Enhanced Photoexcited Carrier Separation in Oxygen-Doped ZnIn2 S4 Nanosheets for Hydrogen Evolution.

Limited by the relatively sluggish charge-carrier separation in semiconductors, the photocatalytic performance is still far below what is expected. Herein, a model of ZnIn2 S4 (ZIS) nanosheets with oxygen doping is put forward to obtain in-depth understanding of the role that doping atoms play in photocatalysis. It shows enhanced photocatalytic activity compared with pristine ZIS. The electron dynamics analyzed by ultrafast transient absorption spectroscopy reveals that the average recovery lifetime of photoexcited electrons is increased by 1.53 times upon oxygen incorporation into the ZIS crystals, indicating enhanced separation of photoexcited carriers in oxygen-doped ZIS nanosheets. As expected, the oxygen-doped ZIS nanosheets show a remarkably improved photocatalytic activity with a hydrogen evolution rate of up to 2120 μmol h(-1)  g(-1) under visible-light irradiation, which is 4.5 times higher than that of the pristine ZIS nanosheets.