Simple organic cooperative assembly of triazine molecules leads to three‐dimensional macroscopic assemblies of low‐dimensional graphitic carbon nitrides (g‐CNs), for example, nanoparticles, nanotubes, and nanosheets. The approach enables the characterization of the cooperative properties and photocatalytic activities of low‐dimensional g‐CN materials in hydrogen evolution reactions from water under visible light.

A turn-on fluorescence sensor, Cu²⁺–c-mpg-C₃N₄, was developed for detection of CN⁻ in aqueous solution by simply mixing cubic mesoporous graphitic carbon nitride (c-mpg-C₃N₄) and aqueous solution of Cu(NO₃)₂. The highly sensitive detection of CN⁻ with a detection limit of 80 nM is not only possible in aqueous solution but also in human blood serum.