual emissions reaching 49-64% by 2050. This difficulty persists even with targeted sectoral decarbonization of the electricity sector, although it is significantly reduced by the availability of BECCS as a CDR option. Under the zero-emission electricity pathway, emissions in buildings and transport sectors are reduced due to rapid electrification. A trade-off emerges in the net zero pathway concerning land allocation for negative emissions versus other land use activities. A key result shows that achieving a net zero target in Africa leads to a cumulative loss of $102 billion in fossil fuel infrastructure within the electricity sector by mid-century, which doubles when the zero-emission electricity goal is achieved.

We present methods and insights for the design of CO 2 capture, transport, and storage systems for industrial facilities with a case study focus on Louisiana. Our analytical framework includes (1) evaluating the scale and concentration of capturable CO 2 emissions at individual facilities for the purpose of estimating the cost of CO 2 capture retrofits that utilize various energy supply sources to meet parasitic demands; (2) screening to identify potential CO 2 storage sites and estimate their capacities, injectivities, and costs; and (3) designing cost-minimized trucking or pipeline infrastructure connecting CO 2 capture plants with storage sites, considering existing land uses, demographics, and a variety of social and environmental justice factors. Estimated levelized costs of capture at Louisiana's 190 industrial facilities range from below $50/tCO 2 to above $500/tCO 2 , depending on facility-specific features. We identified 98 potential storage sites with storage costs ranging from $8 to $17/tCO 2 . We find that in most situations, pipelines are the least-costly mode of CO 2 transport. When industrial facilities in a region share pipelines, aggregate pipeline mileage and average transport costs are dramatically lower than without sharing. Shared pipeline networks designed to avoid disadvantaged communities require right-of-way areas compared to those for networks that transect such communities, but result in 25% higher average per-tonne transport cost.

China's advancements in addressing air pollution and reducing CO 2 emissions offer valuable lessons for collaborative strategies to achieve diverse environmental objectives. Previous studies have assessed the mutual benefits of climate policies and air pollution control measures on one another, lacking an integrated assessment of the benefits of synergistic control attributed to refined measures. Here, we comprehensively used coupled emission inventory and response models to evaluate the integrated benefits and synergy degrees of various measures in reducing air pollutants and CO 2 in China during 2013-2021. Results indicated that the implemented measures yielded integrated benefits value at 6.7 (2.4-12.6) trillion Chinese Yuan. The top five contributors, accounting for 55%, included promoting non-thermal power, implementing end-of-pipe control technologies in power plants and iron and steel industry, replacing residential scattered coal, and saving building energy. Measures demonstrating high synergies and integrated benefits per unit of reduction (e.g., green traffic promotion) yielded low benefits mainly due to their low application, which are expected to gain greater implementation and prioritization in the future. Our findings provide insights into the effectiveness and limitations of strategies aimed at joint control. By ranking these measures based on their benefits and synergy, we offer valuable guidance for policy development in China and other nations with similar needs.

Respiratory particles produced during vocalized and nonvocalized activities such as breathing, speaking, and singing serve as a major route for respiratory pathogen transmission. This work reports concomitant measurements of exhaled carbon dioxide volume (VCO 2 ) and minute ventilation (VE), along with exhaled respiratory particles during breathing, exercising, speaking, and singing. Exhaled CO 2 and VE measured across healthy adult participants follow a similar trend to particle number concentration during the nonvocalized exercise activities (breathing at rest, vigorous exercise, and very vigorous exercise). Exhaled CO 2 is strongly correlated with mean particle number ( r = 0.81) and mass ( r = 0.84) emission rates for the nonvocalized exercise activities. However, exhaled CO 2 is poorly correlated with mean particle number ( r = 0.34) and mass ( r = 0.12) emission rates during activities requiring vocalization. These results demonstrate that in most real-world environments vocalization loudness is the main factor controlling respiratory particle emission and exhaled CO 2 is a poor surrogate measure for estimating particle emission during vocalization. Although measurements of indoor CO 2 concentrations provide valuable information about room ventilation, such measurements are poor indicators of respiratory particle concentrations and may significantly underestimate respiratory particle concentrations and disease transmission risk.

To explore whether oxidative stress caused by 100% CO 2 is an inhibitory mechanism against Shewanella putrefaciens , the oxidative stress reaction, antioxidant activity, and damage to the cell membrane, protein, and DNA of CO 2 -incubated S. putrefaciens at 4 °C were evaluated. Research demonstrated that CO 2 caused more severe reactive oxygen species (ROS) accumulation. Simultaneously, weaker • OH/H 2 O 2 / O 2 •- -scavenging activity and decreased T-VOC and GSH content were also observed. The activities of antioxidant enzymes (SOD, POD, CAT, and GPX) continuously declined, which might be attributed to the CO 2 -mediated decrease in the pH value. Correspondingly, the cell membrane was damaged with hyperpolarization, increased permeability, and more severe lipid peroxidation. The expression of total and membrane protein decreased, and the synthesis and activity of extracellular protease were inhibited. DNA was also subjected to oxidative damage and expressed at a lower level. All results collaboratively confirmed that ROS excitation and inhibition of antioxidant activity were important inhibition mechanisms of CO 2 on S. putrefaciens .

This study addresses the fundamental processes that drive the photomineralization of dissolved organic matter (DOM) to carbon dioxide (CO 2 ), deconvoluting the role of direct and sensitized photolysis. Here, a suite of DOM isolates and model compounds were exposed to simulated sunlight in the presence of various physical and chemical quenchers to assess the magnitude, rate, and extent of direct and sensitized photomineralization to CO 2 . Results suggest that CO 2 formation occurs in a biphasic kinetic system, with fast production occurring within the first 3 h, followed by slower production thereafter. Notably, phenol model chromophores were the highest CO 2 formers and, when conjugated with carboxylic functional groups, exhibited a high efficiency for CO 2 formation relative to absorbed light. Simple polycarboxylated aromatic compounds included in this study were shown to be resistant to photomineralization. Quencher results suggest that direct photolysis and excited triplet state sensitization may be largely responsible for CO 2 photoproduction in DOM, while singlet oxygen and hydroxyl radical sensitization may play a limited role. After 3 h of irradiation, the CO 2 formation rate significantly decreased, and the role of sensitized reactions in CO 2 formation increased. Together, the results from this study advance the understanding of the fundamental reactions driving DOM photomineralization to CO 2 , which is an important part of the global carbon cycle.

