Mesostructured graphitic carbon nitride composites with silver nanoparticle decoration as the best visible-light-driven photocatalysts for dye degradation and H₂ production

Water-splitting photocatalysis on the surface of semiconductors has emerged as a promising approach for wastewater treatment to remove organic pollutants from aqueous media in various industrial fields. However, developing efficient photocatalysts with sufficient activity is challenging owing to the rapid recombination of photogenerated electrons and holes in the available functional materials. Aiming to fabricate photocatalysts to remove pollutants with reduced electron-hole recombination, mesostructured graphitic carbon nitride (MCN) composites made of Ag-doped melamine were designed and synthesized at room temperature. The structural and optical properties of the prepared MCN composite indicate that it is well-suited for use as a visible-light-driven photocatalyst. A morphological analysis using transmission and scanning electron microscopy showed that the Ag nanoparticles were uniformly distributed on the surface of the MCN sheets, promoting the photocatalytic property of the Ag/MCN composites. Adding silver nanoparticles onto MCN facilitates the rapid transfer of photo-generated electrons from MCN to the silver nanoparticles. This is due to the presence of an interfacial electric field across the junctions, leading to a reduction in the recombination process, resulting in superior photocatalytic activity in the degradation of reference organic pollutants like methylene blue and crystal violet, more than 96% of degradation was achieved in the presence of the MCN\Ag-MCN composite. An astonishing photocatalytic hydrogen evolution rate of 5.24 mmol. g- 1.h-1 was observed for the optimized MCN/Ag-MCN nanocomposite.