Effect Of Co-doping Research Articles

Effect of co-doping of Na+ and Bi3+ ions on magnetotransport and thermopower studies of La0.67Sr0.33MnO3 manganite

Effect of co-doping of Na+ and Bi3+ ions on magnetotransport and thermopower studies of La0.67Sr0.33MnO3 manganite

Structural and Optical Properties of Cobalt-Doped Zinc Oxide Thin Films Prepared By Spray Pyrolysis Technique

Undoped and Co-doped zinc oxide (CZO) thin films have been prepared by spray pyrolysis technique using solution of zinc acetate and cobalt chloride. The effect of Co dopants on structural and optical properties has been investigated. The films were found to exhibit maximum transmittance (~90%) and low absorbance. The structural properties of the deposited films were examined by x-ray diffraction (XRD). These films, deposited on glass substrates at (400? C), have a polycrystalline texture with a wurtzite hexagonal structure, and the grain size was decreased with increasing Co concentration, and no change was observed in lattice constants while the optical band gap decreased from (3.18-3.02) eV for direct allowed transition. Other parameters such as Texture Coefficient (Tc), dislocation density (?) and number of crystals (M) were also calculated .

Effect of Ni and Dy co-doping on the structural, electrical, and dielectric properties of Strontium Y-type hexaferrite

Effect of Ni and Dy co-doping on the structural, electrical, and dielectric properties of Strontium Y-type hexaferrite

Self-supported FeCoNi(OHy)Ox oxy-hydroxide doped with Cr and Cu as robust low-loading catalyst for the alkaline oxygen evolution reaction

Self-supported FeCoNi(OHy)Ox oxy-hydroxides co-doped with Cr and Cu were obtained from a CrFeCoNiCu low ordered high entropy precursor synthesised by electrodeposition onto carbon cloth fibres (act-CrFeCoNiCu/CC). For comparison a dopant-free FeCoNi(OHy)Ox catalyst (act-FeCoNi/CC) was also synthesised following the same route. No heat treatment was performed to retain their low ordered structure. When assessed towards the oxygen evolution reaction (OER) in alkaline electrolyte, act-CrFeCoNiCu/CC and act-FeCoNi/CC catalyst reached a comparable current density of 10 mA cm−2 at ca. 1.6 VRHE (η10 of 380–390 mV). Nevertheless, Cr and Cu co-doping translated into improved stability. Evident degradation was observed during OER for act-FeCoNi/CC after 12 h operating at 100 mA cm−2, whereas no signs of degradation were detected for act-CrFeCoNiCu/CC under the same reaction conditions. The latter catalyst even delivered a constant potential for 160 h at 50 mA cm−2 aided to the stabilizing effect of Cr and Cu co-doping.

Electronic and optical properties of Cr-Mn co-doped in monolayer MoS2: A first-principles study

The effects of Cr-Mn co-doping of neighboring and spacer sites on the electronic and optical properties of monolayer molybdenum disulfide (ML-MoS2) are investigated using a first-principles plane-wave pseudopotential method based on density-functional theory (DFT). The results show that the band structure (BS) and the bandgap of pristine ML-MoS2 are in good agreement with the available experimental and theoretical data. Electronic analysis implies that the bandgap of Cr-Mn co-doped ML-MoS2 is smaller than that of the pristine ML-MoS2 and the bandgap of Cr-Mn co-doped ML-MoS2 at spacer sites is the smallest. Moreover, the ML-MoS2 changes from a direct bandgap to an indirect bandgap semiconductor, which facilitates electron-hole pair transfer. In addition, pristine ML-MoS₂ has no magnetism, while Cr-Mn co-doped ML-MoS2 at neighboring and spacer sites present ferromagnetism. Studies of optical properties have shown that doped ML-MoS2 systems, especially Cr-Mn co-doped at spacer sites, exhibit higher sensitivity to visible and ultraviolet (UV) light along the x-axis as well as to UV light along the z-axis. This suggests the possibility of applications in photodetectors, solar cells, and photocatalysis. It is noteworthy that Cr-Mn co-doping at the spacer sites significantly improves the photovoltaic performance and light utilization efficiency of ML-MoS2 by increasing the dielectric tensor, absorption coefficient, and photoconductivity while decreasing the extinction coefficient compared with pristine ML-MoS2.

