Graphene oxide modulated dual S-scheme ultrathin heterojunctions with iron phthalocyanine and phase-mixed bismuth molybdate as wide visible-light catalysts

Herein, a phase-mixed Bi3.2Mo0.8O7.5-Bi2MoO6 (2.7BMO) S-scheme nanosheet heterojunction (similar to 4 nm) is successfully synthesized using a microwave-assisted hydrothermal method firstly and then coupled with two-layered iron phthalocyanine (FePc) (similar to 1 nm) via a hydroxyl-induced assembly prior to graphene oxide (G) modification for fabricating an interface-modulated dual S-scheme ultrathin heterojunction (FePc/G/2.7BMO), in which the used G with abundant hydroxyl groups greatly improves the dispersion of FePc on 2.7BMO nanosheets to increase the optimized loading amount from 0.5 to 0.8 wt% with more exposed Fe-N-4 sites. The amount-optimized heterojunction displays greatly improved visible-light activity for tetracycline (TC) degradation, which is 8.5 and 4.3 times higher than those of bare Bi3.2Mo0.8O7.5 and Bi2MoO6 nanosheets, respectively. The exceptional visible-light activity can be attributed to the enhanced charge separation due to the formed interface-modulated dual S-scheme heterojunction, and the extended wide visible-light response and the promoted O-2 activation via the Fe-N-4 sites from the assembled FePc.

Automated summary

In this study, a phase-mixed Bi3.2Mo0.8O7.5-Bi2MoO6 S-scheme nanosheet heterojunction with a size of about 4 nm was synthesized using a microwave-assisted hydrothermal method. The heterojunction was further modified with two-layered iron phthalocyanine (FePc) and graphene oxide (G), resulting in an interface-modulated dual S-scheme ultrathin heterojunction (FePc/G/2.7BMO). The optimized heterojunction demonstrated significantly improved visible-light activity for tetracycline degradation, which was attributed to enhanced charge separation and extended wide visible-light response facilitated by the formed heterojunction and the Fe-N-4 sites on FePc.