BiVO4 Composites Research Articles

Enhanced photocathodic protection performance of Co3S4 nanoparticles modified porous BiVO4 composites for 304 stainless steel

A nanoporous Co3S4/BiVO4 composites were successfully fabricated via electrodeposition, immersion and oil-bath heating methods. ZIF-67 was used as a cobalt source and template. Co3S4/BiVO4 obtained by treatment for 6 h displayed the best photocathodic protection (PCP) performance. Under light, Co3S4–6 h/BiVO4 reduced the potential of 304 stainless steel (SS) to −490 mV vs. SCE, which was 200 mV below that of pure BiVO4. In addition, the photocurrent densities of 304 SS coupled with Co3S4–6 h/BiVO4 were up to 13 μA cm−2, which was more than 4 times that of pure BiVO4. Remarkably, the Rct of 304 SS coupled with Co3S4–6h/BiVO4 (142.6 Ω·cm2) was 1/27 of that of pure BiVO4 (3918 Ω·cm2). The outstanding PCP property of Co3S4/BiVO4 can be owed to the synergistic effects of strong visible light absorption, improved charge transfer efficiency, and enhanced electron storage capacity. These advantages make Co3S4/BiVO4 a promising candidate for providing effective PCP effects on metals.

Construction of the Z-Scheme Heterogeneous HKUST-1/BiVO4 Nanorod Composite for Enhanced Piezo-Photocatalytic Reduction Performance of Cr(VI).

In recent years, piezo-photocatalysis has become a promising strategy for solving environmental pollution problems by adding additional mechanical energy to the photocatalysis process. This work reported the effective synthesis of a variety of HKUST-1/BiVO4 heterogeneous materials by combining monoclinic BiVO4 and porous HKUST-1 semiconductors. The piezo-photocatalytic properties of HKUST-1/BiVO4 were studied by the reduction of hexavalent chromium (Cr(VI)) under visible-light irradiation and ultrasonic waves. In the piezo-photocatalysis process, the best reduction rates among as-prepared HKUST-1/BiVO4 composites were up to 96.20% of 10 ppm Cr(VI) solution, which was approximately 1.80 times that under visible light and about 4.13 times that under ultrasound. Under the action of the piezoelectric potential, the availability of free radicals increased the reduction rate of Cr(VI) and reached a synergistic effect of 1.14-fold.

Synergistic effect of facet-regulated and photocatalytic-peroxymonosulfate activation of Fe(II)/decahedron monoclinic BiVO4 composites for efficient degradation of tetracycline

The efficient activation of peroxymonosulfate (PMS) in advanced oxidation technology is hindered by the low Fe(II)→Fe(III)→Fe(II) cycle efficiency. Herein, we report a Fe(II)/decahedral monoclinic BiVO4 composite photocatalyst with a highly exposed (010) facet prepared by a hydrothermal method combined with a wet impregnation strategy. The numerous photogenerated electrons on the (010) facet promote the cycling of Fe(II)→Fe(III)→Fe(II) process, thereby significantly enhancing the PMS activation rate. The charge transfer mode of 1% Fe(II)/BiVO4 was inferred from in situ X-ray photoelectron spectra. The composite catalyst exhibits significantly higher activity (96.7%) than the pristine BiVO4 without facet regulation (56%). Controlling the crystal facets can effectively separate the photogenerated carriers of BiVO4; the photogenerated electrons catalyze the cyclic transformation of Fe(III)/Fe(II) to efficiently activate PMS and degrade antibiotics. This work confirms the synergistic effect of facet engineering and the photocatalytic PMS activation system and provides a new perspective for the degradation of antibiotics.

