Fully Condensed Poly (Triazine Imide) Crystals: Extended π-Conjugation and Structural Defects for Overall Water Splitting

Conventional polymerization for the synthesis of carbon nitride usually generates amorphous heptazine-based melon with an abundance of undesired structural defects, which function as charge carrier recombination centers to decrease the photocatalytic efficiency. Herein, a fully condensed poly (triazine imide) crystal with extended pi-conjugation and deficient structure defects was obtained by conducting the polycondensation in a mild molten salt of LiCl/NaCl. The melting point of the binary LiCl/NaCl system is around 550 degrees C, which substantially restrain the depolymerization of triazine units and extend the pi-conjugation. The optimized polymeric carbon nitride crystal exhibits a high apparent quantum efficiency of 12% (lambda = 365 nm) for hydrogen production by one-step excitation overall water splitting, owing to the efficient exciton dissociation and the subsequent fast transfer of charge carriers.

Automated summary

A fully condensed poly(triazine imide) crystal with extended pi-conjugation and deficient structural defects was successfully synthesized by conducting polycondensation in a mild molten salt of LiCl/NaCl. The optimized polymeric carbon nitride crystal exhibits high apparent quantum efficiency for hydrogen production in overall water splitting due to efficient exciton dissociation and fast transfer of charge carriers.