Development of a membrane-electrolyte composite for inhibiting metal cation transport in alkaline CO2 electrocatalysis

Abstract: With earth’s energy consumption rapidly growing, need for alternate energy sources is crucial. Electrochemical CO₂ reduction is a very attractive option in this category, as it turns a waste into useful chemicals fuels and feedstocks, thus closing the carbon cycle and moving towards a carbon-neutral economy.  

Electrolyzers are the first choice for reducing CO₂ electrochemically, but the technology is still at growing stage. Alkaline CO₂ electrolyzers are most promising with their higher selectivity to fuel products than any other type of electrolyzers. However, there are certain drawbacks associated with the different components of the cell, which needs improvement for higher energy efficiency of the device and an overall long-term performance.

The transport inside the CO₂ electrolyzer is extremely important in terms of overall cell performance. For that, a perfect membrane-electrolyte combination is required to improve the cell efficiency and longevity and needs to be worked on. In an alkaline electrolyzer, a combination of alkali metal hydroxides/bicarbonates as the electrolyte, and commercial anion exchange membranes (AEMs), specific towards anion transport from cathode to anode in the cell is used. However, the commercial membranes are not always specific to anions, and transport the metal cations to the cathode side, leading to formation of (bi)carbonate salts. As the salt concentration on the cathode exceeds the solubility product, solid salt crystals start precipitating, blocking the active sites, and the flow channels in long term operation. However, the presence of metal cations is important for tuning the electric field and increase the CO₂ reduction efficiency increasing the product formation. Hence, identifying the factors affecting the ion transport and to optimize them (both cation and anions) to achieve superior performance of electrolyzer thus remains a research question to the scientific community.

Work description: The student will perform systematic screening of the electrolyte/membrane/electrode assembly in the electrolyzer system at imec. The ion transports will be quantified by ICP-MS and gas chromatograph, respectively. pH analysis and mathematical models will also be used to confirm and optimize the ion transports. Initial experiments will be conducted on planar electrodes, and then the optimized system will be used on nanomesh electrodes developed at imec.

Contacts: philippe.vereecken@imec.be

                 debittree.choudhury@imec.be