Zn Substitution Research Articles

Multiplicity of Zn coordination sites at cubic spinel ferrites: magnetism and influence of the Zn d band

Zinc substituted nickel ferrite (ZnxNi1 − xFe2O4) is investigated under density functional theory (DFT) within the DFT + U approximation for x ≤ 0.50, with particular interest in understanding the effect of Zn on the net magnetization. Using as a reference ZnFe2O4, the localization of the Zn d band is proved to have a large impact on the preference for Zn to occupy either tetrahedral (ZnA) or octahedral (ZnB) coordination sites, which in ZnFe2O4 is equivalent to the relative stability of the direct and inverse spinel forms. This affects the lattice volume, with ZnA favoring larger lattice expansions. Additional important consequences emerge on the magnetism of the system, as ZnA and ZnB alter the balance of atoms at the magnetic sublattices in a different way: while ZnA enhances the global magnetization by reducing the minority spin contribution, the opposite occurs for ZnB. On the other hand, the dominant magnetic exchange interactions are not significantly altered by Zn independently of its distribution, while the magnetic anisotropy of soft NiFe2O4 is further weakened. Our simulations support the presence of a significant ratio of Zn atoms at octahedral positions at ZnxNi1 − xFe2O4, mainly as the Zn concentration increases, putting limits to the ability to increase the magnetization of NiFe2O4 by Zn substitution.

Marigold flower shaped nanopetteled Co0.7Zn0.3Fe1.7Ni0.3O4 microspheres as efficient glucose sensor

The spinel-type porous Co0.7Zn0.3Fe1.7Ni0.3O4 mesoporous flower alike microspheres were fabricated using hydrothermal technique. Electron microscopic investigations reveal interconnected porous nano lamella which construct highly stable microspheres. XRD results demonstrate an increase in the values of lattice constants due to effective substitution of Zn and Fe. The electrochemical characterizations, cyclic voltammetry (CV), chronoamperometry techniques, and electrochemical impedance spectroscopy (EIS) are conducted in three electrode system. The EIS and CV results indicate frequency dependent conductivity of the compound obeyed the Jonscher's power law. A glucose concentration range from 0.1 mM/L to 11.1 mM/L is chosen to cover non-diabetic to diabetic person. The sensitivity response of the electrochemical sensor for glucose is 92% in contrast with urea (13%), folic acid (9.1%), ascorbic acid (9%), potassium chloride (1%) and NaCl (2.2%) interferers. Further, on the same electrode the repetitive responses display its reproducibility and excellent sensitivity towards glucose; point to its potential application as effective glucose sensor.

Biomimetic ion substituted and Co-substituted hydroxyapatite nanoparticle synthesis using Serratia Marcescens

