Unique S-scheme structures in electrostatic self-assembled ReS2-TiO2 for high-efficiency perfluorooctanoic acid removal

Perfluorinated compounds (PFCs), recognized as persistent organic pollutants, resist degradation in the environment due to the high bond energy of the C–F. Increasing carrier density via adopting electrostatic self-assembly strategy has been shown to effectively cleave C–F bonds. In this work, a unique S-scheme structure was fabricated by combining oppositely charged semiconductors, TiO 2 and ReS 2 , through electrostatic self-assembly. The resulting 2 % ReS 2 -TiO 2 composite achieved a photodegradation efficiency of 98 % for perfluorooctanoic acid (PFOA), considerably higher than the 62 % efficiency observed for pure TiO 2 . Additionally, the 2 % ReS 2 -TiO 2 composite demonstrated broad applicability for the removal of other PFCs. The introduction of ReS 2 , with a lower work function than TiO 2 , could generate an internal electric field (IEF) to facilitate electron transfer from TiO 2 to ReS 2 under continuous irradiation and thereby enhance charge separation efficiency.