The photo-Fenton process employs light, iron species, and H2O2 to oxidize organic pollutants. In this study, a coordination complex, Fe(II)–terpyridine, was covalently grafted onto TiO2 surfaces via a light-harvesting linkage for use in the photo-Fenton reaction. The surface Fe(II)–terpyridine complex was characterized with techniques, including microscopy and spectroscopy, and was investigated in the degradation of Orange II in the presence of H2O2. Under visible-light irradiation, slightly higher activity was obtained using the surface Fe(II)–terpyridine catalyst than using photoactivated TiO2 nanoparticles under UV light. Furthermore, the Fe(II)–terpyridine complex grafted on TiO2 showed significantly greater activity than the same complex grafted on ZrO2 in the degradation of Orange II. A possible explanation for this observation was discussed that involves the formation of high valent oxoiron species on TiO2 in the photo-Fenton process.
