Pure BiVO4 Research Articles

Architecting a Double Charge-Transfer Dynamics In2S3/BiVO4 n-n Isotype Heterojunction for Superior Photocatalytic Oxytetracycline Hydrochloride Degradation and Water Oxidation Reaction: Unveiling the Association of Physicochemical, Electrochemical, and Photocatalytic Properties.

To surmount incompatibility provoked efficiency suppression of an anisotype heterojunction and to pursue an improved intrinsic photocatalytic activity by manipulating oriented transfer of photoinduced charge carriers, an In2S3/BiVO4 (1:1) n–n isotype heterojunction was fabricated successfully through a simple two-step calcination method, followed by a wet-chemical deposition method. The formation of an n–n isotype heterojunction was confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and UV–visible diffuse reflectance spectroscopy. The photocatalytic efficiency of the In2S3/BiVO4 catalyst was examined over degradation of oxytetracycline hydrochloride (O-TCH) and oxygen (O2) evolution reaction. Consequently, an n–n In2S3/BiVO4 isotype heterojunction exhibits a superior O-TCH degradation efficiency (94.6%, 120 min) and O2 evolution (695.76 μmol, 120 min) of multiple folds as compared to the pure BiVO4 and In2S3 solely. This is attributed to the proper band alignment and intimate interfacial interaction promoted charge carrier separation over the n–n isotype heterojunction. The intimate interfacial contact was confirmed by transmission electron microscopy (TEM), high-resolution TEM, and field emission scanning electron microscopy analysis. The proper band alignment was confirmed by Mott–Schottky analysis. The photoelectrochemical linear sweep voltammetric study shows a superior photocurrent density (269 μA/cm2) for In2S3/BiVO4 as compared to those for pristine BiVO4 and In2S3, which is in good agreement with the photocatalytic results. Furthermore, the superior charge antirecombination efficiency of the n–n isotype heterojunction was established by photoluminescence, electrochemical impedance spectroscopy, Bode analysis, transient photocurrent, and carrier density analysis. The improved photostability of the heterojunction was confirmed by chronoamperometry analysis. An orderly corelationship among physicochemical, electrochemical, and photocatalytic properties was established, and a possible mechanistic pathway was presented to better understand the outcome of the n–n isotype heterojunction. This study presents an effective way to develop new n–n isotype heterojunction-based efficient photocatalysts and could enrich wide applications in other areas.

Charge Transport Properties of Cu2S/Bivo4 Composite Photocatalyst

The Cu2S/BiVO4 composite photocatalysts had been synthesised by a simple solution adsorption method. The obtained samples were characterised by means of field emission scanning electron microscope (SEM), X-ray diffraction patterns (XRD), UV-visible absorption spectrum techniques and transient photovoltage spectra (TPV). The results showed that the Cu2S nanoparticles were evenly loaded on the surface of the dumbbell-like BiVO4 composites. Compared with pure BiVO4, Cu2S/BiVO4 composites had better photocatalytic activity. Furthermore, the photogenerated charge transport properties of Cu2S/BiVO4 composites were investigated by means of TPV technique. The interface between BiVO4 and Cu2S enhanced the separation efficiency of photogenerated charge carriers, thus, the photocatalytic activitie of Cu2S/BiVO4 composites was enhanced.

Fabrication of novel fibrous BiVO4/CdS heterostructures by electrospinning method for efficient visible light photodegradation

