Facet-Heterojunction-Based Z-Scheme BiVO₄{010} Microplates Decorated with AgBr-Ag Nanoparticles for the Photocatalytic Inactivation of Bacteria and the Decomposition of Organic Contaminants

Abstract

In the past few years, BiVO4 has received much research attention as one of the most promising photocatalysts to deal with pathogenic bacteria and organic pollutants in wastewater. However, low photocatalytic efficiency is still the main obstacle to its practical applications. Herein, we first fabricated a facet-heterojunction-based Z-scheme photocatalyst AgBr-Ag-BiVO4{010} (BiVO4{010} microplates decorated with AgBr-Ag nanoparticles) to boost the photocatalytic activity of BiVO4 for bacterium inactivation and organic pollution treatment. On account of the directed migration of photogenerated electrons in BiVO4, Ag nanoparticles were selectively produced on the {010} facets of BiVO4 microplates during photoreduction, and the out layer of Ag nanoparticles was subsequently transformed into AgBr via the co-operation of Fe3+ and Br–. The photocatalytic Escherichia coli K-12 inactivation results indicated that AgBr-Ag-BiVO4{010} displays optimal photocatalytic activity for bacterium inactivation among the current BiVO4-based photocatalytic materials, which was ∼4 and 15 times higher than those of Ag-BiVO4{010} and BiVO4, respectively. Scanning electron microscope (SEM) results revealed that the inactivation of E. coli bacteria is due to the breaking of their cell wall and leakage of the cytoplasm. Moreover, AgBr-Ag-BiVO4{010} also shows excellent photocatalytic activity in terms of tetracycline (TC) and Rhodamine B (RhB) degradation compared with BiVO4 and Ag-BiVO4{010}. On the basis of photoluminescence and photoelectrochemical analyses, we can deduce that the extraordinary photocatalytic activity of AgBr-Ag-BiVO4{010} is ascribed to the high separation efficiency of photogenerated charge carriers in the facet-heterojunction-based Z-scheme structure. The free radical trapping and electron paramagnetic resonance (EPR) spin-trap experiments disclosed that the active species in charge of organic degradation are h+, •OH, and •O2 –, while only h+ and •O2 – take part in the inactivation of bacteria. We believe that this study paves a feasible way for constructing cost-efficient facet-heterojunction-based Z-scheme photocatalysts with high efficiency to remediate pathogenic bacteria and organic pollutants in wastewater.

BiVO4 Microparticles Decorated with Cu@Au Core-Shell Nanostructures for Photocatalytic H2O2 Production

“…BiVO 4 , a visible light-responsive photocatalyst, has been extensively applied in photocatalytic H 2 O 2 production owing to its suitable energy-band structure (Figure A) and good stability. − However, pure BiVO 4 lacks active sites of oxygen reduction reaction, which limits its H 2 O 2 production. To solve the above problems, nano-cocatalyst modification is deemed to be a valid method to boost the photocatalytic performance. − Among various electron cocatalysts, nano-Au has been proven to be an excellent cocatalyst owing to its special d-band electrons, which can result in weak “side-on” adsorption configuration to O 2 and thus promote the selective two-electron O 2 reduction to H 2 O 2 . − Benefiting from the above specific catalytic property and its excellent stability, nano-Au has been considered as an efficient electron cocatalyst to improve the photocatalytic H 2 O 2 production performance of BiVO 4 .…”

Type-II Heterojunction CdIn2S4/BiVO4 Coupling with CQDs to Improve PEC Water Splitting Performance Synergistically

“…The X-ray photoelectron spectroscopy (XPS) could detect the elements for Bi, V, O, Cd, In, and S in the total survey spectrum of CdIn 2 S 4 /BiVO 4 (Figure S2), and the high-resolution XPS spectra of CdIn 2 S 4 /BiVO 4 in Figure a–d indicate the combination between CdIn 2 S 4 and BiVO 4 . In Figure a the high-resolution XPS of Bi 4f has two peaks at 159.0 and 164.3 eV, ,, and the high-resolution XPS of S 2p also has two peaks at 161.6 and 162.9 eV. , The high-resolution XPS spectra of O 2p and V 2p are displayed in Figure b; there are two oxygen chemical states at the binding energy of ∼ 531.8 eV for lattice oxygen (O L ) and ∼533.1 eV for the chemical absorbed oxygen (O C ), ,, and V 2p has a characteristic peak at ∼516.6 eV . In Figure c, the characteristic peaks for Cd 3d are at 405.2 and 411.9 eV, and in Figure d, the characteristic peaks for In 3d are at the binding energies of 444.9 and 452.4 eV .…”

“…In Figure 2a In Figure 3a the high-resolution XPS of Bi 4f has two peaks at 159.0 and 164.3 eV, 5,7,45 and the high-resolution XPS of S 2p also has two peaks at 161.6 and 162.9 eV. 46,47 The highresolution XPS spectra of O 2p and V 2p are displayed in Figure 3b; there are two oxygen chemical states at the binding energy of ∼ 531.8 eV for lattice oxygen (O L ) and ∼533.1 eV for the chemical absorbed oxygen (O C ), 21,26,48 and V 2p has a characteristic peak at ∼516.6 eV.…”

Unconventional Substitution for BiVO4 to Enhance Photoelectrocatalytic Performance by Accelerating Polaron Hopping

“…25,29,30 Compared with BiVO 4 , Ti:BiVO 4 has a low-energy shift of Bi 4f and V 2p (Figure 3b,c), suggesting the reduced elements for the presence of oxygen vacancies (O V ). 6,25,31 For the O 1s spectrum in Figure 3d, there are three oxygen chemical states at ∼529.45, ∼532.21, and ∼531.25 eV for lattice oxygen (O L ), for chemisorbed O 2 and H 2 O (O C ), and for O V , respectively. 32−34 The peak area of O V in Ti:BiVO 4 is larger than that of the original BiVO 4 , attributed to the formation of oxygen vacancies.…”