Synthesis of Cu-doped TiO2 modified BiVO4 for photocatalytic oxidative desulfurization (PODS) of a model fuel

In the present study, a photocatalytic oxidation desulfurization method is used to eliminate dibenzothiophene as one of the aromatic sulfur derivatives in fuel, using a Cu-TiO2/BiVO4 composite. The structure of the synthesized compounds was characterized by FT-IR and Raman spectroscopy, XRD, DRS, UV–Vis, BET, TEM, FE-SEM, elemental mapping, EDS, XPS, and ICP-MS methods. To find the best results in this photocatalytic system, different parameters such as type of solvent, the amount of photocatalyst, reaction time, amount of oxidizing agent, reaction temperature, and the ratio of extracting solvent to n-heptane as the model fuel was investigated and optimized. Desulfurization tests were carried out including extraction-absorption test (without H2O2), in the absence of photocatalyst, and test in dark conditions followed by oxidation extraction test. The efficiency of this photocatalytic system for dibenzothiophene removal reached 93% under optimal reaction conditions for the model fuel. The photocatalyst was recycled three times and exhibited good efficiency in dibenzothiophene removal.

Research progress on composite material of bismuth vanadate catalyzing the decomposition of Quinolone antibiotics

Since quinolone is a kind of synthetic broad-spectrum antibacterial drugs, with the widespread use of this class of antibiotics, the risk and harm to human health have been attendant to the sewage containing quinolones which are discharged into the environment. Photocatalysis is considered as a promising technology for antibiotic degradation for its strong redox properties and reaction rate. As a metal oxidizing substance, Bismuth vanadate (BiVO4) is such a popular and hot material for the degradation of organic pollutants recently due to its good photocatalytic activity and chemical stability. Numerous studies have confirmed that BiVO4 composites can overcome the shortcomings of pure BiVO4 and cleave the main structure of quinolone under photocatalytic conditions. This paper mainly outlines the research progress on the preparation of BiVO4 composites and the degradation of quinolone antibiotics from the perspective of improving the catalysis and degrading the efficiency mechanism of BiVO4 composites.

Composite photocatalyst C3N4/BiVO4 for adsorption/photocatalytic degradation of drugs in water

C3N4/BiVO4 composites as co-photocatalyst were successfully synthesized via hydrothermal method by varying the weight ratio of g-C3N4/BiVO4. The prepared samples were characterized using X-ray diffraction instrument, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. The morphological properties of composites show that g-C3N4 particles is deposited on the surface of BiVO4 while the crystal structure study shows that co-catalysts are existed by X-ray diffraction pattern. The photocatalytic degradation shows improvement by the composite with a ratio of 5% g-C3N4/BiVO4, the adsorption/photodegradation of Rhodamine B and Methyl Orange were about 97% and 88%, respectively within 40 min. The result indicates that g-C3N4/BiVO4 are paired their properties which are adsorption/photocatalyst, consequently, efficient spatial charge carrier separation. This finding was applied to remove ciprofloxacin and paracetamol in water. about 65% of paracetamol was removed from water compared with 15% of ciprofloxacin, this result revealing that excellent photodegradation of paracetamol by 5% g-C3N4/BiVO4 composite.

Preparation of ZIF-67/BiVO4 composite photoanode and its enhanced photocathodic protection performance of 316 SS under visible light

BiVO4 is a potentially promising photoanode for photocathodic protection (PCP) of metals. Nonetheless, the fast charge recombination and low electron mobility restrict its further utilization. In this work, a cobalt-based metal-organic frameworks (MOFs), zeolitic imidazolate framework-67 (ZIF-67) is incorporated to form the composite ZIF-67/BiVO4 via a facile electrodeposition method. Results show that the ZIF-67/BiVO4 photoanodes present significantly enhanced PCP performance for 316 stainless steel (SS) in comparison with pure BiVO4. The ZIF-67 modified BiVO4 composites with electrodeposition time of 150 s possess the optimal protection performance. The open circuit potential of 316 SS coupled with ZIF-67/BiVO4 could reach − 0.52 V vs. SCE under visible light irradiation in 3.5 wt% NaCl solution without the hole scavengers. The incorporation of ZIF-67 could enhance the visible light absorption ability (λ > 500 nm). In addition, the sensitization of ZIF-67, the increased specific surface area, and the construction of Z-scheme heterojunctions could dramatically promote the separation of electron-hole pairs and retain the strong redox ability of holes or electrons. The photocurrent density of ZIF-67/BiVO4 could reach 99 μA cm−2, which is about 2.5 times that of pure BiVO4. This work shows that porous ZIF-decorated BiVO4 photoelectrodes can provide highly effective PCP for metals, which suggests a promising idea for designing other BiVO4-based photoelectrodes.