Biomimicry is becoming deep-rooted as part of bioceramics owing to its numerous functional advantages. Naturally occurring hydroxyapatite (HA) apart from primary nano structures are also characterised by various ionic substitutions. The ease of accommodating such key elements into the HA lattice is known to enhance bone healing properties of bioceramics. In this work, hydroxyapatite synthesized via biomimetic approach was substituted with individual as well as multiple cations for potential applications in bone repair. Ion substitutions of Sr, Mg and Zn was carried out on HA for the first time by using Serratia grown in a defined biomineralization medium. The individual ions of varying concentration substituted in Serratia HA (SHA) (Sr SHA, Mg SHA and Zn SHA) were analysed for crystallinity, functional groups, morphology and crystal size. All three showed decreased crystallinity, phase purity, large agglomerated aggregates and needle-shaped morphologies. Fourier transform infrared spectroscopy (FTIR) spectra indicated increased carbonate content of 5.8% resembling that of natural bone. Additionally, the reduced O–H intensities clearly portrayed disruption of HA lattice and subsequent ion-substitution. The novelty of this study lies primarily in investigating the co-substitution of a combination of 1% Sr, Zn and Mg in SHA and establishing the associated change in bone parameters. Scanning electron microscope (SEM) and transmission electron microscope (TEM) images clearly illustrated uniform nano-sized agglomerates of average dimensions of 20–50 nm length and 8–15 nm width for Sr SHA; 10–40 nm length and 8–10 nm width for both Zn SHA and Mg SHA and 40–70 nm length and 4–10 nm width in the case of 1% Sr, Zn, Mg SHA. In both individual as well as co-substitutions, significant peak shifts were not observed possibly due to the lower concentrations. However, cell volumes increased in both cases due to presence of Sr2+ validating its dominant integration into the SHA lattice. Rich trace ion deposition was presented by energy dispersive X-ray spectroscopy (EDS) and quantified using inductively coupled plasma optical emission spectrometer (ICP-OES). In vitro cytotoxicity studies in three cell lines viz. NIH/3T3 fibroblast cells, MG-63 osteosarcoma cells and RAW 264.7 macrophages showed more than 90% cell viability proving the biocompatible nature of 1% Sr, Zn and Mg in SHA. Microbial biomineralization by Serratia produced nanocrystals of HA that mimicked “bone-like apatite” as evidenced by pure phase, carbonated groups, reduced crystallinity, nano agglomerates, variations in cell parameters, rich ion deposition and non-toxic nature. Therefore ion-substituted and co-substituted biomineralized nano SHA appears to be a suitable candidate for applications in biomedicine addressing bone injuries and aiding regeneration as a result of its characteristics close to that of the human bone.

Synergistic performance of Zn2+ incorporated bimetallic Cobalt sulfide for the hydrogen evolution reaction in an alkaline medium

Cobalt sulfide (CoS) has gathered attention as a hydrogen evolution reaction (HER) catalyst. However, further research is required to enhance the catalytic performance CoS in terms of its durability, electrocatalytic activity and understanding its fundamental mechanism. Herein, we report a facile hydrothermal synthesis of Zn-substituted CoS with excellent electrocatalytic activity and stability towards the HER. Zn substitution in CoS has been carried out using different ratios of Zn. As a result, the synergistically doped ZnCoS-1 achieved an overpotential of 227 mV for the HER in order to achieve a current density of 10 mA cm−2 in 1 M KOH electrolyte. The performance enhancement observed with ZnCoS-1 is attributed to the Zn2+ dopant, which forms a bimetallic phase with CoS and acts as a strong Lewis acid that regulates the electronic characteristics for enhanced intermedial binding for catalytic activity. The prepared ZnCoS-1 catalyst exhibits excellent catalytic activity and robust stability towards the HER demonstrating the potential possibility to construct a water electrolyzer for sustainable hydrogen production.

Structural, optical, electrical and magnetic tuning based on Zn substitution at A site in yttrium doped spinel ferrites

The series of Zn2+ doped Co–Ni–Y spinel ferrites with compositional formula Co0.6Ni0.4-xZnxFe1.9Y0.1O4 where x = 0.0, 0.1, 0.2, 0.3, 0.4 were synthesized by chemical co-precipitation technique. Structural, optical, electrical and magnetic properties were explored by X-ray diffraction (XRD), Ultra violet spectroscopy (UV–Vis), Fourier transformation infrared spectroscopy (FTIR), four-point probes I–V technique and Vibrating sample magnetometer (VSM), respectively. Variations in lattice constants were detected with the insertion of Zn due to the difference in ionic radii of Zn2+ (0.82 Å) and Ni2+ (0.79 Å). FTIR outcomes exposed the existence of tetrahedral frequency absorption band in the range of 545.24–522.34 cm−1. Optical band gap energy (Eg) determined from the UV–Vis data was observed to be decreased from 3.86 to 1.84 eV. DC electrical resistivity of synthesized nanoferrites showed decreased nature in the range of 1.46 x 1010–7.78 x 107 Ω-cm for x = 0.0–0.4, respectively. Remarkable values of coercivity and microwave frequency signified that fabricated nanoferrites are highly applicable in high frequency switching devices.

