RSC Adv., 2016, 6, 76259

Synergistic interactions of Cu and N on surface
altered amorphous TiO2 nanoparticles for
enhanced photocatalytic oxidative desulfurization
of dibenzothiophene†

Amorphous TiO2 (AT) nanoparticles were prepared by a simple sol–gel method and subsequent
incorporation with copper (5–20 wt%) via an electrochemical method in the presence of a supporting
electrolyte, tetraethylammonium perchlorate (TEAP), was used to synthesize CuO/TiO2 (CAT) catalysts.
The physicochemical properties of the catalysts were studied by XRD, N2 adsorption–desorption, TEM,
FTIR, XPS, ESR and UV-Vis DRS. Photocatalytic testing on the oxidative desulfurization of
dibenzothiophene (DBT) under UV and visible light irradiation demonstrated that the CAT catalysts were
active under both conditions. It was found that Ti3+ surface defects (TSD), oxygen vacancies (Vo), CuO,
Ti–O–N/O–Ti–N and Ti–O–Cu bonds played an important role in photooxidation. The TSD, Vo, CuO, N
1s and Cu 2p states in the CAT catalysts acted as electron trappers to hinder electron–hole
recombination. In addition, these TSD, Vo, N 1s and Cu 2p species also contributed to the lowering of
the CAT band gap, which enabled photooxidation to be carried out in the visible light region. The
photooxidation followed a pseudo-first order Langmuir–Hinshelwood model with adsorption being the
controlling step.