Figure 1 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
Source publication
In the present work, we assessed the photocatalytic performance of the new 3-D/3-D Z-scheme heterojunction composite for the degradation of dimethyl phthalate (DMP). The composite was composed by marimo-like Bi2WO6 and mammillaria-like ZnO which was named BWZ. The composite was successfully fabricated using a hydrothermal-precipitation method and a...
Contexts in source publication
Context 1
... analysis was used to analyze the crystalline structure of as-prepared products. As illustrated in Figure 1a, the peaks at 2θ angles of 31.8°, 34.4°, 36.3°, ...
Context 2
... results indicated that the crystallite size of Bi2WO6 and ZnO did not change significantly in the composite. To investigate further, the FTIR spectra were applied to characterize the functional groups of as-prepared samples (Figure 1b). The absorption bands at 3435 and 1646 cm −1 were designated for O-H stretching and bending vibration of free water [24,25]. ...
Context 3
... analysis was then performed to assess the chemical state of 20-BWZ. The sample contained elements of Zn 2p, O 1s, Bi 4f and W 4f. Figure 1c shows that the binding energy peaks at 1023.2 and 1046.3 eV of Zn 2p, corresponding to the Zn 2p3/2 and Zn 2p1/2, respectively, and indicated the chemical states of zinc element was divalent [29]. In the case of O 1s spectrum (Figure 1d), two characteristic peaks were detected. ...
Context 4
... sample contained elements of Zn 2p, O 1s, Bi 4f and W 4f. Figure 1c shows that the binding energy peaks at 1023.2 and 1046.3 eV of Zn 2p, corresponding to the Zn 2p3/2 and Zn 2p1/2, respectively, and indicated the chemical states of zinc element was divalent [29]. In the case of O 1s spectrum (Figure 1d), two characteristic peaks were detected. The peak that appeared at 530.1 eV was ascribed to the lattice oxygen species while the peak detected at 531.6 eV was assigned to the hydroxyl groups [30,31]. ...
Context 5
... peak that appeared at 530.1 eV was ascribed to the lattice oxygen species while the peak detected at 531.6 eV was assigned to the hydroxyl groups [30,31]. The XPS spectrum of Bi 4f (Figure 1e) showed two asymmetric peaks with binding energies of 157.9 and 163.2 eV. These were ascribed to the doublets of Bi 4f7/2 and Bi 4f5/2, respectively, and the splitting energy of 5.3 eV was characteristic of Bi 3+ [17,32]. ...
Context 6
... were ascribed to the doublets of Bi 4f7/2 and Bi 4f5/2, respectively, and the splitting energy of 5.3 eV was characteristic of Bi 3+ [17,32]. In Figure 1f, the peaks at 31.4 eV and 34.2 eV corresponded to W4f7/2 and W4f5/2, respectively, indicating the existence of metallic tungstate in the composite [33]. ...
Similar publications
Industrial effluents are a leading major threat for water contamination, subsequently which results in severe health associated risks. Hence, purifying wastewater before releasing into the water resources is essential to avoid contamination. In this study, ZnO/Cu-DPA nano-composites were prepared by altering the percentage of Cu-DPA (20%, 30%, 40%,...
Citations
... Conversely, TBA had no discernible effect on the photocatalytic degradation of the materials, suggesting that •OH only has a minor function in the reaction system. In order to further verify that •O 2 − is the main active substance in the reaction system, electron paramagnetic resonance (EPR) experiments were performed using 5,5-dimethyl-1-pyrrdine-N-oxide (DMPO) [53][54][55]. As can be seen in Fig. 9b, no signal appeared in the absence of light, and when light was applied for 10 min, the signal of DMPO •O 2 − was clearly visible. ...
