N-doped rutile TiO2/C hybrids with enhanced charge transfer capability derived from NH2-MIL-125(Ti) for the photocatalytic degradation of tetracycline

Abstract

The photocatalytic efficiency of rutile is limited by the degree of visible light-harvesting absorption, electronic transfer capacity and surface reactivity. In this work, N-doped rutile TiO2/C (NM-A-900) is synthesized by calcinating NH2-MIL-125(Ti) for photocatalytic degrading tetracycline (TC). Several characterizations are employed to study the physicochemical and photoelectrochemical properties of the calcinated materials. Apart from the enhanced visible light-harvesting ability and charge transfer capability, N-doped rutile TiO2/C even demonstrates better photocatalytic performance than that of N-doped anatase TiO2/C (NM-A-700) and N-doped mixed-phase TiO2/C (NM-A-800) and the TC degradation efficiency of NM-A-900 reaches 96%. The generations of ·O2− and ·OH radicals are studied to analyze the photocatalytic mechanism of NM-A-900. Because of the existence of heteroatoms, charge transfer from the interior of N-doped TiO2 to the catalyst surface before further migrating to N-doped C for rapid migration and react with adsorbed water and oxygen to form radicals for the TC mineralization.