Modulating interfacial Zn2+ deposition mode towards stable Zn anode via bimetallic co-doped coating

Artificial coatings represent the promising means to address the interfacial issues of Zn anode, but it poses a significant challenge to their stability due to the fatigue and resulting cracking of coatings during repeated cycling. Here, a functional coating with the synergistic effect of bimetallic co-doping was developed, which changes the Zn2+ deposition mode to interlayer deposition in coating. The simultaneous doping of Cu2+ and In3+ reduces the pyrrolic N content and enhances the adsorption of Zn2+ in the active sites. Bimetallic co-doping results in an increase in specific surface area and a decrease in pore size, thus providing more active sites. As well as enhanced electrical conductivity, electrons can enter between the coatings, thus promoting redox reactions between the layers. Therefore, it endows surface coating with low polarization and stress buffering simultaneously, which avoids cracking and stripping of coatings during cycling. As a result, the cycle life of CuInZIF-8@Zn||CuInZIF-8@Zn symmetric cell exhibits more than 1200 h at 5 mA cm−2 and 5 mAh cm−2. The CuInZIF-8@Zn anode can match multiple types of cathodes and achieve excellent cycling stability; For instance, it can cycle stably for 3000 cycles when paired with vanadium-based cathode. This work provides a new perspective of artificial coatings towards highly stable Zn anode.

Achieving enhanced power factor using dual substitution at Cu and S sites in tetrahedrites thermoelectric materials Cu12Sb4S13

Thermoelectric (TE) materials-based devices are valuable for translating heat into electricity, but the cost is largely driven by the use of purified metals required for efficient TE performance. This study focuses on tetrahedrite materials, which are cost-effective due to their abundance in copper ore mining waste and status as one of the most widespread sulfosalts on Earth. The research investigates the effects of co-doping and iso-valent doping on the TE properties of p-type tetrahedrite samples, specifically Cu10Mn2Sb4S11Se2 (Sample A) and Cu10MnZnSb₄S11Se2 (Sample B). These samples were synthesized using hot pressing at 773 K and compared with the existing pristine compound (Cu10Mn2Sb4S13). Doping with Mn and Zn (1:1) at the Cu site was found to optimize carrier concentration and enhance phonon scattering, leading to an improved power factor. Additionally, the Se substitution at the S site also introduced band degeneracy, further increasing the power factor. Further, sample B exhibited the highest Seebeck coefficient (∼300 μV/K) at 650 K, in comparison to Sample A (∼225 μV/K) and the pristine compound (∼250 μV/K). On the other hand, Sample A demonstrated significantly higher electrical conductivity (∼0.76 × 10⁴ S/m at 650 K), ∿ three times greater than that of the other prepared samples. Notably, the power factor of Sample A (∼0.389 mW/mK2 at 650 K) was more than twice that of Sample B (∼0.141 mW/mK2) and the pristine compound (∼0.160 mW/mK2). These findings suggest that dual-site substitution at the Cu and S positions presents a promising strategy to augment the TE performance of tetrahedrite compounds.

The effect of magnesium impurities on the optical and spectral characteristics of calcium orthovanadate single crystals doped with chromium and manganese

The effect of magnesium co-doping on growth conditions, crystal composition, optical and spectral properties of manganese or chromium-doped Ca3(VO4)2 (CVO) crystal was studied. The single crystals were grown by the Czochralski method. Effective segregation coefficients of manganese and chromium in the CVO matrix with magnesium co-doping were calculated. A redistribution of the absorption lines intensities was observed in the absorption spectra of CVO:Mn:Mg and CVO:Cr:Mg. Low (15 K) temperature fluorescence measurements confirmed that co-doping CVO crystal with Mg ions leads to the redistribution of Mn ions concentration in different valence states, but does not cause changes in their spectral properties. In the presence of magnesium, additional annealing of the materials resulted in a slower reduction of the valence state of doping ions and a noticeable change in crystal coloration. All investigated impurities have practically no effect on the specific ferroelectric domain structure of CVO.

Unraveling quantum capacitance of black phosphorene by the doping of non-metals for energy storage applications using DFT method