Boosting catalytic efficiency via BiVO4 surface heterojunction-induced interfacial Z-scheme NiFe2O4/{0 1 0}BiVO4 composite

In this work, a unique recyclable interfacial Z-scheme NiFe2O4/{010}BiVO4 composite was successfully designed by selectively loading NiFe2O4 onto the {010} facet of BiVO4 for the removal of norfloxacin (NOR) in aqueous solution. Under ultrasonic irradiation, the interfacial Z-scheme NiFe2O4/{010}BiVO4 composite exhibited a remarkable NOR removal efficiency of 98.97 % within 60 min (at an initial NOR concentration of 10 mg/L). The outstanding catalytic performance was attributed to the interfacial Z-scheme structure, which facilitates the spatial separation and transport of photo-generated carriers, and significantly prolongs their lifespan. The formation of interfacial Z-scheme NiFe2O4/{010}BiVO4 composite occurs when the {110} and {010} facets of BiVO4 are exposed to create a surface heterojunction. Moreover, the results of the recycling studies indicate the catalyst had superior stability, while its magnetic characteristics allows easy recovery. The probable degradation pathways of NOR was proposed based on the major degradation intermediates identified. This study demonstrates the idea of reducing photo-generated carrier recombination with construction of interfacial Z-scheme heterojunction, which is a promising strategy for the development of efficient catalysts.

Effects of Tb-Doped BiVO4 on Degradation of Methylene Blue

Bismuth vanadate (BiVO4) is a narrow-bandgap semiconductor (~2.41 Ev) that responds to visible light. The efficiency of degradation of organic dyes is indexed by methylene blue (MB). After 150 min, the efficiency of MB degradation by pure BiVO4 was about 20%. Its adsorption performance and electron–hole pair migration ability are weak, and the photocatalytic activity of pure BiVO4 needs to be improved. BiVO4 doped with rare earth ions can facilitate the separation of photogenerated electron–hole pairs, thereby enhancing photocatalytic activity in the visible light range. This study investigates changes in the structure and morphology of BiVO4 doped with different atomic percentages of terbium (Tb). BiVO4 powders were prepared by the hydrothermal method with different atomic percentages of Tb (at% = 0, 1, 3, and 5). Doping Tb benefits the coexistence of monoclinic/tetragonal heterostructures, which changes the band gap and improves degradation efficiency. After 150 min of visible light irradiation, the photocatalyst doped with 3 atomic percent of Tb exhibited 98.2% degradation of methylene blue. The degradation percentage of MB remained stable in the presence of 3at%Tb-doped BiVO4 composite. The optimal parameters for the amount of photocatalyst added were studied. Real-field simulations of metal ions and inorganic salts both retain high levels of degradation efficiency.

Fabrication of g-C3N4 decorated BiVO4 composites and their application in photoelectrocatalytic and electrocatalytic oxidative desulfurization of dibenzothiophene under visible light irradiation

Fabrication of g-C3N4 decorated BiVO4 composites and their application in photoelectrocatalytic and electrocatalytic oxidative desulfurization of dibenzothiophene under visible light irradiation

BiVO4-Deposited MIL-101-NH2 for Efficient Photocatalytic Elimination of Cr(VI).

In this study, a flower-like BiVO4/MIL-101-NH2 composite is synthesized by a facile and surfactant-free process. The -COO--Bi3+ ionic bond construction was conductive to enhance the interface affinity between BiVO4 and MIL-101-NH2. Due to the highly efficient light capture and sufficient electron traps induced by oxygen vacancies and the formation of a heterostructure, the improved separation and transportation rates of charge carriers are realized. In addition, the MIL-101-NH2/BiVO4 composite is favorable for Cr(VI) photocatalytic removal (91.2%). Moreover, FNBV-3 (Fe/Bi = 0.25) also exhibited an excellent reusability after five cycles.

