Cl Co-doping Research Articles

Study on the Influence of Mn and Cl Co-Doping on the Electrochemical and Mechanical Properties of LiFePO4: A First-Principles Investigation

Study on the Influence of Mn and Cl Co-Doping on the Electrochemical and Mechanical Properties of LiFePO4: A First-Principles Investigation

Cobalt and chlorine co-doped Bi5O7I catalysts for LED-induced photocatalytic or PMS-activation antibiotics degradation

Multifunctional semiconductor catalysts can meet the urgent needs for the removal of antibiotic pollutants in water. Bifunctional catalysts, cobalt and chlorine co-doped Bi5O7I (signed as Co-BIC) catalysts, were purposefully designed through a two-step aqueous strategy. The preformed Bi5O7I precursor provided one-dimensional structure and Bi-rich character for the construction of Co-BIC catalysts. Co and Cl co-doping in Bi5O7I crystals can form a doping energy level and improve the internal electric field, which led to enlarged visible-light absorption and charge separation efficiency during the photocatalytic reaction process. These advantages made Co-BIC crystals exhibit good photocatalytic activities for the removal of antibiotic levofloxacin (LEV), ciprofloxacin (CIP) and tetracycline (TC) under visible LED (100 W) light irradiation. The degradation efficiency of LEV, CIP and TC over the typical Co-BIC-60 catalyst can reach more than 80 % under 60 min of LED irradiation. In the system of Co-BIC activated peroxymonosulfate (PMS), ∼ 90 % of LEV, CIP and TC degraded within 20 min over 20 mg of Co-BIC-60 catalyst. The mechanism of photocatalytic degradation and PMS oxidation degradation over Co-BIC catalysts was proposed on band structures of Co-BIC catalysts and the active species in the capture experiments. This work could provide new ideas for the preparation of bismuth oxyhalide catalysts coupled with transition metal elements.

Na and Cl co-doping modified LiNi0.5Co0.2Mn0.3O2 as cathode for lithium-ion battery

In recent years, ternary nickel-rich layered oxides have gradually replaced traditional binary cathode materials in the lithium-ion battery market due to their advantages of high energy density and environmental protection. However, their structural instability of cathode materials has seriously affected the cycle performance of the battery. In order to optimize the internal structure of LiNi0.5Co0.2Mn0.3O2 (NCM523), the modified LiNi0.5Co0.2Mn0.3O2 was prepared by in situ doping Na and Cl wet grinding solid phase method. After 80 cycles at 1 C, the capacity retention rate was 80.91%, which was higher than that of LiNi0.5Co0.2Mn0.3O2 by 70.00%. Scanning electron microscopy showed that the surface corrosion of LiNi0.5Co0.2Mn0.3O2 was effectively alleviated by Na and Cl co-doping. In addition, the band structure, state density and volume changes were obtained by simulation. The results show that the impedance, capacity and capacity retention data are very compatible with the simulation results. Therefore, Na and Cl doping can effectively optimize the internal structure of LiNi0.5Co0.2Mn0.3O2 and improve its electrochemical performance. The combination of simulation and experiment provides a new approach for the modification of ternary cathode materials.

Using the synergistic effect of co-doping to engineer magnesium and chlorine co-doping to improve the electrochemical performance of Li2FeSiO4/C cathodes

To compensate for the insufficiency of single doping and to exert the synergistic effect between the elements, further improving the electrochemical performance, a series of Mg and Cl co-doped Li2Fe1−xMgxSiO4–2xCl2x/C (x = 0, 0.01, 0.02, 0.03) nanocomposites (LFS, LFS-1, LFS-2, and LFS-3) have been synthesized by solvothermal method. Experimentally, Mg and Cl co-doping in Li2Fe1−xMgxSiO4–2xCl2x/C were confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, high resolution transmission electron microscope, and field-emission gun scanning electron microscopy elemental mapping, while electrochemical cycling performance showed improved performance. According to the results, LFS-2 outperforms other nanocomposites in terms of electrochemical performance, rate capability, and initial discharge capacity, with a capacity of 238.3 mAh·g−1 after 100 cycles of charging and discharging at 0.05 C. This is because it has a stable monoclinic structure free of impurities, a lower charge transfer resistance, and a higher Li-ion diffusion coefficient. Our findings suggest that Mg and Cl co-doping might be a feasible low-cost technique to enhance the electrochemical performance of silicate-based cathode materials, taking into account potential and electronic conductivity advantages.

