This week’s publication highlights relate to direct air capture, marine carbon dioxide removal and ocean alkalinity enhancement.
MOF-74: A Leading Contender for Direct Air Capture, Navigating the Path from Promise to Practicality
Abstract
The urgent need for negative emissions technologies has positioned Direct Air Capture (DAC) as a critical climate solution, yet the ultra-dilute nature of atmospheric CO₂ demands adsorbents with exceptional affinity and selectivity. Among these, the metal-organic framework MOF-74 has emerged as a leading contender, renowned for its record-high CO₂ uptake at low pressures, driven by a high density of open metal sites (OMS). This review critically assesses the journey of MOF-74 from its promising intrinsic properties toward practical DAC application. We elucidate the central paradox of the material: the very OMS that grant its superior CO₂ capacity also render it highly susceptible to hydrolytic degradation in ambient humidity, creating a significant practicality gap. The analysis systematically explores advanced material engineering strategies-including metal node selection, chemical functionalization of linkers, and composite formation—to navigate the critical trade-off between capacity and stability. Furthermore, we highlight the pivotal role of computational modeling and machine learning in accelerating the design of next-generation, water-resistant variants. While pilot-scale validations demonstrate MOF-74’s potential for efficient, low-energy DAC cycles, economic viability and scalable synthesis remain hurdles. We conclude that the path forward hinges on a multidisciplinary research agenda focused on developing robust, multi-metallic frameworks and advanced composite systems, underpinned by holistic sustainability assessments to translate the immense promise of MOF-74 into a practical DAC technology.
Anyanwu. J. et al. (2026) MOF-74: A Leading Contender for Direct Air Capture, Navigating the Path from Promise to Practicality 32(12) Adsorption.
Read the full paper here: MOF-74: A Leading Contender for Direct Air Capture, Navigating the Path from Promise to Practicality I Adsorption.
Air-Sea Gas Exchange in the Coastal Baltic Sea: Implications for Marine Carbon Dioxide Removal
Abstract
Air-sea gas exchange affects the biogeochemical cycling of trace gases such as CO2 and dimethyl sulfide (DMS) on a global scale, thereby influencing Earth’s climate. In nearshore regions, differences in wind fetch and surfactants are expected to have an impact on gas transfer velocity (k). Accurate determination of air-sea gas exchange in nearshore regions is crucial for assessing the efficacy of carbon dioxide removal (CDR) techniques, as many CDR methods are expected to be deployed in these regions. In this study, we used the 3He/SF6 dual tracer technique to determine k and investigate factors that control air-sea gas exchange in a nearshore inland sea ecosystem, the coastal Baltic Sea. We found that k was, on average, about 39% lower than in other coastal and offshore regions at the same wind speed, with a more pronounced reduction at higher wind speeds and during developing wave conditions. Most of the wind speed/gas exchange parameterizations proposed for the Baltic Sea were found to overestimate k. The lower k was likely due to wind fetch limitation, wind-wave interactions, and the presence of surfactants.
Dobashi, R. et al. (2026) Air-Sea Gas Exchange in the Coastal Baltic Sea: Implications for Marine Carbon Dioxide Removal 131(2) Journal of Geophysical Research: Oceans.
Read the full paper here: Air-Sea Gas Exchange in the Coastal Baltic Sea: Implications for Marine Carbon Dioxide Removal I Journal of Geophysical Research: Oceans.
Ocean Alkalinity Enhancement in an Estuary
Abstract
A high-resolution numerical ocean model is used to assess ocean alkalinity enhancement (OAE) in the San Francisco Bay (SFB) estuary. A novel tracer-based approach is introduced to simulate alkalinity release and the subsequent CO2 ingassing. The model is run for 6 days and accurately reproduces observational data of currents, density, and tides. Estuarine dynamics induce mixing, advect buoyant water out of the Bay, and transport the added alkalinity from deep in the estuary to the surface of the open ocean. Over 80% of the tracer remains in the upper 15 m throughout the simulation. The estimated air-sea equilibration rate of the added alkalinity is approximately 2% per day. Alkalinity exported to the open ocean plays a disproportionately large role in increasing the CO2 ingassing rate compared to that in the estuary. This rate is relatively fast compared to open-ocean OAE studies due to the San Francisco Bay buoyant plume, which confines the released alkalinity to the surface mixed layer. While estuaries offer many benefits for OAE releases, further studies are needed to quantify their biogeochemical and ecosystem impacts.