Novel fibrous BiVO4/CdS heterostructures were fabricated for photodegradation of Rhodamine B (RhB) dyes. Caterpillar shaped BiVO4 nanofibers were produced by electrospinning and post calcinations. Controllable quantity of CdS nanoparticles were uniformly decorated on BiVO4 fiber surface by electrostatic interaction. Both the BiVO4 nanofibers and CdS nanoparticles present high crystallinity. The integration of CdS can significantly enhance the absorption of visible light and separation efficiency of photo-generated charge in BiVO4/CdS composites. As a result, the photocatalytic efficiency and apparent reaction rate constant of the optimized BiVO4/CdS-2 display 1.6 and 3 times as high as that of pure BiVO4 after 120 min irradiation under visible light, respectively. Moreover, the BiVO4/CdS-2 nanofibers show good stability for repeated visible light photocatalytic application. The scavengers added photocatalytic experiments indicate the crucial roles of •O2− and h+ for the degradation process, and a Z-scheme photocatalytic mechanism was proposed for the BiVO4/CdS system. Due to the simple and low-cost synthetic method, the fibrous BiVO4/CdS catalysts are suitable for practical applications.

Plasmonic Z-scheme Pt-Au/BiVO4 photocatalyst: Synergistic effect of crystal-facet engineering and selective loading of Pt-Au cocatalyst for improved photocatalytic performance

Constructing Z-scheme photocatalysts is one of the most effective technologies to enhance the photocatalytic reduction or oxidation ability in artificial photosynthesis. For the BiVO4 photocatalyst, it usually shows limited photocatalytic ability because of the severe bulk recombination of photogenerated carriers and the poor reduction reaction of photogenerated electrons. In this paper, a novel plasmonic Z-scheme Pt-Au/BiVO4 single-crystal photocatalyst was constructed to solve the above issues. Here, Au nanoparticles are selectively deposited on the electron-rich (0 1 0) facet of BiVO4, while Pt nanoparticles are selectively modified on the Au surface. Photocatalytic results indicated that the resultant Pt-Au/BiVO4 Z-scheme photocatalyst exhibits an obviously higher photocatalytic performance than pure BiVO4, Au/BiVO4, randomly deposited BiVO4(Pt-Au/BiVO4(R)) and conventional Pt-Au/BiVO4. More importantly, compared with the well-known Pt/BiVO4(2.0 wt%), the Pt-Au/BiVO4 not only exhibits a higher photocatalytic performance, but also loads a lower amount of high-cost Pt cocatalyst. The excellent photocatalytic activity of the plasmonic Z-scheme Pt-Au/BiVO4 photocatalyst can be attributed to the synergistic effect of crystal-facet engineering and selective loading of Pt-Au, which results in the orientation transfer of photogenerated carriers in the single-crystal BiVO4, the enhanced reduction power of photogenerated electrons, and the rapid oxygen-reduction reaction on Pt cocatalyst.

Synthesis of g-C3N4/BiVO4 and Its Photocatalytic Performance for Hydrogen Production

In this study, ultrasonic hybridization was used to improve the photocatalytic efficiency and stability of the g-C3N4/BiVO4 photocatalyst, which was synthesized using Bi(NO3)3·5H2O and NaVO3 via the hydrothermal method to obtain BiVO4, and further modified by g-C3N4. Moreover, the obtained photocatalyst was studied using X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller, ultraviolet–visible spectroscopy and electrochemical impedance spectroscopy. Subsequently, the photocatalytic performance for hydrogen production of the obtained photocatalyst was determined in a photocatalytic reactor under visible light, with methanol as the sacrificial agent and chloroplatinic acid as the promoter. The experimental results showed that the photocatalytic activity of BiVO4 considerably improved under visible light condition when its surface was modified with g-C3N4. When the amount of g-C3N4 was 5% of the amount of BiVO4, the hydrogen production rate was 53.25 μmol/h, which was 77.17 times higher than that of pure BiVO4. This improved performance can be attributed to the larger specific surface area, the better electron transfer efficiency and the electron–hole pair separation efficiency of g-C3N4/BiVO4. A possible mechanism model for the formation of g-C3N4/BiVO4 composite photocatalyst has also been proposed.