A model was developed to conduct techno-economic analysis (TEA) and life cycle assessment (LCA) for reactive carbon capture (RCC) and conversion of carbon dioxide (CO 2 ) to methanol. This RCC process is compared to a baseline commercialized flue gas CO 2 hydrogenation process. An ASPEN model was combined with existing TEA and LCA models into a larger TEA/LCA framework in Python. From preliminary experimental data, the model found a levelized cost of $0.79/kg methanol for the baseline process and $0.99/kg for the RCC process. The cradle-to-gate carbon intensity of the baseline process was 0.50 kg-CO 2 e/kg-methanol, compared to 0.55 kg-CO 2 e/kg-methanol for the RCC process. However, water consumption for RCC (10.21 kg-H 2 O/kg-methanol) is greatly reduced compared to the baseline (12.89 kg-H 2 O/kg-methanol). Future improvements in hydrogen electrolysis costs will benefit the RCC. A target H 2 /methanol mass ratio of 0.26 was developed for RCC laboratory experiments to reduce methanol cost below the baseline. If a ratio of 0.24 can be achieved, a levelized cost of $0.76/kg methanol is projected, with a carbon intensity of 0.42 kg-CO 2 e/kg-methanol.

Reducing air pollutants and CO 2 emissions from energy utilization is crucial for achieving the dual objectives of clean air and carbon neutrality in China. Thus, an optimized health-oriented strategy is urgently needed. Herein, by coupling a CO 2 and air pollutants emission inventory with response surface models for PM 2.5 -associated mortality, we shed light on the effectiveness of protecting human health and co-CO 2 benefit from reducing fuel-related emissions and generate a health-oriented strategy for the Yangtze River Delta (YRD). Results reveal that oil consumption is the primary contributor to fuel-related PM 2.5 pollution and premature deaths in the YRD. Significantly, curtailing fuel consumption in transportation is the most effective measure to alleviate the fuel-related PM 2.5 health impact, which also has the greatest cobenefits for CO 2 emission reduction on a regional scale. Reducing fuel consumption will achieve substantial health improvements especially in eastern YRD, with nonroad vehicle emission reductions being particularly impactful for health protection, while on-road vehicles present the greatest potential for CO 2 reductions. Scenario analysis confirms the importance of mitigating oil consumption in the transportation sector in addressing PM 2.5 pollution and climate change.

Enhanced rock weathering (EW) is an emerging atmospheric carbon dioxide removal (CDR) strategy being scaled up by the commercial sector. Here, we combine multiomics analyses of belowground microbiomes, laboratory-based dissolution studies, and incubation investigations of soils from field EW trials to build the case for manipulating iron chelators in soil to increase EW efficiency and lower costs. Microbial siderophores are high-affinity, highly selective iron (Fe) chelators that enhance the uptake of Fe from soil minerals into cells. Applying RNA-seq metatranscriptomics and shotgun metagenomics to soils and basalt grains from EW field trials revealed that microbial communities on basalt grains significantly upregulate siderophore biosynthesis gene expression relative to microbiomes of the surrounding soil. Separate in vitro laboratory incubation studies showed that micromolar solutions of siderophores and high-affinity synthetic chelator (ethylenediamine- N , N '-bis-2-hydroxyphenylacetic acid, EDDHA) accelerate EW to increase CDR rates. Building on these findings, we develop a potential biotechnology pathway for accelerating EW using the synthetic Fe-chelator EDDHA that is commonly used in agronomy to alleviate the Fe deficiency in high pH soils. Incubation of EW field trial soils with potassium-EDDHA solutions increased potential CDR rates by up to 2.5-fold by promoting the abiotic dissolution of basalt and upregulating microbial siderophore production to further accelerate weathering reactions. Moreover, EDDHA may alleviate potential Fe limitation of crops due to rising soil pH with EW over time. Initial cost-benefit analysis suggests potassium-EDDHA could lower EW-CDR costs by up to U.S. $77 t CO 2 ha -1 to improve EW's competitiveness relative to other CDR strategies.

The use of renewable electricity to catalyze carbon dioxide reduction is a promising method for CO2 utilization. However, the lack of highly efficient catalysts for CO2 reduction seriously limits its industrial applications. As a prototype, an ultrathin indium sulfide nanosheet (In2S3 NS) was synthesized and fabricated in situ on reduced graphene oxide (RGO) to obtain an In2S3–RGO composite. Induced by the two-dimensional (2D) structure of graphene oxide, the thickness of the In2S3 NSs was reduced from 30.2 to 3.9 nm. Simultaneously, the (440) plane of In2S3 NSs was preferentially grown parallel to the graphene plane, which was proven to possess a higher selectivity in catalyzing CO2 electroreduction to formate than the (111) and (311) planes by density functional theory calculations. Attributed to the 2D structure and full exposure of the (440) planes, a large electrochemically active surface area and high density of optimum active sites were both realized on the In2S3–RGO hybrids, leading to 91% faradaic efficiency of formate at −1.2 V versus The reversible hydrogen electrode in 0.1 M KHCO3 is 3.5 times that of bulk In2S3 (26%). Our work provides an effective way to prepare 2D transition metal catalysts with controllable crystal face exposure for specific reactions. [ABSTRACT FROM AUTHOR]

Health and safety considerations of indoor occupants in enclosed spaces are crucial for building management which involves the strict control and monitoring of carbon dioxide levels to maintain acceptable air quality standards. For this study, we developed a wireless, noninvasive, and portable platform for the continuous monitoring of carbon dioxide concentration in enclosed environments, i.e., academic rooms. The system aimed to monitor and detect carbon dioxide using novel low-cost metal oxide-based chemoresistive sensors, achieving sensing performance comparable to those of commercially available detectors based on optical working principle, e.g., nondispersive infrared sensors. In particular, a predictive study of carbon dioxide levels was performed by exploiting random forest and curve fitting algorithms on chemoresistive sensor data collected in an academic room, then comparing the results with lab-based measurements. The performance of the models was evaluated with real environment conditions during 7 weeks. The field measurements were conducted to validate and support the development of the system for real-time monitoring and alerting in the presence of relevant concentrations (above 1,000 ppm). Therefore, the study highlighted that the curve fitting model obtained was able to recognize with an F -score of 0.77 the presence of poor air quality, defined as concentration above 1,000 ppm of carbon dioxide as reported by the Occupational Safety and Health Administration.1 -score of 0.77 the presence of poor air quality, defined as concentration above 1,000 ppm of carbon dioxide as reported by the Occupational Safety and Health Administration.