Ho, M. et al. (2026) Ocean Alkalinity Enhancement in an Estuary 7 Frontiers in Climate.
Read the full paper here: Ocean Alkalinity Enhancement in an Estuary I Frontiers in Climate.
Role of Epoxide Functionalization of Amines for Development of Direct Air Capture Sorbents with High Cyclic Working Capacity at Low Desorption Temperatures
Abstract
Broad implementation of the direct air capture (DAC) technology requires sorbents that can achieve high cyclic CO2 working capacities (WCcyclic) at low desorption temperatures. This study shows that appropriate degrees of butylene oxide (BO) functionalization on amines with different molecular weights (polyethyleneimine (PEI1200 and PEI300) and tris(2-aminoethyl)amine (TREN)) can achieve excellent WCcyclic at low desorption temperatures (40–70°C). Through systematic screening, 0.30BO-PEI300-SY and 0.54BO-TREN-SY are identified as the optimal sorbents with the highest WCcyclic at desorption temperatures of 45 and 40°C, respectively. Both sorbents exhibit excellent stability under oxygen-rich and humid conditions, maintaining outstanding WCcyclic compared to other benchmark DAC materials. Molecular dynamics simulations reveal that CO2 adsorption on 1° amine sites plays a dominant role in determining the overall CO2 capture capacity of pristine amines, and the reduction in CO2 uptake after BO treatment is primarily attributable to the loss of accessible 1° amine sites. Both experimental and simulation results highlight that the fraction of 1° amines is a key factor governing WCcyclic and desorption behavior after BO modification.
Han, J. et al. (2026) Role of Epoxide Functionalization of Amines for Development of Direct Air Capture Sorbents with High Cyclic Working Capacity at Low Desorption Temperatures e75091 Advanced Science.
Read the full paper here: Role of Epoxide Functionalization of Amines for Development of Direct Air Capture Sorbents with High Cyclic Working Capacity at Low Desorption Temperatures I Advanced Science.
The Future of Direct Air Capture in Canada: A Systematic Scenario-based Exploration of Barriers and Possibilities
Abstract
Integrated assessment models often overlook the interdependencies of socio-political factors shaping the deployment direct air capture (DAC), leading to projections that may be overly optimistic. To address this gap, we systematically explore the conditions under which DAC may (or not) emerge as a competitive carbon dioxide removal (CDR) option in Canada using the system-theoretical scenario method cross-impact balances (CIB), which accommodates both qualitative and quantitative scenario factors. Based on the literature, we identified 10 key factors affecting DAC deployment such as interjurisdictional regulations, public perception, and clean electricity availability. Their interrelationships were assessed by 27 experts to develop an expert-informed CIB model that identified 15 internally consistent scenarios. Results reveal inter-related constraints that DAC must overcome to become competitive with other CDR methods. The cost of DAC remains a significant barrier; unless technological breakthroughs or economies of scale push costs down, DAC is unlikely to play a major future role. Even with cost improvements, public perception remains key—strong societal opposition, particularly around CO₂ transport and storage infrastructure—can delay or block projects. Additionally, interjurisdictional policy coherence matters to advance DAC deployment. From a domestic decision-maker perspective, some of these barriers—such as DAC cost—are influenced largely by global deployment and may be outside their control. However, others—such as policy coherence—can be shaped by domestic policy action. By integrating expert knowledge of qualitative factors using systematic scenario analysis, this study highlights how different institutional and socio-political configurations condition the feasibility of large-scale DAC deployment in Canada.
Motlaghzadeh, K. and Schweizer, V. (2026) The Future of Direct Air Capture in Canada: A Systematic Scenario-based Exploration of Barriers and Possibilities 134 (104640) Energy Research & Social Science.
Read the full paper here: The Future of Direct Air Capture in Canada: A Systematic Scenario-based Exploration of Barriers and Possibilities I Energy Research & Social Science.