Mn Doping Research Articles

Mn dopant-enabled BiFeO3 with enhanced magnetic and photoelectric properties

In this study, BiFe1−XMnXO3 (BFMXO, x = 0, 0.03, 0.05, 0.07, 0.10, and 0.15) nanoparticles were synthesized using the sol-gel technique. The XRD patterns confirm that the BFMXO nanoparticles exhibit a rhombic structure with the addition of Mn dopant, while structural distortion occurred as the doping concentration increased. In particular, Mn doping effectively induced lattice shrinkage and enhanced the lattice strain. The SEM and TEM images showed increased uniformity and grain size reduction as Mn doping concentration increased. The XPS spectra show that the conversion of Fe2+ to Fe3+ leads to the increase of oxygen vacancy concentration. Further, the M−H loops show that the saturation magnetization and residual magnetization of all Mn-doped samples were successfully improved with the gradual transformation from antiferromagnetism to ferromagnetism. Therefore, BiFe0.93Mn0.07O3 reached a maximum Ms and Mr of approximately 0.956 and 0.054 emu/g, respectively. Further, BiFe0.93Mn0.07O3 exhibited 4–5 times higher photoconductivity than the pristine sample. First-principles calculations further accounted for the improved magnetic and electrical properties of BFMXO induced by the Mn dopant. This study demonstrates an effective method for controlling the structure and characteristics of BFO-based nanomaterials for multifunctional device applications.

Insight into the promotional effect of Mn-modified nitrogenous biochar on the NH3-SCR denitrification activity at low temperatures

A series of Mn-doped nitrided cotton straw biochar catalysts were prepared, and the effect of Mn doping on the denitrification activity at low temperatures was investigated. The microstructure and surface chemistry of the catalyst were studied. The results showed that the low-temperature denitrification activity of the Mn-doped nitride cotton straw biochar was significantly improved, and the optimal reactivity temperature was broadened. The catalyst with 6 wt% Mn/NCAC-1.5-7 (Mn(6)/NCAC-1.5-7) removed 100 % of NO in the temperature range of 140–200 °C, and the N2 selectivity is close to 100 % throughout the reaction temperature interval of 50–260 °C. The presence of many different Brønsted and Lewis acid sites on the catalyst enhanced its NH3 adsorption capacity. The monodentate nitrite produced by Mn doping could be reduced by NH3 at low temperatures, which may be why the doping of Mn improved the low-temperature denitrification activity of the catalyst. In addition, an Eley-Rideal (E-R) mechanism existed for the reaction of adsorbed NH3 linked to Lewis acid sites with gaseous NO over Mn-modified nitrided cotton straw biochar catalysts. There was also a Langmuir-Hinshelwood (L-H) mechanism between the adsorbed NH3 and adsorbed NO states. The E-R mechanism dominated the low temperature NH3-SCR reaction.

Preparation of LiFe0.99Mn0.01PO4 Cathode Material with Lower Fe-Li Antisite via Wet-Lithiation Following by Tavorite-Olivine Phase Transition

Mn doping is widely used to improve the kinetic properties of LiFePO4 cathode materials. In this work, we synthesized LiFe0.99Mn0.01PO4 cathode material by a novel phase transition from the tavorite LiFePO4OH structure to the olivine LiFePO4 structure at 600 °C. A lower crystallization temperature not only results in a looser lattice for LiFePO4 material but also prevents crystal growth in higher temperatures and shortens the ion diffusion path. Experiments reveal that Mn doping can further broaden the lattice on this basis and thus ameliorate the Li+ diffusion property. The Density-Functional Theory (DFT) calculations not only support the above argument, but also predict that the LiFePO4 cathodes obtained from LiFePO4OH-to-LiFePO4 phase transition own lower Fe-Li antisite concentration (due to the high Fe-Li antisite formation energy of pre-lithiated precursor LiFePO4OH). As a result, the obtained LiFe0.99Mn0.01PO4 yields a discharge capacity close to the theoretical capacity of 169.2 mAh g−1 at a low rate of 0.2 C, 142.9 mAh g−1 at a high rate of 10 C and a capacity retention of 97.8% till 1000 cycles at 1 C. These findings indicate that the LiFePO4OH enabled by prelithiation in liquid provides a new idea for realizing substitution-modified LiFePO4 with optimal electrochemical performance.

