A A novel three-dimensional microspheres mediator-free Z-scheme Ag3VO4/BiVO4 heterojunction photocatalyst was successfully obtained for the first time. The photocatalytic performance of the as-prepared photocatalyst was systematically examined via the photocatalytic reduction of Cr6+ and oxidation of Bisphenol S under visible-light irradiation. Among these samples, 0.24-Ag3VO4/BiVO4 exhibits the highest photocatalytic performances, the photocatalytic reduction and oxidation efficiency of 74.9 and 94.8%, respectively, can be achieved. The enhanced photocatalytic performance is attributed to the build-in electric field assisted charge transfer between the Ag3VO4 and BiVO4, and the increasing lifetime of the charge carrier confirmed by the results of time-resolved fluorescence spectra and photoelectrochemical measures. Moreover, based on the results of free radical scavenging activity test, and EPR experiments, it has been verified that the Ag3VO4/BiVO4 heterostructures follow a typical Z-scheme charge transfer mechanism rather than conventional type-II heterojunction charge transfer mechanism. Furthermore, the theoretical understanding of the underlying mechanism was also supported, while the energy band structure, and Fermi level were systematically calculated using the density functional theory approach. The results show that a built-in electric field directed from Ag3VO4 to BiVO4 surface was established as an equalized Fermi level was reached, which benefits the separation of photogenerated charge carriers in the way of a Z-scheme charge transfer mechanism. The strategy to form the three-dimensional microspheres Z-scheme heterojunction photocatalyst may offer new insight into the Z-scheme charge transfer mechanism for applications in the field of solar energy conversion.

A novel Z-scheme Ag3VO4/BiVO4 heterojunction photocatalyst: study on the excellent photocatalytic performance and photocatalytic mechanism

A review on heterogeneous photocatalysis for environmental remediation: From semiconductors to modification strategies

Recent advances in g-C3N4-based heterojunction photocatalysts

To achieve high efficiency photochemical energy conversion, the most challenging task is to seek a full-spectrum-driven photocatalyst with superior charge separation efficiency from UV to NIR region. Herein, we reported a full-spectrum-driven CdIn2S4/W18O49 photocatalyst with dual-channel charge-carriers transfer path. The experimental results indicate that the synergistic effect of Z-scheme heterojunction and LSPR effect markedly improves interfacial charge transfer efficiency and light-harvesting capacity of CdIn2S4/W18O49 composites. It can effectively activate molecular oxygen to generate reactive oxygen species (ROS) for superior photocatalytic E. coli inactivation and tetracycline (TC) degradation. The enhanced molecular oxygen activation capacity was confirmed by nitroblue tetrazolium (NBT) and p-phthalic acid (TA) transformation experiments. Based on density functional theory (DFT) calculations and scavenger experiments, a possible photocatalytic reaction mechanism was proposed. This work provides a strategy for fabricating full-spectrum-driven photocatalyst with excellent photocatalytic activity, which furnishes a new insight for interface charge transfer and molecular oxygen activation.

Dual-channel charges transfer strategy with synergistic effect of Z-scheme heterojunction and LSPR effect for enhanced quasi-full-spectrum photocatalytic bacterial inactivation: new insight into interfacial charge transfer and molecular oxygen activation

The introduction of oxygen vacancies (Ov) has been regarded as an effective method to enhance the catalytic performance of photoanodes in oxygen evolution reaction (OER). However, their stability under highly oxidizing environment is questionable but was rarely studied. Herein, NiFe-metal-organic framework (NiFe-MOFs) was conformally coated on oxygen-vacancy-rich BiVO4 (Ov-BiVO4 ) as the protective layer and cocatalyst, forming a core-shell structure with caffeic acid as bridging agent. The as-synthesized Ov-BiVO4 @NiFe-MOFs exhibits enhanced stability and a remarkable photocurrent density of 5.3±0.15 mA cm-2 at 1.23 V (vs. RHE). The reduced coordination number of Ni(Fe)-O and elevated valence state of Ni(Fe) in NiFe-MOFs layer greatly bolster OER, and the shifting of oxygen evolution sites from Ov-BiVO4 to NiFe-MOFs promotes Ov stabilization. Ovs can be effectively preserved by the coating of a thin NiFe-MOFs layer, leading to a photoanode of enhanced photocurrent and stability.

Activity and Stability Boosting of an Oxygen-Vacancy-Rich BiVO 4 Photoanode by NiFe-MOFs Thin Layer for Water Oxidation