Supercapacitor plays a pivotal role as energy storage devices in the context of eliminating energy resources. Black Phosphorene (BP) is highly regarded as a potential electrode for supercapacitor (SC) because of its outstanding properties, including excellent carrier mobility and unique electronic properties. In this research work, the monolayer of BP and bilayer of BP (BP/BP) structure is investigated by using DFT. Moreover, the effect of doping and co-doping of non-metal (oxygen, nitrogen) in the mono- and bi-layer was also investigated to increase their performance by modulating the charge storage, and electronic properties of BP. The structural properties, density of states, quantum capacitance, surface charge density, bader charge analysis, isosurface charge density difference, integrated charge density of monolayer and bilayer are studied. The density functional theory (DFT) is used to calculate all above mention properties. DFT-D3 method with Becke-Johnson damping function is used as dispersion correction factor for all the calculations of bilayer. The calculated results find that bilayer structure gives better results as compared to monolayer structure. In this work, results also revealed that doping of oxygen and nitrogen atom significantly enhance the CQ and Q of mono- and bi-layer structure. For aqueous system, all the composites exhibited asymmetrical behavior except BP/BP bilayer. BP-N/BP-N (1369.8µC/cm2), and BP-O/BP-O (-1298.1µC/cm2) bilayer structure are best for anode and cathode material. In case of ionic/organic system, all composites showed asymmetrical behavior. BP-O/BP-O (-6053.5µC/cm2), and BP-N/BP-N (9329.8µC/cm2) bilayer structure is best cathode and anode material.

Effects of Co-doping on the microstructure and electrochemical performance of nickel vanadate (Ni3V2O8) electrode material for aqueous symmetric supercapacitor

Recently, there has been an increased focus on supercapacitors due to their reliable electrochemical energy storage capabilities. This study utilized an environmentally friendly facile hydrothermal method to prepare the nickel vanadate (NiVO) and cobalt-doped nickel vanadate (Co-doped Ni3V2O8) composite for supercapacitor applications. The prepared materials of pure and Co-doped Ni3V2O8 with different concentrations of Co (10 % and 15 %) were evaluated through three electrode assemblies. It is significant to note that although Co smoothed the surface of NiVO, most of the nickel vanadate crystals broke apart into tiny particles and increased the number of electroactive sites. Pure NiVO has a specific capacitance (Cs) of 1638.06 F/g at 5 mV/s. It has been observed that the electrochemical performance has been improved by adding Co 10 % and 15 % in NiVO. The 15 % Co-doped NiVO exhibits an outstanding Cs of 2641.99 F/g at a scan rate of 5 mV/s with a high capacitance retention of 98.14 % after 1k charge-discharges cycles. This excellent performance of the material is due to more electroactive sites and synergistic effects among Co and Ni in the composite. To further elaborate the electrochemical performance of 15 % Co-doped NiVO, it is employed for the fabrication of a symmetries supercapacitor (SSC) device, which shows that the fabricated device has a capacitance of 286 F/g at a current density (CD) of 0.5 A/g and high energy density of 39.7 Wh/kg at a power density of 333.33 W/kg. The symmetric device maintains a cyclic stability of 93.8 % while undergoing 5000 consecutive charge–discharge cycles at a current density of 10 A/g. Based on rigorous testing and analysis, these findings suggest that the prepared electrode material is reliable and suitable for implementation in forthcoming wearable electronic systems.

Factors controlling the organ-specific T1 contrast effect of silica nanoparticles co-doped with both Mn2+ ions and oleate-coated iron oxides

The present work introduces the synergistic effect of co-doping of both oleate-coated superparamagnetic iron oxide nanoparticles (SPIONs) and Mn(NO3)2 into silica nanoparticles (SNs) on the T1-relaxivity of Mn2+ ions. The observed synergism can be attributed to the limited oxidation of Mn2+ ions when they are doped into the outer layer of SNs doped with SPIONs, despite the alkaline synthesis conditions. The electrochemical behaviour of the manganese ions inside co-doped SNs corroborates the predominance of their oxidation state +2. Moreover, the T1 relaxivities of co-doped SNs have been determined to be 20.0 mM−1s−1 and 30.0 mM−1s−1 at 0.47 T. The T2 relaxivity of co-doped SNs can be tuned by incorporating 6 or 13 nm SPIONs with different saturation magnetizations, which allows the T2/T1 relaxation ratios to be limited to 0.8–5.9. The incorporation of amino groups on the surface of co-doped SNs by substituting silanol groups with propylamino groups reduces T1 relaxivity to 9.0 mM−1s−1, which is nevertheless sufficient to provide a brightening of the abdominal organs and mouse brain in magnetic resonance imaging at 11.7 T. The preferential localisation of co-doped SNs in the kidneys and intestines compared to the liver is a consequence of the specificity of amino-substituted SNs compared to bare SNs.

Synthesis and Effect of MgSO4 co-doping on the Optical, IR, and Raman Spectroscopic Studies of Eu3+-Doped Alkaline Silica Borate Glasses Produced with SLS Glass as a Silica Source

Synthesis and Effect of MgSO4 co-doping on the Optical, IR, and Raman Spectroscopic Studies of Eu3+-Doped Alkaline Silica Borate Glasses Produced with SLS Glass as a Silica Source

A Theoretical Study of the Effects of Co-Doping Ions at K and Nb Sites on the Properties of KNbO3 Nanoparticles.

