Improved photodegradation of a superabsorber via carbon dots as electron transfer stations

Superabsorbers have been widely used in industrial and daily chemical products. Polymerized sodium acrylate (PAA-Na) is the most popular superabsorber used in diapers. Here we report the enhanced photodegradation of PAA-Na via carbon dots (CDs) in aqueous solutions. For a system comprising PAA-Na and CDs, CDs act as photosensitizers which improve the photodegradation efficiency by ∼5.6% compared with PAA-Na alone. Moreover, for PAA-Na+TiO2+CDs system, CDs also play the role of transfer stations of excited electrons which facilitate electron transfer from TiO2 nanoparticles (NPs) to PAA-Na and further boost the photodegradation efficiency of PAA-Na by ∼9.8%. Based on the spectral results, electrons can hardly transfer from TiO2 NPs to PAA-Na directly even with a bigger driving force compared with CDs; however, CDs can provide effective electron transfer channels within CDs-TiO2 NPs and CDs-PAA-Na which finally build an efficient pathway for electron transfer from TiO2 NPs to PAA-Na. This study reveals the great potential applications of CDs in photodegradation fields as photosensitizers or mediators to promote electron transfer efficiency.