An effective strategy to improve dynamic and cyclic stability of HQC/TiO^sub 2^ photocatalyst by introducing carbon quantum dots or iron ion via metal-complex

A novel photocatalyst, 8-hydroxy-Quinoline-7-carboxylic acid/TiO2 (HQC/TiO2) was synthesized and used to decompose phenol under visible light irradiation. It exhibited excellent photocatalytic activities, about 95.9% of phenol can be degraded after 2 h visible light illumination. However, the recycling efficiency is not very ideal. In order to improve its photostability during recycling process, we had adopted a novel and effective strategy for the introduction of carbon quantum dots or iron ions into the photocatalytic system. Two other novel catalysts, CQDs/HQC/TiO2 and Fe(HQC)3/TiO2 were prepared. After investigated the structure and morphology characteristics of HQC/TiO2, CQDs/HQC/TiO2 and Fe(HQC)3/TiO2 by analysis of X-ray diffraction, FTIR spectra, UV-vis absorption and diffuse reflectance spectra, X-ray photoelectron spectroscopy, transmission electron microscopic and photoelectrochemical properties, the possible and different photocatalytic mechanisms for these three photocatalysts were proposed. On the basis of this, the key factors affecting the dynamic and cyclic stability of HQC/TiO2 by introducing CQDs or Fe3+ ions via Fe-HQC complex were explored.