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2 × 2 × 3 ZnO supercell with a wurtzite structure and view of the Mn2+-doped ZnO (1 0 0) surface. (b) Calculated DOS of ZnO and 4.2% Mn2+-doped ZnO in the form of a bulk crystal. (c,d) Electron densities of states of bulk ZnO and 4.2% Mn2+-doped ZnO. The energy of the valence band maximum of the bulk phase is taken to be zero.
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Here we report a high efficiency photocatalyst, i.e., Mn²⁺-doped and N-decorated ZnO nanofibers (NFs) enriched with vacancy defects, fabricated via electrospinning and a subsequent controlled annealing process. This nanocatalyst exhibits excellent visible-light photocatalytic activity and an apparent quantum efficiency up to 12.77%, which is 50 tim...
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... by Mn 2+ in ZnO lattice. To investigate Mn doping effect on orderly ZnO crystal, the bandgap for Mn 2+ -doped ZnO (Mn-ZnO) crystal has been calculated from first-principles using a 48 atom supercell, and the structure of Mn-ZnO (1 0 1 0) surface is shown for replacing one Zn atom with a Mn atom, which corresponds to 4.2 at.% Mn doping, shown in Fig. 5a. Figure 5b shows the total density of states (DOS) for pure and 4.2% Mn 2+ -doped ZnO (0.042 Mn-ZnO), where the Fermi level is set at zero and the "scissor operator" has been set to 1.26 eV. The calculated band gap for bulk ZnO and 0.042 Mn-ZnO crystals after using scissor operator are 3.37 and 3.23 eV, respectively. Thus, it is ...
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... doping, shown in Fig. 5a. Figure 5b shows the total density of states (DOS) for pure and 4.2% Mn 2+ -doped ZnO (0.042 Mn-ZnO), where the Fermi level is set at zero and the "scissor operator" has been set to 1.26 eV. The calculated band gap for bulk ZnO and 0.042 Mn-ZnO crystals after using scissor operator are 3.37 and 3.23 eV, respectively. ...
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... it is evident that 4.2% Mn doping could lower the band gap by 0.14 eV, compared with the undoped counterpart. Figures 5c,d depict the partial DOS of states, which indicate that the valence band is mainly contributed by O 2p and Zn 3d states, while the conduction band comes mainly from Zn 4s and O 2p states. In the inset of Fig. 5d, electron density distributions of the conduction band for 0.042Mn-ZnO sample are shown. ...
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... eV, respectively. Thus, it is evident that 4.2% Mn doping could lower the band gap by 0.14 eV, compared with the undoped counterpart. Figures 5c,d depict the partial DOS of states, which indicate that the valence band is mainly contributed by O 2p and Zn 3d states, while the conduction band comes mainly from Zn 4s and O 2p states. In the inset of Fig. 5d, electron density distributions of the conduction band for 0.042Mn-ZnO sample are shown. Noticeably, neither the Zn 3d and 4s nor the O 2p introduce mid-gap states, the effect state that produces a gap is the Mn 4d (indi- cated by an arrow). Because the lower-energy mid-gap states are derived from hybridization of the Mn 4d orbital with ...
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... the high level of V O + , trapping at nanofiber surface, drastically affects the band gap and the quan- tum efficiency of Mn-ZnO nanofibers. Moreover, Figure S5 illustrates our proposed mechanism of the synergetic effects for Mn 2+ and N doping in ZnO photocatalyst. The electrons, instead of generating from the VB, could be first excited from N2p levels to the defect energy states, then transfer to the Mn4d states, or excited from N2p levels to Mn4d states directly 54 . ...
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Citations
... However, its relatively wide bandgap exhibits optimal photocatalytic activity only in ultraviolet, with reduced performance under visible light [17]. Therefore, incorporating other materials or doping other metals is necessary to enhance SnO 2 's absorption of visible light and consequently improve its visible light photocatalytic activity [18][19][20]. ...