Utilization of Bi2WO6-encapsulated polyaniline-based redox reactions for the efficient detoxification of organic pollutants

Water contamination by toxic organic pollutants remains a serious public health problem for humans due to their long-lasting effects, so attention on specific methods and technologies to remove organic pollutants from waste water is desired. Numerous methods and photocatalysts are reported for the degradation of organic pollutants. In this work, BiVO4/Bi2WO6@polyaniline nanostructures were prepared successfully through facile wet chemical co-precipitation method and in sequence deposited over the BiVO4 surface for the first time. The surface morphology of synthesized photocatalysts was observed by scanning electron microscopy (SEM) and structural properties were investigated by X-ray diffraction (XRD). The addition of polyaniline and Bi2WO6 into BiVO4 shifted the characteristic peaks of BiVO4 towards lower 2θ angle which is clear evidence of doping of these elements into BiVO4 structure under these conditions. In addition, the crystallite size of BiVO4 was also decreased due to incorporation of doping elements. Compared with pure BiVO4, hybrid photocatalysts exhibit higher photocatalytic activity and stability for degradation of phenol and ciprofloxacin under visible-light irradiation. When the effect of PANI in BiVO4–Bi2WO6 was examined, 1% PANI/BiVO4–Bi2WO6 heterojunction exhibited the highest photocatalytic performance. The degradation efficiency for phenol was 98% and 99% for ciprofloxacin at 90 min and this value was about seven times and three times higher than as compared to pure BiVO4 and BiVO4–Bi2WO6, respectively. The obviously improved photocatalytic performance of BiVO4–Bi2WO6/PANI composite was mainly ascribed to unique hierarchical structures, harvesting extended region of visible light, higher surface area, higher crystallinity, electronic transmission and narrow band gap, which significantly enriched the adsorption capacity and accordingly facilitated the separation of photogenerated charge carriers. The current findings may provide new insights into the employment of hybrid photocatalysts and improving the photocatalytic activity to address energy and environmental issues.

Synthesis of novel BiVO4/Cu2O heterojunctions for improving BiVO4 towards NO2 sensing properties

To develop a high sensitive and low temperature NO2 gas sensor, the novel BiVO4/Cu2O heterojunctions were synthesized by a modified metal organic decomposition method to decorate BiVO4 nanoplates using Cu2O nanoparticles for enhancement of BiVO4 sensing performance to NO2. The structure and morphology of BiVO4, Cu2O and BiVO4/Cu2O composites were characterized by XRD, SEM and TEM spectra. The results indicate that the BiVO4/Cu2O heterojunctions are composed of monoclinic BiVO4 nanoplates with the thickness about 1.0–1.2 μm and 30–40 nm diameters of cubic Cu2O nanoparticles. The gas-sensing tests display that the composite exhibits rapid and linear responses to low concentration NO2 (from 100 ppb to 8.0 ppm), the highest response reaches 4.2 towards 4 ppm NO2 at 60 °C and relative humidity of 28.3%, which is more than 2 times of pure BiVO4 at the same condition. The enhanced sensing properties benefit from the novel p-n heterojunction between BiVO4 and Cu2O, which forms a depletion layer at the interface, leading to resistance increase of composites in NO2. The work demonstrates the as-synthesized BiVO4/Cu2O is a promising sensing material to detect NO2 gas.

Synthesizing Co3O4-BiVO4/g-C3N4 heterojunction composites for superior photocatalytic redox activity

In this study, a novel coral-like Co3O4-BiVO4/g-C3N4 ternary composite catalyst was successfully synthesized via high temperature polymerization and controlled hydrothermal reaction. In the Co3O4-BiVO4/g-C3N4 ternary hybrid system, the bulk Co3O4 particles were uniformly dispersed on the coral-like BiVO4 nanosheet, which not only enhanced to increase the response range and absorption to visible light, also contributed to suppress the recombination of photogenerated electron holes. The introduction of flocculent g-C3N4 increased the specific surface area of the catalytic system while accelerating the transmission efficiency of photogenerated carriers. After being illuminated for 90 min under the visible light, the degradation efficiency of pure BiVO4 and g-C3N4 catalysts were 81% and 80.2%, respectively. And the two binary catalysts, Co3O4-BiVO4 and BiVO4/g-C3N4 composite catalyst, performed the higher photocatalytic activity, which reached 94.8% and 96.8%, while ternary catalyst Co3O4-BiVO4/g-C3N4 composite catalyst showed the highest photocatalytic activity, the removal rate of KN-R was up to 99.6% after being irradiated for only 30 min with visible-light. Even more, its optical and electrochemical properties were greatly improved, making it as a forceful candidate for practical photocatalysts under visible light. In summary, this work not only provided a highly efficient heterojunction-structured visible-light photocatalyst, but also supplied a novel method to diminish the photo-carriers recombination.

