Ruhr-University Bochum researchers are constantly pushing the limits of technology by breaking new ground in CO2 conversion. The goal is to turn the harmful greenhouse gas into a valuable resource. A novel catalyst system could help reach the CO2 recycling goal.

Research groups around the world are developing technologies to convert carbon dioxide (CO2) into raw materials for industrial applications.

Most experiments under industrially relevant conditions have been carried out with heterogeneous electrocatalysts, i.e. catalysts that are in a different chemical phase to the reacting substances. However, homogeneous catalysts, which are in the same phase as the reactants, are generally considered to be more efficient and selective.

To date, there haven’t been any set-ups where homogeneous catalysts could be tested under industrial conditions. A team headed by Kevinjeorjios Pellumbi and Professor Ulf-Peter Apfel from Ruhr University Bochum and the Fraunhofer Institute for Environmental, Safety and Energy Technology UMSICHT in Oberhausen has now closed this gap.

The researchers outlined their findings in the journal Cell Reports Physical Science.

 Professor Apfel said, “Our work aims to push the boundaries of technology in order to establish an efficient solution for CO2 conversion that will transform the climate-damaging gas into a useful resource.”

His group collaborated with the team led by Professor Wolfgang Schöfberger from the Johannes Kepler University Linz and researchers from the Fritz Haber Institute in Berlin.

Efficiency and long-lasting stability

The team explored the conversion of CO2 using electrocatalysis.

With this electrolysis cell, the researchers showed that homogeneous catalysts can be used for CO2 conversion. Image Credit: Ruhr-University Bochum © RUB, Marquard. Click the press release link for more and larger images.

In the process, a voltage source supplies electrical energy, which is fed to the reaction system via electrodes and drives the chemical conversions at the electrodes.

A catalyst facilitates the reaction; in homogeneous electrocatalysis, the catalyst is usually a dissolved metal complex.

In a so-called gas diffusion electrode, the starting material CO2 flows past the electrode, where the catalysts convert it into carbon monoxide. Carbon monoxide is a common starting material in the chemical industry.

The researchers integrated the metal complex catalysts into the electrode surface without bonding them to it chemically.

They showed that their system could efficiently convert CO2: It generated current densities of more than 300 milliamperes per square centimeter. Moreover, the system remained stable for over 100 hours without showing any signs of decay.

No need to anchor the catalyst

 All this means that homogeneous catalysts can generally be used for electrolysis cells.

“However, they do require a specific electrode composition,” stressed Ulf-Peter Apfel.

More specifically, the electrodes must enable direct gas conversion without solvents so that the catalyst isn’t leached from the electrode surface.

Contrary to what is often described in specialist literature, there’s no need for a carrier material that chemically couples the catalyst to the electrode surface.

“Our findings open up the possibility of testing and integrating high-performance and easily variable homogeneous electrocatalysts in application scenarios for electrochemical processes,” concluded Apfel.


For many the seeming abundance of CO2 is alarming. For others we’re not halfway back to normal from the last glacier period. But it seems that there is enough to have some direct harvesting take place. Your humble writer might regret saying that in few years if this kind of technology really takes off.

And it does look like this tech has the makings of a practical technology for making use of CO2 that yields a new raw stock of CO, form which lots of products can be made.

Lets hope this tech improves and is adaptable to the most prolific sources of atmosphere CO2.


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