Double Z-scheme TiO2 (R)/C-TiO2 (A) heterojunction greatly enhanced efficiency of photocatalytic desulfurization under sunlight

In this paper, rutile phase titanium oxide/Sb-SnO₂/anatase phase titanium oxide (TiO₂ (R)/C-TiO₂ (A)) heterostructured nanocomposites were prepared by a sol–gel method and a hydrothermal method. By optimizing the mass ratio between TiO₂ (R) and C-TiO₂ (A), the rod-ball heterostructures of TiO₂ (R)/C-TiO₂ (A) were formed and exhibited enhanced simulated sunlight-driven photocatalytic desulfurization performance. According to the results, the desulfurization rate of TiO₂ (R)/C-TiO₂ (A) was 93.98% after 60 min, which is higher than C-TiO₂ (A) and TiO₂ (R)/TiO₂ (A). In addition, the photocatalytic recyclability test indicated that after three times the reuse of TiO₂ (R)/C-TiO₂ (A) could still reach 85.98%. The enhanced photocatalytic performance could be attributed to the double Z-scheme heterojunction in the TiO₂ (R)/C-TiO₂ (A) and the uniformly structure of rod array, which resulted in the higher separation efficiency of electrons and holes. Furthermore, the results of photocatalytic active radical species trapping experiments showed that the main substances in the photocatalytic reaction are ∙O₂⁻ and h⁺. This paper also established the double Z-scheme heterojunction reaction mechanism.