Direct air capture with CO 2 storage (DACCS) is among the carbon dioxide removal (CDR) options, with the largest gap between current deployment and needed upscaling. Here, we present a geospatial analysis of the techno-economic performance of large-scale DACCS deployment in Europe using two performance indicators: CDR costs and potential. Different low-temperature heat DACCS configurations are considered, i.e., coupled to the national power grid, using waste heat and powered by curtailed electricity. Our findings reveal that the CDR potential and costs of DACCS systems are mainly driven by (i) the availability of energy sources, (ii) the location-specific climate conditions, (iii) the price and GHG intensity of electricity, and (iv) the CO 2 transport distance to the nearest CO 2 storage location. The results further highlight the following key findings: (i) the limited availability of waste heat, with only Sweden potentially compensating nearly 10% of national emissions through CDR, and (ii) the need for considering transport and storage of CO 2 in a comprehensive techno-economic assessment of DACCS. Finally, our geospatial analysis reveals substantial differences between regions due to location-specific conditions, i.e., useful information elements and consistent insights that will contribute to assessment and feasibility studies toward effective DACCS implementation.

Massive soil erosion occurs in the world's Mollisol regions due to land use change and climate warming. The migration of Mollisol organic matter to river systems and subsequent changes in carbon biogeochemical flow and greenhouse gas fluxes are of global importance but little understood. By employing comparative mesocosm experiments simulating varying erosion intensity in Mollisol regions of northeastern China, this research highlights that erosion-driven export and biomineralization of terrestrial organic matter facilitates CO 2 and CH 4 emission from receiving rivers. Stronger Mollisol erosion, as represented by a higher soil-to-water ratio in suspensions, increased CO 2 efflux, particularly for the paddy Mollisols. This is mechanistically attributable to increased bioavailability of soluble organic carbon in river water that is sourced back to destabilized organic matter, especially from the cultivated Mollisols. Concurrent changes in microbial community structure have enhanced both aerobic and anaerobic processes as reflected by the coemission of CO 2 and CH 4 . Higher greenhouse gas effluxes from paddy Mollisol suspensions suggest that agricultural land use by supplying more nitrogen-containing, higher-free-energy organic components may have enhanced microbial respiration. These new findings highlight that Mollisol erosion is a hidden significant contributor to greenhouse gas emissions from river water, given that the world's four major Mollisol belts are all experiencing intensive cultivation.

The aviation industry is responsible for over 2% of global CO 2 emissions. Synthetic jet fuels generated from biogenic feedstocks could help reduce life cycle greenhouse gas (GHG) emissions compared to petroleum-based fuels. This study assesses three processes for producing synthetic jet fuel via the synthesis of methanol using water and atmospheric CO 2 or biomass. A life cycle assessment and cost analysis are conducted to determine GHG emissions, energy demand, land occupation, water depletion, and the cost of producing synthetic jet fuel in Switzerland. The results reveal that the pathway that directly hydrogenates CO 2 to methanol exhibits the largest reductions in terms of GHG emission (almost 50%) compared to conventional jet fuel and the lowest production cost (7.86 EUR kg JF -1 ); however, its production cost is currently around 7 times higher than the petroleum-based counterpart. Electrical energy was found to be crucial in capturing CO 2 and converting water into hydrogen, with the sourcing and processing of the feedstocks contributing to 79% of the electric energy demand. Furthermore, significant variations in synthetic jet fuel cost and GHG emissions were shown when the electricity source varies, such as utilizing grid electricity pertaining to different countries with distinct electricity mixes. Thus, upscaling synthetic jet fuels requires energy-efficient supply chains, sufficient feedstock, large amounts of additional (very) low-carbon energy capacity, suitable climate policy, and comprehensive environmental analyses.

Artificial channels, common features of inland waters, have been suggested as significant contributors to methane (CH 4 ) and carbon dioxide (CO 2 ) dynamics and emissions; however, the magnitude and drivers of their CH 4 and CO 2 emissions (diffusive and ebullitive) remain unclear. They are characterized by reduced flow compared to the donor river, which results in suspended organic matter (OM) accumulation. We propose that in such systems hydrological controls will be reduced and OM accumulation will control emissions by promoting methane production and outgassing. Here, we monitored summertime CH 4 and CO 2 concentrations and emissions on six newly constructed river-fed artificial channels, from bare riparian mineral soil to lotic channels, under two distinct flow regimes. Chamber-based fluxes were complemented with hydrology, total fluxes (diffusion + ebullition), and suspended OM accumulation assessments. During the first 6 weeks after the flooding, inflowing riverine water dominated the emissions over in-channel contributions. Afterwards, a substantial accumulation of riverine suspended OM (≥50% of the channel's volume) boosted in-channel methane production and led to widespread ebullition 10× higher than diffusive fluxes, regardless of the flow regime. Our finding suggests ebullition as a dominant pathway in these anthropogenic systems, and thus, their impact on regional methane emissions might have been largely underestimated.

Electromicrobial production (EMP), where electrochemically generated substrates (e.g., H 2 ) are used as energy sources for microbial processes, has garnered significant interest as a method of producing fuels and other value-added chemicals from CO 2 . Combining these processes with direct air capture (DAC) has the potential to enable a truly circular carbon economy. Here, we analyze the economics of a hypothetical system that combines adsorbent-based DAC with EMP to produce n -butanol, a potential replacement for fossil fuels. First-principles-based modeling is used to predict the performance of the DAC and bioprocess components. A process model is then developed to map material and energy flows, and a techno-economic assessment is performed to determine the minimum fuel selling price. Beyond assessing a specific set of conditions, this analytical framework provides a tool to reveal potential pathways toward the economic viability of this process. We show that an EMP system utilizing an engineered knallgas bacterium can achieve butanol production costs of <$6/gal ($1.58/L) if a set of optimistic assumptions can be realized.

