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XRD patterns of (A) Bi, (B) BiVO 4 , (C) Bi 2 WO 6 , and (D) Bi 2 Mo 3 O 12 electrodes. The peaks generated from the FTO substrate are denoted by asterisks.
Source publication
The major limitation to investigating a variety of ternary oxides for use in solar energy conversion is the lack of synthesis methods to prepare them as high-quality electrodes. In this study, we demonstrate that Bi-based n-type ternary oxides, BiVO4, Bi2WO6, and Bi2Mo3O12, can be prepared as high-quality polycrystalline electrodes by mild chemical...
Citations
... Kang et al demonstrated that the electrodeposited Bi dendritic electrodes followed by the introduction of a V precursor solution during the oxidation process can lead to BiVO 4 NPs. The resultant BiVO 4 thin film had a high surface area and a good electrical continuity among the particles [29]. Using the similar electrodeposition procedure, Bai et al fabricated Cu 2 O/BiVO 4 p-n heterojunction photoanode and obtained the maximum photocurrent density of 1.72 mA·cm −2 (1.23 V vs RHE), which is 4.5 times higher than that of pristine BiVO 4 thin film (∼0.38 mA·cm −2 ) at the same applied potential [30]. ...
... Scheme 1 presents the synthesis procedure to prepare ZnO NDs coated with BiVO 4 NPs, which could be converted from electrodeposited Bi metal using a modified version of the previously described chemical and thermal treatments [29]. In the first step, the plating solution was prepared by dissolving 20 mM of bismuth(III) nitrate pentahydrate (Bi(NO) 3 .5H 2 O, Sigma Aldrich) in 100 ml ethylene glycol (HOCH 2 CH 2 OH, Sigma Aldrich) solution. ...
... It should be pointed out that the electrodeposited Bi crystals did not cover the entire ITO surface ( figure 2S(b)). This island morphology of Bi is attributed to the poor dissolution of Bi deposits [28,29]. However, as shown in figure 4(c), the ITO surface was almost fully covered with porous, uniform, and nanocrystalline BiVO 4 . ...
Photoanodes with a large electrochemically active surface area, rapid charge transfer, and broadband light harvesting capacity are required to maximize the photoelectrochemical (PEC) water splitting performance. To address these features, we demonstrate that 3D hierarchal ZnO nanodendrites (NDs) can be sensitized with BiVO4 nanoislands by chemical and thermal treatments of electrodeposited Bi metal films. The flat band measurements and optical characterization suggested that the resulting heterojunction had type-II band alignment with a viable charge transfer from BiVO4 to ZnO NDs. In parallel, PL analysis revealed inhibition of the charge recombination rate by the electron transfer between BiVO4 and ZnO NDs. Upon AM 1.5 G illumination, BiVO4/ZnO NDs heterojunction yielded the highest photocurrent efficiency (0.15 mA·cm⁻² at 1.2 V vs. NHE), which was attributed to its enhanced surface area (due to the presence of small dendrite branches), extended broadband light absorption extending from UV to visible light regions, and the most efficient interfacial charge transfer as proven by electrochemical impedance spectroscopy (EIS) studies. Besides, the incident photon-to-current conversion efficiency and applied bias photon-to-current efficiency tests confirmed an improved spectral photoresponse of the heterojunction based photoanode, particularly towards the visible light spectrum. The results outline a promising synthesis route for building heterojunctions between visible light active and wide band gap semiconductors for the use as a highly efficient photoanodes in a PEC cell.
... It is proposed that the product selectivity is associated with Bi-BiVO 4 heterojunctions, which can be formed by Bi-metallic on the BiVO 4 surface when a negative potential of À1.0 V vs. Ag/AgCl is applied. [18][19][20] This hypothesis is based on the potential-pH equilibrium diagram for Bi, which shows that, in any cathodic region below Hydrogen evolution potential, metallic Bi is stably formed. On the other hand, in the same potential range, it is expected that V 2 O 3 is still stable, as shown in Fig. 4. Indeed, both the Bi-BiVO 4 heterojunction and the external potential applied would contribute to addressing the 3 Total production of liquid chemicals from CO 2 R using assynthesized BiVO 4 as catalysts and induced by photocatalysis (using different UV and LED illumination), electrocatalysis, and photoelectrocatalysis (using both electrons and photons by UV or LED illumination) sources. ...
Here, we explore monoclinic BiVO4 as a cathode in a photoelectrochemical (PEC) system for CO2 reduction (CO2R). The catalyst was prepared using a simple oxidant peroxide method with crystallization under hydrothermal conditions, and subsequently sprayed on the FTO substrate. CO2R was carried out in an inflow and sealed electrochemical system for 6 h. The best performance was found to be under photoelectrocatalysis powered by a light-emitting diode (LED) as an illumination source when compared to photocatalysis (using different halogen UV and LED illumination), electrocatalysis, and photoelectrocatalysis powered by a halogen UV illumination source, with total production values of 22 and 5.5 μmol cm⁻² for methanol and acetic acid, respectively. This achievement occurs because, even though BiVO4 as a photocatalyst does not have sufficient potential to drive CO2R, an external potential can be applied to drive the reaction. Moreover, the photogenerated electron–hole pairs are guided by the external potential, improving the charge separation and promoting the rapid electron transfer to reduce CO2 on the photoelectrocathode at a lower overpotential when compared to electrocatalysis. LED illumination produced higher amounts of products than UV illumination because UV light affects the catalyst surface altering the number of catalytic sites available for the reaction and reducing their performance.
