I actually don't think this would be that useful for space flight or terraforming really. CO2 is still two parts oxygen. Assuming the atmosphere isn't already full of O2 and we want it to be, we want to convert it from CO2 into O2 (like plants do), not into this form. I guess it could be useful if we want to decrease atmospheric pressure too maybe?

It could be useful for a short-term solution, where we don't need to recover CO2 for breathing, and just want to remove it and store it. I don't think it'd likely ever be more efficient than existing technology for this though.