Effect of Surface Site Defects on Photocatalytic Properties of BiVO4/TiO2 Heterojunction for Enhanced Methylene Blue Degradation

Combining a super photoresponsive BiVO4 catalyst to the large band gap TiO2 material seems to be a great interest in order to improve the visible‐light‐driven photodegradation of hazardous pollutants. BiVO4/TiO2 heterojunction composites have been synthesized via a simple one‐pot hydrothermal route. Herein, we carefully highlighted the effect of BiVO4 content on the physicochemical and photocatalytic properties of solids towards the decomposition of methylene blue (MB) under solar light irradiation. The main results revealed that the formation of the heterostructures catalyst by incorporating BiVO4 into TiO2 stabilizes the anatase phase of TiO2 by inhibiting its crystal growth and improves significantly the light absorbance of titanium dioxide. The results showed that the best photocatalytic performance is assigned to the catalyst with 2 wt% BiVO4 loading which is higher than both pure BiVO4 and TiO2. This improvement of photocatalytic activity is related to the synergetic effect between both materials. Furthermore, the constructed junction leads to an increase in the concentration of oxygen defects on the semiconductor surface which could create an acceptor energy level into the valence band of TiO2. Four cyclic runs for the photocatalytic degradation of MB on BiVO4/TiO2 composite revealed its stability and sustainable reusability.

Ag2O-decorated electrospun BiVO4 nanofibers with enhanced photocatalytic performance.

Semiconductor photocatalysts are emerging as tools for pollutant degradation in industrial wastewater, air purification, antibacterial applications, etc. due to their use of visible light, which is abundant in sunlight. Here, we report a new type of p–n junction Ag2O/BiVO4 heterogeneous nanostructured photocatalyst with enhanced photocatalytic performance. P-type Ag2O nanoparticles were in situ reduced and assembled on the surface of electrospun BiVO4 nanofibers using ultraviolet (UV) irradiation; this process hindered the recombination of localized photogenerated electron–hole pairs, and hence resulted in the enhanced photocatalytic activity of the BiVO4/Ag2O nanocomposites. The photocatalytic activities of the obtained BiVO4 and BiVO4/Ag2O nanocomposites were assessed by measuring the degradation of rhodamine B (RhB) under visible light. The 10 wt% Ag2O/BiVO4 sample yielded the optimum degradation of RhB (98.47%), much higher than that yielded by pure BiVO4 nanofibers (64.67%). No obvious change in the XRD pattern of an Ag2O/BiVO4 sample occurred as a result of its use in the photocatalytic reaction, indicating its excellent stability. The high photocatalytic performance observed was attributed to the large surface-to-volume ratio of the essentially one-dimensional electrospun BiVO4 nanofibers and to the in situ growth of p-type Ag2O on the surface of the n-type BiVO4 nanofibers.

One-step hydrothermal deposition of F:FeOOH onto BiVO4 photoanode for enhanced water oxidation

Abstract While BiVO4 is considered one of the most promising candidates for photoelectrochemical (PEC) water oxidation, its further application is hampered by severe surface charge recombination. Herein, F-incorporated FeOOH (F:FeOOH) cocatalyst is used to modify the BiVO4 photoanode via a one-step hydrothermal deposition method. The composite photoanode (F:FeOOH/BiVO4) shows an impressive photocurrent density of 2.7 mA/cm2 (at 1.23 VRHE) and a notable initial potential that is negatively shifted by 150 mV relative to the pure BiVO4 electrode. These excellent PEC performances owe much to the formation of p-n junction between F:FeOOH and BiVO4 in the electrodes.

