In situ growth of carbon nitride coatings on silica-alumina-based engineering materials via phosphorus-mediated interfacial anchoring for visible-light photodegradation.

Although photocatalytic functional coatings represent a promising pathway for self-cleaning engineering materials, most existing systems suffer from poor durability due to weak physical attachment and limited solar energy utilization owing to their reliance on ultraviolet light. In this work, an H3PO4-assisted polymerization strategy is employed to construct a stable photocatalytic coating, enabling the growth of phosphorus-doped carbon nitride on glass mosaic tiles primarily composed of SiO2 and Al2O3, which exhibits efficient photodegradation of methylene blue, rhodamine B, and methyl orange under visible-light irradiation (400-700 nm), with apparent pseudo-first-order rate constants of 0.04282, 0.02239, and 0.00831 min-1, respectively (at complete decolorization, the mineralization rates reached 59.2%, 59.6%, and 48.8%, respectively). Mechanistically, H3PO4 not only participates in interfacial reactions with SiO2 and Al2O3 in Tile, generating P-containing anchoring environments that couple P-CN to the substrate, but also serves as the P source for doping the CN framework, thereby modulating its electronic structure, extending light absorption into the visible region, and promoting the separation and migration of photogenerated charge carriers, ultimately enabling efficient visible-light-driven photocatalysis. Notably, proof-of-concept experiments further extend this interfacial growth strategy to other silica/alumina-based materials, including mullite and clay bricks, supporting its potential for integrating photocatalysts with durable self-cleaning engineering materials.