Development of highly-efficient 0D/1D/0D dual Z-scheme CdS/ZnWO4/ZnS heterojunction photocatalysts in pollutant removal and involved mechanism

Abstract

Rational design of heterostructures is an important strategy for improving photogenerated-carrier separation and photocatalytic activity of semiconductors. Herein, zero-dimensional (0D) CdS and ZnS quantum dots were assembled onto one-dimensional (1D) ZnWO4 (ZWO) nanorods to construct 0D/1D/0D dual Z-scheme CdS/ZWO/ZnS heterojunction photocatalysts. The photodegradation capacities of the photocatalysts were compared by using methylene blue as target pollutant under simulated-sunlight irradiation. The photocatalytic experiments reveal that the dual Z-scheme heterojunction photocatalyst with composition 40 %ZnS/(40 %CdS-ZWO) exhibits an extremely high photodegradation activity with η(50 min) = 99.9 % and kapp = 0.14867 min−1, which is higher than that of bare ZWO, CdS and ZnS as well as that of binary CdS/ZWO and ZnS/ZWO heterojunctions. Multiple measurement techniques, response surface methodology and density functional theory calculation were used to elucidate the characteristics and photocatalytic mechanism of the CdS/ZWO/ZnS photocatalysts. Moreover, the potential application of the CdS/ZWO/ZnS photocatalysts in degrading various organic pollutants (including organic dyes, antibiotics and other serious organic pollutants) was also investigated.