This research successfully synthesized SnO2@ZnIn2S4 composites for photocatalytic tap water splitting using a rapid two-step microwave-assisted synthesis method. This study investigated the impact of incorporating a fixed quantity of SnO2 nanoparticles and combining them with various materials to form composites, aiming to enhance photocatalytic hydrogen production. Additionally, different weights of SnO2 nanoparticles were added to the ZnIn2S4 reaction precursor to prepare SnO2@ZnIn2S4 composites for photocatalytic hydrogen production. Notably, the photocatalytic efficiency of SnO2@ZnIn2S4 composites is substantially higher than that of pure SnO2 nanoparticles and ZnIn2S4 nanosheets: 17.9-fold and 6.3-fold, respectively. The enhancement is credited to the successful use of visible light and the facilitation of electron transfer across the heterojunction, leading to the efficient dissociation of electron–hole pairs. Additionally, evaluations of recyclability demonstrated the remarkable longevity of SnO2@ZnIn2S4 composites, maintaining high levels of photocatalytic hydrogen production over eight cycles without significant efficiency loss, indicating their impressive durability. This investigation presents a promising strategy for crafting and producing environmentally sustainable SnO2@ZnIn2S4 composites with prospective implementations in photocatalytic hydrogen generation.
... A promising strategy for minimizing recombination losses, while simultaneously improving surface charge transfers, is through introduction of co-catalysts on the ZnO surface. It has been found in many studies that the amount of modifying element used affects the structural, optical and photocatalytic activities of the catalyst [18,19]. The incorporation of a transition metal or transition metal oxide which can form heterojunctions with ZnO and selectively accumulate either of the photogenerated charge carriers, thus reducing the semiconductor band gap [20]. ...
This work aims to enhance the photocatalytic activity of ZnO films for persistent organic pollutants. The photocatalysis method has gained significant interest as a sustainable and environmentally friendly approach to enhance the safety of clean water by eliminating persistent organic pollutants. Zinc oxide as a transition metal oxide is recognized as a highly effective material for photocatalysis. Even so, ZnO can be modified to increase its action and result in a more significant degradation of organic pollutants. In the photocatalytic process, an electron from the valence band is excited and moves to a higher energy level, the conduction band. Thus, an electron-holepair is formed. Unstoichiometry transition metal oxides, such as MnOx are hole-trapping co-catalysts that promote oxidation processes.This research reported the sol-gel synthesis of ZnO nanostructured films co-catalytic modified with MnOx for organic dye degradation. The confirmed features of ZnO/MnOx films are characterized by different analytical tools such as atomic force microscopy (AFM), X-ray diffraction analysis (XRD) and UV-Vis spectroscopy. The surface of the zinc oxide revealed a hexagonal wurtzite structure and a visible ganglia-like pattern. MnOx co-catalytic modification plays a vital role in the percent degradation of the organic dye under UV-irradiation conditions.
... Thus, using CNFs as a composite material for ZnO represents a promising avenue to develop highly efficient and sustainable photocatalysts for the wastewater treatment [22]. However, reports on Mn-doped ZnO decorated carbon nanofibers for photocatalytic degradation of organic dye pollutants are still limited [23][24][25][26]. ...
... The combination of enhanced adsorption due to a higher specific surface area and an improved degradation efficiency from the efficient charge separation results in an overall increase in photocatalytic activity for the (5) Mn-ZnO/CNFs sample. These findings align with previous studies [24,25] that have demonstrated the importance of a specific surface area and charge separation in influencing the photocatalytic performance. ...
In this study, Mn-doped ZnO composite carbon nanofibers (Mn-ZnO/CNFs) were prepared via a simple blending and electrospinning (ES) method, followed by a thermal treatment. These fibers were used to investigate the photocatalytic degradation of an organic dye under UV and visible light irradiation. The results showed that Mn-ZnO/CNFs were successfully prepared under the same conditions used for CNFs preparation conditions, which induced a morphological change from a smooth to a rough surface compared to the CNFs. Energy dispersive X-ray (EDX), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS) analyses confirmed the formation of Mn-doped ZnO on the CNFs' surface. Furthermore, the addition of the catalyst significantly increased in the specific surface area, and a N2 adsorption-desorption isotherm analysis revealed that all samples had mesoporous characteristics with a type IV isotherm index. The photocatalytic activity of the Mn-ZnO/CNFs carbonized at 650 ℃ using methylene blue (MB) dye as a model pollutant was investigated. All prepared samples effectively removed the MB with a degradation rate of 70-90%. The kinetic reaction rate was described using the simplified Langmuir-Hinshelwood equation. Overall, the CNFs and composites nanofibers developed through moderate thermal treatment processes possessed a high specific surface area and oxygen vacancy, enabling their potential use as adsorbents and as a catalyst support for reactions at room-to-elevated temperatures, as well as photocatalysts for the removal of organic contaminants.