... 25 In our study, bismuth tungstate (Bi 2 WO 6 ) was selected as a prototypical photocatalyst, 26,27 which has shown promise in C−H activation but has received less attention in the photocatalysis literature. 28 On the one hand, its inherent activity is lower than more widely studied photocatalysts, such as TiO 2 and ZnO, which offers an opportunity to minimize overoxidation. On the other hand, Bi 2 WO 6 is anticipated to feature tunable surface oxygen species. ...
... In some of them, electrochemical procedures were developed to prepare a high-surface-area polycrystalline metal electrode of bismuth as a precursor, on which a chemical reaction with vanadium precursor was carried [17]. Hence, the photoelectrochemical properties may vary due to surface defects of the synthesized material, resulting in enhanced carrier transport and ban gap reduction [18]. ...
This paper reports the synthesis, characterization, and photoelectrochemical evaluation of BiVO4 thin films. Bi thin films were obtained by electrodeposition and then thermally oxidized. Before thermal oxidation, the vacuum annealing temperature of the metallic Bi films significantly changed the final properties. Increasing the annealing temperature of the samples reduced their thickness and increased compaction and the growth in grain size. At the same time, this increase reduced the energy band gap, improved the electrical properties, including the charge carrier absorption and transport, and broadened the Urbach energy. The best performance was obtained with a film vacuum annealed at 10 mTorr and 200 °C, while the thin film annealed at 250 °C showed a deterioration of the material. The energy band gap ranged from 2.44 to 2.53 eV, while the calculated carrier density ranged from 6.24 × 10¹⁷ to 3.70 × 10¹⁸ cm⁻³. Based on Mott-Schottky plots, these materials exhibited Vfb of 0.441–0.611 V vs. NHE, making them suitable for photoanodes in solar water splitting and promising routes for hydrogen production.
... [13,28] As a result, various Bi-based mixed oxides were developed as visible light responsive photocatalysts and photoelectrodes. [29,30] BiVO 4 , as one of the most extensively investigated Bi-based semiconductors, was thus analyzed and evaluated based on its physical properties, especially those of optics and charge transport. ...
Solar energy‐driven overall water splitting (OWS) is an attractive way for generating clean and renewable green hydrogen. One key challenge is the construction of OWS systems with high solar energy conversion efficiencies, in which how to manipulate photoexcited charge carriers to efficiently participate in the reaction is the top priority. In recent years, bismuth vanadate (BiVO4) has emerged as one of the most promising materials for photo(electro)catalytic OWS and considerable progress has been achieved. In this review, recent advances of BiVO4‐constituted OWS systems in both photoelectrocatalytic and photocatalytic approaches are presented in a mainline of effective charge carrier utilization. Various strategies for improved charge carrier utilization, including band structure engineering, improving charge separation, reducing charge recombination, and accelerating reaction kinetics, are summarized and analyzed in detail. Finally, perspective and outlook on further exploring the application potential of BiVO4 are proposed.
... Zr-doped BiVO 4 films were prepared following a previously reported method. 61 Metallic Bi was electrodeposited on glass substrates coated with fluorine-doped tin oxide (FTO), followed by a reaction with the vanadium precursor in DMSO at 450°C for 2 h. Zr precursor was added as 2.5 mol % to the bismuth solution, according to a previously reported optimization process. ...
The present study proposes a laser irradiation method to superficially reduce BiVO4 photoelectrodes and boost their water oxidation reaction performance. The origin of this enhanced performance toward oxygen evolution reaction (OER) was studied using a combination of a suite of structural, chemical, and mechanistic advanced characterization techniques including X-ray photoelectron (XPS), X-ray absorption spectroscopy (XAS), electrochemical impedance spectroscopy (EIS), and transient absorption spectroscopy (TAS), among others. We found that the reduction of the material is localized at the surface of the sample and that this effect creates effective n-type doping and a shift to more favorable energy band positions toward water oxidation. This thermodynamic effect, together with the change in sample morphology to larger and denser domains, results in an extended lifetime of the photogenerated carriers and improved charge extraction. In addition, the stability of the reduced sample in water was also confirmed. All of these effects result in a two-fold increase in the photocurrent density of the laser-treated samples.
... [70,71] Hosseini et al. [72] synthesized BiVO 4 films in different morphological structures. To confirm that, the resultant SEM images [92,93] showed uniform nanodendritic structures with length of dendrite trunks of more than 1 μm and diameter of branches less than 100 nm. The branches were very ordered on each side of the trunk. ...
