Structure Of BiVO4 Research Articles

The Role of PEG 6000 and PVP as Stabilizing and Surfactant Agents in the Photoelectrochemical Properties of BiVO4 Monoclinic Structure

Nanocrystalline BiVO4 on monoclinic phase was obtained by a modified-solution combustion synthesis (SCS) using poly(ethylene glycol) (PEG 6000) and polyvinylpyrrolidone (PVP) as stabilizing and surfactant agents, respectively. An active photoanode was built using a simple procedure by dip-coating deposition process on fluorine-doped tin dioxide (FTO). The structure, morphology and optical properties of FTO/BiVO4 photoanode were evaluated by means of X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM) and diffuse reflectance UV-Vis spectroscopy. The photoelectrochemical performance measurements were carried out by linear sweep voltammetry (LSV), chronoamperometry and electrochemical impedance spectroscopy (EIS) under InGaN blue light emitting diode (LED) illumination condition (about 450 nm). In Na2SO4 electrolyte solution, the electrode has presented better photoelectroactivity than in NaNO3 solution, as evidenced by photoelectrochemical parameters such as: the highest photocurrent density (js) value, cathodic shifts of the onset potential (OP) and lower charge-transfer resistence (Rct). In the methyl orange (MO) degradation reaction the FTO/BiVO4 electrode has presented high photoelectroactivity, where the estimated kinetic constant rate (kobs) is 4.74 × 10−3 and 7.54 × 10−3 min−1 in NaNO3 and Na2SO4 solutions, respectively. This remarkable performance of the as-prepared electrode is due to the morphological BiVO4 structure,with elongated-shape nano-sized domain particles, besides the considerable porosity and roughness levels on electrode surface.

A simple flame strategy for constructing W‐doped BiVO 4 photoanodes with enhanced photoelectrochemical water splitting

Bismuth vanadate (BiVO4) with narrow band gap has been widely reported in photoelectrochemical (PEC) water splitting. However, the low kinetic of water splitting is still the key for limiting the PEC performance of BiVO4. Herein, a W-doped BiVO4 (W-BVO) photoanode has been controllably prepared by a fast flame method within 40 seconds. The preparation condition including calcination time and quantity of W precursor has been systemically investigated, in order to optimize the PEC performance of W-BVO. X-ray photoelectron spectroscopy indicates that the introduction of W did not obviously cause the formation of oxygen vacancies, revealing that W has been doped into the crystal structure of BiVO4 by flame method. The electrochemical impedance spectroscopy further confirmed that the W-BVO possesses a lower charge transfer resistance with fast transfer ability of carriers. Based on the incident photon-to-electron conversion efficiency, the acceptable solar to electron conversion efficiency of 5.79% (340 nm, 1.23 V vs RHE) has been achieved in the W-BVO system. A PEC mechanism has been proposed to demonstrate the promotion of kinetic for PEC water splitting. This work offers a promising alternative route for the design and fabrication of efficient photoanodes in other PEC systems.

Fabrication of effective visible-light-driven ternary Z-scheme ZnO-Ag-BiVO4 heterostructured photocatalyst for hexavalent chromium reduction

A simple hydrothermal technique was used for the synthesis of a ternary ZnO-Ag-BiVO4 nanocomposite. The morphology, structure and optical performance of ZnO-Ag-BiVO4 were analyzed by XPS, TEM, XRD, FT-IR, FE-SEM, PL, and DRS. The sharp peaks of ZnO-Ag-BiVO4 indicated the good crystalline nature of the photocatalyst. FE-SEM images depicted the hexagonal structure of ZnO and the plate-like structure of BiVO4. The heterostructured catalyst Ag-ZnO-BiVO4 is capable of reducing 20 ppm of Cr(VI) from potassium dichromate in 100 mL aqueous solution to 97% within 70 min under visible light. The first-order rate constant value of 0.0371 min−1 and a 97% reduction for the ZnO-Ag-BiVO4 catalyst show its maximum photoreduction efficiency. The optimum pH for effective Cr(VI) reduction on ZnO-Ag-BiVO4 is 5 and it is steady and recyclable. The photo generated electron acts mainly in the photocatalytic reduction of hexavalent chromium. The photocurrent analysis shows that the ZnO-Ag-BiVO4 composite material can enhance the photoexcited charge production, separation and migration, which improved the photocatalytic reduction of Cr(VI). Proposed Z-scheme mechanism of ternary ZnO-Ag-BiVO4 clearly explains the electron-hole separation and higher efficiency of this nanocomposite in the photoreduction.

