Preparation of tungstophosphoric acid/cerium-doped NH₂-UiO-66 Z-scheme photocatalyst: a new candidate for green photo-oxidation of dibenzothiophene and quinoline using molecular oxygen as the oxidant

The goal of this study was to introduce an effective visible-light induced photocatalytic system with a good ability for photocatalytic oxidative desulfurization (PODS) and denitrogenation (PODN) using molecular oxygen (O₂) as an oxidant. In this regard, tungestophosphoric acid (PW₁₂) was supported onto cerium-doped NH₂-UiO-66 (PW₁₂/Ce-NUiO-66) and employed for the photo-oxidation of dibenzothiophene (DBT) and quinoline (Qu). Herein, using cerium (Ce) as a “mediator” facilitated the separation of charge carriers, while NH₂-UiO-66 remarkably enhanced the surface area with plentiful adsorption sites and shifted the adsorption edge of PW₁₂to the visible region. The sum of these factors resulted in superior photocatalytic ability and maximum efficiency of 99 ± 1% was achieved by using 30PW₁₂/Ce-NUiO-66 as the optimum photocatalyst in the PODN system and 89 ± 1% in the PODS system under visible light irradiation for 90 min. The traditional Z-scheme mechanism was proposed as the main pathway for this photocatalytic system.