Direct Growth of Highly Organized Crystalline Carbon Nitride from Liquid-Phase Pulsed Laser Ablation

The novel technique of liquid-phase pulsed laser ablation has been used to obtain unique, highly ordered nanostructures of crystalline carbon nitride (C 3 N 4 ) via ablation of a graphite target submerged in aqueous ammonia solution. Transmission electron microscopy (TEM) analysis shows that the morphology of the carbon nitride material changes at different length scales, depending upon the synthesis conditions. The initial ablation product comprises spherical nanoparticles of carbon nitride, which then elongate to nanorods (10 nm by ∼200 nm) with further ablation. Given sufficient concentration, the nanorods aggregate to form multilayered structures, and then ultimately larger, ordered “leaf-shaped” structures 30−50 nm by ∼200 nm in size. With even higher concentration, these leaflike structures can themselves aggregate to create interconnected networks of large micrometer scale clusters, which ultimately rearrange to micrometer-sized flowerlike structures. The various nanostructures were characterized using a number of analysis techniques, and their composition was found to be consistent with that of crystalline α- or β-phase carbon nitride. A formation mechanism for these structures is proposed that rationalizes the observed morphologies.