Crystal structure and performance modification of a novel triclinic CaMgP2O7 microwave dielectric ceramic with low sintering temperature

In this study, crystal structure and microwave dielectric properties of phosphate CaMgP2O7 were comprehensively investigated. As a novel microwave dielectric ceramic, CaMgP2O7 consists of highly dense structure with optimal microwave dielectric properties (εr = 7.8 ± 0.124, Q×f = 13,165 ± 836 GHz, and τf = −85.04 ± 1.205 ppm/℃) at a low sintering temperature (950 ℃). The Rietveld refinement of XRD patterns revealed that CaMgP2O7 belongs to a triclinic system with P-1 symmetry type. Moreover, the substitution of Zn2+ for Mg2+ in CaMgP2O7 can further reduce the sintering temperature, effectively promote the densification process, and improve the Q×f value. The effects of porosity (or density) and chemical bond characteristics on the performance of CaMg1-xZnxP2O7 ceramics were carefully analyzed as well. Outstanding performance (εr = 8.05 ± 0.12, Q×f = 20,670 ± 923 GHz, and τf = −87.59 ± 3.24 ppm/℃) can be achieved for the CaMg0.84Zn0.16P2O7 ceramic sintered at 875 ℃ for 3 h.

The three-dimensionally ordered microporous CaTiO3 coupling Zn0.3Cd0.7S quantum dots for simultaneously enhanced photocatalytic H2 production and glucose conversion

Glucose conversion assisted photocatalytic water splitting technology to simultaneously produce H2 and high value-added chemicals is a promising method for alleviating the energy shortage and environmental crisis. In this work, we constructing type II heterojunction by in-situ coupling Zn0.3Cd0.7S quantum dots (ZCS QDs) on three-dimensionally ordered microporous CaTiO3 (3DOM CTO) for photocatalytic H2 production and glucose conversion. The DFT calculations demonstrate that substitution of Zn on the Cd site improves the separation and transmission of photogenerated carriers. Therefore, 3DOM CTO-ZCS composite exhibits best H2 production performance (2.81 mmol g-1h−1) and highest apparent quantum efficiency (AQY) (5.56 %) at 365 nm, which are about 47 and 18 times that of CTO nanoparticles (NPs). The improved catalytic performance ascribed to not only good mass diffusion and exchange, highly efficient light harvesting of 3DOM structure, but also the efficient charges separation of type Ⅱ heterojunction. The investigation on photocatalytic mechanism indicates that the glucose is mainly converted to gluconic acid and lactic acid, and the control reaction step is gluconic acid to lactic acid. The selectivity for gluconic acid on 3DOM CTO-ZCS is 85.65 %. Our work here proposes a green sustainable method to achieve highly efficient H2 production and selective conversion of glucose to gluconic acid.

Theoretical Study of Intrinsic and Extrinsic Point Defects and Their Effects on Thermoelectric Properties of Cu2SnSe3.

Current understanding of the intrinsic point defects and potential extrinsic dopants in p-type Cu2SnSe3 is limited, which hinders further improvement of its thermoelectric performance. Here, we show that the dominant intrinsic defects in Cu2SnSe3 are CuSn and VCu under different chemical conditions, respectively. The presence of VCu will damage the hole conduction network and reduce hole mobility. Besides, we find that the substitution of Al, Ga, In, Cd, Zn, Fe, and Mn for Sn can inhibit the formation of VCu; introducing CuSn, FeSn, MnSn, and NiCu defects can significantly enhance electronic density of states near the Fermi level due to the contribution of 3d orbitals. Therefore, increasing the Cu content and/or introducing the above beneficial dopants appropriately are expected to cause enhancement of carrier mobility and/or thermopower of Cu2SnSe3. Furthermore, introducing AgCu, AlSn, ZnSn, GeSn, and MnSn defects can induce large mass and strain field fluctuations, lowering lattice thermal conductivity remarkably. Present results not only deepen one's insights into point defects in Cu2SnSe3 but also provide us with a guide to improve its thermoelectric properties.