Peatlands are recognized as crucial greenhouse gas sources and sinks and have been extensively studied. Their emissions exhibit high spatial heterogeneity when measured on site using flux chambers. However, the mechanism by which this spatial variability behaves on a very fine scale remains unclear. This study investigates the fine-scale spatial variability of greenhouse gas emissions from a subantarctic Sphagnum peatland bog. Using a recently developed skirt chamber, methane emissions and ecosystem respiration (as carbon dioxide) were measured at a submeter scale resolution, at five specific 3 × 3 m plots, which were examined across the site throughout a single campaign during the Austral summer season. The results indicated that methane fluxes were significantly less homogeneously distributed compared with ecosystem respiration. Furthermore, we established that the spatial variation scale, i.e., the minimum spatial domain over which notable changes in methane emissions and ecosystem respiration occur, was <0.56 m 2 . Factors such as ground height relative to the water table and vegetation coverage were analyzed. It was observed that Tetroncium magellanicum exhibited a notable correlation with higher methane fluxes, likely because of the aerenchymatous nature of this species, facilitating gas transport. This study advances understanding of gas exchange patterns in peatlands but also emphasizes the need for further efforts for characterizing spatial dynamics at a very fine scale for precise greenhouse gas budget assessment.

Despite decades of research and management efforts, eutrophication remains a persistent threat to inland waters. As nutrient pollution intensifies in the coming decades, the implications for aquatic greenhouse gas (GHG) emissions are poorly defined, particularly the responses of individual GHGs: carbon dioxide (CO 2 ), methane (CH 4 ), and nitrous oxide (N 2 O). The biogeochemical controls of each gas can differ, making it difficult to predict the overall effect of nutrient pollution on the net radiative forcing of aquatic ecosystems. Here, we induced eutrophication of small nitrogen (N)-limited agricultural reservoirs and measured changes in diffusive GHG emissions within a before-after-control-impact (BACI) study design during June to September 2021. Each gas exhibited a unique response to 300% increases in primary production, with a shift from an overall CO 2 source to a sink, a modest increase in N 2 O flux, and, unexpectedly, no significant change in CH 4 emissions. The lack of net directional change in CO 2 -equivalent GHG emissions in fertilized reservoirs during the summer contrasts findings from empirical studies of eutrophic lakes. Our findings illustrate the difficulty in extrapolating among different sized ecosystems and suggest that forecast 2-fold increases in agricultural N fertilization by 2050 may not result in consistently elevated GHG emissions during summer, at least from small reservoirs in continental grassland regions.

Cities represent a significant and growing portion of global carbon dioxide (CO 2 ) emissions. Quantifying urban emissions and trends over time is needed to evaluate the efficacy of policy targeting emission reductions as well as to understand more fundamental questions about the urban biosphere. A number of approaches have been proposed to measure, report, and verify (MRV) changes in urban CO 2 emissions. Here we show that a modest capital cost, spatially dense network of sensors, the Berkeley Environmental Air Quality and CO 2 Network (BEACO 2 N), in combination with Bayesian inversions, result in a synthesis of measured CO 2 concentrations and meteorology to yield an improved estimate of CO 2 emissions and provide a cost-effective and accurate assessment of CO 2 emissions trends over time. We describe nearly 5 years of continuous CO 2 observations (2018-2022) in a midsized urban region (the San Francisco Bay Area). These observed concentrations constrain a Bayesian inversion that indicates the interannual trend in urban CO 2 emissions in the region has been a modest decrease at a rate of 1.8 ± 0.3%/year. We interpret this decrease as primarily due to passenger vehicle electrification, reducing on-road emissions at a rate of 2.6 ± 0.7%/year.

Biomass waste-derived engineered biochar for CO 2 capture presents a viable route for climate change mitigation and sustainable waste management. However, optimally synthesizing them for enhanced performance is time- and labor-intensive. To address these issues, we devise an active learning strategy to guide and expedite their synthesis with improved CO 2 adsorption capacities. Our framework learns from experimental data and recommends optimal synthesis parameters, aiming to maximize the narrow micropore volume of engineered biochar, which exhibits a linear correlation with its CO 2 adsorption capacity. We experimentally validate the active learning predictions, and these data are iteratively leveraged for subsequent model training and revalidation, thereby establishing a closed loop. Over three active learning cycles, we synthesized 16 property-specific engineered biochar samples such that the CO 2 uptake nearly doubled by the final round. We demonstrate a data-driven workflow to accelerate the development of high-performance engineered biochar with enhanced CO 2 uptake and broader applications as a functional material.

