For constructing MOF, chemicals as well as solvents (ethyl acetate, hexane, dichloromethane, acetone, diethyl ether) are needed for synthesis and purification. We also need some budget for analysis of the structure (Nuclear magnetic resonance, high-resolution mass spectrometry, X-ray diffraction). The remaining budget will be used for acquiring chemical and electrochemical equipments.

Additional Information

Here is the full description of the projects and execution plans.

The urgency of mitigating climate change is driving a wave of innovative strategies aimed at reducing atmospheric CO₂ levels. The effects of climate change—rising global temperatures, ocean acidification, and increasingly extreme weather patterns—demand the rapid development of scalable and efficient methods for carbon capture. While many global initiatives focus on various greenhouse gas removal strategies, current technologies such as Direct Air Capture (DAC) have inherent limitations in cost and scalability, which prevent their widespread implementation.

The ocean, as Earth's largest CO₂ reservoir, represents an underexplored and vastly more concentrated opportunity for CO₂ capture. The dissolved CO₂ concentration in the ocean, mainly in the form of bicarbonate ions, exceeds that of atmospheric CO₂ by over 100 times. This immense potential positions the ocean as an ideal, yet largely untapped, target for large-scale CO₂ removal efforts.

Innovation and Creativity

The Direct Ocean Electrocapture (DOE) project proposes a novel approach, leveraging Metal-Organic Frameworks (MOFs) for efficient bicarbonate capture directly from seawater. MOFs are crystalline materials composed of metal ions and organic ligands that form porous structures. Due to their customizable design, high surface area, and tunable properties, MOFs are often described as "molecular sponges" that can capture gases such as CO₂ within their pores. While MOFs have been extensively explored for DAC applications, their use in ocean-based carbon capture has not yet been studied.

DOE seeks to capitalize on the ocean’s high dissolved CO₂ content by focusing on designing MOFs that can selectively bind bicarbonate ions or allow their passage through the framework. Renewable electricity derived from wind, solar, or tidal power, will drive the electrochemical processes that concentrate bicarbonate ions. Ultimately, the bicarbonate can be treated with calcium ions—also abundant in seawater—to form calcium carbonate, a stable material that locks away CO₂ for long-term sequestration. As a separate note, calcium carbonate is major components of marble, high-value construction material. Thus, DOE product can be marketed as sustainable marine-derived marble.

Feasibility and Technical Soundness

Although the concept of removing CO2 as bicarbonate from the ocean has gained recent attention, the electrochemical removal of bicarbonate was only recently demonstrated by a team at MIT (Energy Environ. Sci., 2023,16, 2030-2044). However, existing systems encounter challenges such as high energy input requirements and the expense of materials used in device construction, impeding scalability. DOE aims to address these challenges by introducing a more energy-efficient solution by developing MOF with high affinity to bicarbonate. Regarding technical soundness, extracting a particular ion from sea water using electrical energy has already been proven feasible. For example, lithium extraction from sea water driven by electrochemical stimuli has recently been demonstrated (see c&en news article: https://cen.acs.org/materials/inorganic-chemistry/Can-seawater-give-us-lithium-to-meet-our-battery-needs/99/i36). Essentially, this proposal aims to extract bicarbonate in conceptually similar manner. Given that bicarbonate is far more concentrated in seawater than lithium (> 100 mg for HCO3 vs several microgram for Li per a litter of sea water), this process may, in fact, be easier and more efficient than lithium extraction.

Potential for Technology to Scale

The scalability of DOE is a core strength of the project. Electrodialysis used in desalination (this can be viewed as a process to remove NaCl from sea water) is already practiced on commercial scale, which serve as a robust evidence that bicarbonate removal from sea water can be successfully scaled. By drawing on the framework of these technologies, DOE has a clear roadmap (described in the section of the goals of the project) to reach industrial scale, offering the potential to make a meaningful impact on global carbon levels.

Impact on Greenhouse Gas Removal Acceleration to Scale

By focusing on the ocean's naturally high CO₂ concentration, DOE positions itself as a more efficient alternative to atmospheric-based CO₂ removal techniques. In fact, ocean contained 38,000 gigatons of CO2 as bicarbonate, which means that even 1% (i.e. 380 gigatones) of bicarbonate sequestration from sea water is more than sufficient to achieve the grand challenge. In this project, we aim to develop the system that sequestrate 10-20% of bicarbonate directly from sea water as a first proof of concept.