Using a microscopic model and Green's function theory, we have investigated the co-doping effect on ferroelectric KNbO3 nanoparticles. Let us emphasize that while the doping with transition metal ions at the Nb site leads an increase in the ferromagnetism and a reduction the band gap, it also decreases the ferroelectricity. On the other hand, doping with La or Ba at the K site leads to enhanced polarization, but does not lead to the appearance of ferromagnetism and reduction in the band gap. Therefore, we have studied co-doping with La/Cr and La/Co ions, which leads to increasing the magnetization and polarization as well as to strongly decreasing the band gap energy. Thus, we observe a multiferroic material with room-temperature ferromagnetism and ferroelectricity as well as small band gap energy which can be tuned using various co-doping ions. There is a good agreement with the existing experimental data.

Ortho to para hydrogen conversion over bimetallic iron and cobalt catalysts

The catalytic conversion of ortho-hydrogen (o-H2) to para-hydrogen (p-H2) serves as a crucial step in the storage of liquid hydrogen. A variety of iron-cobalt bimetallic catalysts (FCO) were synthesized using a precipitation method, incorporating diverse levels of Co doping into Fe-based catalysts. The effects of Co doping on the crystal structure, porosity, and magnetism of FCO catalysts were studied by XRD, N2 physical adsorption, FTIR, XPS, and VSM analyses. The efficiency of ortho-para hydrogen conversion over FCO at 77 K was evaluated. It was found that the catalyst’s lag coefficient was significantly improved by Co doping, leading to an increase of magnetic moment. The catalyst of FCO-5 with a Fe/(Fe + Co) molar ratio of 0.5 exhibited the highest activity in ortho-para hydrogen conversion. The corresponding conversion rate, outlet p-H2 content, and the reaction rate constant were 99.2%, 49.7% and 291.7 mol·L−1·s−1, respectively, under a gas hourly space velocity of 5400 h−1.

Co doping induces CoxP-Ni2P bimetallic site and acid synergistic effect to achieve efficient hydrodeoxidation

The development of highly efficient hydrodeoxidation (HDO) catalyst is the key to upgrade the quality of bio-oil. CoxP-Ni2P/SiO2-y catalysts (y is the initial P/(Ni+Co) molar ratio) comprised of CoxP-Ni2P bimetallic sites and acidic site were prepared by doping Co into Ni2P active phase using mesoporous SiO2 as the support. The structure and chemical properties of the catalyst were characterized by XRD, BET, XPS, H2-TPR, NH3-TPD, Py-FTIR and TEM methods. The effects of Co doping and P/M molar ratio on the HDO performance of Ni2P/SiO2 catalyst were investigated taking m-cresol as the model compound. The results show that Co doping not only creates new CoxP active sites, but also optimizes the electronic structure of Ni2P, thus improving the HDO activity of the catalyst. Among the CoxP-Ni2P/SiO2-y catalysts, CoxP-Ni2P/SiO2-0.5 with P/M molar ratio of 0.5 exhibits the best catalytic performance, with the m-cresol conversion of 98.7% and selectivity to the deoxidized product methylcyclohexane (MCH) of 95.6% at 275 °C, 2 MPa and 1 h. The HDO of m-cresol over the CoxP-Ni2P/SiO2-y catalyst mainly proceeded through hydrogenation-deoxygenation (HYD) pathway.

Effect of Ca and Nb co-doping on optical and magnetoelectric properties of polycrystalline BiFeO3 ceramics

Effect of Ca and Nb co-doping on optical and magnetoelectric properties of polycrystalline BiFeO3 ceramics

Effect of co-doping of CeO2 and Sc2O3 on mechanical properties and CMAS corrosion resistance of YSZ ceramics

Effect of co-doping of CeO2 and Sc2O3 on mechanical properties and CMAS corrosion resistance of YSZ ceramics

Theoretical Study of Co-Doping Effects with Different Ions on the Multiferroic Properties of BiFeO3 Nanoparticles.

