Ag/Bi_2MoO_(6-x) with enhanced visible-light-responsive photocatalytic activities via the synergistic effect of surface oxygen vacancies and surface plasmon

摘要

Graphical abstractA rational designed and fabricated photocatalyst Ag/Bi2MoO6−xwith surface oxygen vacancies (SOVs) and surface plasmonic (SP) Ag shows a very highly catalytic performance for the RhB photodegradation due to dual synergistic effect of SOVs and SP resonance.Display OmittedHighlights•The preparation of Bi2MoO6−xwith surface oxygen vacancies.•The fabrication of heterostructured Ag/Bi2MoO6-xphotocatalyst.•Synergistic effect of surface oxygen vacancy and surface plasma resonance effect.•Very highly catalytic performance of Ag/Bi2MoO6-xfor the RhB photodegradation.AbstractIn this study, a heterostructured Ag/Bi2MoO6-xphotocatalyst was rationally designed and successfully fabricatedviathe deposition of plasmonic silver nanoparticles onto the surface of Bi2MoO6with surface oxygen vacancy (denoted as Bi2MoO6−x). Bi2MoO6−x(Abbr. BMO6-xwas first synthesizedviaa solvothermal synthesis and calcination process. The plasmonic silver nanoparticles were then loaded onto the surface of BMO6−xusing a simple photoreduction process to form Ag/BMO6−xcomposite. Surface oxygen vacancies (SOVs) in BMO6−xwere confirmed by electron paramagnetic resonance (EPR) spectrum. The structures of BMO6−xand Ag/BiMoO6−x) were characterized using high-resolution transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. Under visible light irradiation, sample Ag/BMO6−xexhibits a highest visible-light-responsive photocatalytic performance compared to those of pure-Bi2MoO6(BMO), BMO6−xand Ag/BMO for the degradation of rhodamine B (RhB), which is attributed predominantly to the synergistic effect of SOVs and Ag surface plasmonic resonance (SPR) on the surface of Bi2MoO6−xleading to the efficient separation and migration of photogenerated electrons/holes and hence broadening light responsive region. The significant improvement of the migration and separation of photogenerated electrons/holes in the Ag/BMO6−xwas evidenced by photoluminescence spectra, time-resolved fluorescence decay, photocurrent, and electrochemical impedance spectrum. The ESR with spin-trap technique and reactive species trapping experiments confirm that the mainly active species O2−and h+are playing key roles in the RhB photodegradation process over Ag/BMO6−x. This study not only provides an understandable synergistic effect of SOVs and SPR Ag but also pioneers a new approach for fabricating a series of highly catalytically active metal-semiconductor photocatalysts with surface atom defects.