Zn substituted Li4P2S6 as a solid lithium-ion electrolyte for all-solid-state lithium batteries

Li-ion conductors are pivotal materials for all-solid-state Li batteries requiring high energy densities and operational safety. PS4-based thio-phosphate materials have been intensively investigated as solid electrolytes; however, studies on more stable P2S6-based materials are scarce. We herein report on the application of Zn-substituted Li4P2S6, Li4−2xZnxP2S6, as a Li-ion conductor. Owing to the slightly smaller ionic radius of Zn2+ than Li+, the unit cell volume decreases gradually upon Zn substitution without introducing significant structural changes. However, the ionic conductivity of the substitution phase was improved by 104 times (3.8 ​× ​10−6 ​S ​cm−1) at x ​= ​0.75 compared to unsubstituted Li4P2S6, which was achieved by generating deficiency on the Li sites via substitution. Such Li-ion deficient site enables Li ions to hop from one site to another in the crystal structure. The 3D diffusion pathway analysis using bond-valence-landscape-energy calculations suggests that the Li diffusion pathways are mostly two-dimensional in the ab plane in this structure. This study shows that an appropriate Li defect concentration within a given structure is critical to improving ionic conductivity.

Defect physics in 2D monolayer I-VII semiconductor AgI

As a brand new two-dimensional (2D) material with promising electronic properties, monolayer I-VII silver iodide (AgI) has the potential for future 2D electronic devices. To advance the development of such devices, the exploration of n-type and p-type conductivities of AgI is indispensable. With first-principles calculations, we systematically investigate the properties of intrinsic defects and extrinsic dopants in monolayer AgI, including atomic structural pictures, formation energies, and ionization energies to offer carriers. Considering the divergence in energies of charged defects in 2D materials when the traditional jellium scheme is used, we adopt an extrapolation approach to overcome the problem. The Ag vacancy (VAg) and Be substitution on Ag site (BeAg) are found to be the most promising p-type and n-type doping candidates, respectively. They could provide bound carriers for transport through the defect-bound band edge states, although the ionization energies are still larger than thermal energy at room temperature. Furthermore, negative-U behaviors are demonstrated in I vacancy (VI), Zn substitution on Ag site (ZnAg), and Cd substitution on Ag site (CdAg). The present work, for the first time, offers a detailed study of the defect physics in 2D I-VII monolayer semiconductor, laying the foundation for subsequent physics and device explorations based on these brand new 2D materials.

Effect of Zn substitution on the electrical transport and magnetic properties of Li–Cu–Mg ferrites

Effect of Zn substitution on the electrical transport and magnetic properties of Li–Cu–Mg ferrites

Structural, conductivity, and complex impedance properties of the La0.7Ag0.3Mn1−xZnxO3 (x = 0 and x = 0.025) samples

In this paper, the structural and dielectric properties of La0.7Ag0.3Mn1−xZnxO3 (x = 0 and 0.025) manganite system are investigated. The x-ray diffraction analysis confirms that all compounds crystallized in the rhombohedral structure with R3̄C space group. The effects of Zn substitution on the crystal structure and the dielectric properties were studied by using the impedance spectroscopy technique at room temperature and over a wide range of frequencies. Electrical conductance curves are found to obey the Jonscher universal power law. We note a decrease in the conductivity when increasing the Zn content from x = 0 to x = 0.025. This behavior can be associated with the introduction of a very low concentration of a non-magnetic Zn ion, which distorts the octahedral MnO6 neighbor. The analysis of the complex impedance spectra reveals a single semicircular arc reflecting a non-Debye-type relaxation process. We conclude from the best fits that the equivalent circuit formed in our case is defined as a grain resistance Rg in series with a parallel combination of grain boundary resistance Rgb and constant phase element impedance (ZCPE).

