Construction of Fe3O4@FeS2@C@MoS2 Z-scheme heterojunction with sandwich-like structure: Enhanced catalytic performance in photo-Fenton reaction and mechanism insight

Abstract

Herein, the sandwich-like Fe3O4@FeS2@C@MoS2 composite was prepared via coating MoS2 shell on the surface of core/shell Fe3O4@C composite. During the coating process, Fe3O4 was partly sulfurized to FeS2, whose energy band was well-matched with that of MoS2 for a Z-scheme heterojunction. The residual Fe3O4 ensured the rapid separation of heterojunction by magnet. In photo-Fenton reaction, 81.5% of tetracycline was degraded within 40 min, which was higher than the sum of degradation efficiency of Fenton reaction and photocatalytic reaction. 93.6% of the degradation efficiency in the 1st cycle was still maintained after 5 cycles. In mechanism study, the sources of •OH, •O2-, 1O2 and h+ were carefully traced, and the contributions of these radicals followed the order: •OHsurf>•O2->1O2>h+>•OHfree. An inner electric field was built at the interface by analyzing the energy band and work functions, which driven the charge carriers transfer followed a Z-scheme path. The findings in this manuscript were beneficial for designing catalysts with high photo-Fenton activity.