Local Light‐Controlled Generation of Calcium Carbonate and Barium Carbonate Biomorphs via Photochemical Stimulation

Photochemical activation is proposed as a general method for controlling the crystallization of sparingly soluble carbonates in space and time. The photogeneration of carbonate in an alkaline environment is achieved upon photo‐decarboxylation of an organic precursor by using a conventional 365 nm UV LED. Local irradiation was conducted focusing the LED light on a 300 μm radius spot on a closed glass crystallization cell. The precursor solution was optimized to avoid the precipitation of the photoreaction organic byproducts and prevent photo‐induced pH changes to achieve the formation of calcium carbonate only in the corresponding irradiated area. The crystallization was monitored in real‐time by time‐lapse imaging. The method is also shown to work in gels. Similarly, it was also shown to photo‐activate locally the formation of barium carbonate biomorphs. In the last case, the morphology of these biomimetic structures was tuned by changing the irradiation intensity.