Tuning the magnetic ordering driven by cationic antisite defects in the Li(ZnMn)As system.

The electronic structure and magnetic properties of Li(ZnMn)As with antisite defects have been investigated by using first-principles calculations within the Perdew-Burke-Ernzerhof generalized gradient approximation. The cation antisite defect induced by Zn substitution for As was considered. Mn-3d, As-4p, Zn-4s, and Zn-4p were involved in the formation of d-sp hybrid orbitals, which enhanced the non-localized properties of Mn-3d electrons and provided a channel of Mn(↑)-As(↓)-ZnAs(↓)-Mn(↑) for indirect exchange of electrons between the magnetic ions. The antisite defect of Zn-substituted As belonged to the acceptor doping, rendering the compound p-type characteristics. The existence of the extra free hole carriers regulated the magnetic ordering transition. The ferromagnetic coupling between the Mn magnetic dopants was more favorable in the system with an antisite defect. In this paper, a novel type of dilute magnetic semiconductor with controllable carriers was designed and the mechanism of ferromagnetic coupling was revealed, which provided a theoretical reference for the subsequent studies.

Spectrophotometric Determination of Trace Amount of Total FeII/FeIII and Live Cell Imaging of a Carboxylato Zn(II) Coordination Polymer.

The coordination polymer, (Zn(II)-CP, 1), {[Zn(2,6-NDC)(4-Cltpy)](H2O)4} (1) (2,6-H2NDC = 2,6-naphthalene dicarboxylic acid and 4-Cltpy = 4'-chloro-[2,2';6',2″]terpyridine) is structurally characterized by single crystal X-ray diffraction measurement and other physicochemical studies (PXRD, FTIR, thermal analysis, microanalytical data). 4-Cltpy acts as end-capping ligand, and NDC2- is a carboxylato bridging motif to constitute ZnN3O2 distorted trigonal bipyramid core that propagates to construct 1D chain. The coordination polymer, 1, detects total iron (Fe3+ and Fe2+) in aqueous solution by visual color change, colorless to pink. Absorption spectrophotometric technique in aqueous medium measures the limit of detection (LOD) 0.11 μM (Fe2+) and 0.15 μM (Fe3+), and binding constants (Kd) are 6.7 × 104 M-1 (Fe3+) and 3.33 × 104 M-1 (Fe2+). Biocompatibility of 1 is examined in live cells, and intracellular Fe2+ and Fe3+ are detected in MDA-MB 231 cells. Zn(II) substitution is assumed upon addition of FeIII/FeII solution to the suspension of the coordination polymer, 1, in water-acetonitrile (41:1) (LZnII + FeIII/II → LFeIII + ZnII, where L is defined as coordinated ligands), which is accompanied by changing from colorless to pink at room temperature. The color of the mixture may be assumed to the charge transfer transition from carboxylate-O to Cltpy via Fe(II/III) bridging center (carboxylate-O-Fe-CltPy). The product isolated from the reaction is finally characterized as Fe(III)@1-CP. It is presumed that product Fe(II)@1-CP may undergo fast aerial oxidation to transform Fe(III)@1-CP. The FeIII exchanged framework (Fe(III)@1-CP) has been characterized by PXRD, IR, TGA and energy dispersive X-ray analysis (EDX)-SEM. The MTT assay calculates the cell viability (%), and the tolerance limit is 100 μM to total Fe2+ and Fe3+.

