Ultrathin mesoporous g-C3N4/NH2-MIL-101(Fe) octahedron heterojunctions as efficient photo-Fenton-like system for enhanced photo-thermal effect and promoted visible-light-driven photocatalytic performance

Highlights: • Ultrathin mesoporous g-C₃N₄/NH₂-MIL-101(Fe) photocatalyst is synthesized. • Ultrathin mesoporous g-C₃N₄ promotes the generation of H₂O₂. • It exhibits excellent photocatalytic performance and photo-thermal effect. • It owes to the coupling effect of photocatalysis and Fenton-like system. Ultrathin mesoporous g-C₃N₄/NH₂-MIL-101(Fe) octahedron heterojunctions photocatalysts are successfully constructed through the solvothermal method of loading the ultrathin mesoporous g-C₃N₄ (U-g-C₃N₄) onto NH₂-Iron metal-organic framework (Fe-MOF). The homogeneous growth of U-g-C₃N₄ on NH₂-MIL-101(Fe) is not only distinctly conducive to the illumination to MOF substrate but also the diffusion of reactants and products. Due to the presence of iron trivalent in Fe-MOF, the Fenton-like system is formed, which can further promote the photocatalytic efficiency. The optimum heterojunction photocatalyst, M101-U₆ (6% mass ratio of ultrathin g-C₃N₄), reveals a highest photocatalytic efficiency to degrade 2,6-dichlorophen and 2,4,5-trichlorophenol, up to 98.7 and 97.3% respectively within 3 h. Meanwhile, the yield of hydrogen peroxide for M101-U₆ is raised to 69 μM within 3 h, about 2.2 times superior to the single ultrathin g-C₃N₄, significantly promoting the formation of hydroxyl radicals. In addition, the photo-thermal effect of M101-U₆ is enhanced for this heterojunction photocatalyst and Fenton-like coupling system, which could further improve the photocatalytic degradation performance. This two-in-one strategy of combining photocatalysis with Fenton-like has broad prospects on establishing novel photocatalysts for eliminating high-toxic organic pollutants and generating O₂ concurrently in aquatic environment.