Case Study: Enabling Breakthroughs in CO₂ Electroreduction with High-Purity Copper from Advent

A research team from institutions including the Fritz Haber Institute of the Max Planck Society, Ruhr-University Bochum, Columbia University, and Penn State University has demonstrated a significant advance in the electrochemical reduction of carbon dioxide (CO₂) to multicarbon products using tailored copper oxide (CuOx) catalysts.

This work was led by Beatriz Roldan Cuenya and Michael Janik and their study, titled "Activity and Selectivity Control in CO₂ Electroreduction to Multicarbon Products over CuOx Catalysts via Electrolyte Design", was published in ACS Catalysis in 2018.

Unlocking the Potential of CO₂ Conversion

Electrochemical CO₂ reduction (CO₂RR) is a promising strategy for turning carbon waste into high-value chemicals and fuels. Copper is unique in its ability to catalyse the formation of C₂⁺ products like ethylene and ethanol, but standard copper surfaces often lack efficiency and selectivity.

This study explored how surface-treated copper, in combination with optimised electrolytes, could overcome those limitations—enhancing both reaction rate and selectivity for multicarbon products.

Role of Advent Research Materials

The researchers used high-purity copper foil (99.995%) supplied by Advent Research Materials Ltd. as the base material for all catalyst preparation.

“Commercial Cu foils (Advent Research Materials Ltd., 99.995%) were first cleaned with acetone and ultrapure water… and then electropolished in phosphoric acid…”
— Experimental Methods, Section 4.1

This copper was then treated with low-pressure oxygen plasma to create CuOx catalysts with enhanced surface reactivity and oxygen content—providing a key platform for testing the impact of different electrolytes.

Key Findings

Electrolyte Design Drives Performance
The team found that using larger alkali metal cations (e.g., Cs⁺ instead of Li⁺ or Na⁺) in the electrolyte significantly boosted both the activity and selectivity of the catalyst. These larger cations helped stabilise reaction intermediates on the copper surface and promoted the formation of carbon–carbon bonds.

Cs⁺ + I⁻ Combination Restructures Surface
Introducing both cesium (Cs⁺) and iodide (I⁻) into the reaction environment caused a visible restructuring of the CuOx surface, forming particles rich in Cu⁺ (copper in a +1 oxidation state), which proved particularly effective for producing C₂⁺ products.

High Efficiency and Selectivity
The optimised system delivered up to 69% Faradaic efficiency for C₂⁺ products at −1.0 V vs RHE, with partial current densities as high as −45.5 mA cm⁻²—performance that rivals or exceeds other reported systems at the time.

Subsurface Oxygen Plays a Supporting Role
Simulations revealed that subsurface oxygen—left over from plasma treatment—enhanced the binding of alkali cations, further boosting intermediate stability and favouring C–C coupling over undesired side reactions.

Conclusion

This study highlights the importance of combining advanced surface engineering with thoughtful electrolyte selection to push the boundaries of CO₂ reduction efficiency. The use of high-purity copper from Advent Research Materials was foundational to the work—enabling precise catalyst preparation and consistent electrochemical performance.

Researchers aiming to explore Cu-based electrocatalysis at this level require dependable, research-grade materials. Advent’s copper foil met the demanding purity and consistency standards required for this pioneering work.

The full study is available via the American Chemical Society:
https://pubs.acs.org/doi/10.1021/acscatal.8b02587