Unassisted photocatalytic H2O2 production under visible light by fluorinated polymer-TiO2 heterojunction

Photocatalytic H2O2 production is one of the most promising methods because it is a safe and sustainable technique. However, the inactiveness of inorganic photocatalysts (TiO2) under visible light irradiation and severe photodecomposition of H2O2 on their surfaces result in low performance for solar H2O2 production. Here, we report for the first time, a hydrophobic organic/inorganic (polymer/TiO2) heterojunction photocatalyst, which not only can utilize visible light, but also suppress H2O2 decomposition. In the absence of a hole scavenger, the photogenerated H2O2 concentration of the poly(9,9-dioctylfluorene-alt-benzothiadiazole) (PFBT)/TiO2 heterojunction photocatalyst (67 mu M) was >70 times higher than that of pristine PFBT polymer. Further, improvement of polymer hydrophobicity by fluorine substitution results in enhanced photogenerated H2O2 concentration (110.4 mu M) on (Poly(9,9-dioctyl fluorine-alt-difluorobenzothiadiazole) (PF2FBT)/TiO2). The atomistic simulation studies substantiate that the low adsorption energy of H2O2 on the heterojunction and the surface shielding of TiO2 induced by the hydrophobicity of the fluorinated polymers significantly improve H2O2 production.