BiVO4@ZnIn2S4/Ti3C2 MXene quantum dots assembly all-solid-state direct Z-Scheme photocatalysts for efficient visible-light-driven overall water splitting

Novel BiVO4@ZnIn2S4/Ti3C2 MXene quantum dots (QDs) assembly all-solid-state direct Z-scheme photocatalyst is fabricated via in-situ growth combined with two-step solvothermal strategy, which forms a hierarchical core-shell structure. The proper energy band structure of BiVO4 and ZnIn2S4 and the formation of a good solid-solid contact interface between them promote the construction of Z-scheme system, which achieves effective charge separation. It is surprisingly discovered that Ti3C2 MXene QDs can be applied as cocatalysts for photocatalytic overall water splitting, which could accelerate the surface redox kinetics of the catalyst due to the unique properties of Ti3C2 MXene QDs. In particular, due to its excellent metal conductivity, a Schottky barrier can be formed at the interface in contact with ZnIn2S4, further promoting charge separation. BiVO4@ZnIn2S4/Ti3C2 MXene QDs achieves effective visible-light-driven pure water splitting into O2 and H2 evolution rates up to 50.83 and 102.67 μmol g−1 h−1 (~1:2). In addition, it also shows high photocatalytic degradation Bisphenol A efficiency of ~96.4 %. The high photocatalytic performance can be ascribed to the all-solid-state direct Z-scheme structure favoring spatial charge separation, Ti3C2 MXene QDs as cocatalysts promoting proton reduction, and hierarchical core-shell structure offering more surface active sites. This work provides new insights to fabricate high-performance direct Z-scheme assembly system.

Rational design and fabrication of frame‐structured doped bismuth vanadate nanoarchitectures as a polysulfide shield to boost the performance of lithium‐sulfur batteries

Lithium-sulfur (Li-S) battery has been evoked increasing attention due to its creditable energy density and the abundant sulfur in nature. Nevertheless, its commercialization is still hampered in virtue of the poor conductivity of sulfur and grievous polysulfide shuttling. To address these issues, in this work, we report a cost-efficient and facile tactic to fabricate frame-structured neodymium-doped bismuth vanadate (BiVO4) nanoarchitectures, which are reasonably designed as a polysulfide shield to alleviate the shuttling effects. The synthesized nanoarchitectures exhibit typical tetragonal phase with a unique frame structure. The frame structure of BiVO4 impedes polysulfide shuttling, and supplies electronic and ionic transmission routes. Furthermore, the rational doping of neodymium within the BiVO4 nanoarchitectures can improve electric conductivity, as well as efficiently alleviate the loss of sulfur and improve activity for sulfur reduction. Benefitting from the structural feature and doping strategy, the Li-S battery performance with a neodymium-doped BiVO4 nanoarchitecture is significantly improved. This strategy is easily adopted for fabricating other nanostructures, providing a feasible way to design cheap and efficient battery materials. This work is further available for synergistically uniting the virtues of the frame nanoarchitectures and doping protocol to develop advanced Li-S batteries.

Yb-substitution triggered BiVO4-Bi2O3 heterojunction electrode for photoelectrocatalytic degradation of organics

As a photocatalyst with visible light response, BiVO4 has been widely investigated for organic wastewater treatment. However, its catalytic activity is greatly restricted because the photogenerated electrons and holes would recombine easily. Herein, we took a Yb-substitution strategy to construct BiVO4-Bi2O3 heterojunction for improving spatial separation of photogenerated electrons and holes. XRD, XPS, FESEM, and TEM investigations demonstrated that Yb-substitution can change the structure of BiVO4 and trigger the formation of BiVO4-Bi2O3 heterojunction. The photoeletrocatalytic activity of the as-synthesized composites was verified by degradation of MB under simulated sunlight. More importantly, the photoeletrocatalytic activity of 0.04Yb-BiVO4-Bi2O3 composite was significantly improved, resulting from the successful construction of BiVO4-Bi2O3 heterointerfaces. Moreover, the 0.04Yb-BiVO4-Bi2O3 composite displayed the best the catalytic performance, and the degradation rate of MB under simulated sunlight irradiation and an applied bias voltage of 1.0 V can reach 83.2 % within 2 h.