Photoelectrochemical performance of W-doped BiVO4 photoanode

One of the crucial challenges in enhancing the photoelectrochemical (PEC) water splitting performance of BiVO4 photoanode is to improve the charge separation and transfer efficiency. Therefore, in this paper, a novel multilayer gradient W-doped BiVO4 photoanode is fabricated for improved performances in solar water splitting. Firstly, different amounts of W mono-doped BiVO4 photoanodes are prepared, and the W (5%)-doped BiVO4 photoanode reaches highest photocurrent density of 0.61 mA cm−2 at 1.23 V versus reversible hydrogen electrode (RHE). Compared with the photocurrent density of the pure BiVO4 photoanode (0.28 mA cm−2), the enhancement can be attributed to the doped W which acts as an electron donor that could reduce the surface charge transfer resistance and facilitate charge transfer. Furthermore, multilayer gradient W-doped BiVO4 photoanodes are prepared to enhance PEC performances. The BVO-530 achieves a photocurrent density of 1.17 mA cm−2 at 1.23 V versus RHE due to the multilayer gradient structure which forms a diffusion path for electron–holes caused by the gradual increase in the Fermi level. The mechanisms of multilayer gradient W-doped BiVO4 photoanodes are discussed in detail based on PEC measurements. This work provides a new strategy for designing and fabricating photoanode systems to enhance the charge separation and transport for efficient water splitting.

Evaluating the photocatalytic efficiency of the BiVO4/rGO photocatalyst

The present study reported the preparation of BiVO4 by co-precipitation method. The as-prepared BiVO4 photocatalyst were deposited on rGO sheets to form BiVO4/rGO via the hydrothermal method. The crystalline structure, morphological, optical properties, and surface properties of the synthesized pure BiVO4 compared to BiVO4/rGO composite were studied using X-ray diffraction (XRD), scanning electronmicroscopy (SEM), photoluminescence (PL) spectrophotoscopy, UV–vis spectrophotometer with an integrating sphere, and N2 adsorption-desorption isotherm based on BET theory. The photocatalytic activity of the prepared samples were evaluated by the degradation of MB dye in aqueous medium under visible light irradiation. The result showed that the BiVO4/rGO composite exhibited greater photocatalytic efficiency compared to pure BiVO4 with the photocatalytic degradation efficiency remains stable up to fifth cycle. The improved activity of the BiVO4/rGO composite might be attributed to the high surface area available to adsorb more MB molecules, and efficient charge separation of BiVO4 through π electron on the rGO structure. According to experimental results, the possible photocatalytic mechanism of the BiVO4/rGO composite were determined and the active species hydroxyl radical were reported. Based on photocatalytic activity inhibition in the presence of both h+ (VB) and O2•− (CB) scavengers over the BiVO4 photocatalyst, it can be proposed that the hydroxyl radical generated during the photocatalytic degradation mechanism is mainly responsible by the main active species of h+ and O2•− at VB and CB positions, respectively.

Excellent performance of a novel dual Z-scheme Cu2S/Ag2S/BiVO4 heterostructure in metronidazole degradation in batch and continuous systems: Immobilization of catalytic particles on α-Al2O3 fiber