In the present work, three novel halogen-appended cadmium(II) metal-organic frameworks [Cd 2 (L1) 2 (4,4'-Bipy) 2 ] n ·4 n (DMF) ( 1 ), [Cd 2 (L2) 2 (4,4'-Bipy) 2 ] n ·3 n (DMF) ( 2 ), and [Cd(L3)(4,4'-Bipy)] n ·2 n (DMF) ( 3 ) [where L1 = 5-{(4-bromobenzyl)amino}isophthalate; L2 = 5-{(4-chlorobenzyl)amino}isophthalate; L3 = 5-{(4-fluorobenzyl)amino}isophthalate; 4,4'-Bipy = 4,4'-bipyridine; and DMF = N , N '-dimethylformamide] have been synthesized under solvothermal conditions and characterized by various analytical techniques. The single-crystal X-ray diffraction analysis demonstrated that all the MOFs feature a similar type of three-dimensional structure having a binuclear [Cd 2 (COO) 4 (N) 4 ] secondary building block unit. Moreover, MOFs 1 and 2 contain one-dimensional channels along the b -axis, whereas MOF 3 possesses a 1D channel along the a -axis. In these MOFs, the pores are decorated with multifunctional groups, i.e., halogen and amine. The gas adsorption analysis of these MOFs demonstrate that they display high uptake of CO 2 (up to 5.34 mmol/g) over N 2 and CH 4 . The isosteric heat of adsorption ( Q st ) value for CO 2 at zero loadings is in the range of 18-26 kJ mol -1 . In order to understand the mechanism behind the better adsorption of CO 2 by our MOFs, we have also performed configurational bias Monte Carlo simulation studies, which confirm that the interaction between our MOFs and CO 2 is stronger compared to those with N 2 and CH 4 and the halogen atom, the Cd(II) metal center, and the carboxylate group from the MOFs are observed, respectively, which may be a reason for the higher carbon dioxide adsorption. Ideal adsorbed solution theory (IAST) calculations of MOF 2 and the halogen atom, the Cd(II) metal center, and the carboxylate group from the MOFs are observed, respectively, which may be a reason for the higher carbon dioxide adsorption. Ideal adsorbed solution theory (IAST) calculations of MOF 1 demonstrate that the obtained selectivity values for CO 2 /CH 4 (50:50) and CO 2 /N 2 (15:85) are ca. 28 and 193 at 273 K, respectively. However, upon increasing the temperature to 298 K, the selectivity value ( S = 34) decreases significantly for the CO 2 /N 2 mixture. We have also calculated the breakthrough analysis curves for all the MOFs using mixtures of CO 2 /CH 4 (50:50) and CO 2 /N 2 (50:50 and 15:85) at different entering gas velocities and observed larger retention times for CO 2 in comparison with other gases, which also signifies the stronger interaction between our MOFs and CO 2 . Moreover, due to the presence of Lewis acidic metal centers, these MOFs act as heterogeneous catalysts for the CO 2 fixation reactions with different epoxides in the presence of tetrabutyl ammonium bromide (TBAB), for conversion into industrially valuable cyclic carbonates. These MOFs exhibit a high conversion (96-99%) of epichlorohydrin (ECH) to the corresponding cyclic carbonate 4-(chloromethyl)-1,3-dioxolan-2-one after 12 h of reaction time at 1 bar of CO 2 pressure, at 65 °C. The MOFs can be reused up to four cycles without compromising their structural integrity as well as without losing their activity significantly.

The Paris Agreement and the Minamata Convention on Mercury are two of the most important environmental conventions being implemented concurrently, with a focus on reducing carbon and mercury emissions, respectively. The relation between mercury and carbon influences the interactions and outcomes of these two conventions. This perspective investigates the link between mercury and CO 2 , assessing the consequences and exploring the policy implications of this link. We present scientific evidence showing that mercury and CO 2 levels are negatively correlated under natural conditions. As a result of this negative correlation, the CO 2 level under the current mercury reduction scenario is predicted to be 2.4-10.1 ppm higher than the no action scenario by 2050, equivalent to 1.0-4.8 years of CO 2 increase due to human activity. The underlying causations of this negative correlation are complex and need further research. Economic analysis indicates that there is a trade-off between the benefits and costs of mercury reduction actions. As reducing mercury emission may inadvertently undermine efforts to achieve climate goals, we advocate for devising a coordinated implementation strategy for carbon and mercury conventions to maximize synergies and reduce trade-offs.

Agrichemical losses are a severe threat to the ecological environment. Additionally, some agrichemical compounds contain abundant salt, which increases the instability of formulations, leading to a lower agrichemical utilization and soil hardening. Fortunately, the biological amphiphilic emulsifier sodium deoxycholate alleviates these problems by forming stable Janus core-shell emulsions through salinity-driven interfacial self-assembly. According to the interfacial behavior, dilational rheology, and molecular dynamics simulations, Janus-emulsion molecules are more closely arranged than traditional-emulsion molecules and generate an oil-water interfacial film that transforms into a gel film. In addition, at the same spray volume, the deposition area of the Janus emulsion increased by 37.70% compared with that of the traditional emulsion. Owing to the topology effect and deformation, the Janus emulsion adheres to rice micropapillae, achieving better flush resistance. Meanwhile, based on response of the Janus emulsion to stimulation by carbon dioxide (CO 2 ), the emulsion lost to the soil can form a rigid shell for inhibiting the release of pesticides and metal ions from harming the soil. The pyraclostrobin release rate decreased by 50.89% at 4 h after the Janus emulsion was exposed to CO 2 . The Chao1 index of the Janus emulsion was increased by 12.49% as compared to coconut oil delivery in soil microbial community. The Janus emulsion ingested by harmful organisms can be effectively absorbed in the intestine to achieve better control effects. This study provides a simple and effective strategy, which turns waste into treasure, by combining metal ions in agrichemicals with natural amphiphilic molecules to prepare stable emulsions for enhancing agrichemical rainfastness and weakening environmental risk.

Recent investments in "clean" hydrogen as an alternative to fossil fuels are driven by anticipated climate benefits. However, most climate benefit calculations do not adequately account for all climate warming emissions and impacts over time. This study reanalyzes a previously published life cycle assessment as an illustrative example to show how the climate impacts of hydrogen deployment can be far greater than expected when including the warming effects of hydrogen emissions, observed methane emission intensities, and near-term time scales; this reduces the perceived climate benefits upon replacement of fossil fuel technologies. For example, for blue (natural gas with carbon capture) hydrogen pathways, the inclusion of upper-end hydrogen and methane emissions can yield an increase in warming in the near term by up to 50%, whereas lower-end emissions decrease warming impacts by at least 70%. For green (renewable-based electrolysis) hydrogen pathways, upper-end hydrogen emissions can reduce climate benefits in the near term by up to 25%. We also consider renewable electricity availability for green hydrogen and show that if it is not additional to what is needed to decarbonize the electric grid, there may be more warming than that seen with fossil fuel alternatives over all time scales. Assessments of hydrogen's climate impacts should include the aforementioned factors if hydrogen is to be an effective decarbonization tool.

