If we could capture carbon by itself, we wouldn't bury it, we could make all kinds of stuff with it. The problem, approximately, is that you get energy from oxidising stuff, and have to put energy in to reduce it.

Of course, turning solar energy plus carbon dioxide into sequestered carbon and O2 is what plants do, but evidently not enough compared to human action. I do wonder whether biological (plants, algae) action, aided by genetic modification, could do more for atmospheric CO2.