Preparation of Hydroxynaphthalene-Modified TiO2 via Formation of Surface Complexes and their Applications in the Photocatalytic Reduction of Nitrobenzene under Visible-Light Irradiation

Visible light-sensitive photocatalysts were designed by the surface modification of TiO2 using hydroxynaphthalenes, i.e., mono- and dihydroxy derivatives of naphthalene, via formation of surface complexes. The differences in the coordination ability on TiO2 were confirmed depending on the numbers and substitution patterns of hydroxy groups. The relatively intense visible light absorption was observed after modification of TiO2 surface by colorless 2,3-dihydroxynaphthalene (2,3-DN) having two neighboring hydroxy groups. Platinized TiO2 (Pt-TiO2) modified with suitable amount of 2,3-DN showed higher photocatalytic performances and good reusability in the reduction of nitrobenzene to aminobenzene with relatively high selectivity under irradiation of visible light (lambda > 420 nm).