Evaluating contaminants in CO2 electrolysis
In today’s post, we will focus on evaluating the contaminants in CO2 electrolysis. The electrochemical CO2RR produces valuable fuels and feedstocks powered by renewable electricity, allowing for a pathway to close the carbon cycle and to restore renewable energy.
As many as sixteen different products have been reported for CO2RR on Cu, highlighting the myriad possible reaction pathways for hydrocarbon and oxygenate production with C-C bond formation. However, particularly at low electrolysis currents, the detection sensitivity becomes more challenging and the possible influence of contaminants is more significant.
One potential source of contaminants is from the ion-exchange membrane commonly employed in electrolysis cells to separate the anode and cathode half reactions. These membranes may still contain an appreciable number of solvents or preservatives used in their fabrication and processing. As researchers become increasingly proficient at designing catalysts and electrochemical systems for CO2RR to complex multi carbon products, it is vital to eliminate sources of error which could contribute to spurious product identification.
A study in the Journal of CO₂ Utilization titled “Assessing contaminants from ion-exchange membranes in the evaluation of aqueous electrochemical carbon dioxide reduction” gives an in-depth study of such contaminants derived from mainstream commercial ion exchange membranes. The study (see table below) shows that Sustainion is the only membrane free of any contaminating products after its recommended KOH pretreatment.