Effect of Mn and Te doping on thermoelectric transport properties of Mg3.2-xMnxSb1.97Te0.03 (0 ≤ x ≤ 0.05) Zintl compound: Synergistic approach for enhanced thermoelectric performance

Effect of Mn and Te doping on thermoelectric transport properties of Mg3.2-xMnxSb1.97Te0.03 (0 ≤ x ≤ 0.05) Zintl compound: Synergistic approach for enhanced thermoelectric performance

Improvement of the photocatalytic activity of ZnO thin films doped with manganese

In the herein report, we synthesized ZnO thin films doped with manganese (Mn). We studied the impact of Mn doping loads (1 %, 3 %, 5 % wt.) on physicochemical properties of the compounds. Furthermore, we presented the photocatalytic efficiency in removal of methylene blue dye. The structural assay indicated ZnO conserve the wurtzite crystalline structure after dopant insertion. Furthermore, the crystalline size of catalysts was reduced after dopant incorporation. The SEM analysis showed a change in surface morphology after modification of ZnO thin films. Furthermore, Raman spectroscopy verified the Mn insertion inside the ZnO lattice. After the doping process, band gap was reduced by 16 %, in comparison to bare ZnO. After the photocatalytic test, the doped catalysts showed better performance than bare ZnO in removing MB. The best test showed a kinetics constant value of 2.9 × 10−3 min−1 after 120 min of visible irradiation. Finally, the Mn(5 %):ZnO thin film was suitable after five degradation cycles, and the degradation process efficiency was reduced by 32%.

Promoting effect of Cu and Mn doping on the Fe/ZSM-5 catalyst for selective catalytic reduction of NO with NH3

In this paper, a series of Fe-based catalysts with Zeolite Socony Mobil-5 (ZSM-5) as supports were synthesized using the sol–gel method to obtain the Fe/ZSM-5, Mn-Fe/ZSM-5, Cu-Fe/ZSM-5 and Cu-Mn-Fe/ZSM-5 catalysts. The synthesized catalysts were examined and characterized via catalytic activity testing, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption/desorption, scanning electron microscope (SEM), temperature-programmed desorption of NH3 (NH3-TPD), temperature-programmed reduction with H2 (H2-TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that the Cu-Mn-Fe/ZSM-5 catalyst had the best catalytic performance compared with the other catalysts. In addition, Fe/ZSM-5 and Cu-Mn-Fe/ZSM-5 all exhibited excellent stability as well as good tolerance to SO2 & H2O under the experimental conditions. Further characterization results showed that with co-doping of Cu and Mn, the amount of Mn4+, Cu+, Fe3+ and surface chemisorbed oxygen (Oβ) on the surface of Fe/ZSM-5 increased, promoting the catalytic performance. The DRIFT studies revealed that the NH3-SCR reaction followed both the E-R and L-H mechanism on the surface of the Fe-based ZSM-5 catalyst. The Fe-based ZSM-5 catalyst is a good candidate for NH3-SCR both in high reactivity and outstanding stability.

A Study on the Influence of Metal Fe, Ag, and Mn Doping and (Fe/Mn and Ag/Mn) Dual-Doping on the Structural, Morphological, Optical, and Antibacterial Activity of CuS Nanostructures

A Study on the Influence of Metal Fe, Ag, and Mn Doping and (Fe/Mn and Ag/Mn) Dual-Doping on the Structural, Morphological, Optical, and Antibacterial Activity of CuS Nanostructures

New Sr2FeMo0.5X0.5O6 (X=Ni, Co, Mn, Zn) cathodes for proton-conducting SOFCs

Transition metal elements were employed to customize the standard Sr2Fe1.5Mo0.5O6 (SFM) material, with the goal of improving the performance of the SFM cathode in proton-conducting solid oxide fuel cells (H–SOFCs). Sr2FeMo0.5X0.5O6 (X = Ni, Co, Mn, Zn) materials were prepared, but it was discovered that only the dopants Ni and Co can form a pure phase, whereas the dopants Mn and Zn produced an obvious secondary phase. When comparing oxygen vacancies and oxygen diffusion kinetics, utilizing the Co-dopant exhibited clear advantages. The Co-doped SFM had a higher oxygen vacancy content and faster oxygen diffusion kinetics than both the standard and Ni-doped SFM cathodes. The energy barrier for the oxygen reduction reaction (ORR) at the Co-doped SFM cathode was 0.76 eV, which was much lower than that for the SFM and Ni-doped SFM, which were 5.52 and 2.28 eV, respectively. As a result, the Co-doped SFM's cathode reaction was greatly accelerated, resulting in a high fuel cell performance of 1306 mW cm−2 at 700 °C. This finding suggests that using the appropriate dopant can alleviate the low-performance problem of the traditional SFM cathode, resulting in a promising cathode option for H–SOFCs.