WO3/Mo:BiVO4 heterojunction structured photoelectrochemical sensor for enhancing hydrogen peroxide monitoring and mechanism investigation

Among the currently multitudinous analytical methods for hydrogen peroxide (H2O2), photoelectrochemical (PEC) sensors stand out for their potential advantages of high sensitivity, low cost, and easy preparation. In this work, WO3/Mo:BiVO4 heterojunction photoanode was constructed for non-enzymatic H2O2 sensing via PEC route. At first, WO3 nanoplates was prepared by chemical bath method, then WO3/Mo:BiVO4 composite was achieved by spin coating Mo:BiVO4 film on the surface of WO3. Such heterojunction structure allow photogenerated electrons transferred into WO3 and holes accumulated on Mo:BiVO4, which boosts the charges separation and decreases charge carrier recombination, thus resulting a remarkable enhancement for H2O2 sensing. As a result, the WO3/Mo:BiVO4 photoanode presents a sensitive response of 186.2 μA cm−2 mM−1 for H2O2 detection in the concentration region of 0.1-2.0 mM accompanied with a good correlation coefficient of 0.996, this sensing performance is much superior than the pristine WO3 photoanode. Furthermore, the fabricated heterojunction sensor has a good stability and distinguish H2O2 from the interferents of ascorbic acid (AA), uric acid (UA), glucose and common inorganic salts, etc. This study provides an efficient way for H2O2 detection and inspires more interests in the design and construction of a novel heterojunction for advanced PEC analysis.

Efficient photocatalytic degradation of ammonia nitrogen by Z-scheme NH2-MIL-101(Fe)/BiVO4 heterostructures

A promising Z-scheme NH2-MIL-101(Fe)/BiVO4 heterostructure was fabricated by in-situ growth of monoclinic BiVO4 onto the surface of NH2-MIL-101(Fe) nanoparticles and employed for ammonia nitrogen removal in water for the first time. Experiments demonstrated that NH2-MIL-101(Fe)/BiVO4 composites displayed boosted performance for ammonia nitrogen removal. And 10%-MBVO exhibited optimal removal rate of ammonia nitrogen as 95.7% and N2 selectivity as 92.3% in 90 min at pH of 9.0 with initial concentration as 30 mgN/L. Moreover, effects of initial solution pH, stirring speed and impurity ions (k+, Ca2+, SO42− and CO32−) were investigated. The end products and net contributions of stripping, adsorption, photolysis, photocatalysis in ammonia nitrogen removal were revealed. The functions of ·OH, ·O2− and h+ in photocatalytic degradation of ammonia were explored by scavenging experiments. The proposed mechanism indicated that the enhancement may be primarily owing to the improved light harvesting capacity and stronger redox ability of photogenerated carriers provided by Z-scheme heterostructures.

Photoreduction of CO2 into CH4 Using Novel Composite of Triangular Silver Nanoplates on Graphene-BiVO4

Plasmonic photocatalysis, combing noble metal nanoparticles (NMNPs) with semiconductors, has been widely studied and proven to perform better than pure semiconductors. The plasmonic effects are mainly based on the localized surface plasmon resonance (LSPR) of NMNPs. The LSPR wavelength depends on several parameters, such as size, shape, the surrounding media, and the interdistance of the NMNPs. In this study, graphene-modified plate-like BiVO4 composites, combined with silver nanoplates (AgNPts), were successfully prepared and used as a photocatalyst for CO2 photoconversion. Triangular silver nanoplates (TAgNPts), icosahedral silver nanoparticles (I-AgNPs), and decahedra silver nanoparticles (D-AgNPs) were synthesized using photochemical methods and introduced to the nanocomposites to compare the shape-dependent plasmonic effect. Among them, T-AgNPts/graphene/BiVO4 exhibited the highest photoreduction efficiency of CO2 to CH4, at 18.1 μmolg−1h−1, which is 5.03 times higher than that of pure BiVO4 under the irradiation of a Hg lamp. A possible CO2 photoreduction mechanism was proposed to explain the synergetic effect of each component in TAgNPts/graphene/BiVO4. This high efficiency reveals the importance of considering the compositions of photocatalysts for converting CO2 to solar fuels.

