<aside> 🔑 Top Results: Now I understand the structure of ECCs.
Currently, my goal is to build an electrolyzer to convert CO2 to battery-grade graphite. The main questions surrounding that are:
Throughout this memo, I try to answer the first question (mostly) and a bit of the second question.
<aside> âť“ A list of common terminology is listed at the bottom of this memo.
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A typical electrochemical converter (ECC) or electrolyzer is comprised of FOUR major parts – the cathode, the electrolyte, the anode, and the ion-exchange membrane.
The cathode is where the CO2 reduction reaction and the competing hydrogen evolution reaction (HER) occur while the oxygen evolution reaction (OER) occurs at the anode.
Since the CO2 reduction happens at the cathode, most research is focused on efficient cathode catalysts for better CO2 reduction/conversion.
Electrochemical reduction of CO2 to graphite was achieved here by Thapaliya et al, where they used a “nickel foam as the cathode in the electrochemical conversion of CO2 in a molten Li2CO3 [electrolyte] resulting in the formation of a structured graphite micro foam.” There is little other public research done in this area. I’ve seen patents from other companies trying to do something similar like Maple Materials which use the same electrolyte, but don’t disclose their cathode.
Choosing a catalyst will likely be its own topic in future memos.
For efficiency, the catalyst should yield a single product with minimal byproducts. Here is the relevant research for some strategies on optimizing the catalyst: