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Deep Eutectic Solvent–Assisted Synthesis of Bismuth-Based Heterostructured Photocatalysts for Water Splitting and Wastewater Treatment
Published in A. Pandikumar, K. Jothivenkatachalam, S. Moscow, Heterojunction Photocatalytic Materials, 2022
Dhayanantha Prabu Jaihindh, Yi-Ru Chen, Yen-Pei Fu
The decomposition of hazardous and harmful organic industrial wastes and inorganic wastes using photosensitized semiconductors as a catalyst has attracted increasing attention. Bismuth vanadate (BiVO4) has been studied as a promising photocatalyst (bandgap 2.4 eV) for pollutant degradation due to its visible light response and relatively stable oxidation properties [26, 27]. The monoclinic scheelite BiVO4 exhibits much higher visible light photocatalytic activity over the other phases of BiVO4, giving rise to more attention and more extensive researches. Besides the crystalline form, the photocatalytic property of BiVO4 also depends strongly on the microstructure of particles [28–31]. To further improve the visible light photocatalytic activity, a few submicron- or nanometer-sized BiVO4 particles with a sheet, tube, rod, or sphere shape have been prepared [32–34]. However, surfactants or organic templates are generally added to the reactions to control their microstructures, causing the production of a lot of acid–alkali wastewater containing refractory organics. Therefore, a new template-free and environmentally benign green route is expected in the preparation of photocatalysts. Further, the low separation efficiency of photogenerated electrons and holes and poor electrical conductivity and adsorptive performance limit the broad application of BiVO4 in the fields of environmental protection and solar conversion. In recent years, BiOCl/BiVO4 p-n heterojunction has been reported to enhance the photocatalytic activity under visible light irradiation [35, 36].
Bismuth Vanadate Based Nanostructured and Nanocomposite Photocatalyst Materials for Water Splitting Application
Published in Mahmood Aliofkhazraei, Advances in Nanostructured Composites, 2019
S. Moscow, K. Jothivenkatachalam
Recently, Bismuth Vanadate (BiVO4) has gained increasing attention for its use as a promising candidate under visible light irradiation among the bismuth metal oxide photocatalyst (Pilli et al. 2011, Moscow and Jothivenkatachalam 2016). The BiVO4 photocatalysts are highly promising for different applications such as renewable energy production systems (i.e., solar fuels production from water and sunlight) and to resolve environmental issues. Bismuth vanadate (BiVO4), which is an n-type semiconductor, has been identified as one of the most promising photocatalytic materials. As it is well known, BiVO4 exists in three polymorphs of monoclinic scheelite, tetragonal scheelite, and tetragonal zircon structures, with band gaps of 2.4, 2.34, and 2.9 eV, respectively. It is reported that BiVO4 mainly exists in three crystalline phases: monoclinic scheelite, tetragonal zircon and tetragonal scheelite structure (Lim et al. 1995, Bhattacharya et al. 1997, Luo et al. 2008) (Figure 2). Monoclinic scheelite BiVO4, (~ 2.3 eV band gap) shows both visible-light and UV absorption while tetragonal BiVO4 (~ 2.9 eV band gap) mainly possesses an UV absorption band. The UV absorption observed in both the tetragonal and monoclinic BiVO4 is associated with band transition from O2p to V3d, whereas visible light absorption is due to the transition from a valence band (VB) formed by Bi6s or a hybrid orbital of Bi6s and O2p to a conduction band (CB) of V3d (Ng et al. 2010). The scheelite structure can have a tetragonal crystal system (space group: I41/a with a = b = 5.1470 Å, c = 11.7216 Å) or a monoclinic crystal system (space group: I2/b with a = 5.1935 Å, b = 5.0898 Å, c = 11.6972 Å, and b = 90.3871), while the zircon-type structure has a tetragonal crystal system (space group: I41/a with a = b = 7.303 Å and c = 6.584 Å) (Park et al. 2013).
Effect of iridium doping on electronic structure and optical properties of m-BiVO4 photocatalytic materials: a first principles study
Published in Molecular Physics, 2022
Jianbo Liu, Fenjun Liu, Haiqiang Bai, Weijun Zhuang, Yunhua Xu
Among many photocatalytic materials, the bismuth vanadate (BiVO4) has become a new type of environmental protection photocatalyst because of its good chemical and optical stability, strong oxidation–reduction ability, non-toxic and without heavy metal elements, narrow band gap, direct degradation of water and organic matter under visible light and other excellent properties [7–11]. The BiVO4 has three main crystal phases: zircon-tetragonal (zt-BiVO4), scheelite-tetragonal (st-BiVO4) and monoclinic scheelite (m-BiVO4) [12,13]. It is found that the three crystal structures can transform to each other under certain conditions. The st-BiVO4 and m-BiVO4 structure will transform into another structure reversibly after heat treatment at 255°C; When the zt-BiVO4 is heat treated at 397–497°C, the lattice will distorted and transform to m-BiVO4 structure unidirectional [14,15]. Because of its special layered and distortion structure, m-BiVO4 has a wide absorption range from ultraviolet region (300 nm < λ < 380 nm) to visible region (λ > 420 nm). Therefore, the m-BiVO4 has more excellent photocatalytic properties [10,16,17].
