Anyone who understands the concentration of CO2 in the air knows that these things are nothing but a PR stunt. You're not going to pull enough out of the air to have any meaningful contribution; there's just not a lot there to pull out. For all the harm it's causing, CO2 makes up a tiny part of air composition, only about 0.04%.
These things are built for idiots who think the solution is as simple as "just run the air through a filter" and don't grasp how much air there actually is, and how little there is to pull out.