Cobalt-doped ZnO (CZO) thin films were deposited on glass substrates at room temperature by radio frequency (RF) magnetron sputtering of a single target prepared with ZnO and Co 3 O 4 powders. Changes in the crystallinity, morphology, optical properties, and chemical composition of the CZO thin films were investigated at various sputtering powers of 45, 60, and 75 W. All samples presented a hexagonal wurtzite-type structure with a preferential c -axis at the (002) plane, along with a distinct change in the strain values through X-ray diffraction patterns. Scanning electron and atomic force microscopy revealed uniform and dense deposition of nanorod CZO samples with a high surface roughness (RMS). The Hall mobility and carrier concentration increased with the introduction of Co + ions into the ZnO matrix, as seen from the Hall effect study. The gradual increase of the power applied on the target source significantly affected the morphology of the CZO thin film, which is reflected in the CO 2 -sensing performance. The best gas response to CO 2 was recorded for CZO-60 W with a response of 1.45 for 500 ppm CO 2 , and the response/recovery times were 72 and 35 s, respectively. The distinguishing feature of the CZO sensor is its ability to effectively and rapidly detect the CO 2 target gas at room temperature (∼27 °C, RT).

Transforming hazardous species into active sites by ingenious material design was a promising and positive strategy to improve catalytic reactions in industrial applications. To synergistically address the issue of sluggish CO 2 desorption kinetics and SO 2 -poisoning solvent of amine scrubbing, we propose a novel method for preparing a high-performance core-shell C@Mn 3 O 4 catalyst for heterogeneous sulfur migration and in situ reconstruction to active -SO 3 H groups, and thus inducing an enhanced proton-coupled electron transfer (PCET) effect for CO 2 desorption. As anticipated, the rate of CO 2 desorption increases significantly, by 255%, when SO 2 is introduced. On a bench scale, dynamic CO 2 capture experiments reveal that the catalytic regeneration heat duty of SO 2 -poisoned solvent experiences a 32% reduction compared to the blank case, while the durability of the catalyst is confirmed. Thus, the enhanced PCET of C@Mn 3 O 4 , facilitated by sulfur migration and simultaneous transformation, effectively improves the SO 2 resistance and regeneration efficiency of amine solvents, providing a novel route for pursuing cost-effective CO 2 capture with an amine solvent.

Physical hydrogels of natural polysaccharides are considered as ideal candidates for wound dressing due to their natural biological activity and no harmful cross-linking agents. However, it remains a challenge to fabricate such hydrogel dressings in a facile and low-cost way. Herein, we reported an easy and cost-effective method to construct CO 2 -mediated alkali-neutralization Curdlan (CR) hydrogels without using an external cross-linking agent. Two types of hydrogels (denoted as CR-NaOH and CR-Na 3 PO 4 , respectively) were fabricated by dissolving CR powders in a NaOH or Na 3 PO 4 aqueous solution, followed by keeping the CR alkaline solutions in air. The obtained pure CR hydrogels possessed a tunable porous structure with walls containing different forms of nanofibrils. These hydrogels exhibited much higher gel strength by comparison with the gels prepared by conventional heating treatment. They were flexible, stretchable, twistable, and conformable to arbitrarily curved skins. Moreover, they exhibited ideal swellability, proper degradability, and water vapor transmission rate, and their physicochemical properties were closely related to CR concentration in the alkaline solution. These two hydrogels also supported the growth of L929 cells. Importantly, studies on wound healing revealed that both 3CR-NaOH and 3CR-Na 3 PO 4 hydrogels were capable of accelerating the wound healing process through recruiting more macrophages/fibroblasts, inducing more collagen deposition and neovascularization (α-SMA and CD31) without carrying any exogenous bioactive components. In conclusion, the present work not only reported promising materials for application in wound therapy but also offered a facile and safe manufacturing procedure for generating pure CR physical hydrogels with better performance.

Noncrystalline zeolitic imidazolate frameworks (ZIFs) tethered with ionic liquids (ILs) were successfully employed as catalysts for mild CO 2 conversion into cyclic carbonates for the first time. Notably, noncrystalline ZIFs exhibit outstanding catalytic performance in terms of activity, stability, and substrate suitability. Z3 was obtained through the simultaneous incorporation of a boronic acid group and ILs into its ZIF framework and exhibited a superior catalytic activity. A reaction mechanism for the propylene oxide-CO 2 cycloaddition has been proposed, which integrates experimental findings with density functional theory calculations. The results indicate that zinc, ILs, and boronic acid play crucial roles in achieving high activity. Zinc and ILs are identified as key contributors to epoxide activation and ring opening, while boronic acid plays a crucial role in stabilizing the turnover frequency-determining transition states. The simplicity of this ZIF synthesis approach, combined with the high activity, stability, and versatility of the products, facilitates practical and efficient conversion of CO 2 and epoxides into cyclic carbonates.

Despite the large carbon footprint of livestock production, animal protein consumption has grown over the past several decades, necessitating new approaches to sustainable animal protein production. In this techno-economic analysis, single cell protein (SCP) produced via gas fermentation of carbon dioxide, oxygen, and hydrogen is studied as an animal feed source to replace fishmeal or soybean meal. Using wind-powered water electrolysis to produce hydrogen and oxygen with carbon dioxide captured from corn ethanol, the minimum selling price (MSP) of SCP is determined to be $2070 per metric ton. An emissions comparison between SCP, fishmeal, and soybean meal shows that SCP has a carbon intensity as low as 0.73 kg CO 2 -equiv/kg protein, while fishmeal and soybean meal have an average carbon intensity of 2.72 kg CO 2 -equiv/kg protein and 0.85 kg CO 2 -equiv/kg protein, respectively. Moreover, SCP production would occupy 0.4% of the land per ton of protein produced compared to soybean meal and would disturb less than 0.1% of the marine ecosystem currently disturbed by fishmeal harvesting practices. These results show promise for the future economic viability of SCP as a protein source in animal feed and indicate significant environmental benefits compared to other animal feed protein sources.

