There's a ton of research happening (99% of it in China, as far as I can tell) around turning CO2 molecules into useful multi-carbon molecules.

This one describes an interesting thermal pathway that uses barium. It stands alongside calcium looping (https://en.wikipedia.org/wiki/Calcium_looping), although this is slightly better in that the temperatures involved are lower and the materials are easier to regenerate.

I'm personally interested in electrochemical pathways to generate fuels, although it seems like these are even further away from commercialization.