The g-C3N4/{010} facets BiVO4 interface Z-scheme photocatalysts is fabricated by ultrasonic dispersion method. The density functional theory (DFT) shows that the differences of the energy levels in the conduction bands and the valence bands between the {010} and {110} facets of BiVO4 is about 0.37 and 0.31 V (vs. NHE, pH = 7), respectively. Therefore, the co-exposed {010} and {110} facets of BiVO4 can form surface heterojunction, which promotes the {010} facets of BiVO4 with negative charge. The zeta potential indicates that layered g-C3N4 with positive charge. The Raman, FT-IR and XPS analysis demonstrates that the layered g-C3N4 is anchored on the {010} facets of BiVO4 through strong interface electrostatic interaction, which leads to form a built-in electric field at the contact interface. Under the built-in electric field driving, photogenerated electrons in the CB of {010} facets of BiVO4 rapidly recombines with the holes in the VB of g-C3N4 to form the interface Z-scheme heterostructure. That is, BiVO4 surface heterojunction ultimately induces the formation of interface Z-scheme heterostructure. The interface Z-scheme heterostructure not only facilitates the space separation of the photogenerated carriers, but also accumulates electrons in the more negative potentiated CB of g-C3N4 and holes in the more positive VB of {110} facets of BiVO4. Consequently, by means of the I-t, LSV and EIS measurements, the g-C3N4/{010} facets of BiVO4 interface Z-scheme photocatalysts presents extraordinary photoelectrochemical performance. More importantly, the degradation rate of g-C3N4/{010} facets of BiVO4 interface Z-scheme photocatalysts can reach the highest 88.3% within 30 min under visible light irradiation, and the mineralization ability (96.03%) is about 2.24 and 3.32 times as high as that of BiVO4 (42.83%) and g-C3N4 (28.89%), respectively.

Photocatalytic properties of the g-C3N4/{010} facets BiVO4 interface Z-Scheme photocatalysts induced by BiVO4 surface heterojunction

Defect-mediated Z-scheme BiO2-x/Bi2O2.75 heterojunction photocatalysts without electron mediator was prepared via a simple low-temperature hydrothermal method. DFT proved that the existence of oxygen vacancies would affect the geometric and electronic structure of BiO2-x and Bi2O2.75, which played an indispensable role in promoting exciton dissociation. BiO2-x/Bi2O2.75 exhibited a higher redox ability compared with the pure BiO2-x due to the Z-scheme photocatalytic mechanism, which could be ascribed to the formation of the build-in electric field induced by Bi and O defects. The as-synthesized photocatalysts exhibited excellent photocatalytic activity over the full solar spectrum from UV to NIR light due to the LSPR effect of oxygen vacancies, indicating its effective utilization of solar energy. The degradation rates of RhB over the optimal BiO2-x/Bi2O2.75 were 8.49, 10.22 and 3.24 times higher than that of the pure BiO2-x under visible light, simulated sunlight and NIR light irradiation, respectively. The excellent photocatalytic activity was ascribed to the synergistic effects of the LSPR effect of oxygen vacancies and the Z-scheme interfacial heterojunction. It was believed that this work provided a new idea to design high active and full solar spectrum-driven photocatalysts for energy conversion and environmental remediation.

Defect-mediated Z-scheme BiO2-x/Bi2O2.75 photocatalyst for full spectrum solar-driven organic dyes degradation

Enhanced photoelectrochemical performance of Zn2SnO4N by interstitial N induced the build-in polarization electric field

The invention provides a zinc oxide/bismuth vanadate heterojunction film with a characteristic of visible light responding, and a preparation method and applications thereof. The preparation method comprises the following steps: at first, preparing a BiVO4 precursor solution and a ZnO precursor solution, then soaking a substrate into the BiVO4 precursor solution to prepare an amorphous BiVO4 film with a certain thickness by utilizing a reverse layer-layer self assembly technology utilizing a hydroxyl layer electrostatic adsorption effect, irradiating the amorphous BiVO4 film by UV rays to form a hydroxyl layer, then soaking the substrate into the amorphous BiVO4 film to carry out secondary reverse layer-layer self assembly to form a BiVO4-ZnO amorphous film, and finally carry out crystallization at a constant temperature of 500 DEG C to obtain the zinc oxide/bismuth vanadate heterojunction film. The process is simple and controllable, the requirements on experiment conditions are low, and the prepared zinc oxide/bismuth vanadate heterojunction film has a wide application prospect in the photocatalysis field.

Zinc oxide/bismuth vanadate heterojunction film with characteristic of visible light responding, and preparation method and applications thereof

The invention provides a titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic as well as a preparation method and application thereof The preparation method comprises the steps of preparing a BiVO4 precursor solution and a TiO2 precursor solution, then putting a substrate into the BiVO4 precursor solution to prepare an amorphous BiVO4 film having certain thickness by using a reverse layer-by-layer self-assembly technology of an electrostatic adsorption effect of a hydroxyl layer, irradiating the amorphous BiVO4 film in ultraviolet light to form a hydroxyl layer, putting the amorphous BiVO4 film into the TiO2 precursor solution, performing second reverse layer-by-layer self-assembly to form a BiVO4-TiO2 amorphous film, and finally performing heat preservation crystallization at 500 DEG C to obtain the titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic The process is simple and easy to control, the requirement for the experimental condition is relatively low, and the prepared TiO2/ BiVO4 heterojunction film has a broad application prospect in the field of photo-catalysis

Titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic as well as preparation method and application thereof

Zhang Xinlei

Papers

Photocatalytic properties of the g-C3N4/{010} facets BiVO4 interface Z-Scheme photocatalysts induced by BiVO4 surface heterojunction

Defect-mediated Z-scheme BiO2-x/Bi2O2.75 photocatalyst for full spectrum solar-driven organic dyes degradation

Enhanced photoelectrochemical performance of Zn2SnO4N by interstitial N induced the build-in polarization electric field

Zinc oxide/bismuth vanadate heterojunction film with characteristic of visible light responding, and preparation method and applications thereof

Titanium oxide/ bismuth vanadate heterojunction film having visible light response characteristic as well as preparation method and application thereof