The visible-light-driven photocatalytic reduction of Cr6+ using BiVO4: assessing the effect of Au deposition and the reaction parameters
Published in Environmental Technology, 2022
Juan C. Durán-Álvarez, K.T. Drisya, Rodrigo García-Tablas, Luis Lartundo-Rojas, Myriam Solís-López, Rodolfo Zanella, Velumani Subramaniam
Among the bismuth-based semiconductors, bismuth vanadate has gained attention due to its high dispersibility, innocuity, photo-chemical stability, and low bandgap value (around 2.5 eV) [12], resulting in a growing number of reports on its photocatalytic activity in the last two decades [13]. BiVO4 has three polymorphs: monoclinic scheelite, tetragonal zircon, and tetragonal, among which the monoclinic phase is highly active within the visible range [14]. The valence band maximum and the conduction band minimum of BiVO4 are comprised by the O 2p and V 3d orbitals, respectively. The reduction potential of the conduction band (−0.26 V vs NHE at pH = 7.0) makes BiVO4 a photocatalyst suitable to perform reduction processes, like water splitting [15] and the conversion of Cr6+ into its reduced species [16], under visible light irradiation. Moreover, the photocatalytic potential of BiVO4 can be improved by forming heterostructures with metallic nanoparticles and other semiconductors [17]. For example, Zhao et al. [18] reported up to 76.5% of Cr6+ photoreduction after 90 min of visible light irradiation using the BiVO4/MoS2 nanocomposite, compared to the lower conversion (12%) achieved when bare BiVO4 was used. Cao et al. [19] observed the rise in the photocatalytic performance of BiVO4 microtubes and nanosheets by the deposition of well-dispersed Au nanoparticles. The improvement in the catalytic performance has been attributed to the electron trap effect and the plasmonic resonance effect, which increase the lifetime of the charge carriers by reducing the recombination rate at the time the redox potential of photo-electrons is modified [20,21].
Synthesis of tetragonally stabilized lanthanum doped bismuth vanadium oxide nanoparticles and its enhanced visible light induced photocatalytic performance
Published in Phase Transitions, 2022
Kaseed Anwar, Faria K. Naqvi, Saba Beg
Organic pollutants and water scarcity, which play an important role in the devastation of the environment, lead to environmental decay. Such problems can be solved by photocatalytic water splitting and organic pollutant degradation [1,2–5]. Until now titanium dioxide (TiO2) is considered as the best candidate for photocatalytic applications [6,7]. While it has a large bandgap (3.2 eV), TiO2 shows a good photocatalytic behavior in the UV-visible region of the spectrum [8]. Since Bi4V2O11 as a visible light driven photocatalyst, it has widely obtained significant interest as a potential for water splitting and water detoxification by organic dye degradation [9,10]. In photocatalytic water splitting, the main purpose is to use visible light effectively to initiate the photoelectrochemical reaction [11,12]. Semiconductors with suitable valence band (VB) edge have received much interest along with a vast number of catalysts used for H2 and O2 evolution in visible light irradiation, due to its narrow band gap of 2.4−2.5 eV and its optimal band edge position [5,13–15]. Bismuth based oxides, such as bismuth vanadate (Bi4V2O11), have gained tremendous attention due to their outstanding properties, such as corrosion resistance[18], nontoxicity, ferro elasticity, ionic conductivity, photostability and low-cost [19]. Due to its poor performance in the field of photocatalytic applications Bi4V2O11 still needs improvement [20]. The photogenerated electron–hole pair is difficult to pass in Bi4V2O11, which is the main reason of poor performance of Bi4V2O11 as a photocatalyst [10,21,22]. To deal with this problem, metal ion doping can enhance the photocatalytic activity of Bi4V2O11 by removing photogenerated electrons from holes [17]. Besides that, due to the weak electron hole separation yield and high electron hole recombination loss of this material, the energy conversion efficiency of Bi4V2O11 has been below our assumptions so far [16,18,23]. Since then, few reports have been made on the synthesis of doped Bi4V2O11 to improve photocatalytic activity in visible light irradiation [24]. The comparative study have been carried out and illustrated in Table 1.