Bismuth vanadate (BVO) has been established as an efficient photocatalyst for water remediation and energy applications. Its crystal structure stability, high light quantum and electronic transmission efficiency, and outstanding energy utilization capacity are the main reasons for its enhanced utilization as a robust photocatalytic material. Several studies have reported many synthesis methods and strategies to design highly efficient BVO photocatalysts with different shapes, morphologies, facets, oxygen vacancies. This review systematically encapsulates the effects of morphologies on the photodegradation properties. Here, we have surveyed the synthesis methods of BVO photocatalysts followed by their different synthesized morphologies. The photosensitization mechanism whereby the organic dye plays both the role of photosensitizer as well as sample to be degraded is addressed. Further, we have highlighted the general sequential photocatalytic processes and the recent advances on degradation of three model pollutants (Methylene Blue, Rhodamine B and Methyl Orange). The 3 steps photocatalytic mechanism of BVO photocatalysts have discussed. This review provides also the effects of crystal facets, heterojunction BVO materials and elemental doping on the photocatalytic efficiency. Finally, current status, challenges to improve the photoactivity and the future possible scenarios are summarized.
... BiVO 4 is also a suitable photoanode material for PEC WS [71][72][73][74]. The direct band gap of BiVO 4 is 2.4-2.5 eV and it is an n-type semiconductor (with a photocurrent of about 7.5 mA cm −2 ), covering the entire visible light range of the solar spectrum, being alkaline with neutral friendly conditions, non-toxic and relatively cheap [75]. ...
... Therefore, it is extremely important to incorporate effective and stable catalysts into photoactive semiconductor materials. There have been studies using ion doping [76][77][78], nanostructures [79], passivation layer or electrocatalyst for surface modification [80,81], and synthesis [73] to solve the above problems. BiVO 4 achieves the maximum catalytic performance at a conversion efficiency of STH 8.1% through a double junction GaAs/InGaAsP photovoltaic (PV) device [82]. ...
... Therefore, considerable efforts have been devoted to the development of efficient and durable heterogeneous catalysts (Monfort et al. 2016). Dealing with the same matter, due to its facile synthesis, good stability, and nontoxicity (Kang et al. 2014), BiVO 4 attracted intensive attention as a promising material for hydrogen production (Lin et al. 2012), photocatalysis (Kudo et al. 1998;Shao et al. 2020), photo-electrocatalysis (Wang et al. 2017), sensors , and separation (Park et al. 2013). Besides, the choice of porous BiVO 4 nanostructures is based on the effectiveness of the large specific surface area between nanostructure and solution and thus to higher exposure of active sites, offering enhanced catalytic activity. ...
Bismuth vanadate (BiVO4) nanostructured films were prepared and successfully applied for peroxymonosulfate (PMS) activation for the degradation of rhodamine B (RhB) in aqueous solution. The BiVO4 thin films were obtained by thermal reaction between electrodeposited bismuth (Bi) films and vanadium precursor. The as-prepared BiVO4 porous, nanoflowers, and cluster nanostructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, and BET analysis. The catalytic performance of BiVO4 nanostructures has been carefully evaluated in activating PMS for the degradation of RhB. The nanoflower-like BiVO4 nanostructures exhibit the best catalytic activity. Under optimized conditions, the complete catalytic degradation of RhB using BiVO4 nanoflowers/PMS system was achieved in 17 min at room temperature as revealed by high-performance liquid chromatography (HPLC) analysis. Quenching experiments suggested that sulfate radicals are the main active species in the degradation process. Additionally, BiVO4 catalyst remained stable without any apparent activity loss after five cycling runs.
... Thus, either the two binary oxide constituents or the two metal components can be electrosynthesized first followed by their thermolytic conversion to the targeted ternary oxide product (see Table 1). [43][44][45][46][47][48] Clearly, these tabulated examples, along with the βÀ Cu 2 V 2 O 7 case highlighted in this work, show that addition of a thermolysis step considerably enhances the scope of electrosynthesis. ...
... In this vein, the thermosynthetic component augments the functionality and thereby obviates the need for a Conversion to product after soaking in VO(acac) 2 and thermolysis in air at 450°C. [43] CuWO 4 Co-deposition of Cu 2 O and WO 3 from an acidic aqueous bath. ...
Adding a thermolysis step to electrosynthesis (as in “electrothermosynthesis”) considerably enhances the scope of electrochemical film deposition and affords multinary compositions previously inaccessible to this otherwise versatile and mild synthetic approach. Copper pyrovanadate (β‐Cu 2 V 2 O 7 ), a member of the Cu‐V‐O family of ternary oxide semiconductors of considerable interest to the solar fuels community, is shown herein to be an exemplar of this approach. The generality of the hybrid approach is finally discussed for a variety of ternary metal oxides.
