In-situ generation of oxygen vacancies and Bi0 clusters on MoSe2/Bi@BiOBr-OV via Fermi inter-level electron transfer for efficient elimination of chlorotetracycline and Cr (VI)

Abstract

Efficient elimination of recalcitrant organics-heavy metals combined pollutants from wastewater is critical. In this study, the MoSe2/Bi@BiOBr photocatalysts were synthesized through simply controlling the amount of MoSe2 in the hydrothermal process, and during which, oxygen vacancies (OVs) and Bi0 nanoclusters (NCs) were in-situ generated on the BiOBr via electron transfer in the Fermi energy level equilibrium process. Results showed that excellent synchronous removals of chlorotetracycline (95.4%) and Cr (VI) (95.6%) by the 15MoSe2/Bi@BiOBr-OV were achieved within 90 min of visible light illumination, attributing to the synergy effect of S-scheme heterojunction, Bi0 NCs and OVs. The oxygen temperature programmed desorption (O2-TPD) demonstrated that OVs could promote adsorption of surface oxygen. Density functional theory (DFT) revealed that Bi0 NCs and OVs possessed electron-rich and hybridized charge orbitals that could facilitate transfer of photogenerated electrons on energy bands. Furthermore, possible degradation pathways of chlorotetracycline were proposed, and most of its intermediates exhibited lower ecotoxicity. This study sheds light on enhancing photocatalytic activity of heterojunctions for pollution control by taking advantage of synergistic effect of OVs and surface metal clusters.