Preparation of RGO film based BiVO4 (040) composites with photocatalytic properties

AbstractGraphene oxide (GO) film was modified by silane coupling agent KH‐560, then bismuth vanadate (BiVO4) was successfully loaded on the modified GO film via hydrothermal method to obtain reduced graphene oxide (RGO) film based BiVO4 composite. The effects of hydrothermal reaction time on BiVO4 morphology and photocatalytic properties were investigated by scanning electron microscopy (SEM), X‐ray diffraction pattern (XRD), ultraviolet visible light absorption spectroscopy (UV‐vis) and photocatalytic activity. The results show that BiVO4 is a porous structure growing towards (040) crystal plane on the composite, and when the synthesis time is 6 h, the degradation rate for Reactive Black 5 by the composite can reach 95 % within 90 min. Furthermore, the composite prepared at the optimal time was characterized by transmission electron microscope (TEM), energy dispersive X‐ray spectroscopy (EDS) and X‐ray photoelectron spectroscopy (XPS). The microphysical process of the separation and combination of photogenerated electron hole pairs was successfully demonstrated by the variations of photoinduced current density with time (i‐t curve) and electrochemical impedance spectroscopies (EIS). Finally, the photocatalytic mechanism was proposed by free radical capture experiment.

Enhanced photocurrent density for photoelectrochemical catalyzing water oxidation using novel W-doped BiVO4 and metal organic framework composites

Doping heteroatoms and decorating co-catalyst are intensively applied to improve photocatalytic ability of BiVO4. In this study, it is the first time to design W-doped BiVO4 coupling MIL-101(Fe) as photocatalyst for water oxidation using electrodeposition and hydrothermal processes. Similar system with Mo as dopant has been reported, but the dopant plays important roles on electrochemical performance. It is worthy to study the efficient system with different dopant. Doping amount of W is optimized to achieve high carrier density without creating serious recombination sites. MIL-101(Fe) is decorated on W-doped BiVO4 to suppress surface recombination, create accessible active sites and improve water oxidation kinetics. Optimized W-doped BiVO4/MIL-101(Fe) electrode shows a high photocurrent density of 4.00 mA/cm2 at 1.23 V versus reversible hydrogen electrode (VRHE) under air mass 1.5-global simulated light illumination without hole scavenger in electrolyte, due to large electrochemical surface area, high carrier density and small charge-transfer resistance. The W-doped BiVO4 and BiVO4 electrodes merely show photocurrent densities of 2.96 and 1.72 mA/cm2 at 1.23 VRHE, respectively. Photocurrent retention higher than 95.5% is obtained for W-doped BiVO4/MIL-101 (Fe) electrode under continuous illumination for 6300 s, suggesting lasting photocatalytic ability of this novel W-doped BiVO4/MIL-101(Fe) electrode.

Facile construction of Z-scheme g-C3N4/BiVO4 heterojunctions for boosting visible-light photocatalytic activity

Photocatalytic technology is one of the effective methods to treat the azo dye wastewater that has posed a serious threat to human environment and health. Composed of graphitic carbon nitride (g-C3N4) nanosheets and BiVO4 hollow spheres, the g-C3N4/BiVO4 composites were successfully assembled by thermal treatment. The uniform BiVO4 hollow spheres were more evenly scattered on the layered structure of g-C3N4 nanosheets, inhibiting the aggregation of nanoparticles. The confirmed g-C3N4/BiVO4 heterojunctions facilitate the transfer and separation of charges. Compared with g-C3N4 nanosheets and BiVO4 hollow spheres, the optimized g-C3N4/BiVO4 composite exhibits the significantly enhanced photocatalytic performance, owing to the formation of the heterojunctions, high charge separation efficiency and strong redox ability. The Z-scheme mechanism over the composite has been proposed to reveal the pathway of separation and transfer of the photo-generated charges in the MO degradation. The g-C3N4/BiVO4 heterojunctions with hollow porous structures could effectively enhance the photocatalytic degradation of pollutants.