SnO2 quantum dots, ranging from 10 to 30%, were combined with ZnO nanosheets to create a heterojunction photocatalyst. This composite was generated using a basic hydrothermal method, which was then followed by high-temperature calcination to enhance the photocatalytic activity of ZnO. The results showed that the synthesized SnO2 nanoparticles with tetragonal rutile phase and ZnO nanosheets with hexagonal fibrillar zincite phase, the coupling of SnO2 quantum dots and ZnO nanosheets improved the separation efficiency of the photogenerated carriers, and at the same time broadened the photoresponse range. Through the degradation of the organic dye Rhodamine B (RhB), the best photocatalytic activity was found at 20% amount of SnO2 in the composite sample (SZ-2), and the degradation efficiency of RhB reached 96.5% at the light irradiation time of 100 min. In addition, an in-depth study of the photocatalytic mechanism of the constructed heterojunction by active group trapping experiments, and the results showed that •O2⁻ and h⁺ were the main active substances in this degradation system. Meanwhile, the SZ-2 photocatalyst was tested for five cycles, and the degradation efficiency of the 5th cycle was 72%. The cycle test indicates that the SZ-2 sample is highly stable and reusable. Therefore, the results showed that the prepared SnO2/ZnO heterojunction photocatalysts are suitable materials for degrading organic dyes.
... Remarkably, the PL spectra align with this prediction, with the principal peak of PT-470 indeed located near 400 nm. Peaks between 450-470 nm originate from the recombination of photogenerated electrons and holes due to oxygen vacancies and surface defects [43,44]. This resonance validates the theoretical projection. ...
ZnTiO3/TiO2 composite photocatalysts were synthesized via the sol–gel technique, and the impact of varying heat treatment temperatures (470, 570, 670 °C) on their crystalline arrangement, surface morphology, elemental composition, chemical state, specific surface area, optical characteristics, and photocatalytic efficacy was systematically investigated. The outcomes revealed that, as the temperature ascends, pure TiO2 undergoes a transition from anatase to rutile, ultimately forming a hybrid crystal structure at 670 °C. The incorporation of ZnTiO3 engenders a reduction in the TiO2 grain dimensions and retards the anatase-to-rutile phase transition. Consequently, the specimens manifest a composite constitution of anatase and ZnTiO3. In contrast, for pure TiO2, the specimen subjected to 670 °C annealing demonstrates superior photocatalytic performance due to its amalgamated crystal arrangement. The degradation efficacy of methylene blue (MB) aqueous solution attains 91% within a 60-min interval, with a calculated first-order reaction rate constant of 0.039 min−1. Interestingly, the ZnTiO3/TiO2 composite photocatalysts exhibit diminished photocatalytic activity in comparison to pristine TiO2 across all three temperature variations. Elucidation of the photocatalytic mechanism underscores that ZnTiO3 coupling augments the generation of photogenerated charge carriers. Nonetheless, concurrently, it undermines the crystalline integrity of the composite, yielding an excess of amorphous constituents that impede the mobility of photoinduced carriers. This dual effect also fosters escalated recombination of photogenerated charges, culminating in diminished quantum efficiency and reduced photocatalytic performance.
... Based on the observed results, a plausible photocatalytic mechanism of BFO can be proposed as follows. In the typical photocatalytic process, upon light irradiation, the electrons (e ‾) are excited to the conduction From these estimations, it is clear that the 2D flake-structure considerably modifies the band structure of BFO more suitable for the effective redox reactions producing both • OH and • O 2 radicals as confirmed by the scavenger studies, while in the case of BFO particles, the photocatalytic reaction is largely driven by • OH radicals [36,44,45]. Nevertheless, in both particles and flakes the photocatalytic reactions are predominantly driven by • OH radicals due to their VB potential, which is more suitable with respect to the potential of H 2 O/ • OH and OH ‾/ • OH formation as confirmed by the terephthalic-assisted • OH radical detection studies. ...
... Therefore, it would be more attractive if a single semiconductor with a narrow-band gap can effectively catalyze the sunlight-driven aerobic photooxidation of BzOH. Among many visible light-responsive semiconductors (e.g., Pt-BiFeO 3 [10], Bi 2 WO 6 /ZnO composite [11]), bismuth oxybromide (BiOBr) has attracted considerable attention owing to its unique layered structure, appropriate-band gap (~2.7 eV) and good chemical stability [12,13]. The layered structure of BiOBr consists of [Bi 2 O 2 ] 2+ layers interleaved with double layers of Br − along the c-axis (Scheme 1), and is beneficial for the separation of photogenerated charge carriers owing to the internal electric field normal to each layer. ...