Synergy of charge pre-separation and direct Z-scheme bridge in BiVO4{0 4 0}/Ag6Si2O7 photocatalyst boosting organic pollutant degradation

The rapid recombination and poor redox capability of photoinduced charge carriers seriously impede the photocatalytic activity. Herein, a direct Z-scheme photocatalyst was fabricated by selectively depositing Ag6Si2O7 nanoparticles (NPs) on the {0 4 0} facets of BiVO4. Owing to the facet-dependent band structure of BiVO4, the photoinduced electrons and holes can be pre-separated upon photoillumination and transfer to {0 4 0} and {1 1 0} facets of BiVO4, respectively. A rapid combination of the separated electrons at the {0 4 0} facets of BiVO4 with holes of the Ag6Si2O7 NPs then takes place triggering a direct Z-scheme photocatalysis. Such a charge pre-separation triggered by the faceted BiVO4, together with Z-scheme at the interface warrants not only effective photoinduced charge separation but also excellent redox capability owing to the increased redox potential. The photocatalytic rate constant of the optimum BiVO4{0 4 0}/Ag6Si2O7 heterostructure is 28.2 and 17.2 times higher than those of pristine BiVO4 and Ag6Si2O7, respectively. This study offers a new insight for constructing direct Z-scheme photocatalysts with high degradation efficiency based on facet-controlled crystals.

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.

Surfactants-assisted preparation of BiVO4 with novel morphologies via microwave method and CdS decoration for enhanced photocatalytic properties

The development of a highly efficient and rapid method for the accurate preparation of photocatalysts with novel morphologies is a hot research topic. The different morphologies of BiVO4 was prepared using surfactants-assisted microwave method, and demonstrated irregular (no surfactant), octahedral (sodium dodecyl benzene sulfonate), olive-like (polyvinylpyrrolidone) and hollow structures (ethylenediaminetetraacetic acid), respectively. The BiVO4-CdS were synthesized using the chemical-bath-deposition method with different morphologies of BiVO4 as the substrates. The hollow structure of BiVO4 displayed the highest photocatalytic performance. Moreover, the photodegradation rates of the hollow structure BiVO4-CdS on tetracycline hydrochloride and ciprofloxacin were about 1.8 and 1.5 times higher than the corresponding BiVO4, indicating that the Z-scheme heterojunction can improve the photogenerated electron pairs separation efficiency. Furthermore, the regulation mechanism of morphology and energy-band position, as produced using the surfactants, has also been thoroughly investigated in this work, which provides a novel insight into the efficient and rapid preparation of photocatalysts with special morphology and high performance.

Degradation of ciprofloxacin antibiotic under visible light by BIVO4 photocatlyst

In this paper, we have successfully synthesized BiVO4 by co-precipitation method. Results of BiVO4 are synthesized under the support of urea, forming a single-line scheelite structure of BiVO4. The synthesized sample were characterized by X-ray diffraction, scanning electron microscopy, raman and UV-visible diffuse reflectance spectra. In this work, the degradation of Ciprofloxacin (CFX) irradiated under visible light (Lamp LED 60W) by BiVO4. The results of SEM images of BiVO4 show that the crystal structure is granular, nanoparticle size and uneven. The Eg value of BiVO4 is 2,312 Ev. The decrease in CFX concentration at pH=3, concentration of 10 ppm and catalyst dosage of 100 mg is the most optimal condition with photodegradation efficiencies of CFX is 75% after 180 min of irradiation. Material obtained in study can be applied in the decomposition of other antibiotics.

