Sustainable Synthesis of P-Doped Carbon Nitride From Fertilizer Sources for Enhanced Photocatalysis

The contamination of rivers, lakes, and oceans by synthetic toxic dyes has become a critical issue that is undermining water safety around the globe. Metal-free semiconductors, and in particular the family of carbon nitrides, represent an appealing solution to degrade pollutants triggered by solar light illumination. Here, we present a new fabrication strategy for phosphorus-doped carbon nitride starting from two abundant fertilizers widely used in agriculture: thiourea and diammonium phosphate. We show that in the resulting P-doped carbon nitride P is incorporated by substitution of C atoms in the lattice, eventually increasing the population of photoexcited states and efficiently suppressing charge-carrier recombination. Doped samples, and specifically the one obtained with an initial 1 %wt of P dopant in the precursor, demonstrate superior abilities in the degradation of four persistent dyes (Rhodamine B, malachite green, indigo carmine, Congo red) compared to the pristine carbon nitride. This P-doped semiconductor efficiently catalyzes the quantitative photodegradation of common dyes in less than 60 min, thus proving noteworthy versatility and applicability for use in environmental remediation applications.