Catalytic Combo Converts CO2 to Solid Carbon Nanofibers

[orthoclad]

6. Many carbon compounds are highly toxic

A quick search turned up a lot of material on carbon nano toxicity, such as this from the American Chemical Society:
"The underlying mechanisms of CNT toxicity include oxidative stress, inflammatory responses, malignant transformation, DNA damage and mutation (errors in chromosome number as well as disruption of the mitotic spindle), the formation of granulomas, and interstitial fibrosis. "
https://pubs.acs.org/doi/10.1021/ar300028m
Carbon is highly reactive.

I'd say they would have to be careful of generating toxic compounds, especially if it goes into building materials and other public-facing uses.

That said, this is promising. We could replace many uses of plastic and metal with carbon, reducing the large energy budget for refining metal plus the horrific mess of plastic pollution. We'd have to be careful, though.