Stability improvement of Fe3S4 for peroxymonosulfate activation by trace Mn doping

Iron sulfide has a great prospect in the field of peroxymonosulfate (PMS) activation due to its high catalytic activity. However, the weak stability of iron sulfide has become an important disadvantage limiting its application. In this study, trace amount of Mn was doped into Fe3S4 with the purpose of reducing metal leaching and improving catalytic efficiency. It was found that trace Mn doping could increase the Fe-S bond energy, thus the structure stability was enhanced and metal leaching was decreased. Moreover, a new (220) plane (3.49 Å) was observed on the surface of trace Mn doped Fe3S4 in addition to the conventional (311) plane. Molecular modelling indicated that the (220) crystal plane was more compact than the (311) crystal plane, which was believed to play an important role in decreasing the metal leaching. Furthermore, a reduction in oxidation potential and electrochemical impedance was also observed for the trace Mn doped Fe3S4, which promoted more efficient activation of PMS to produce higher amount of reactive oxygen species (ROS). Quenching tests and EPR analysis demonstrated both sulfate radicals and singlet oxygen were generated in the PMS activation process, in which the singlet oxygen was the dominant ROS for BPA degradation. This work provides a new idea for the design of stable and efficient iron sulfide catalytic materials.

Modification of physicochemical and electrical characteristics of lead sulfide (PbS) nanoparticles (NPs) by manganese (Mn) doping for electronic device and applications

Modification of physicochemical and electrical characteristics of lead sulfide (PbS) nanoparticles (NPs) by manganese (Mn) doping for electronic device and applications

Rational design of microflower-like manganese-doped ultrathin cobalt hydroxide nanosheets as bifunctional electrode materials for electrochemical sensing and supercapacitor applications

Noble metal-based electrocatalyst must be replaced for electrochemical applications by earth-rich, highly active, low-cost, and highly efficient dual-function electrocatalysts. In this study, transition metal-based hydroxides (TMHs), such as 2D manganese-doped cobalt hydroxide (Mn-Co(OH)2) ultrafine nanosheets, are investigated using a very simple large-scale co-precipitation method for efficient electrochemical sensing (nitrofurantoin (NFT)) and supercapacitor (SC) applications. The characterization results show that the porous and large surface area, polycrystalline nature, confinement of the 2D orientation, and strong synergistic effect contribute to the admirable electrochemical concert of Mn-Co(OH)2 for both sensing and SC applications. CV, GCD, EIS, and DPV techniques are used to thoroughly investigate electrochemical and physicochemical properties. As an electrochemical sensor, the Mn-Co(OH)2 modified disposable screen-printed carbon electrode (Mn-Co(OH)2/SPCE) shows excellent electrochemical assets for NFT detection with broad linear ranges (0.05–219 μM and 262–641 μM), low detection limit (0.012 μM) and good anti-interference ability. The obtained specific capacitance of Mn-Co(OH)2 is 348.8 F g−1 at 1 A g−1 with a maintenance capacitance of 80.76 % after 5000 cycles at 10 A g−1. The enhanced electrochemical behavior of Mn-Co(OH)2 may be related to the fast diffusion pathways of Mn doping and the enhanced redox reaction (cobalt ions) of the flower-like ultrathin nanosheets owing to their high surface area (214 m2/g). The characterization results and electrochemical performance (sensing and SCs) provide important and noteworthy insights into the synthesis of noble metal-free and high-efficiency transparent 2D TMHs nanosheets with high performance that can be widely used in various applications.

Synthesis and elucidation of structural, optical, vibrational and magnetic properties of Mn-doped V2O5 dilute magnetic semiconductor nanocrystals

Undoped and Mn-doped (5% and 10%) V2O5 nanocrystals have been synthesized by the chemical co-precipitation process followed by heating of the chemically obtained materials at 600°C. X-ray diffractometry, transmission electron microscopy, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, micro-Raman spectroscopy, UV–visible absorption spectroscopy, photoluminescence spectroscopy, vibrating sample magnetometry and electron spin resonance spectroscopy have been used for material characterization. Williamson-Hall analyses revealed higher crystallite size but lower lattice strain, lattice stress and energy density of the Mn-doped V2O5 nanocrystals as compared to undoped ones. The vibrational properties were found to be influenced by the presence of Mn ions while photoluminescence results suggested the presence of vanadium vacancy and vanadium interstitial defects in the nanocrystals. The undoped V2O5 nanocrystals exhibited weak room-temperature ferromagnetic behaviour that got significantly stronger after Mn doping. The dilute magnetic semiconductor Mn-doped V2O5 nanocrystals are promising materials for applications in spintronics devices.