High thermoelectric properties realized in earth abundant Bi2S3 bulk materials via Se and Cl co-doping in solution synthesis process

• Se and Cl co-doped nanostructured Bi 2 S 3 powders were successfully synthesized via hydrothermal. • A high σ value of 483 S cm −1 is obtained at 300 K for the Bi 2 S 2.4 Se 0.4 Cl 0.20 sample. • A high PFave. of 411 μW m −1 K −2 is achieved for the Bi 2 S 2.4 Se 0.4 Cl 0.20 . • The highest ZT value of 0.66 is achieved at 673 K for the Bi 2 S 2.4 Se 0.4 Cl 0.20 sample. Bi 2 S 3 -based alloys are considered promising thermoelectric materials due to their large Seebeck coefficient and low lattice thermal conductivity. However, low electrical conductivity usually leads to poor electrical transport properties, which seriously restricts their further application in thermoelectric refrigeration and/or power generation. In this work, Bi 2 S 3 with high electrical transport properties is synthesized hydrothermally via Se and Cl co-doping. The maximum electrical conductivity value of 483 S cm −1 was obtained for the Bi 2 S 2.4 Se 0.4 Cl 0.20 sample at room temperature. The significant improvement of electrical conductivity gives rise to a high average power factor of 411 μW m −1 K −2 during the measuring temperature range and a peak value of 456 μW m −1 K −2 at 673 K. Benefiting from the largely improved electrical transport properties, a superior ZT value of approximately 0.66 and ZT ave . of 0.36 were obtained for Bi 2 S 2.4 Se 0.4 Cl 0.20 , and the theoretically calculated conversion efficiency reached 5.7%. The results indicate that Bi 2 S 3 is a promising candidate for thermoelectric applications at medium temperatures. A high ZT value in Bi2S3 system of ∼0.66 was achieved at 673 K for Bi2S3 with Se and Cl co-doped through a facile hydrothermal followed by spark plasma sintering.

Cation/Anion Codoped and Cobalt-Free Li-Rich Layered Cathode for High-Performance Li-Ion Batteries.

Lithium-rich layered oxides have received great attention due to their high energy density as cathode material. However, the progressive structural transformation from layered to spinel phase triggered by transition-metal migration and the irreversible release of lattice oxygen leads to voltage fade and capacity decay. Here, we report a Fe, Cl codoped and Co-free Li-rich layered cathode with significantly improved structural stability. It is revealed that the Fe and Cl codoping can facilitate the Li-ion diffusion and improve the rate performance of the materials. Moreover, the calculations show that the structural stability is enhanced by Fe and Cl codoping. As a result, the Fe and Cl codopant reduces the irreversible release of lattice oxygen, mitigates voltage fade, and improves the first-cycle Coulombic efficiency. This work provides a low-cost, environmentally friendly, practical strategy for high-performance cathode materials.

A Na-rich fluorinated sulfate anti-perovskite with dual doping as solid electrolyte for Na metal solid state batteries

High-conductivity solid electrolytes are crucial components for the development of Na-based solid state batteries. However the electrolyte structure prototype and corresponding synthesis method are still lacking. The conventional oxide and sulfide electrolytes are precursor-expensive (e.g. Na2S) or energy-intensive in sintering synthesis (e.g. at 1000 ​°C). Here, we propose a novel anti-perovskite solid electrolyte of Na-rich fluorinated sulfate (Na3SO4F) benefiting from Mg and Cl co-doping by solid state reaction from low-cost precursors at moderate temperature (500 ​°C). The tailored dual doping enables an improvement of ionic conductivity by three orders of magnitude close to 10−4 ​S ​cm−1 at 60 ​°C. The creation of Na vacancies (by aliovalent Mg doping) and lattice expansion (by substituting F sites with larger-sized Cl ions) are responsible for the conductivity upgrade. A Na–Sn/Fe [Fe(CN)6]3 solid state battery based on Na2.98Mg0.01SO4F0.95Cl0.05 electrolyte can reversibly run with a first discharge capacity as high as 91.0 mAh g−1 and a reversible capacity preserved at 77.0 mAh g−1. This result paves a way to novel anti-perovskite family of fluorinated sulfates as potential alkali metal ion solid electrolytes beyond already reported A3OX (A ​= ​Li or Na, X ​= ​heavy halogen or hydrogenide anions) anti-perovskites.

