Gas Diffusion Electrodes for continuous electrochemical CO2 reduction to chemical feedstock

Supervisory Team: Scientia Prof Rose Amal, Dr Xunyu Lu, and Dr Rahman Daiyan

Description: A variety of technologies to reduce greenhouse gases (CO2) emissions have been studied and explored considerably. One promising route for CO2 reduction can be through the electrochemical reduction of CO2 using homogeneous and heterogeneous catalysts to produce value added chemicals. This method mimics the photosynthesis process occurring in plants. Electrochemical CO2 reduction reactions (CO2RR) can be carried out in ambient conditions through the application of external bias and also provides the opportunity to be coupled with electricity generated from renewable energy resources. If the electricity is drawn from renewable energy sources such as from solar panels, CO2RR will provide additional benefits of storing the diffusive and intermittent renewable energy resources in the form of chemical fuels, such as methanol, ethanol, formic acid, formaldehyde, methane, etc.

It is generally accepted that ideal CO2RR catalysts should possess the following characteristics: (i) high product selectivity for CO2RR and suppression of HER, (ii) long term stability, (iii) large current density, (iv) lower overpotential and (v) low fabrication costs. Most electrocatalysts however suffer from the drawbacks of requiring high overpotentials and typically exhibit a trade-off between selectivity and current density. To circumvent such challenges, in-house PartCat have developed three-dimensional and porous Ag Foam electrodes that converts CO2 to CO. The next step is to further minimize catalyst costs through fabrication of metal-free Graphitic Carbon Nitride/Carbon Nanotube Composite catalysts and further improve the performance of the catalyst through defect engineering. This catalytic performance is among the highest of metal-free catalysts and is even on par with the benchmarked metallic catalysts. Most of the electrodes used in the electroreduction of CO2 are the in the above mentioned form of metal plates, metal granules, or electrodeposited metals on a substrate. However, due to low solubility of CO2 in water under ambient conditions, the reaction rates and current densities of CO2RR are limited by mass transfer of CO2 from the bulk to the solid electrode surface. To improve the reduction process, gas diffusion electrodes (GDE) have been proposed to improve mass transfer limitations across the gas liquid interface and to the catalyst surface. A GDE is a porous composite electrode made of polymer bonded catalyst particles on a carbon support. As GDE can be operated at higher current density, exhibiting high porosity and partial hydrophobicity, GDEs form a characteristic gas-solid-liquid three phase interface, which promote homogenous distribution over catalyst surface.

The aim of this project is to develop a high throughput gas diffusion electrode system and optimized the catalyst performance to improve the production rate of alcohol, so to make this technology financially viable.

The students selected for this project will be given opportunity to work in Particles and Catalysis Research Group (PartCat) at School of Chemical Engineering, under the supervision of Scientia Professor Rose Amal, and Dr Xunyu Lu. The students will have access to state-of-the-art experimentation facilities, mentoring opportunities and fun and nurturing working environment to gain necessary expertise facilitating their career in industry or academic research.

Suitable for: Chemical Engineers and Industrial Chemistry students. Project maybe available to do during summer semester.

Level of difficulty: Challenging

Further information can be obtained by contacting Professor Rose Amal (r.amal@unsw.edu.au) or Dr Xunyu Lu (xunyu.lu@unsw.edu.au