Making better use of CO2

ARC Centre of Excellence for Electromaterials Science (ACES) researchers Mr Yong Zhao, Dr Caiyun Wang and Professor Gordon Wallace from the University of Wollongong together with Ms Jiaojiao Liang and Professor Jianmin Ma from Hunan University in China have demonstrated how to electrochemically convert carbon dioxide (CO2) into gas products or liquid fuels that could potentially help solve environmental problems caused by excessive use of non-renewable fossil fuels.

The research titled ‘Tunable and Efficient Tin Modified Nitrogen-doped Carbon Nanofibers for Electrochemical Reduction of Aqueous Carbon Dioxide’ was published this month in Advanced Energy Materials.

Dr Wang explained that electrochemically converting CO2 into useful chemicals or liquid fuels has the potential to create energy rich by-products as well as solve the environmental problems arising from the excessive use of non-renewable fossil fuels.

“The conversion process however isn’t yet efficient,” Dr Wang said.

“Recycling CO2 into valuable fuels and chemicals requires too much energy to split the stable CO2 molecules. There are also other problems – including most catalysts channelling more of the available electrons into splitting water which creates competitive hydrogen (H2) evolution, rather than converting CO2 to the preferred end products.”

Dr Wang said while nanostructured noble-metal-based electrocatalysts have performed well for formic acid or carbon monoxide (CO) production, noble metals are costly and scarce, and processing them into nanostructured electrocatalysts is complicated, limiting large-scale application.

The ACES researchers have demonstrated how a low-cost tin (Sn) modified nitrogen (N)-doped carbon nanofiber hybrid catalyst can be developed using a simple electrospinning-pyrolysis technique.

“This low cost catalyst’s electrocatalytic activity and selectivity to CO2 reduction can be tuned. Tin nanoparticles on the surface of N-doped carbon nanofibers can drive efficient formic acid formation and after a simple acidic leaching treatment the retained atomically dispersed Sn species switch the dominant product from formic acid to CO.”

ACES Director Professor Wallace said this important research provides a route towards the development of tunable non-precious metal hybrid electrodes for conversion of CO2 to valuable formic acid or CO as needed. More importantly, it demonstrates the crucial role of the electronic interaction between metallic active sites and supporting materials in tuning the catalytic activity and product selectivity. The use of well-established electrospinning technology to produce other metal-based hybrid catalysts integrated with heteroatom-doped carbon nanofibers, such as boron (B), nitrogen and phosphorus (P), now makes it possible to easily fabricate an expanding materials family of inexpensive, robust catalysts.

You can read the published research here.