Heterostructured PHI-PTI/Li+Cl- Carbon Nitrides for Multiple Photocatalytic Applications

Abstract

[EN] Two series of novel carbon nitride photocatalysts, Rho-CN ("rhodizonate-doped carbon nitride") and Rho-CN-TC (Rho-CN treated in potassium thiocyanate melt), are synthesized in a multistep fashion via copolymerization of cyanamide with potassium rhodizonate. The formed ionic carbon nitrides are composed of poly(triazine imide) (PTI/Li+Cl-) and potassium poly(heptazine imide) (K-PHI) phases and provide a broad absorption range up to 800 nm. The photocatalysts are characterized by several techniques (including diffuse reflectance ultraviolet-visible, powder X-ray diffraction, Fourier transform infrared, scanning electron microscopy, and electrochemical methods) and studied in a series of photocatalytic reactions, including red light-promoted benzylamine oxidation, dual photoredox/nickel C-N cross-coupling, and hydrogen peroxide evolution. The optimal ratio of rhodizonate dopant in its mixture with cyanamide is found to be 0.5 mol%. The performance of the newly synthesized materials is comparable to the activities of the benchmark catalysts K-PHI and CN-OA-m (defective poly(heptazine imide) doped with oxamide), while not requiring more expensive nitrogen sources for preparation, like 5-aminotetrazole, or multiple oven cycles.