Crystallizer devices and methods of direct air capture of carbon dioxide are described herein. The methods include providing one or more polymeric strands in contact with an alkaline capture solution. Each of the polymeric strands is comprised of a plurality of polymeric fibers that combine to form an outer surface of the polymeric strand. The outer surface of the strand forms a crystallizing surface. The alkaline capture solution travels by way of capillary force from the outer surface of the strand inwardly through intra-strand pores and from a first end of the strand in a direction towards a second end of the strand through intra-strand pores. The methods also include, as the alkaline solution travels towards the second end, contacting the one or more polymeric strands with ambient air such that KOH within the alkaline solution reacts with CO.sub.2 to form K.sub.2CO.sub.3 precipitate at the crystallizing surface.