Researchers from Oregon State University have created novel compounds that can rapidly absorb large amounts of carbon dioxide from the atmosphere. This is a crucial strategy for reducing the effects of climate change. The study was published in the journal Chemistry of Materials.
Scanning electron microscope images of the carbon capture titanium molecules before (left) and after (right) exposure to air. The molecules release oxygen gas upon capture of carbon dioxide, creating a spongelike substance that enables reactivity throughout the crystals, not just on the surface. Image Credit: May Nyman and Karlie Bach, OSU College of Science.
The study, centered on titanium peroxides, expands upon their previous research on vanadium peroxides. The study is a component of a larger federal initiative to develop new materials and techniques for the direct air capture of carbon dioxide, which is created when fossil fuels are burned.
May Nyman and Karlie Bach from Oregon State University led the study.
In 2021, Nyman, the Terence Bradshaw Chemistry Professor in the College of Science, was selected to lead one of nine direct air capture projects in which the Department of Energy initially invested $24 million.
May Nyman group is investigating how certain transition metal complexes can react with air to extract carbon dioxide and transform it into a metal carbonate, a substance present in many minerals that occur naturally.
Transition metals are named for the transition of electrons from low to high energy states and back again, which results in unique colors. These metals are found close to the center of the periodic table.
Carbon dioxide air filtration facilities are still in their infancy. More advanced technologies, such as power plants, are available to reduce carbon dioxide emissions at the point of entry into the atmosphere. According to scientists, both forms of carbon capture are probably required if the planet is to escape the worst effects of climate change.
There are currently 18 direct air capture plants in operation in the US, Canada, and Europe, and plans are underway to build another 130 worldwide. Direct air capture presents significant energy and cost challenges compared to working with industrial exhausts.
The low concentration of carbon dioxide in the atmosphere (four parts per million) makes it difficult for carbon capture materials to function effectively.
We opted to look into titanium as it is 100 times cheaper than vanadium, more abundant, more environmentally friendly, and already well established in industrial uses. It also is right next to vanadium on the periodic table, so we hypothesized that the carbon capture behavior could be similar enough to vanadium to be effective.
Karlie Bach, Graduate Student, Oregon State University
Bach, Nyman, and the rest of the research team created several new tetraperoxo titanate structures, which are composed of a titanium atom coordinated with four peroxide groups.
These structures demonstrated different capacities to remove carbon dioxide from the atmosphere because peroxide groups are strong oxidizing agents, and tetrapterous structures are often very reactive.
The potential applications of related peroxotitanates in environmental chemistry, materials science, and catalysis have been investigated. However, Bach could use low-cost materials for high-yield chemical reactions; the tetraperoxotitanates in this study had never been definitively synthesized.
Our favorite carbon capture structure we discovered is potassium tetraperoxo titanate, which is extra unique because it turns out it is also a peroxosolvate. That means that in addition to having the peroxide bonds to titanium, it also has hydrogen peroxide in the structure, which is what we believe makes it so reactive.
Karlie Bach, Graduate Student, Oregon State University
The measured carbon capture capacity was about 8.5 mmol of carbon dioxide per gram of potassium tetraperoxo titanate, which is about twice as much as vanadium peroxide.
“Titanium is a cheaper, safer material with a significantly higher capacity,” Bach said.
Titanium, named after Greek mythological titans, is just as strong as steel but much lighter. It is found in trace amounts in rocks, soil, plants, and even the human body. It is the ninth most abundant element in the Earth's crust and is non-toxic and resistant to corrosion.
Additional authors include Assistant Professors Tim Zuehlsdorff and Konstantinos Goulas, postdoctoral researcher Eduard Garrido Ribó, graduate students Jacob Hirschi, Zhiwei Mao, and Makenzie Nord, and crystallographer Lev Zakharov, interim manager of OSU’s X-Ray Diffraction Facility.
The Murdock Charitable Trust also funded the study through an instrument grant.
Journal Reference:
Bach, K., et al. (2024) Tetraperoxotitanates for High-Capacity Direct Air Capture of Carbon Dioxide. Chemistry of Materials. doi.org/10.1021/acs.chemmater.4c01795.