Photoelectrochemical water splitting using lithium doped bismuth vanadate photoanode with near-complete bulk charge separation

Photoelectrochemical performance of BiVO4 photoanode is limited by poor light absorption, charge separation and transfer efficiencies. For the first time in the literature, Li doped nano-porous BiVO4 photoanode showed complete bulk charge separation efficiency (~100%) at 1.23 V vs RHE along with enhanced light absorption for water splitting. Li doping showed an increase (>20 times) in the photoelectrochemical water splitting compared to pristine BiVO4 photoanode. In particular, oxygen evolution catalyst was also employed for further improving the photoelectrochemical performance (4.2 ± 0.18 mA cm−2) of Li:BiVO4 photoanodes. The density functional theory calculations showing the formation of inter-band with band gap reduction due to interstitial Li doping in BiVO4 structure support enhancement in photoelectrochemical performance. In addition, Li doping in the BiVO4 lattice void positions led to a record photocurrent density of 7.3 ± 0.36 mA cm−2 at 1.23 V vs RHE in the presence of hole scavenger under one sun illumination. Further, present study systematically demonstrates role of Li in BiVO4 host for water oxidation through a detailed characterization and study of optical and charge transport properties.

Highly enhanced performance of heterojunction Bi2S3/BiVO4 photoanode for photoelectrocatalytic hydrogen production under solar light irradiation

A heterojunction structure of BiVO4 coupled with a narrow bandgap photocatalyst Bi2S3 was fabricated forming a composite material with strong capacity in visible light absorption and enhancement in the separation rate of photogenerated charge carriers owing to their suitable band structures. As a result, efficiency of hydrogen production through photoelectrocatalysis is highly enhanced. The morphology and composition of as-prepared sample electrodes are measured through X-Ray Diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and X-ray photoelectron spectroscopy (XPS). The performance of the hybrid nanostructure Bi2S3/BiVO4 photoelectrode was found to be related to the growing process of Bi2S3 nanowire during the hydrothermal preparation process. The composited Bi2S3/BiVO4 photoanode achieved a photoconversion efficiency of 2.9% which is nearly 3-fold that of the bare BiVO4 electrode under visible light irradiation, while the hydrogen production was greatly enhanced by nearly 5-fold in the photoelectrocatalytic hydrogen production reaction.

Fabrication of high surface area AgI incorporated porous BiVO4 heterojunction photocatalysts

The low surface area and photogenerated charge carrier recombination rate severely affects the usability of a photocatalysts. In this work, a visible light active AgI/BiVO4 photocatalyst was fabricated via a low temperature one step hydrothermal method. Low temperature preparation results in a porous and very high surface area (114 m2/g) BiVO4 photocatalysts. XRD, FTIR, Raman and BET surface area analysis revealed that AgI is bonded as well as embedded in the porous structure of BiVO4, which causes shrinking of the BiVO4 lattice. Compare to bare BiVO4, the AgI/BiVO4 photocatalyst shows nearly 1.7 times higher photocurrent response and 43% higher photocatalytic activity. The significantly high photocatalytic activity ascribed to the very high surface area, and the effective charge separation at the AgI/BiVO4 p-n heterojunction. Further, based on UV-DRS and Mott-Schottky measurements, a plausible charge transfer mechanism is proposed.

Enhanced photoelectrocatalytic degradation of bisphenol a by BiVO4 photoanode coupling with peroxymonosulfate

Peroxymonosulfate (PMS) was introduced into a photoelectrocatalytic (PEC) system with a bismuth vanadate (BiVO4) photoanode to enhance the PEC oxidation of bisphenol A (BPA). With the addition of 5 mM PMS, the degradation efficiency of 10 mg/L BPA was significantly improved from 24.2% to 100.0% within 120 min and the side reaction of O2 evolution was avoided at a potential as low as 0.25 V. The electron spin resonance and radicals quenching results suggested that photogenerated holes instead of SO4•− and OH were primarily responsible for the BPA degradation. To further explore the role of PMS, a photocatalytic fuel cell with the structure of BiVO4 (photoanode)|10 mg/L BPA|proton exchange membrane (separator)|5 mM PMS|Pt (cathode) was constructed and demonstrated that PMS played a key role as electrons acceptor instead of the precursor of SO4•−. The PEC tests including open-circuit potential, linear sweep voltammetry and electrochemical impedance spectroscopy indicated that a more efficient separation of photogenerated charges was achieved in the PEC process with the help of PMS, thus generating more photogenerated holes for enhanced BPA degradation. This work may provide a novel way to enhance the separation of photogenerated charges at the photoanode.