... Besides, the Zn-S bond is said to be responsible for the S-2p signal at 161.2 eV [54]. The binding energy of Mn-2p 3/2 is characterized by a level of 640.1 eV [49, 55,56], confirming the +2 -oxidation state of manganese. The weak Mn-2p 3/2 spectral peak intensity indicates a low level of Mn 2+ in QDs. ...
In this study, we used a starch paste stabilizer to synthesize ZnSe: Mn/ZnS- Starch and ZnSe/ZnS: Mn/ZnS-starch quantum dot (QDs) in a non-toxic aqueous solvent. The -CH2-OH group of the starch paste promotes dispersibility and improves the compatibility of quantum dots with antibodies, its bonding is observed in the FTIR spectrum. Besides, the Mn-doped ZnS buffer shell with various concentrations (1, 3, 5, 7, and 9%) influence structure, optical, and photoluminescence of QDs properties were investigated in detail. The greatest luminescence intensity is achieved at a molar ratio of 3% Mn²⁺/Zn²⁺. Moreover, the ZnS: Mn buffer shell helps to enhance the fluorescence intensity and quantum yield (QY) of the ZnSe/ZnS: Mn/ZnS QDs, which are higher than ZnSe: Mn/ZnS-starch QDs. Through protein A and EDC bridging, ZnSe/ZnS:3%Mn/ZnS- Starch resulted in good signal and sensitivity, with no toxicity to E. coli O157:H7 and MRSA strains.
... By functional group, in XPS spectra of LNP the C-O peak at around 284 eV can be assigned to phenolic hydroxyl groups, and C--O peak at around 289 eV can be assigned to acetyl groups which is well documented with FTIR results in (Fig. 3c). After curcumin loading in LNP/ ZnO, the C line shape became sharper and intensity of atomic percentage increased to 75.69 % which is attributed to the modification of lignin along with the formation of O 2− state of lattice oxygen (Zn-O) group [38]. Which is stable and highly reactive site for biocompatibility [39]. ...
... All density functional theory (DFT) calculations were performed with the DMol 3 module of Materials Studio 7.0 [25,26]. The exchange and correlation functional were described within the generalized gradient approximation (GGA) with the Perdew-Burke-Ernzerhof (PBE) [27]. The van der Waals (vdW) correction was corrected via Grimme's D2 methods [28]. ...
Two-dimensional materials have aroused the attention of many scientists due to its remarkable chemical, magnetic, optical, and electronic characteristics. However, the specific interaction mechanism between various amino acids with arsenene surfaces has not been explored. We systematically investigated the interactions of 20 amino acids with arsenene by calculating the adsorption energy, electronic structure, sensitivity, and recovery time using density functional theory with Grimme’s dispersion correction. Moreover, applying biaxial strains can drastically change the adsorption energy. For the first time, it was discovered that the arsenene monolayer has strong adsorption specificity, high sensitivity, and short recovery time for amino acid molecules through van der Waals interactions. Our findings indicate that the arsenene may be used as a sensing medium for amino acids.
... Notably, s-d and p-d interactions significantly impact the d n electronic configuration of transition metals when they are utilized as foreign doping elements. The quantity of the doping element utilized, on the other hand, has been shown to have an impact on the doped oxide's structural, optical, and photocatalytic characteristics, as has been mentioned in several research [16][17][18][19] . ...
... The band gap is also influenced by structural deformation. These deformations may result in piezoelectric polarization in the system, creating local electric fields which produce band-bending effects 14,18 . The dielectric studies were carried out using an LCR meter. ...
This study explored the structural, optical, and dielectric properties of Pure and Mn⁺² doped ZnO nano-particles (Zn1−xMnxO) with x ≥ 20%, synthesized by co-precipitation method followed by annealing at 450⁰C. Different characterization techniques were conducted to characterize the as-prepared nano-particles. X-ray Diffraction analysis of the pure and Mn⁺² doped presented a hexagonal wurtzite structure and a decreased crystallite size with increasing doping concentration. Morphological analysis from SEM revealed finely dispersed spherical nanoparticles with particle size of 40–50 nm. Compositional analysis from EDX confirmed the incorporation of Mn⁺²ions in ZnO structure. The Results of UV spectroscopy showed that changing the doping concentration affects the band gap, and a red shift is observed as the doping concentration is increased. The band gap changes from 3.3 to 2.75 eV. Dielectric measurements exhibited decrease in the relative permittivity, dielectric loss factor and ac conductivity by increasing Mn concentration.