Using a microscopic model and the Green's function theory, the size and co-doping effects on the multiferroic and optical (band gap) properties of BiFeO3 (BFO) nanoparticles are investigated. The magnetization increases, whereas the band gap energy decreases with decreasing nanoparticle size. The substitution with Co/Mn, Nd/Sm, Ce/Ni, and Cd/Ni is discussed and explained on a microscopic level. By the ion co-doping appear different strains due to the difference between the doping and host ionic radii, which leads to changes in the exchange interaction constants for tuning all properties. It is observed that by co-doping with Nd/Sm at the Bi site or with Co/Mn at the Fe site, the multiferroic properties are larger than those by doping with one ion. Moreover, by doping with Ni, the multiferroic properties are reduced. But by adding another ion (for example Ce or Cd), an increase in these properties is obtained. This shows the advantages of the co-doping, its flexibility, and its greater possibility of tuning the multiferroic properties compared to single ion substitution. The band gap energy decreases for all co-dopants. The polarization increases with increasing magnetic field. This is evidence of magnetoelectric coupling, which is enhanced by co-doping with Co/Mn. The observed theoretical results are in good qualitative agreement with the existing experimental data.

An insight into synergistic effects of Cu and Ag co-doping in nanocrystalline MgFe2O4 for enhancing the photocatalytic degradation of crystal violet and benzimidazole

Herein, the optical bandgap of magnetically separable, reusable and visible light active photocatalyst i.e. soft and n- type spinel ferrite MgFe2O4 is tailored to enhance its catalytic efficacy. The un-doped spinel ferrite MgFe2O4, and doped spinel MgFe2O4 i.e. Cu@MgFe2O4 (Cu0.05Mg0.95Fe2O4), Ag@MgFe2O4 (Ag0.1MgFe1.9O4), and Cu/Ag@MgFe2O4 (Cu0.05Ag0.1Mg0.95Fe1.9O4) were prepared by facile co-precipitation technique. Powder X-ray Diffraction (PXRD) and Fourier Transform Infrared (FTIR) spectroscopy were performed to confirm the successful synthesis of all prepared materials. The fabricated samples were used as photocatalysts for the degradation of Crystal violet (azo dye) and Benzimidazole (colorless pollutant). The results of photocatalytic experiment obtained from UV-Visible analysis showed about 71 %, 82 %, 85 %, and 93 % degradation of crystal violet by MgFe2O4, Cu@MgFe2O4, Ag@MgFe2O4, and Cu/Ag@MgFe2O4 respectively. Hence, the transition metal (Cu) and noble metal (Ag) co-doped MgFe2O4 exhibited about 22 % increase in its catalytic activity against crystal violet as compared to pure MgFe2O4. The highest catalytic performance of Cu/Ag@MgFe2O4 could be assigned to its decreased crystallite size (18 nm) and moderate band gap (2.17 eV) as compared to its counter parts i.e. MgFe2O4 (26 nm, 2.0 eV), Cu@MgFe2O4 (22.5 nm, 2.03 eV), and Ag@MgFe2O4 (21 nm, 2.05 eV). Furthermore, ∼84 % degradation of benzimidazole was observed using Cu/Ag@MgFe2O4 as catalyst. The enhanced degradation activity of Cu/Ag@MgFe2O4 (Cu0.05Ag0.1Mg0.95Fe1.9O4) photocatalyst for both dye and colorless compound could be accredited to the synergistic effects of structural engineering and optical bandgap tuning by the co-doping of Cu and Ag in MgFe2O4. Hence, Cu0.05Ag0.1Mg0.95Fe1.9O4 could be a remarkable photocatalyst in future for the removal of harmful industrial pollutants.

Synergistic effects of zinc thiocyanate on the performance of cesium lead bromide perovskite phosphors for solid-state lighting applications

All inorganic lead halide perovskites have led to a new paradigm shift in display and lighting technologies because of significant cost and performance advantage over the current state-of-the-art optoelectronics. However, the applications of these perovskites are undermined due to the toxicity and severe degradation of the materials in response to external stimuli. This research highlights the synergetic effects of co-doping of CsPbBr3 nanocrystals (NCs) at its B- and X-site using zinc thiocyanate (Zn(SCN)2). The adopted doping strategy helps to improve the photoluminescence stability of the pristine NCs when stored under ambient conditions for 156 days. This is attributed to the enhanced local structural order and reduced inhomogeneous strain between the lattices of the NCs due to the synchronized effect of Zn2+ and SCN–. The composite NCs are integrated as color-converting layers (thin 3D printing layer coated with NCs) with a blue LED chip to obtain the white light. It exhibits bright white emissions with a color rendering index of 86, correlated color temperature of 6046 K, and color coordinates close to standard white light. This work emphasizes the strong potential of inexpensive and earth-abundant Zn(SCN)2-based CsPbBr3 composites to meet consumer needs.