Sonophotocatalytic Dye Degradation Using rGO-BiVO4 Composites.

Reduced graphene oxide (rGO)/bismuth vanadate BiVO4 composites are fabricated with varied rGO amounts (0, 1, 2, and 3 wt%) through the synergetic effects of ultrasonication, photoinduced reduction, and hydrothermal methods, and the materials are tested as tools for sonophotocatalytic methylene blue (MB) dye degradation. The effect of rGO content on the sonophotocatalytic dye degradation capabilities of the composites are explored. Characterization of the proposed materials is done through transmission electron microscopy (TEM), X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), Fourier transformation infrared spectroscopy as well as scanning electron microscopy. The coexistence of BiVO4 and rGO is confirmed using Raman spectroscopy and XRD. TEM confirms the existence of interfaces between rGO and BiVO4 and XPS affirms the existence of varied elemental oxidation states. In order to investigate the charge carriers transportation, time‐dependent photocurrent responses of BiVO4 and 2 wt%‐ rGO/BiVO4 are done under visible light irradiation. The sonophotocatalytic MB dye degradation in an aqueous medium displays promising enhancement with rGO doping in rGO/BiVO4 composite. The 2 wt%‐ rGO/BiVO4 sample exhibits ≈52% MB dye degradation efficiency as compared to pure BiVO4 (≈25%) in 180 min of the sonophotocatalysis experiment. Phytotoxicity analysis through germination index is done using vigna radiata seeds.

Nanoarchitectonics of three-dimensional ZnO–BiVO4 for trace nitrogen dioxide gas detection

In the present study, several novel three-dimensional (3D) ZnO–BiVO4 composites were prepared using the hydrothermal method, and their ability to detect nitrogen dioxide (NO2) gas was assessed. The fabricated sensing materials were examined using X-ray diffraction, transmission electron microscopy, energy dispersive spectrometry, scanning electron microscopy, ultraviolet–visible spectrophotometry, X-ray photoelectron spectroscopy, and surface-area and porosity analysis. The sensing material assessments verified that 3D ZnO–BiVO4 was successfully prepared; the sensing data revealed that 3D ZnO–BiVO4 exhibited excellent sensing response (24.6) to 1-ppm NO2 at room temperature. The composites exhibited a fast response (28 s) and short recovery time (75 s) when detecting 1-ppm NO2; they also exhibited long-term stability (decline of approximately 7% after 30 days) and selectivity to 10-ppm NO2 gas. A reasonable NO2 gas sensing mechanism for 3D ZnO–BiVO4 heterojunction was also proposed in this paper.

Functionalized role of highly porous activated carbon in bismuth vanadate nanomaterials for boosted photocatalytic hydrogen evolution and synchronous activity in water

Energy crises and water pollution have become the key challenges in current era of technology. In this research work, activated carbon modified BiVO4 photocatalysts have been prepared using simple hydrothermal methods for efficient hydrogen evolution through water splitting under visible light irradiation and degradation, simultaneously. The properties of the synthesized photocatalysts were studied through SEM, UV, XRD, BET and PL emission spectroscopy. The 4%AC/BiVO4 exhibited highest degradation efficiency ≈98% in 60 min and production of hydrogen energy ≈510 h−1g−1 which is much higher when compared to pure BiVO4. The enhancement in the efficiency was due to large surface area, large absorption region. High crystallinity, small band gap and synergetic effect between the composites. The activated carbon based BiVO4 composites showed high stability which shows its vital role in practical applications.