Cavity-enhanced direct frequency comb spectroscopy (CE-DFCS) is widely used as a highly sensitive gas sensing technology in various gas detection fields. For the on-axis coupling incidence scheme, the detection accuracy and stability are seriously affected by the cavity-mode noise, and therefore, stable operation inevitably requires external electronic mode-locking and sweeping devices, substantially increasing system complexity. To address this issue, we propose off-axis cavity-enhanced optical frequency comb spectroscopy from both theoretical and experimental aspects, which is applied to the detection of single- and dual-gas of carbon monoxide (CO) and carbon dioxide (CO 2 ) in the near-infrared. An erbium-doped fiber frequency comb with a repetition frequency of ∼41.709 MHz is coupled into a resonant cavity with a length of ∼360 mm in an off-axis manner, exciting numerous high-order modes to effectively suppress cavity-mode noise. The performance of multiple machine learning models is compared for the inversion of a single/dual gas concentration. A few absorbance spectra are collected to build a sample data set, which is then utilized for model training and learning. The results demonstrate that the Particle Swarm Optimization Support Vector Machine (PSO-SVM) model achieves the highest predictive accuracy for gas concentration and is ultimately applied to the detection system. Based on Allan deviation, the detection limit for CO in single-gas detection can reach 8.247 parts per million by volume (ppmv) by averaging 87 spectra. Meanwhile, for simultaneous CO 2 /CO measurement with highly overlapping absorbance spectra, the LoD can be reduced to 13.196 and 4.658 ppmv, respectively. The proposed optical gas sensing technique indicates the potential for the development of a field-deployable and intelligent sensor system capable of simultaneous detection of multiple gases.

Conventional biological nutrient removal processes rely on external aeration and produce significant carbon dioxide (CO 2 ) emissions. This study constructed a phototrophic simultaneous nitrification-denitrification phosphorus removal (P-SNDPR) system to treat low carbon to nitrogen (C/N) ratios wastewater and investigated the impact of sludge retention time (SRT) on nutrient removal performance, nitrogen conversion pathway, and microbial structure. Results showed that the P-SNDPR system at SRT of 15 days had the highest nutrient removal capacity, achieving over 85% and 98% removal of nitrogen and phosphorus, respectively, meanwhile maintaining minimal CO 2 emissions. Nitrogen removal was mainly through assimilation at SRTs of 5 and 10 days, and nitrification-denitrification at SRTs of 15 and 20 days. Stable partial nitrification was facilitated by photoinhibition and low DO levels. Flow cytometry sorting technique results revealed SRT drove community structural changes in translational activity (BONCAT+) microbes, where BONCAT+ microbes were mainly simultaneous nitrogen and phosphorus removal bacteria (Candidatus Accumulibacter ), denitrifying bacteria (Candidatus Competibacter and Plasticicumulans ), ammonia-oxidizing bacteria ( Nitrosomonas ), and microalgae ( Chlorella and Dictyosphaerium ). The P-SNDPR system represents a novel, carbon-neutral process for efficient nutrient removal from low C/N ratio wastewater without aeration and external carbon source additions.

Understanding geochemical dissolution in porous materials is crucial, especially in applications such as geological CO 2 storage. Accurate estimation of reaction rates enhances predictive modeling in geochemical-flow simulations. Fractured porous media, with distinct transport time scales in fractures and the matrix, raise questions about fracture-matrix interface dissolution rates compared to bulk dissolution rate and the scale-dependency of reaction rate averaging. Our investigation delves into these factors, studying the impact of flow rate and mineralogy on interface dissolution patterns. By injecting carbonated water into carbonate rock samples containing a central channel (mimicking fracture hydrodynamics), our study utilized μCT X-ray imaging at 3.3 μm spatial resolution to estimate the reaction rate and capture the change in pore morphology. Results revealed dissolution rates significantly lower (up to 4 orders of magnitude) than batch experiments. Flow rate notably influenced fracture profiles, causing uneven enlargement at low rates and uniform widening at higher ones. Ankerite presence led to a dissolution-altered layer on the fracture surface, showing high permeability and porosity without greatly affecting the dissolution rate, unlike clay-rich carbonates. This research sheds light on controlling factors influencing dissolution in subsurface environments, critical for accurate modeling in diverse applications.

A simple approach was developed to computationally construct a polymer dataset by combining simplified molecular-input line-entry system (SMILES) strings of a targeted polymer backbone and a variety of molecular fragments. This method was used to create 14 polymer datasets by combining seven polymer backbones and molecules from two large molecular datasets (MOSES and QM9). Polymer backbones that were studied include four polydimethylsiloxane (PDMS) based backbones, poly(ethylene oxide) (PEO), poly(allyl glycidyl ether) (PAGE), and polyphosphazene (PPZ). The generated polymer datasets can be used for various cheminformatics tasks, including high-throughput screening for gas permeability and selectivity. This study utilized machine learning (ML) models to screen the polymers for CO 2 /CH 4 and CO 2 /N 2 gas separation using membranes. Several polymers of interest were identified. The results highlight that employing an ML model fitted to polymer selectivities leads to higher accuracy in predicting polymer selectivity compared to using the ratio of predicted permeabilities.

Direct air capture (DAC) of CO 2 has gained attention as a sustainable carbon source. One of the most promising technologies currently available is liquid solvent DAC (L-DAC), but the significant fraction of fossil CO 2 in the output stream hinders its utilization in carbon-neutral fuels and chemicals. Fossil CO 2 is generated and captured during the combustion of fuels to calcine carbonates, which is difficult to decarbonize due to the high temperatures required. Solar thermal energy can provide green high-temperature heat, but it flourishes in arid regions where environmental conditions are typically unfavorable for L-DAC. This study proposes a solar-powered L-DAC approach and develops a model to assess the influence of the location and plant capacity on capture costs. The performed life cycle assessment enables the comparison of technologies based on net CO 2 removal, demonstrating that solar-powered L-DAC is not only more environmentally friendly but also more cost-effective than conventional L-DAC.