Investigation of the effects of Sr and Mn doping on corrosion tribocorrosion and cyclic voltammetry performances of TiO2 nanotubes

In this study, manganese (Mn) and strontium (Sr) were doped into TiO2 nanotubes (TNT), which are frequently used in energy storage equipment. The aim of this study is to compare the corrosion tribocorrosion and cyclic voltammetry performances of doped TNTs after examining their structural characteristics. XRD and SEM were used to characterize the nanotubes. After the anodization processes, the inclusion of Mn and Sr in the TNT structure was confirmed by XRD analysis. In SEM analysis, it was observed that with the addition of Mn and Sr into the solution, longer nanotubes were formed with increased electrical conductivity. Increasing the nanotube length and shrinking the nanotube's inner diameter provided increased corrosion resistance. Increased surface hardness resulted in increased tribocorrosion resistance. In cyclic voltammetry experiments, the capacitance increased approximately 5 times in Sr-doped TNT compared to undoped TNT, while it increased 10 times in Mn-doped TNT.

Theoretical study of the structural, electronic, mechanical, and optical of transition metal (mn, co, and ni) doped FrGeI3 perovskites

Emergence of inorganic metal halide perovskites as multifunctional optoelectronic materials are due to their exceptional tunability in optoelectronic properties. This study sought to enhance the physical and mechanical properties of lead-free FrGeI3 perovskites by introducing transition metal dopants (Mn, Co, and Ni). First-principle calculations based density functional theory (DFT) have been utilized to illustrate the impact of transition-metal doping on the structural, electronic, and light-matter interaction properties of FrGeI3. The study found that transition metal doping in FrGeI3 perovskites leads to an increase in the electronic bandgap leading to semiconducting behavior after phase stability confirmation. This study provides a sound understanding of the underlying mechanisms of transition metal doping in Fr-contained halide perovskites, which could pave the way to the headway of new optoelectronic and biomedical devices based on these materials.

Investigation of the dynamic interaction between dopants and oxygen vacancies in amorphous Nb2O5: Simulation and experimental study

Resistive random-access memory can potentially be used to construct high-speed, low-power, and high-density data-storage drives. Managing oxygen flow at the electrode-oxide interface is vital for improving endurance. Dopant-oxygen interactions govern ion diffusion and vacancy creation. The interactions between multivalent dopants and oxygen vacancies in Nb2O5 have been investigated in previous studies. In this study, we simulated the relationship between a multivalent dopant Mn and oxygen vacancies in amorphous Nb2O5. We introduced oxygen vacancies and Mn ions with different oxidation states to determine the effects of spin densities and band gaps. Experimental results obtained from deposited amorphous thin films validated the simulation results, demonstrating a close agreement between the experimentally obtained (1.11 eV) and predicted bandgaps (0.93 eV). The results of study illuminate the amorphous structure of Nb2O5, the interactions between multivalent Mn dopants and oxygen vacancies, and the resulting electronic properties, offering the potential for designing and optimizing functional materials.

Boosted urea electro-oxidation over Ni3N-based nanocomposite via systematic regulation tactic

Exploiting high-efficiency Ni-based materials for electrocatalytic urea oxidation reaction (UOR) is critical for urea-related technologies. The catalytic site density, intrinsic activity, charge transfer, and mass diffusion determine overall electrocatalytic efficiency. Simultaneous modulation over the above four factors promises advanced electrocatalysis, yet challenging. Herein we propose a systematic regulation tactic over composition and geometric structure, constructing a nanocomposite comprising Mn doped Ni3N nanoparticles anchored on reduced graphene oxide (rGO/Mn-Ni3N), achieving elegant integration of four design principles into one, thereby eminently boosting UOR. Particularly, Mn doping in Ni3N can modulate electronic state to induce intrinsic activity regulation. Combining metallic Mn-Ni3N with rGO to engineer hierarchical architecture not only promotes charge transfer, but also enriches active site population. Intriguingly, improved hydrophilicity could impart better electrolyte penetration and gas escape. Consequently, such system-optimized rGO/Mn-Ni3N demonstrates state-of-the-art-level UOR electrocatalysis. This work offers a novel paradigm to create advanced catalysts via systematic and integrated modulation.

