Scaling Carbon Dioxide Removal
A high school student will be able to give you a list of materials that will react with carbon dioxide - there are plenty of them. One might also research for years and come up with novel materials that absorb, adsorb or transform carbon dioxide.
That is not all. This is only the first part.
The challenge lies in scaling. The challenge lies in disproportionately scaling carbon capture or removal with respect to the cost in a given period of time, so as to bring down the cost per tonne.
It does not only require innovation in chemistry or material science but also in engineering.