Strength of Team and Plan

The applicant has a strong background in synthetic chemistry and electrochemistry, with a proven track record in developing molecular-based solutions for sustainable production of chemicals and pharmaceuticals. My extensive experience in designing and synthesizing molecules would be directly translatable to MOF design and synthesis, positioning the project suitable and feasible to realize DOE at practically meaningful level.

A brief proposed work plan begins with designing MOFs with high bicarbonate affinity, followed by small-scale proof-of-concept experiments to demonstrate their effectiveness in seawater. Future efforts will focus on optimizing the material for scale-up and integrating the system into larger-scale electrochemical setups, with the ultimate goal of achieving gigaton-level CO₂ removal.

Project goals and milestones

The Direct Ocean Electrocapture (DOE) project aims to achieve several key goals:

Goal 1: Develop Novel MOFs with High Bicarbonate Affinity

The primary objective of DOE is to design and synthesize Metal-Organic Frameworks (MOFs) capable of efficiently capturing dissolved bicarbonate ions from seawater. These MOFs will act as selective "molecular sponges," optimized for bicarbonate absorption. Initial designs will incorporate organic cationic units, such as guanidinium or pyridinium-based cations, which have been shown to form stable bicarbonate salts via strong hydrogen bonding (Chem. Commun., 2020, 56, 10272-10280). This will serve as a foundational concept to create bicarbonate-specific MOFs for DOE.

Milestone 1: A variety of organic cation-incorporated building units will be synthesized, and these will be used to construct the MOF frameworks. The selectivity of these MOFs for bicarbonate will be tested by submerging them in a solution containing a mixture of anions and measuring the changes in anion concentrations. For optimal performance, both the organic cation building blocks and the metal centers connecting these units will be systematically screened to fine-tune bicarbonate selectivity.

Goal 2: Demonstrate Bicarbonate Sequestration from Seawater at Bench-Scale

The second major goal of the project is to demonstrate the practical application of these MOFs by concentrating bicarbonate from seawater in a small-scale, bench-top setup. Two potential configurations for this proof of concept are envisioned:

Milestone 2:

Configuration 1 (Electrochemical Cell with MOF-Coated Anode): In this setup, the MOF will be attached to the anode of an electrochemical cell. An electric potential will be applied to attract bicarbonate ions to the MOF-coated anode. After a short period (ranging from seconds to several minutes), the electrodes will be transferred to a separate container with calcium ions to precipitate calcium carbonate (CaCO₃), which will then be quantified.

Configuration 2 (MOF as a Selective Bicarbonate Filter): Alternatively, the MOF could act as a selective filter for bicarbonate ions in a system similar to those used for lithium extraction from brine (doi.org/10.1016/j.matt.2024.07.014). The MOF will capture and concentrate bicarbonate ions from seawater.

In either approach, the goal is to achieve a 10-20% removal of bicarbonate from seawater, serving as a strong proof of concept. Although this removal rate may seem modest, considering that the ocean contains 38,000 gigatons of CO₂ (mostly in the form of bicarbonate), even this efficiency is significant enough to suggest potential gigaton-scale carbon sequestration.

Goal 3: Outline a Pathway for Future Scale-Up and Optimization

While large-scale implementation is beyond the scope of this initial one-year project (with a limited budget of $50,000), a brief outline for future scale-up will be developed. This includes:

Milestone 3:

i) Cost reduction of MOF materials for large-scale production.

ii) Automation of the electrochemical bicarbonate concentration and CaCO₃ precipitation steps in a continuous-flow system.

iii) A demonstration using 50 kg of seawater to test the feasibility of the process at a semi-pilot scale.

iv) Further optimization and scale-up of the system, or replication of the 50 kg module (scale-out) to eventually reach a 1-ton seawater processing scale.

This roadmap provides a clear trajectory for advancing the DOE process beyond the initial research phase, with a focus on long-term scalability and cost-efficiency.