A ternary heterojunction of Cu2S/Ag2S/BiVO4 with enhanced charge transfer ability was synthesized via hydrothermal method and stabilized on the α-Al2O3 fiber. Catalysts were characterized by XRD, XRF, FT-IR, BET-BJH, FE-SEM, EDS, pHzpc, UV–Vis DRS, and PL spectra. Compared with pure BiVO4, at the optimal operational condition with 50 mg/l of metronidazole, 1 g/l of catalyst, irradiation time of 105 min, and at pH = 3, the degradation of contaminant was obtained as 52, 74.7, 85.8, and 94.5% by BiVO4, 5 wt% Ag2S/BiVO4, 15 wt% Cu2S/Ag2S/BiVO4, and 15 wt% Cu2S/Ag2S/BiVO4@α-Al2O3 respectively. The significant increment of photocatalytic activity of Cu2S/Ag2S/BiVO4 was related to the higher specific area, synergistic interfacial charge transfers, and promotion of electron-hole pair separation in the dual Z-scheme system. The α-Al2O3 acts as a photo-generated charge trapper which restrains the recombination of electron-hole pairs. The presence of α-Al2O3 drastically reduced the PL intensity of Cu2S/Ag2S/BiVO4. According to the quenching experiments, a reasonable mechanism of Cu2S/Ag2S/BiVO4 was also proposed. The effects of temperature and light intensity were also tested and the optimal values were determined at 25 °C and 400 w/m2 respectively. In the continuous system, at the optimum flow rate (2.4 ml/min), metronidazole degradation was 96.2% by Cu2S/Ag2S/BiVO4@α-Al2O3.

Study of the interfacial charge transfer in bismuth vanadate/reduce graphene oxide (BiVO4/rGO) composite and evaluation of its photocatalytic activity

We prepared unique BiVO4/reduce graphene oxide (BiVO4/rGO) nanocomposite with enhanced photocatalytic ability by hydrothermal method applying Bi(NO3)3·5H2O, NH4VO3 and graphene oxide as precursors. The physical and chemical attributes were characterized by various analytical techniques; X-ray diffractometer, scanning electron microscope, energy dispersive spectrum analysis, Fourier-transform infrared spectroscopy, X-ray photon spectroscopy, surface area Brunauer–Emmett–Teller analyzer and photoluminescence. Methylene blue was used as a pollutant and degraded under visible light irradiation; the photocatalytic activity of BiVO4/rGO nanocomposite was observed 29% higher than the pure BiVO4 catalyst. The graphene enhanced the surface adsorption property and increased the charge separation efficiency of photo-created charge carriers; moreover, the photoactivity of BiVO4 increased considerably. The mechanism for the BiVO4/rGO nanocomposite was purposed and discussed critically, which suggests that graphene acts as electron trapper and tuning the bandgap energy led to superior photocatalytic activity.

BiVO4-nanorod-decorated rutile/anatase TiO2 nanofibers with enhanced photoelectrochemical performance

Bismuth vanadate (BiVO4) nanorods (NRs)/bi-phase TiO2 hierarchical nanofibers have been successfully synthesized by electrospinning combined with hydrothermal process. Experimental results demonstrate that BiVO4/bi-phase TiO2 hierarchical nanofibers present the multilevel structures composed of BiVO4 NRs inlaid into TiO2 nanofibers. The as-prepared samples have the lower electron-hole recombination rates and higher transmission efficiency compared with pure BiVO4 NRs and bi-phase TiO2 nanofibers. The photocatalytic activities of the as-prepared samples are evaluated by photodegrading 4-nitrophenol (4-NP) solution, and the photocatalytic degradation rate of the BiVO4/bi-phase TiO2 hierarchical nanofibers reaches as high as 95.7% under simulated sunlight irradiation. The high photoelectrocatalytic properties of BiVO4/bi-phase TiO2 hierarchical nanofibers could be attributed to the successful establishment of BiVO4 and TiO2 heterojunctions.