... The identical XRD peaks at 2θ values of 12. Figure 2e shows the XPS spectra curves of ZnMoO 4 and Mn-ZnMoO 4 . The spectra for both ZnMoO 4 and Mn-ZnMoO 4 display peaks of Zn2p, Mo3d and O1s [34], whereas a peak of Mn was detected in the Mn-ZnMoO 4 sample but was absent in the ZnMoO 4 spectrum [35]. The X-ray diffraction (XRD) method was used to analyze the resultant complex According to Figure 2c, the synthesized zinc molybdate nanomaterials were crystalline nature [32,33]. ...
Citation: Singh, A.; Ahirwar, R.C.; Borgaonkar, K.; Gupta, N.; Ahsan, M.; Rathore, J.; Das, P.; Ganguly, S.; Rawat, R. Synthesis of Transition-Metal-Doped
... The identical XRD peaks at 2θ values of 12. Figure 2e shows the XPS spectra curves of ZnMoO 4 and Mn-ZnMoO 4 . The spectra for both ZnMoO 4 and Mn-ZnMoO 4 display peaks of Zn2p, Mo3d and O1s [34], whereas a peak of Mn was detected in the Mn-ZnMoO 4 sample but was absent in the ZnMoO 4 spectrum [35]. The X-ray diffraction (XRD) method was used to analyze the resultant complex According to Figure 2c, the synthesized zinc molybdate nanomaterials were crystalline nature [32,33]. ...
A facile single-step wet chemical synthesis of a transition-metal-doped molybdate derivative was achieved via an Ocimum tenuiflorum extract-mediated green approach. The Synthesized nanomaterials of doped molybdate were characterized by optical and other spectroscopic techniques, which confirmed the size of nanocrystalline (~27.3 nm). The thermal stability of the nanomaterials confirmed through thermogravimetric analysis showed similarity with nanomaterials of Mn-ZnMoO4. Moreover, the nanoparticles displayed a non-toxic nature and showed antibactericidal activity. The impact of doping was reflected in band gap measurements; undoped ZnMoO4 showed relatively lower band gap in comparison to Mn-doped ZnMoO4. In the presence of light, ZnMoO4 nanomaterials a exhibited photocatalytic response to solochrome dark blue dye with a concentration of 50 ppm. OH− and O2*− radicals also destroyed the blue color of the dye within 2 min and showed potential antibactericidal activity towards both Gram-positive and Gram-negative bacteria, representing a unique application of the green-synthesized nanocatalyst.
... In general, irradiation of light on a photocatalytic material results in photogenerated an electron-hole pair. These electrons and holes combine with oxygen and water molecules resulting in the formation of strong hydroxyl radicals and super oxides, which cause the degradation of toxic organic dyes into non-toxic end products, e.g., H 2 O, CO 2 and some mineral acids [63]. The pristine ZnO exhibits less activity than the W-doped material because the W-ion generates an intermediate energy level between the valance band and conduction band, causing the deception of photo-excited electrons from the conduction band level. ...
Robust hybrid g-C3N4/ZnO-W/Cox heterojunction composites were synthesized using graphitic carbon nitride (g-C3N4) and ZnO-W nanoparticles (NPs) and different concentrations of Co dopant. The hybrid heterojunction composites were prepared by simple and low-cost coprecipitation methods. The fabricated catalyst was explored and investigated using various characterization techniques such as FTIR, XRD, FESEM and EDX. The surface morphology of the as-prepared hybrid nanocomposites with particle sizes in the range of 15–16 nm was validated by SEM analysis. The elemental composition of the synthesized composites was confirmed by EDS analysis. Photocatalysis using a photon as the sole energy source is considered a challenging approach for organic transformations under ambient conditions. The photocatalytic activity of the heterojunctions was tested by photodegrading methylene blue (MB) dye in the presence of sunlight. The reduced band gap of the heterojunction composite of 3.22–2.28 eV revealed that the incorporation of metal ions played an imperative role in modulating the light absorption range for photocatalytic applications. The as-synthesized g-C3N4/ZnO-W/Co0.010 composite suppressed the charge recombination ability during the photocatalytic degradation of methylene blue (MB) dye. The ternary heterojunction C3N4/ZnO-W/Co0.010 composite showed an impressive photocatalytic performance with 90% degradation of MB under visible light within 90 min of irradiation, compared to the outcomes achieved with the other compositions. Lastly, the synthesized composites showed good recyclability and mechanical stability over five cycles, confirming them as promising photocatalyst options in the future.
