The defluorination efficiency substantially decreased without hole scavengers (TEOA), owing to the photocorrosion of CdS NCs (Supplementary Fig. ). In addition, the presence of molecular oxygen resulted in low defluorination efficiency (Supplementary Fig. ). Several researchers have suggested that hydroxyl radicals generated by photogenerated holes are involved in PFAS decomposition. Although we detected hydroxyl radicals with a hydroxyl radical probe (terephthalate anion) upon light irradiation, the generation of hydroxyl radicals was suppressed by the addition of TEOA (Supplementary Fig. ). These results suggest that the photogenerated holes mainly lead to photocorrosion and do not contribute to the decomposition of PFOS in this system.