Photodegradation of antibacterial cefotaxime using Mn doped ZnO nanosphere

Elimination of pharmaceutical waste is essential for aquatic system preservation. In this report, the ZnO and Mn-ZnO nanospheres (MZNs) were effectively synthesized via facile co-precipitation method with different Mn doping concentrations as catalyst for photodegradation of cefotaxime. The structure features of the synthesized MZNs were successfully investigated. The obtained data were confirmed the successful fabrication of nanosphere ZnO and MZNs. The designed MZNs with various Mn concentrations were utilized in photodegradation of cefotaxime under optimum conditions. The photodegradation parameters such as antibiotic initial concentrations, catalyst dosage, and medium pH were carried out under UV irradiation. The superior photocatalytic activity was revealed when the MZNs molar ratio is 0.75 mol.%. The results show that the degradation efficiency of cefotaxime was 99% within 2 h at operating condition (initial concentration 30 mg/L, catalyst amount 0.5 g/ L and pH 9). The photodegradation mechanism of antibacterial cefotaxime drug in water is based on superoxide radicals which are considered the main reactive species. The developed MZNs exhibit high stability for removal of cefotaxime that reached to 98% after four times recycling. The MZNs demonstrated a simple and effective model for photocatalytic degradation of pharmaceutical waste.

The unexpected diffuse phase transition in relaxor-PbTiO3 ferroelectrics via acceptor modification

The diffuse phase transition (DPT) and domain structure are essential to the functional properties of relaxor ferroelectrics and are extremely sensitive to the ion doping. The utilization of acceptor doping has been observed to be an effective method in enhancing the high-power properties of relaxor ferroelectric materials. The present study aims to examine the acceptor-doped DPT and domain structure in single crystals of Pb(In1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-PbTiO3. An unexpected physical phenomenon was identified in which Mn-doping increased dielectric diffusion and lowered domain size while suppressing dielectric relaxation. Traceability investigations suggest that Mn-doping inhibited the growth of polar nanoregions by enhancing random electric fields, which increases dielectric diffusion while decreasing the domain size. Meanwhile, Mn doping redistributes the relaxation time function, which results in a reduction in dielectric relaxation. The current research deepens the understanding of the physical basis of DPT and can be applied to the development of high-performance piezoelectric materials.

Enhancing performance of NiCo Sulfide composite cathode by Mn doping in Li-S batteries

A sulfurophilic Ni-Co bimetallic sulfide (NiCo2S4) with Mn doping is synthesized as the electrocatalyst for the cathode of lithium-sulfur batteries. The characterization showed that the incorporation of Mn into the NiCo2S4 effectively altered the size and crystallinity of the particles. The NiCoMn-S/CNT composite were further produced as the sulfur host by combining the Mn-doped NiCo2S4 with space-rich CNTs. This structure physically restricts polysulfides and improves the redox reaction kinetics of polysulfide conversion. Therefore, the NiCoMn-S/CNT@S (4:6) as optimal ratio enables stable cycling with an initial capacity of ∼1149 mAh g−1 at 0.2 C and a lower capacity fade rate (∼0.08% per cycle upon 500 cycles) at 0.5 C. Additionally, the cathode with a sulfur loading of 2.1 mg cm−2 delivers a reversible areal capacity (597.2mAh g−1) over 200 cycles. The results indicate that doping metallic ions into the NiCo2S4 lattice is an effective strategy for enhancing the electrochemical performance of the material in lithium-sulfur batteries.

Enhanced bipolar fatigue resistance by few oxygen vacancies of PZN-PNN-PZT ceramics near MPB

The bipolar fatigue behavior for Mn-doped PZN-PNN-PZT ceramics with composition near the MPB region was investigated at both 0.6 Ec and 2 Ec (where Ec is a coercive field). It was found that fatigue behavior depends on both the Mn doping content (or oxygen vacancies and the amplitude of the applied electric fields. Compared to no Mn doping ceramics, enhanced bipolar fatigue resistance was observed in 0.1 wt% Mn doping samples by nearly no variation of remnant polarization up to 106 cycles. The enhanced fatigue behavior is proposed to the weak pinning effect of few oxygen vacancies on domain walls, which hinders the microcrack propagation and stabilizes the domain structure. As Mn doping content increased, rich oxygen vacancies exist in ceramics, and the remnant polarization deteriorated due to the severe pinning effect of defect dipoles. Besides, different fatigue behaviors at 0.6 Ec and 2 Ec indicate that fatigue behavior can be controlled by the orientation of defect dipoles under repeated fatigue cycling.