Probing the effect of Zn2+ on the local structure, dielectric and magnetic properties of La2CuMnO6 by solid state synthesis

The comparable ionic-radius cation substitution provides a route to investigate the origin of the physical properties of ceramics on the local structure and electronic charge state background. In analogy to our previous work [19] of La2CuMnO6 (LCM) prepared via solid-state route, here we are reporting the effect of Zn substitution at the Cu site of LCM. The detailed structural analysis confirmed the Jahn-Teller (JT) distortion in LCM and Zn2+ substituted LCM (i.e., LCZM) ceramics. Raman analysis further confirmed the JT distortion in these oxides. O K-edge and Mn K-edge XANES spectra confirmed the mixed hybridization states for Mn. A frequency-dependent relaxor state was observed in the dielectric study of LCM and LCZM. The dielectric responses of these systems are prominently driven by electron-phonon coupling. Their magnetic studies showed positive-Curie temperature (TC) and non-zero coercivity, indicating the ceramics' canted-antiferromagnetic nature.

Triggering the Phase Conversion of GeP from Monoclinic to Cubic by Zn Substitution toward a High‐Rate Ge1−xZnxP Solid Solution Anode for Li‐Ion Batteries

AbstractThe monoclinic GeP with large capacity, low plateau, and high initial coulombic efficiency (ICE) has been proved to be alternative anode for Li‐ion batteries. However, the heavy use of Ge raw material with its high price, hinders its further development. Herein, the Zn atom is proposed for substitution into GeP and replaces part of the Ge owing to its low price, suitable plateau, and similar radius. Interestingly, a novel Ge1−xZnxP solid solution with a wide range tunable region (0.143 < x < 0.6) is achieved, reducing the heavy use of Ge and cutting the GeP price down. More intriguingly, such Ge1−xZnxP possesses a new phase, different from monoclinic GeP, which is first verified to be a cubic system in F‐43m. Compared to semi‐conducting GeP, this cubic Ge1−xZnxP phase possesses metallic conductivity, thus enabling a better rate performance than monoclinic GeP (e.g., 881 vs 283 mAh g−1 at 2000 mA g−1), while keeping the great advantages of large capacity, low plateau, and high ICE of GeP as well. Consequently, the assembled LiCoO2//Ge1−xZnxP full cell exhibits large capacity over 1000 mAh g−1. This unique phase control strategy by atomic substitution can be easily extended to manipulate electrochemical behaviors of other multi‐phase materials toward advanced energy storage.

Zn substituted hydroxide/oxyhydroxide heterostructure activates proton conduction

The recent explorations on high performance aqueous electrode materials have witnessed an intensive interest in proton conduction. Transitional metal layer double hydroxides (LDHs) are considered as one potential candidate due to their rich detachable hydrogen atoms, however, proton conduction in LDH has rarely been reported. Herein, we construct a NiCo-hydroxide/oxyhydroxide heterostructure by Zn substitution. Experimental and theoretical results verify that Zn dopant can accelerate the partial transition of hydroxides to oxyhydroxides with the fixed interlayer distance, which just like locks, effectively restrains the interlayer expansion of neighboring LDH in electrochemical process. As a result, the OH− shuttle between interlayers is prohibited and the proton conduction is activated by a unique concerted mode between O-H bonds and water molecules in interlayer space, achieving a capacity rise of 160% and a superior cyclability with capacity retention of 120% after 37000 cycles at 30 A g−1. This success on proton conduction in LDH affords new insights into rational design and preparation of advanced aqueous electrode materials by activating proton conduction.

