We can draw carbon from the atmosphere, sure. It's an inefficient process costing a lot of energy, but given they're making the final rings molecule by molecule

We can draw carbon from the atmosphere, sure. It's an inefficient process costing a lot of energy, but given they're making the final rings molecule by molecule, it isn't as if we'd need a lot. ...for the purposes of scrubbing CO2 from the air? There's absolutely no reason we'd use this as the final product. Graphite or diamond would do the trick just as well, and either is cheap to make.