From Melamine-Cyanuric Acid Supramolecular Aggregates to Carbon Nitride Hollow Spheres

Graphitic carbon nitride (g‐CN) is a promising heterogeneous metal‐free catalyst for organic photosynthesis, solar energy conversion, and photodegradation of pollutants. Its catalytic performance is easily adjustable by modifying texture, optical, and electronic properties via nanocasting, doping, and copolymerization. However, simultaneous optimization has yet to be achieved. Here, a facile synthesis of mesoporous g‐CN using molecular cooperative assembly between triazine molecules is reported. Flower‐like, layered spherical aggregates of melamine cyanuric acid complex (MCA) are formed by precipitation from equimolecular mixtures in dimethyl sulfoxide (DMSO). Thermal polycondensation of MCA under nitrogen at 550 °C produces mesoporous hollow spheres comprised of tri‐s‐triazine based g‐CN nanosheets (MCA‐CN) with the composition of C3N4.14H1.98. The layered structure succeeded from MCA induces stronger optical absorption, widens the bandgap by 0.16 eV, and increases the lifetime of photoexcited charge carriers by twice compared to that of the bulk g‐CN, while the chemical structure remains similar to that of the bulk g‐CN. As a result of these simultaneous modifications, the photodegradation kinetics of rhodamine B on the catalyst surface can be improved by 10 times. Simple molecular engineering of triazine precursors enables simultaneous optimization of the texture and photoelectric properties of graphitic carbon nitride (g‐CN). Thermolysis of flower‐like supramolecular aggregates of melamine and cyanuric acid yields the formation of mesoporous g‐CN hollow spheres with the typical nanosheet‐type structure preserved in the microspheres. Such structures are highly active in the photocatalytic degradation of organic pollutants.