Synthesis and Photocatalytic Decolorization Performance of a THPP/TiO₂/Ag@ACF Aerogel Multiphase Composite

Recoverable photocatalysts with broad optical response are of interest for practical water treatment. A 5,10,15,20-tetrakis(4-hydroxyphenyl)porphyrin (THPP)/TiO₂/Ag composite was prepared hydrothermally and immobilized on activated carbon fiber (ACF) aerogel by silane-assisted dip coating. The design combined potential THPP photosensitization and Ag-mediated interfacial effects with TiO₂ photocatalytic sites and an adsorptive, recoverable ACF support. Structural and spectroscopic characterization supported incorporation of the components and changes in optical response and emission behavior. Overall apparent methylene blue removal reached 88.7% under UV irradiation and 88.0% under xenon-lamp irradiation. The concentration profiles were approximately fitted using an apparent pseudo-first-order model. Increasing the number of immersion cycles did not further improve the photocatalytic performance. These results demonstrate adsorption-assisted dye removal using an immobilized multiphase composite. The proposed charge-transfer pathway is presented as a mechanistic interpretation rather than a directly established electronic configuration.