Carbon capture, utilization, and storage (CCUS) are widely recognized as a promising technology for mitigating climate change. CO 2 mineralization using Ca-rich fluids and high-concentration CO 2 gas has been studied extensively. However, few studies have reported CO 2 mineralization with atmospheric CO 2 , owing to the difficulty associated with its low concentration. In seawater, the biomineralization process promotes Ca accumulation and CaCO 3 precipitation, assisted by specific organic matter. In this study, we examined the conversion of atmospheric CO 2 into CaCO 3 in seawater using shell powders ( Pinctada fucata , Haliotis discus , Crassostrea gigas , Mizuhopecten yessoensis , Turbo sazae , and Saxidomus purpurata ). Among the six species, the shell powder of S. purpurata showed the highest rate of CaCO 3 formation and recovery of CaCO 3 . NaClO treatment test revealed that the organic matter in the shells enhanced the CO 2 mineralization. All materials used in this study, including atmospheric CO 2 , seawater, and shells, are economically feasible for large-scale applications. Using shell powder for CO 2 mineralization in seawater embodies an innovative technological advancement to address climate change.

To reduce the global CO 2 footprint of plastics, bio- and CO 2 -based feedstock are considered the most important design features for plastics. Oxalic acid from CO 2 and isosorbide from biomass are interesting rigid building blocks for high T g polyesters. The biodegradability of a family of novel fully renewable (bio- and CO 2 -based) poly(isosorbide- co -diol) oxalate (PISOX-diol) copolyesters was studied. We systematically investigated the effects of the composition on biodegradation at ambient temperature in soil for PISOX (co)polyesters. Results show that the lag phase of PISOX (co)polyester biodegradation varies from 0 to 7 weeks. All (co)polyesters undergo over 80% mineralization within 180 days (faster than the cellulose reference) except one composition with the cyclic codiol 1,4-cyclohexanedimethanol (CHDM). Their relatively fast degradability is independent of the type of noncyclic codiol and results from facile nonenzymatic hydrolysis of oxalate ester bonds (especially oxalate isosorbide bonds), which mostly hydrolyzed completely within 180 days. On the other hand, partially replacing oxalate with terephthalate units enhances the polymer's resistance to hydrolysis and its biodegradability in soil. Our study demonstrates the potential for tuning PISOX copolyester structures to design biodegradable plastics with improved thermal, mechanical, and barrier properties.

Humans are the primary sources of CO 2 and NH 3 indoors. Their emission rates may be influenced by human physiological and psychological status. This study investigated the impact of physiological and psychological engagements on the human emissions of CO 2 and NH 3 . In a climate chamber, we measured CO 2 and NH 3 emissions from participants performing physical activities (walking and running at metabolic rates of 2.5 and 5 met, respectively) and psychological stimuli (meditation and cognitive tasks). Participants' physiological responses were recorded, including the skin temperature, electrodermal activity (EDA), and heart rate, and then analyzed for their relationship with CO 2 and NH 3 emissions. The results showed that physiological engagement considerably elevated per-person CO 2 emission rates from 19.6 (seated) to 46.9 (2.5 met) and 115.4 L/h (5 met) and NH 3 emission rates from 2.7 to 5.1 and 8.3 mg/h, respectively. CO 2 emissions reduced when participants stopped running, whereas NH 3 emissions continued to increase owing to their distinct emission mechanisms. Psychological engagement did not significantly alter participants' emissions of CO 2 and NH 3 . Regression analysis revealed that CO 2 emissions were predominantly correlated with heart rate, whereas NH 3 emissions were mainly associated with skin temperature and EDA. These findings contribute to a deeper understanding of human metabolic emissions of CO 2 and NH 3 .

Monitoring of carbon dioxide (CO 2 ) body levels is crucial under several clinical conditions (e.g., human intensive care and acid-base disorders). To date, painful and risky arterial blood punctures have been performed to obtain discrete CO 2 measurements needed in clinical setups. Although noninvasive alternatives have been proposed to assess CO 2 , these are currently limited to benchtop devices, requiring trained personnel, being tedious, and providing punctual information, among other disadvantages. To the best of our knowledge, the literature and market lack a wearable device for real-time, on-body monitoring of CO 2 . Accordingly, we have developed a microneedle (MN)-based sensor array, labeled as CO 2 -MN, comprising a combination of potentiometric pH- and carbonate (CO 3 2- )-selective electrodes together with the reference electrode. The CO 2 -MN is built on an epidermal patch that allows it to reach the stratum corneum of the skin, measuring pH and CO 3 2- concentrations directly into the interstitial fluid (ISF). The levels for the pH-CO 3 2- tandem are then used to estimate the P CO 2 in the ISF. Assessing the response of each individual MN, we found adequate response time ( t 95 < 5s), sensitivity (50.4 and -24.6 mV dec -1 for pH and CO 3 2- , respectively), and stability (1.6 mV h -1 for pH and 2.1 mV h -1 for CO 3 2- ). We validated the intradermal measurements of CO 2 at the ex vivo level, using pieces of rat skin, and then, with in vivo assays in anesthetized rats, showing the suitability of the CO 2 -MN wearable device for on-body measurements. A good correlation between ISF and blood CO 2 concentrations was observed, demonstrating the high potential of the developed MN sensing technology as an alternative to blood-based analysis in the near future. Moreover, these results open new horizons in the noninvasive, real-time monitoring of CO 2 as well as other clinically relevant gases.

The hydration of CO 2 suffers from kinetic inefficiencies that make its natural trapping impractically sluggish. However, CO 2 -fixing carbonic anhydrases (CAs) remarkably accelerate its equilibration by 6 orders of magnitude and are, therefore, "ideal" catalysts. Notably, CA has been detected in ureolytic bacteria, suggesting its potential involvement in microbially induced carbonate precipitation (MICP), yet the dynamics of the urease (Ur) and CA genes remain poorly understood. Here, through the use of the ureolytic bacterium Sporosarcina pasteurii , we investigate the differing role of Ur and CA in ureolysis, CO 2 hydration, and CaCO 3 precipitation with increasing CO 2(g) concentrations. We show that Ur gene up-regulation coincides with an increase in [HCO 3 - ] following the hydration of CO 2 to HCO 3 - by CA. Hence, CA physiologically promotes buffering, which enhances solubility trapping and affects the phase of the CaCO 3 mineral formed. Understanding the role of CO 2 hydration on the performance of ureolysis and CaCO 3 precipitation provides essential new insights, required for the development of next-generation biocatalyzed CO 2 trapping technologies.