Visible active reduced graphene oxide-BiVO4-ZnO ternary photocatalyst for efficient removal of ciprofloxacin

A highly effective rGO-BiVO4-ZnO photocatalyst was synthesized by hydrothermal method and characterized by XRD, FE-SEM, HR-TEM, XPS, Photoluminescence, FT-Raman, FT-IR and Diffuse reflectance spectroscopy. The narrow peaks of rGO-BiVO4-ZnO reveal good crystallinity and strong diffraction peaks of GO at 11.30° and 42.43° correspond to the layered structure of GO. Average crystalline size of the rGO-BiVO4-ZnO was 35 nm. TEM images reveal the presence of nanorods of ZnO and pristine structure of BiVO4 on the rGO sheet. The band gap energy for rGO-BiVO4-ZnO is 2.35 eV. The reduced PL emission at 524.6 nm by rGO-BiVO4-ZnO relative to the synthesized ZnO, reveal a decrease of recombination of the photon-induced electron-hole pair by loading of BiVO4 on ZnO. Ternary nanocomposite rGO-BiVO4-ZnO exhibits highest photodecomposition activity, achieving 98.4% decomposition efficiency for ciprofloxacin in 60 min under visible light irradiation. Photogenerated holes play a major role in the photocatalytic decomposition of ciprofloxacin (CIP), Low cost rGO-BiVO4-ZnO is stable and recyclable for effective decomposition of ciprofloxacin. Based on the GC-MS analysis, the CIP decomposition pathway as well as decomposition mechanism of piperazine ring oxidation are proposed. The photodecomposition efficiency is mainly due to charge transfer and excellent electron hole separation by doping of rGO.

Hydrothermal synthesis of C doped ZnO nanoparticles coupled with BiVO4 and their photocatalytic performance under the visible light irradiation

For the first time, C-ZnO/BiVO4 heterostructured nanocomposite has been synthesized from BiVO4 and carbon-doped ZnO nanoparticles. X-ray diffraction (XRD) study showed themonoclinic scheelite structure of BiVO4 and the hexagonal wurtzite structure of ZnO in the C-ZnO/BiVO4 composite. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) images revealed the spherical nanoparticles of size 20 to 30 nm for C-ZnO. The band gap of the ZnO has turned towards the visible region by doping with carbon as well as a composite formation with visible light active material BiVO4. The chemical states of Zn, O, C and Zn, O, C, Bi, V species in C-ZnO, and C-ZnO/BiVO4 composite respectively were confirmed by X-ray photoelectron microscopy (XPS) analysis. Also, the XPS spectra showed the significant peaks shift in the electronic states of Zn, O, and C for the heterojunction composite. The suppression of the electron-hole recombination rate was confirmed from the quenching of photoluminescence (PL) intensity for the composite. The adsorption study has performed, and the experimental results fit well with the Langmuir isotherm model for understanding the catalytic activity of the samples. The possible Z-scheme photocatalytic mechanism of the C-ZnO/BiVO4 nanocomposite photocatalyst has proposed. The nanocomposite exhibited the enhanced catalytic activity with the higher degradation rate constant of 0.050 min−1 for 50 min irradiation of visible light compared with their counterparts.