High Performance and Structural Stability of K and Cl Co-Doped LiNi0.5Co0.2Mn0.3O2 Cathode Materials in 4.6 Voltage.

The high energy density lithium ion batteries are being pursued because of their extensive application in electric vehicles with a large mileage and storage energy station with a long life. So, increasing the charge voltage becomes a strategy to improve the energy density. But it brings some harmful to the structural stability. In order to find the equilibrium between capacity and structure stability, the K and Cl co-doped LiNi0.5Co0.2Mn0.3O2 (NCM) cathode materials are designed based on defect theory, and prepared by solid state reaction. The structure is investigated by means of X-ray diffraction (XRD), rietveld refinements, scanning electron microscope (SEM), XPS, EDS mapping and transmission electron microscope (TEM). Electrochemical properties are measured through electrochemical impedance spectroscopy (EIS), cyclic voltammogram curves (CV), charge/discharge tests. The results of XRD, EDS mapping, and XPS show that K and Cl are successfully incorporated into the lattice of NCM cathode materials. Rietveld refinements along with TEM analysis manifest K and Cl co-doping can effectively reduce cation mixing and make the layered structure more complete. After 100 cycles at 1 C, the K and Cl co-doped NCM retains a more integrated layered structure compared to the pristine NCM. It indicates the co-doping can effectively strengthen the layer structure and suppress the phase transition to some degree during repeated charge and discharge process. Through CV curves, it can be found that K and Cl co-doping can weaken the electrode polarization and improve the electrochemical performance. Electrochemical tests show that the discharge capacity of Li0.99K0.01(Ni0.5Co0.3Mn0.2)O1.99Cl0.01 (KCl-NCM) are far higher than NCM at 5 C, and capacity retention reaches 78.1% after 100 cycles at 1 C. EIS measurement indicates that doping K and Cl contributes to the better lithium ion diffusion and the lower charge transfer resistance.

Electronic and magnetic properties of phosphorene tuned by Cl and metallic atom co-doping.

Using first-principles calculations based on density functional theory, we studied the electronic and magnetic properties of phosphorene co-doped with Cl and a metal atom (including Sc, Ti, V, Cr, Mn, Fe, Co, and Ni). It is found that Cl atom doping makes it much easier for metallic atoms to dope into phosphorene. Phosphorene co-doped with Cl and V, Cr, Mn, or Fe is magnetic, which is determined by the number of valence electrons. Taking V-Cl and Co-Cl co-doped phosphorene as an example, analyses are carried out on the reasonable selection of the doping sites, which distinctly affect the stability, band gap and magnetic moment. The stability is closely relevant to the electronegativity of impurity atoms. With the biaxial strain ranging from -4% to 4%, the magnetic moment of V-Cl co-doped phosphorene and the band gap of Co-Cl co-doped phosphorene are greatly tunable between 1.757-0.951 μB and 0.687-0.496 eV, which come from the electron transfer from V to the surrounding P atoms and the weakened bond between Co and Cl, respectively. These investigations provide a reference for regulating the electronic structure and magnetic properties of diluted magnetic semiconductors and promote the applications of phosphorene in spintronics and nanodevices.

Effects of Mn, Cl co-doping on the structure and photoluminescence properties of novel walnut-shape MAPb0.95Mn0.05I3-xClx films

The novel walnut shape MAPb0.95Mn0.05I3-xClx film was successfully synthesized by a one-step method followed by chlorobenzene anti-solvent treatment. The bandgap energy and PL intensity of perovskite film can be effectively tuned by Mn and Cl co-doping. The enlarged bandgap energy is mainly attributed to the synergistic effect of strengthened Pb-I interaction, Cl incorporation and smaller electronegativity of Mn dopants. The stronger coupling between the Mn d- and Pb p-bands, extended carriers diffusion length and more emitting defect-associated states caused by Mn and Cl co-doping are the main reasons for the enhancing PL intensity of MAPb0.95Mn0.05I3-xClx walnut shape film. This work not only helps to in-depth understand the correlation between co-doping elements and optical properties of nanostructured perovskite films, but also provides important strategy for future designing the lower-toxic nanostructured perovskite materials with enhanced electrical and optical properties.

