Lum Yanwei A simple strategy for boosting CO2 reduction

SUSTAINABILITY

6 Jun 2025

A Simple Strategy for Boosting CO₂ Reduction

A small change to catalyst support materials may lead to big efficiency gains for a promising green strategy

Assistant Professor Lum Yanwei

NUS Chemical and Biomolecular Engineering

SUSTAINABILITY

6 Jun 2025

A Simple Strategy for Boosting CO₂ Reduction

A small change to catalyst support materials may lead to big efficiency gains for a promising green strategy

Assistant Professor Lum Yanwei

NUS Chemical and Biomolecular Engineering

Global carbon emissions from fossil fuels reached a record high in 2024 ^[1]. As the urgency to tackle climate change intensifies, scientists are racing to develop ways to turn carbon dioxide from a pollutant into a resource.

One approach with enormous potential is CO₂R, or the electrochemical reduction of carbon dioxide. CO₂R centres on converting carbon dioxide into high value chemicals and fuels, using electricity from renewable sources. This method mitigates carbon emissions, while closing the loop on industrial systems.

CO₂R can produce valuable chemicals and fossil fuel alternatives, promoting a circular carbon economy

However, CO₂R currently faces significant technical challenges in its quest for widespread industrial adoption, such as high operating costs, low energy efficiency and low yields for desired products. For CO₂R to be commercially viable, academics need to urgently improve the performance metrics of its electrochemical cell.

A recent study published in Science Advances, led by Assistant Professor Lum Yanwei from NUS Chemical and Biomolecular Engineering, offers a simple but potentially powerful strategy: add fluorine to the carbon catalyst supports.

Catalyst supports are usually seen as inert materials upon which catalysts can be attached. However, introducing impurities to the catalyst support, in a process known as doping, may influence the catalytic performance of the material. This was shown in a previous study where carbon supports were doped with small amounts of nitrogen.

Likening the support material to a dinner table and the catalyst to the food on top, Prof Lum quipped: “You can think of it as the table is actually changing the taste of the food. It makes your food taste better.”

Improving catalytic performance with fluorine

Asst Prof Lum’s study compared carbon supports doped with atoms of low electronegativity, like boron, to high electronegativity, such as fluorine. The most electronegative supports, the researchers discovered, outperformed the undoped supports, while the less electronegative did poorer.

The catalyst with the fluorine-doped carbon support, they were surprised to find, displayed the highest Faradic efficiency (FE) value towards the desired multicarbon products. This meant that based on the total charge passed, the reaction produced the greatest amount of multicarbons relative to its theoretical potential.

Fluorine-doped carbon supports improve FE towards multicarbon products in copper-mediated CO₂R

It wasn’t obvious to them at the beginning that fluorine would work the best, Lum commented, as nitrogen is the more common choice in the literature.

Exploring industrial applicability

Based on their observations, the team designed a catalyst composite made with copper and fluorine-doped carbon, to steer CO₂R pathways towards forming high-value multicarbon products, like ethylene and ethanol.

The researchers tested the composite in a gas diffusion electrode (GDE) flow cell, to mimic current densities found in industrial conditions. For CO₂R to be commercially viable, higher current densities are needed to make the system cost-effective enough for large-scale production.

Compared to the control, the team’s composite consistently demonstrated greater FE in producing multicarbons across different current densities. It peaked at an impressive 82.5% at an industrially relevant current density of 400 milliampere per square centimetre, maintaining a stable performance over a 44-hour period.

Finally, the researchers tested the composite against simulated flue gas, mimicking the dirty exhaust produced by real world factories. Results showed that it was more efficient at avoiding the production of water, facilitating more direct conversion to valuable chemicals.

Real world flue gas contains oxygen, explained Lum. “[Oxygen] is like a parasitic species. It likes to steal electrons because the oxygen likes to turn into water,” he said. “But you don’t want to make water, because water is very cheap.”

In their experiments with simulated flue gas, the composite was over five times more efficient at producing multicarbons than a standard copper catalyst.

Product FE comparison between the catalyst composite and the control, with simulated flue gas and high current density

Moving from lab to factory

CO₂R may still be a long way from being a practical reality, but this study lights the way towards a scalable electrochemical cell with commercial viability.

Unmodified carbon supports are already commonly used in CO₂R, noted Lum. Just by tweaking this cheap, oft overlooked material, researchers can move one step closer to realising sustainable, large-scale carbon capture and utilisation.

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Improving catalytic performance with fluorine

Exploring industrial applicability

Moving from lab to factory

References