Dilution of a polar magnet: Structure and magnetism of Zn-substituted Co2Mo3O8

We report crystal structure, magnetization, and specific heat measurements on single crystals of the hexagonal polar magnet ${\mathrm{Co}}_{2\text{\ensuremath{-}}x}{\mathrm{Zn}}_{x}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$ magnetically diluted by replacing Co by Zn. In contrast to the transformation from the antiferromagnetic to a ferrimagnetic state observed in the isostructural ${\mathrm{Fe}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$ upon small Zn doping, a robust antiferromagnetic behavior is preserved in Zn-doped ${\mathrm{Co}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$ up to $x=0.55$. The N\'eel temperature decreases from ${T}_{\mathrm{N}}=40$ K at $x=0$ to 23 K at $x=0.55$, thus extrapolating to $x=1.27$ (36% filling) as the percolation threshold typical for a three-dimensional, highly coordinated network. This indicates strong magnetic couplings beyond the honeycomb planes in ${\mathrm{Co}}_{2}{\mathrm{Mo}}_{3}{\mathrm{O}}_{8}$. A sharp peak in the specific heat and a clear cusp in the susceptibility associated with the onset of magnetic order is observed up to $x=0.55$, whereas at $x=0.66$ these features are broadened due to increased disorder. Interestingly, the in-plane lattice parameter, the Curie-Weiss temperature, and the magnetic entropy vary with $x$ in a concerted but nonmonotonic manner. These observations can be traced back to the observed site-selective Zn substitution. We found that in the low-doping regime ($x<0.2$) ${\mathrm{Zn}}^{2+}$ ions primarily occupy the octahedrally coordinated sites, although they have a clear preference for occupying the tetrahedrally coordinated sites at higher doping levels. Due to the multiple interlayer exchange paths, dependent on the coordination of the ${\mathrm{Co}}^{2+}$ ions, this behavior is reflected in the nonmonotonic variation of the Curie-Weiss temperature and magnetic entropy with substitution.

The Role of Zn Substitution in Improving the Electrical Properties of CuI Thin Films and Optoelectronic Performance of CuI MSM Photodetectors.

Pure CuI and Zn-substituted CuI (CuI:Zn) semiconductor thin films, and metal-semiconductor-metal (MSM) photodetectors were fabricated on glass substrates by a low-temperature solution process. The influence of Zn substitution concentration (0-12 at%) on the microstructural, optical, and electrical characteristics of CuI thin films and its role in improving the optoelectronic performance of CuI MSM photodetectors were investigated in this study. Incorporation of Zn cation dopant into CuI thin films improved the crystallinity and increased the average crystalline size. XPS analysis revealed that the oxidation state of Cu ions in all the CuI-based thin films was +1, and the estimated values of [Cu]/[I] for the CuI:Zn thin films were lower than 0.9. It was found that the native p-type conductivity of polycrystalline CuI thin film was converted to n-type conductivity after the incorporation of Zn ions into CuI nanocrystals, and the electrical resistivity decreased with increases in Zn concentration. A time-resolved photocurrent study indicated that the improvements in the optoelectronic performance of CuI MSM photodetectors were obtained through the substitution of Zn ions, which provided operational stability to the two-terminal optoelectronic device. The 8 at% Zn-substituted CuI photodetectors exhibited the highest response current, responsivity, and EQE, as well as moderate specific detectivity.

Structural, Optical and Photocatalytic Properties of Mn Doped ZnO Nanoparticles Used as Photocatalysts for Azo-Dye Degradation under Visible Light

Doping ZnO with appropriate foreign metal and/or non-metal ions is one of the most promising ways to improve both the extension of ZnO photosensitization to the visible region and the separation of charge carriers. Herein, Mn-doped ZnO nanoparticles were synthesized using a precipitation method. The effect of the Mn amount on the physico-chemical properties of these nanomaterials was investigated using X-ray diffraction, Fourier-transform infrared spectroscopy, UV–visible diffuse reflectance spectroscopy, photoluminescence spectroscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy. The photocatalytic properties of the synthesized nanomaterials were assessed through methyl orange (MO) under visible light. The obtained results showed that the structural and optical properties of the synthesized Mn-ZnO nanomaterials depended greatly on the Mn amount. It was found that the substitution of Zn2+ by Mn2+/Mn3+ within the lattice of ZnO occurred. The photocatalytic experiments revealed that the sample containing 10 wt% exhibited the best MO conversion. For this sample, the discoloration reached 96%, while the chemical oxygen demand reached 1% after 820 min of visible illumination. The enhanced photocatalytic activity was attributed to the efficient separation of charge carriers. The active species quenching experiments showed that the holes are the main active species in MO degradation under visible light in the presence of 10%Mn-ZnO.