Enhanced photocatalytic degradation performance of organic contaminants by heterojunction photocatalyst BiVO4/TiO2/RGO and its compatibility on four different tetracycline antibiotics

Photocatalytic performance of four tetracycline antibiotics using BiVO4/TiO2/RGO composites was investigated. To make full use of catalysis, optimum preparation conditions involved RGO content, solution pH and hydrothermal temperature on the structure forming of BiVO4/TiO2/RGO composites were investigated. Subsequently, the obtained visible light-driven photocatalyst was used to degrade four kinds of tetracycline antibiotics involved tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DXC) for wastewater treatment. Results showed that BiVO4/TiO2/RGO photocatalyst exhibited excellent photocatalytic activity and high compatibility due to the enhanced separation efficiency of photo-generated carriers with high reduction and oxidation capability. The degradation process of four kinds of tetracycline antibiotics was traced and detected through identifying intermediates produced in the reaction system. And a possible catalytic mechanism for BiVO4/TiO2/RGO photocatalyst was put forward based on band gap structure of BiVO4 and TiO2.

Synthesized BiVO4 was by the co-precipitation method for Rhodamine B degradation under visible light

Recently, BiVO4 photocatalysts has been received much attention in field of catalysts. Because it can be used to degrade harmful organic catalysts in visible light, irradiation produces CO2, H2O and less harmful organic matter. In this study, we have successfully synthesized a BiVO4 photocatalysts via co-precipitation method in the presence of urea and different calcined temperatures. The survey calcined temperatures as 300°C; 350°C; 400°C and 450°C. The obtained materials were characterized by Scanning electron microscope (SEM) and X-ray diffraction (XRD). The photocatalytic activity was evaluated by the photocatalytic degradation of rhodamine B (RhB) degradation under visible compact Philip lamp (40W) light irradiation. The result indicates that all samples calcined are monoclinic scheelite structure of BiVO4. The BiVO4-350°C sample performed the best in the photodegradation of RhB.

Synthesis of BiVO4 nanoflakes decorated with AuPd nanoparticles as selective oxidation photocatalysts

The ultrathin BiVO4 nanoflakes decorated with Pd and AuPd nanoparticles (NPs) were respectively synthesized and optimized for the enhanced photocatalysis towards selective oxidation of aromatic alcohols. The monometallic Pd(x)-BiVO4 samples presented hump-like variation in the photocatalytic activity with increasing Pd amount (x) from 0 to 2.0 wt%. Subsequently, coupling Au with Pd on BiVO4 nanoflakes resulted in a further improvement in the photocatalysis, with retaining the high selectivity (>99%) for aldehyde production. By tuning metal loading, the typical Au(0.5)Pd(0.5)-BiVO4 photocatalyst exhibited the highest benzaldehyde yield of 887.7 μmol·g−1·h−1, which was 6.0 times that of bare BiVO4 nanoflakes and 1.35 times that of Pd(1.0)-BiVO4 photocatalyst. A series of characterizations and DFT calculations confirmed the enhanced light harvesting and charge separation of the Au(0.5)Pd(0.5)-BiVO4 material, owing to the strong electronic couplings in AuPd NPs and its remarkable influence on the band structure of BiVO4. The photocatalytic mechanism studies indicated that the selective oxidation of aromatic alcohols was achieved by the cooperation of photogenerated holes and O2− radical, and this process was promoted by the interfacial synergism between AuPd NPs and BiVO4 nanoflakes. This work demonstrates a systematic study on optimizing photocatalysts to improve their performance in light-driven organic transformations as well as highlights the synergistic effect of metal-metal coupling and metal-semiconductor interface on photocatalysis.

Charge-transfer peculiarities in mesoporous BiVO4 surfaces with anchored indoline dyes

Mesoporous thin films of bismuth vanadate were synthesized by sol–gel method with defined deposition parameters and annealing treatments leading to nano-textured surfaces. The stabilization of monoclinic BiVO4 structure was demonstrated by structural investigations and nano-islands morphology of the films illustrated by Atomic Force Microscopy (AFM) studies. Indoline dyes (D149) were used to sensitize the film surfaces able to show photoinduced charge transfer on the hybrid surfaces using Kelvin force microscopy (KFM). The distributions of the surface electrical potentials were compared as function of the surface texture and the sensitization by dyes. A model of the band alignment in hybrid systems was proposed to account for the observed charge transfer. The photocatalytic activity of the hybrid films was also investigated and discussed.