... Among many visible light-responsive semiconductors (e.g., Pt-BiFeO3 [10], Bi2WO6/ZnO composite [11]), bismuth oxybromide (BiOBr) has attracted considerable attention owing to its unique layered structure, appropriate-band gap (~2.7 eV) and good chemical stability [12,13]. The layered structure of BiOBr consists of [Bi2O2] 2+ layers interleaved with double layers of Br − along the c-axis (Scheme 1), and is beneficial for the separation of photogenerated charge carriers owing to the internal electric field normal to each layer. ...
Semiconductor photocatalytic performances can be modulated through morphology modification. Herein porous hierarchical BiOBr microspheres (BiOBr-MS) of ~3 μm was firstly self-assembled without the assistance of a template via a facile solvothermal synthesis in triethylene glycol (TEG) at 150 °C for 3 h. KBrO3 was exploited as a bromine source, which slowly provided bromide ions upon reduction in TEG and controlled the growth and self-assembly of primary BiOBr nanoplates. The addition of PVP during solvothermal synthesis of BiOBr-MS reduced the particle size by about three-fold to generate BiOBr sub-microspheres (BiOBr-sMS) of <1 μm. BiOBr-sMS exhibited significantly higher photocatalytic activity than BiOBr-MS for aerobic photooxidation of benzyl alcohol (BzOH) to benzaldehyde (BzH) under simulated sunlight irradiation (conversions of BzOH (50 mM) over BiOBr-sMS and BiOBr-MS were, respectively, 51.3% and 29.6% with 100% selectivity to BzH after Xenon illumination for 2 h at 25 °C). The photogenerated holes and ·O2− were found to be main reactive species for the BzOH oxidation over BiOBr spheres by scavenging tests and spin-trapping EPR spectra. The higher photocatalytic activity of BiOBr-sMS was attributed to its more open hierarchical structure, efficient charge separation, more negative conduction-band position and the generation of larger amounts of ·O2−.
... , OHand O 2 -) have been observed when photons of particular light are striking on the surface of photocatalyst. For the possible illustration of possible photodegradation mechanism by considering the reported research works [38,[66][67][68][69][70]. At the time of irradiation of light, the electrons are moving from valence band to conduction of band, thereby creating a hole in the valence band as shown in Scheme 3. ...
... At the time of irradiation of light, the electrons are moving from valence band to conduction of band, thereby creating a hole in the valence band as shown in Scheme 3. This scenario offers the simultaneous production of electron and hole pairs and they have been interacting with the water and generate wide range of oxidizing radicals like hydroxyl (OH) and superoxide (O 2 -) [38,[66][67][68][69][70]. Later, these highly active radicals participate in the degradation of organic pollutants like MB and MG [65]. ...
The use of plant extract for the synthesis of nanomaterials has been preferred over conventional growth techniques due to its safety, simple, ecofriendly, cost-effective and biocompatibility properties. The present study includes environmentally friendly approach for synthesis of ZnO–NPs using milky sap of Calotropis procera (CP) parts. The biosynthesized ZnO–NPs were investigated in terms of crystalline, morphology, and optical characterization. The CP has resulted spherical-shaped oriented nanoparticles, hexagonal phase and significantly reduced crystallite size of − 26.1 nm. The photodegradation of malachite green (MG) and methyl blue (MB) dye under the illumination of UV light was investigated using biosynthesized ZnO–NPs. The effect of different volumes of milky sap of CP was considered as a point of care to demonstrate its role towards the enhancement of photodegradation effectiveness of ZnO against two different organic dyes like malachite and methylene blue owing their issues raised for aquaculture and worsen environmental impacts. The degradation of both dyes was followed by pseudo first-order kinetics and highest volume of milky sap of CP has given out high rate constant value. The degradation efficiency of milky sap of CP-assisted ZnO nanostructures was found about 85.3% and 86.3% for MG and MB, respectively. However, we studied the effect of pH of dye solution on the photocatalytic performance of ZnO and it has revealed highly enhanced degradation efficiency. The increased functionality of ZnO was connected to the reduced particle size, optical bandgap, and tunable surface properties with the use of terminal oxygenated groups.
