A catalyst with a ‘handed’ shape could give scientists a new way to control what happens when carbon dioxide is turned into useful chemicals.
Turning CO₂ into useful chemicals is complicated by an unwanted side reaction that produces hydrogen instead. This problem has frustrated scientists for years. However, now a team of researchers at the National Laboratory of the Rockies (NLR) has found a way around it.
In their latest study, they have shown that twisting copper into a helical, chiral structure can manipulate the spin of electrons at its surface—and use that spin to push hydrogen out of the way during CO₂ reduction.
Their chiral copper catalyst could offer a new way to steer CO₂ reduction toward useful carbon products.
Giving copper a twist
The researchers fabricated electrodes with helical copper structures via electrodeposition using a chiral templating reagent. Chiral simply means that an object has left-handed and right-handed versions that are mirror images of each other, much like human hands.
The key idea was the chiral-induced spin selectivity (CISS) effect. When electrons move through a chiral structure, the structure can favor one direction of electron spin over the other. The twisted copper can therefore act somewhat like a filter for electron spin.
The team tested the electrodes during CO₂ reduction in CO₂-saturated 1 M potassium bicarbonate (KHCO₃) solution at pH 7.8.
The chiral copper showed reduced hydrogen evolution while producing carbon monoxide and formate. The corresponding non-chiral electrodes did not show the same behavior. This builds on broader efforts to develop electrochemical systems that turn CO₂ into useful fuels.
“We observed efficient production of desired carbon monoxide and formate products during CO2RR, as well as suppression of hydrogen evolution when employing the chiral structures, but not when we used electrodes that have no chirality. This tells us that catalytic structures with chirality have a strong effect on these reactions,” Van de Lagemaat, one of the study authors and a scientist at NLR, said.
Watching electron spins at work
However, observing a change in the products was not enough. The researchers needed evidence that spin was actually involved.
They used time-resolved Kerr ellipticity (TRKE), an ultrafast optical technique that can detect changes associated with electron spin. The experiment used an ultrafast Seebeck current to generate spin-polarized carriers and tracked them as they moved through the material.
The measurements showed spin accumulation at the chiral copper surface, supporting the idea that the helical structure was creating spin polarization.
The proposed chemistry is surprisingly intuitive. Hydrogen molecules contain two hydrogen atoms whose electron spins must pair appropriately to form the H–H bond.
Since H–H bond formation requires the appropriate pairing of electron spins, the researchers propose that this spin polarization makes hydrogen formation less favorable. Hydrogen evolution is therefore suppressed, leaving more opportunity for CO₂-derived pathways that produce carbon monoxide and formate.
The work builds on growing research into chirality and spin as tools for controlling electrocatalysis.
For instance, a 2024 article examined the growing evidence for chiral-induced spin selectivity and the ways it could be used to control electron transport and chemical reactions. A later study using helically twisted gold nanoflakes reported highly selective CO production.
However, unlike these approaches, the new copper study focuses on linking measured spin polarization to suppression of the competing hydrogen reaction while producing CO and formate.
A new control knob for chemical factories
The researchers are not presenting the copper electrode as a finished industrial catalyst. Instead, the work provides evidence for a mechanism that could eventually help engineers make CO₂ electrolyzers more selective, potentially reducing the costs associated with unwanted hydrogen and mixed products.
Other researchers are also developing electrodes that capture CO₂ and convert it directly into formic acid.
The idea could extend beyond CO₂. The team suggests chiral catalysts might also help control reduction reactions involving nitrogen or carbon monoxide, where hydrogen evolution can compete strongly.
The broader significance is that catalyst design may no longer have to focus only on composition, surface structure and reaction conditions. The handedness of the catalyst—and the spin it imposes on electrons—could become another way to steer chemistry.
The study is published in the journal Nature Energy.