Fluorine-chlorine co-doped TiO2/CSA doped polyaniline based high performance inorganic/organic hybrid heterostructure for UV photodetection applications

Fluorine-Chlorine, co-doped TiO2 and CSA, doped Polyaniline based n-p heterostructures (F-Cl-TiO2/CSA-PANI) are fabricated on ITO-coated glass substrate by spin coating at room temperature. The Al/CSA-PANI/F-Cl-TiO2/ITO, structures are highly sensitive to UV illumination with a considerable photo-to-dark current contrast ratio of ∼381 at −1V, exceptional ideality factor ∼1.9, substantial barrier height ∼0.73eV at zero bias, significantly large responsivity ∼24.9A/W, photoconductive gain ∼84.59 and reasonable rise/fall time ∼0.6/1.6s. The CSA-PANI/F-Cl-TiO2 interface/surface morphology, phase analysis, elemental composition and the optical properties of F-Cl-TiO2 are investigated by FESEM, X-ray diffraction, EDX and UV–vis spectroscopy. The significant enhancement in photo current is elucidated with the proposed energy band model and a corresponding collateral conduction mechanism as anticipated for the F and Cl doping in TiO2 based hybrid photodiode. The long-living radiant trapping sites and enhanced photoactivity by F and Cl co-doping divulge a potential candidature of the heterostructure as an alternate for next generation UV photodetection applications.

Enhancement of the thermoelectric properties of n-type PbTe by Na and Cl co-doping

In an attempt to reduce our reliance on fossil fuels, associated with severe environmental effects, the current research is focused on the enhancement of the direct thermal to electrical thermoelectric efficiency of n-type PbTe by Na and Cl co-doping.

Effects of Li and Cl Codoping on the Electrochemical Performance and Structural Stability of LiMn2O4 Cathode Materials for Hybrid Electric Vehicle Applications

LiMn2O4, Li1.05Mn1.95O4, and Li1.05Mn1.95O3.95Cl0.05 are prepared by a solution-based process to investigate the influences of codoping of Li and Cl on the electrochemical performance and structural stability of Li1+xMn2-xO4-yCly (x, y = 0, 0.05). Li1.05Mn1.95O3.95Cl0.05 features an improved cycling performance and rate capability compared with LiMn2O4 and Li1.05Mn1.95O4, which originate from the improved structural stability and the reduction in Mn dissolution into electrolyte by the codoping of Li and Cl. The improvement in the cycling performance of Li1.05Mn1.95O3.95Cl0.05 is more appreciable at a higher temperature. Further, the electrode resistance of Li1.05Mn1.95O3.95Cl0.05 is much lower than that of LiMn2O4 over the first charge, suggesting that LiMn2O4 with high electrode resistance is structurally unstable during cycling. Both the suppressed Mn dissolution and the reduced electrode resistance of Li1.05Mn1.95O3.95Cl0.05 are attributed to the reinforcement of MnO6 octahedral in Li1.05Mn1.95O3.95Cl0...

Laser-induced doping and fine patterning of massively prepared luminescent ZnS nanospheres

The laser-induced doping and fine patterning of luminescent ZnS nanospheres is reported. Monodispersive ZnS nanospheres were synthesized in a large scale (gram-quantity) by a low temperature (70 °C) aqueous method following a self-aggregation and size-limiting process. The nanospheres were in a narrow (60–80 nm) diameter distribution and were formed by aggregated nanocrystals (∼4 nm in diameter). Laser-induced doping to obtain luminescent patterns was realized by performing a laser irradiation (wavelength: 1064 nm) on the films of nanospheres mixed with dopant precursors (i.e. MnCl2 or AlCl3). Patterns on both the flat and highly curved substrates were fabricated. Fine luminescent microarrays with sizes of ∼15 μm were fabricated by further performing a laser-induced “peel-off” on the doped films. Single-element (Mn) doping and dual-element (Al–Cl) co-doping were demonstrated. Strong photoluminescence spectra centered at ∼590 nm and ∼513 nm were attained from the Mn doped and Al–Cl co-doped patterns, respectively, while the corresponding cathodoluminescence revealed a slight blue shift. The formation of a donor–acceptor pair was proposed to interpret the luminescence intensity enhancement of the featured Al–Cl co-doped ZnS. This work provides an approach to produce fine luminescent patterns for application in high resolution displays, multi-color light emitting diodes and X-ray imaging.