... Recent advances in the chemical treatment of wastewater involve the oxidative degradation of organic contaminants dissolved in water. To overcome these challenges, heterogeneous photocatalysis using semiconductor materials has emerged as the most effective and ecofriendly advanced oxidation process for the removal of textile dyes from wastewater [8,9]. On the other hand, the large bandgap of a photocatalyst limits the photoabsorption to only the UV region of the solar spectrum, which accounts for approximately 4% of solar energy [10]. ...
... Therefore, it is crucial to design, create, and modify the physicochemical and optical properties in order to utilize the most of a significant portion of the solar spectrum. In fact, several research papers have been published on the doping of transition metals to engineer their electrical and photocatalytic capabilities in photodegradation of organic pollutants [9,[11][12][13][14]. Vanadium pentoxide is an oxyanion of vanadium with a bandgap of 2.3 eV [15]. ...
... Then, the potential radicals were attacked, causing the dye to be degraded into a variety of chemical intermediates, which were then fully mineralized into carbon dioxide, water, ammonium, and nitrate ions [9,12,42,43], as in Equation (7). The h + VB and e − CB pairs that were photogenerated were transported to the catalyst surface. ...
The current study applies the eco-friendly principle of “wastes treat wastes”. By swift methods, a composite photocatalyst was prepared from waste-extracted oxides, namely V2O5, Ag, and ZnO. The metal–lixiviant complexes were used as metal precursors, where the lixiviants act as auto-templates and increase the compatibility between the mixed metallic species, and their controlled thermal removal generates pores. The tri-constitute composite catalyst was doped with nitrogen. The constitution, surface composition, and optical properties of the doped catalysts were investigated by XRD, SEM, TEM, BET surface analysis, XPS, diffuse reflectance, and PL spectra. The as-prepared catalysts were employed in the photodegradation of Congo red dye (CR) under visible irradiation at ambient temperature. The degree of Ag dispersion had a significant effect on the bandgap, as did metal and metal-nonmetal co-doping. The efficiency of dye removal changes dramatically with time up to 120 min, after which it begins to decrease. According to the pH effect, the normal pH of Congo red dye (6.12) is optimal. At a catalyst dose of 1 g L−1 and an irradiation period of 120 min, photodegradation efficiency reached 89.9% and 83.4% over [Ag0.05 ZnO0.05 V2O5(0.90)] and [Ag0.05 ZnO0.05 V2O5(0.90)]N, respectively. The kinetic study depicted the significant role of mass transfer in the reaction rate. The obtained rate constants were 0.995 mole L−1 S−1 and 0.998 mole L−1 S−1 for [Ag0.05 ZnO0.05 V2O5(0.90)] and [Ag0.05 ZnO0.05 V2O5(0.90)]N, respectively.
... Among them, the construction of Z-scheme heterojunction has been proved to be an effective method to inhibit the recombination of electron-hole pairs [17]. Successful cases include Bi 2 WO 6 /BiPO 4 [18], Bi 2 WO 6 /CdS [19], Bi 2 WO 6 /CuBi 2 O 4 [20], Bi 2 WO 6 /Ta 3 N 5 [21], Bi 2 WO 6 /WO 3 [22], Bi 2 WO 6 /TiO 2 [23] and Bi 2 WO 6 /ZnO [24], and so forth. ...
In this work, a Z-scheme Bi2WO6/BiO2−x heterojunction was successfully prepared using a self-assembly strategy. Various characterization techniques demonstrated that the formation of the heterojunction not only accelerated the separation of photoinduced carriers but also weakened the recombination rate of photogenerated electron–hole pairs-. The Bi2WO6/BiO2−x composites had a wider absorption edge than Bi2WO6 in the range of 200–800 nm, which improved the photocatalytic performance of ciprofloxacin (CIP) degradation under xenon lamps. As a result, the Z-scheme heterojunction Bi2WO6/BiO2−x composite exhibited excellent photocatalytic activity. Catalyzed by the optimal 20% Bi2WO6/BiO2−x (0.5 g/L), the removal rate of CIP (10.0 mg/L) was 91.8% within 2 h irradiated by visible light, which was 2.37 times that of the BiO2−x catalyst. This work will provide a fresh perspective on the construction of visible-driven Z-scheme photocatalysts for wastewater treatment.
Photodegradation is considered as one of the most promising methods to protect the environment from pollutants. Exploring the photodegradation mechanism and monitoring the degradation process is one of the main...
