Bismuth vanadate (BiVO4) is a promising visible-light driven semiconductor photocatalyst with various benefits such as low production cost, low toxicity, high photostability, resistance to photo-corrosion and narrow band gap with a good response to visible-light excite. However, the fast recombination of photoinduced charge carriers restricts their photocatalytic activity. In the past decades, many attempts were adopted to enhance the photocatalytic activity of BiVO4. Significant advances in understanding the fundamental issues and the development of an efficient photocatalyst have been made in current years. In this review, we have provided a comprehensive overview of the latest progress on the morphology control and growth mechanism of BiVO4 micro/nano-structures, doping with metal and non-metal elements and semiconductor coupling along with some highlights in the photodegradation of organic pollutants under visible-light illumination. This review may benefit the researchers and engineers in the arena of material chemistry for designing new BiVO4 based photocatalysts with low production cost and high efficiency.

A review on BiVO4 photocatalyst: Activity enhancement methods for solar photocatalytic applications

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

Facile construction of hierarchical flower-like Z-scheme AgBr/Bi2WO6 photocatalysts for effective removal of tetracycline: Degradation pathways and mechanism

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

The Nd/Er co-doped tetragonal BiVO4 photocatalysts are synthesized by a microwave hydrothermal method, and the crystal structures, morphologies and optical properties are characterized. The substitution of Nd3+ and Er3+ for Bi3+ sites leads to distortion of the [VO4] tetrahedron chains and induces the monoclinic structure transforming into the tetragonal structure, with the morphology evolving from nano particle agglomerations to disorganized regular rods agglomerations. The impurity energy levels induced by Nd3+ and Er3+ in the energy band of BiVO4 act as electron traps and have further energy transfer in the up-conversion processes to facilitate the photocarriers’ separation. The more positive VB positions in the co-doped BiVO4 band structures can also effectively enhance oxidation capacity. Based on the above synergetic effect, the degradation rate the degradation rate of co-doped tetragonal BiVO4 photocatalyst can reach the highest 96% within 150 min under simulated sunlight and 20 min under the NIR irradiation.

Enhanced photocatalytic mechanism of the Nd-Er co-doped tetragonal BiVO4 photocatalysts

Photocatalytic properties of Bi2WO6/BiPO4 Z-scheme photocatalysts induced by double internal electric fields

The novelties in this paper are embodied in the fast interfacial charge transfer in α-Fe2O3−δCδ/FeVO4−x+δCx−δ@C bulk heterojunctions with controllable phase compositions. The carbon source-glucose plays an important role as the connecting bridge between the micelles in the solution, forming interfacial C-O, C-O-Fe and O-Fe-C bonds through dehydration and polymerization reactions. Then the extra VO3− around the FeVO4 colloidal particles can react with unstable Fe(OH)3, resulting the phase transformation from α-Fe2O3 (47.99–7.16%) into FeVO4 (52.01–92.84%), promoting photocarriers’ generation capacities. After final carbonization, a part of C atoms enter into lattices of α-Fe2O3 and FeVO4, forming impurity levels and oxygen vacancies to increase effective light absorptions. Another part of C sources turn into interfacial carbon layers to bring fast charge transfer by decreasing the charge transition resistance (from 53.15 kΩ into 8.29 kΩ) and the surface recombination rate (from 64.07% into 7.59%). The results show that the bulk heterojunction with 90.29% FeVO4 and 9.71% α-Fe2O3 shows ideal light absorption, carriers’ transfer efficiency and available photocatalytic property. In general, the synergistic effect of optimized heterojunction structure, carbon replacing and the interface carbon layers are critical to develop great potential in stable and recoverable use.

Fast interfacial charge transfer in α-Fe 2 O 3−δ C δ /FeVO 4−x+δ C x−δ @C bulk heterojunctions with controllable phase content

The invention discloses a bismuth tungstate/carbon nitride composite photo-catalyst and a preparation method and application thereof. The bismuth tungstate/carbon nitride composite photo-catalyst is synthesized through an ultrasonic stirring method by taking C3N4 obtained by co-firing Bi2WO6 synthesized in a microwave hydro-thermal way, melamine and urea as raw materials and taking methanol as a solvent. Bismuth tungstate/carbon nitride composite powder prepared by the method has a high degree of crystallinity, a heterojunction structure is formed among components, a compounding process is carried out at the room temperature, reaction conditions are mild, and the photocatalytic performance of the powder can be remarkably enhanced in comparison to Bi2WO6 powder and C3N4 powder after compounding; the bismuth tungstate/carbon nitride composite photo-catalyst has a wide application prospect on the aspect of photocatalytic degradation of organic pollutants.

Su Yuning

Papers

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

Enhanced photocatalytic mechanism of the Nd-Er co-doped tetragonal BiVO4 photocatalysts

Photocatalytic properties of Bi2WO6/BiPO4 Z-scheme photocatalysts induced by double internal electric fields

Fast interfacial charge transfer in α-Fe 2 O 3−δ C δ /FeVO 4−x+δ C x−δ @C bulk heterojunctions with controllable phase content

Bismuth tungstate/carbon nitride composite photo-catalyst and preparation method and application thereof