Direct Z-scheme photocatalyst for efficient water pollutant degradation: A case study of 2D g-C3N4/BiVO4

The structure design on semiconductor photocatalyst is important for enhancing the photocatalytic performance of state-of-art materials to solve current environmental or energy issues. In this work, guided by the design principle for direct Z-scheme photocatalytic system, we construct a direct Z-scheme photocatalyst comprised of 2D g-C3N4/BiVO4 for environmental photocatalytic application. The chemical structures, morphologies, as well as the photo-electrochemical properties are detailed studied using multiple characterizations. The photocatalytic experiments show that the 2D g-C3N4/BiVO4 exhibits significantly enhanced degradation performance than the pure BiVO4, owing to the enhanced charge separation efficiency and maintained stronger redox capacity. More importantly, the proposed Z-scheme mechanism is also demonstrated by combing the ESR result and redox potential for the catalyst. The presented strategy to enhance the photocatalytic performance based on Z-scheme system may provide insights for the development of high-efficiency photocatalyst for environmental and energy applications.

Preparation and photocatalytic properties of Mo-doped BiVO4

Mo-doped BiVO4 microcrystals with tetragonal structures were prepared by a hydrothermal method. The phase transformation from monoclinic to tetragonal was observed as the concentration of molybdenum ions increased up to 10 mol%. Accordingly, the morphology of the as-preparation samples evolved from plate-shaped (molybdenum-free BiVO4) to pie-like (BiVO4:Mo). The photocatalytic activity of BiVO4:Mo with a tetragonal structure was much higher than that of the pure BiVO4 host with a monoclinic phase by using RhB as the simulated pollutants under sun-like irradiation. The degradation rate of RhB was increased from 40% with molybdenum-free BiVO4 to 97.8% with the Mo-doped BiVO4 materials.

A negative effect of carbon phase on specific capacity of electrode material consisted of nanosized bismuth vanadate embedded in carbonaceous matrix

Lithium-ion batteries (LIBs) are widely used all over the world. The LIBs belong to a renewable energy source and energy storage devices. The increase in energy demand causes that new materials of higher energy and higher power densities are still under investigation. Herein, we compare electrochemical properties of bismuth vanadate (BiVO4) embedded and not embedded into carbonaceous matrix as an anode material along with structural changes. Material incorporated into carbon phase (BiVO4@C) exhibited much better electrochemical stability but with lower specific capacity (128 mA h/g) in comparison with pure BiVO4 (217 mA h/g). XRD measurements showed the change in crystallographic structure due to lithium ion intercalation/extraction process. Hence, it seemed obvious that the presence of carbon affected the interfacial structural and electrochemical properties of bismuth vanadate based electrodes.

Visible light‐activated degradation of microcystin‐LR by ultrathin g‐C3N4 nanosheets‐based heterojunction photocatalyst

AbstractMicrocystins (MCs) is a harmful toxin generated by blue‐green algae in water, which has seriously threatened the ecological safety of water and human body. It is urgent to develop new catalysts and techniques for the degradation of MCs. A feasible electrostatic self‐assembly method was carried out to synthesize BiVO4/g‐C3N4 heterojunction photocatalyst with highly efficient photocatalytic ability, where BiVO4 nanoplates with exposed {010} facets anchored to the g‐C3N4 ultrathin nanosheets. The morphology and microstructure of the heterojunction photocatalysts were identified by XRD, SEM, TEM, XPS, and BET. The g‐C3N4 nanosheets have huge surface area over 200 m2/g and abundant mesoporous ranging from 2‐20 nm, which provides tremendous contact area for BiVO4 nanoplates. Meanwhile, the introduction of BiVO4 led to red‐shift of the absorption spectrum of photocatalyst, which was characterized by UV‐vis diffuse reflection spectroscopy (DRS). Compared with pure BiVO4 and g‐C3N4, the BiVO4/g‐C3N4 heterojunction shows a drastically enhanced photocatalytic activity in degradation of microcystin‐LR (MC‐LR) in water. The MC‐LR could be removed within 15 minutes under the optimal ratio of BiVO4/g‐C3N4. The outstanding performance of the photocatalyst is attributed to synergetic effect of interface Z‐scheme heterojunction and high active facets {010} of BiVO4 nanoplates, which provides an efficient transfer pathway to separate photoinduced carriers meanwhile endows the photocatalysts with strong redox ability.