Enhanced adsorption and photocatalytic removal of PFOA from water by F-functionalized MOF with in-situ-growth TiO2: Regulation of electron density and bandgap

• F-TiO 2 @MIL-125 was adsorption-photocatalytic dual-functional. • The linked fluorine groups acted as primary adsorption sites for PFOA. • The in-situ growth TiO 2 had better synergy with MOF in photocatalysis. • The enhanced degradation was due to narrowed bandgap and electron density variation. • F-TiO 2 @MIL-125 exhibited stability and universality in different water applications. PFOA has caused enormous environmental risks with recalcitrance, toxicity, and bioaccumulation, while the degradation of PFOA is still a challenging topic related to the high energy of C F bonds. However, the conventional methods such as biological oxidation, electrochemical oxidation and membrane separation have their own drawbacks. Actually, adsorption-photocatalysis is considered a potential treatment due to effectiveness and thoroughness. Instead of preparing the composite material by adding TiO 2 , the method to in-situ grow TiO 2 in the MOF (MIL-125(Ti)) was carried out, which achieved narrowed band gap and improved the photoresponse ability, simultaneously. Furthermore, the surface F-functionalized MOF provided more available special adsorption sites for PFOA enrichment. Linked fluorine groups not only improved the adsorption capacity (185.151 μmol/g) but also enhanced the photocatalytic rate (1.221 E −4 /s) by altering the electronic density of VB and CB. The constructed F-TiO 2 @MIL-125 stepwise degraded PFOA through a dominant ·OH attack pathway and maintained the oxidize ability of h + to PFOA. As a bifunctional material for adsorption and photocatalysis, F-TiO 2 @MIL-125 was able to be applied in various water environments repeatedly, which has unlimited environmental application potential.