Phenyl-grafted carbon nitride semiconductor for photocatalytic CO ₂ -reduction and rapid degradation of organic dyes

Molecular engineering of graphitic carbon nitride (g-C ₃ N ₄ ) is achieved by the copolymerization of π-conjugated phenyl urea, melamine, and urea. Integration of aromatic phenyl rings into the heptazine network of g-C ₃ N ₄ alters its structural, optical and electronic properties. The fusion of the polymeric g-C ₃ N ₄ core with aromatic phenyl groups induces band gap tuning, which greatly improves the separation and lifetime of charge-carriers. As a result, CO ₂ photoreduction experiments conducted by using phenyl-grafted g-C ₃ N ₄ afford methane and formic acid in high yields. Furthermore, a selective model organic pollutant rhodamine B dye is rapidly decomposed under visible-light irradiation. This work suggests that pyrolysis of a suitable aromatic π-deficient molecular dopant such as phenyl urea can drastically alter the photo-response of the carbon nitride photocatalyst and may enhance its photocatalytic activity. Hence, the present work is expected to be of significant value in sustainable energy production and environmental remediation.