ZnS:Tm grown by metalorganic chemical vapor deposition with Cl codoping

ZnS:Tm and ZnS:Tm,Cl thin films were grown by metalorganic chemical vapor deposition (MOCVD), using diethylzinc, H2S, Tm(thd)3 (thd=2,2,6,6-tetramethyl-3,5-heptanedione), and HCl. The ZnS:Tm did not contain oxygen which might be introduced through the thd-radical. It thus has only codopant-free Tm3+ luminescent centers probably associated with native defects. The electroluminescence (EL) spectrum of the ZnS:Tm,Cl showed three satellite emission lines in addition to the original emission of the ZnS:Tm, indicating the existence of Tm–Cl complex centers. In contrast, the photoluminescence (PL) spectrum of the ZnS:Tm,Cl under host excitation showed no discernible satellite emission lines. Hence, though the Tm ions in the Tm–Cl complex centers are expected to be charge compensated by Cl or a certain Cl-induced defect, they are rather inactive in the PL excitation while active in the EL excitation. The same properties were observed for the MOCVD-grown ZnS:Sm and ZnS:Sm,Cl [A. Kato, M. Katayama, A. Mizutani, N. Ito, and T. Hattori, J. Appl. Phys. 77, 4616 (1995)], and therefore they probably occur for other rare-earth luminescent centers with Cl codopant.

ZnS:Sm grown by metalorganic chemical vapor deposition with Cl codoping

Sm-doped ZnS thin films were grown by metalorganic chemical vapor deposition using diethyl- zinc, H2S, Sm(thd)3 (thd=2,2,6,6-tetramethyl-3,5-heptanedione), Sm(hfa)3 (hfa=1,1,1,5,5,5- hexafluoro-2,4-pentanedione), SmCl3, and HCl. The following films were prepared: an undoped ZnS, a ZnS:Sm grown with Sm(thd)3 and without HCl, a ZnS:Sm,Cl grown with both Sm(thd)3 and HCl, a ZnS:Cl grown only with HCl, and a ZnS:SmCl3 grown with SmCl3. Very little Sm was incorporated when Sm(hfa)3 was used as the dopant source. In the ZnS:Sm, the Sm was not segregated at grain boundaries, at least at concentrations below 0.2 at. %. In the ZnS:Sm and the ZnS:Sm,Cl, the (200), (220), and (311) reflections of the cubic structure that the undoped ZnS and the ZnS:Cl exhibited were not detected, and preference for the (00⋅1) hexagonal orientation became stronger. The electroluminescence spectrum of the ZnS:Sm,Cl showed three satellite peaks appearing in each of the 7 nm ranges around the three dominant peaks seen in the ZnS:Sm. The total electroluminescence intensity of the ZnS:Sm,Cl increased as a result of the appearance of the satellite peaks. While the ZnS:Sm,Cl showed photoluminescence attributed to the self-activated centers, its intensity was less than 10−2 of that of the ZnS:Cl. A model is suggested that Sm-VZn (zinc vacancy)-Cl complex centers are formed by the Cl codoping and give rise to the satellite peaks.

Satellite peak generation in the electroluminescence spectrum of ZnS:Sm grown by metalorganic chemical vapor deposition with Cl codoping

ZnS:Sm, ZnS:Sm,Cl, and ZnS:Cl thin films were grown by metalorganic chemical vapor deposition using the thd-chelate (thd=2,2,6,6-tetramethyl-3,5-heptanedione) of Sm and hydrogen chloride. The electroluminescence spectrum of the ZnS:Sm,Cl showed three satellite peaks appearing in each of the 7 nm ranges around the three dominant peaks that the ZnS:Sm has originally. The ZnS:Sm,Cl also showed photoluminescence attributed to the self-activated centers, but its intensity was less than 10−2 of that of the ZnS:Cl. The effect of the Cl codoping on Sm3+ luminescent properties is discussed on the basis of the Sm-VZn (zinc vacancy)-Cl complex formation.