Cl Doping Research Articles

Effect of Cl doping on the structural and electrochemical properties of LiNi0.4Co0.2Mn0.4O2 as cathode materials for Lithium-ion Batteries

Effect of Cl doping on the structural and electrochemical properties of LiNi0.4Co0.2Mn0.4O2 as cathode materials for Lithium-ion Batteries

Cl-doped Bi2S3 homojunction nanorods with rich-defects for collaboratively boosting photocatalytic reduction performance

Due to the slow charge separation and low efficiency of surface reactive site, developing efficient catalysts to achieve the conversion of toxic Cr (VI) to non-toxic Cr (III) faces huge challenges. Herein, a synthesis route by involving homojunction and surface defects is employed to design defect-rich Cl-doped Bi2S3 homojunction nanorods, which considerably boosted the aqueous Cr (VI) photoreduction activity without co-catalyst, extra photosensitizer or sacrificial agent. Cl-doped Bi2S3 nanorods with surface sulfur defect are grown via the sulfuration of BiOCl and the doping of Cl. The homojunction originates from oriented attachment of the nanoparticles by controlling the synthesis conditions and the introduction of Cl−. Analysis of the defects and homojunctions disclosed that the sulfur defects are mainly concentrated on the exposed {1–12} facet of the homojunction rather than the exposed {010} facet. The engineered sulfur defects are able to tune the electronic structure of Cl-doped Bi2S3 and serve as the surface active site to activate adsorbed pollutant species. Meanwhile, the homojunction structure with different exposed facets can enhance the electron-hole separation. Thanks to homojunction and surface defects, the defect-rich Cl-doped Bi2S3 homojunction nanorods display 19 and 45 times improved Cr (VI) photoreduction rate than the Bi2S3 and BiOCl.

Solution-Based, Anion-Doping of Li4 Ti5 O12 Nanoflowers for Lithium-Ion Battery Applications.

Solution-based, anionic doping represents a convenient strategy with which to improve upon the conductivity of candidate anode materials such as Li4 Ti5 O12 (LTO). As such, novel synthetic hydrothermally-inspired protocols have primarily been devised herein, aimed at the large-scale production of unique halogen-doped, micron-scale, three-dimensional, hierarchical LTO flower-like motifs. Although fluorine (F) doping has been explored, the use of chlorine (Cl) dopants is the primary focus here. Several experimental variables, such as dopant amount, lithium hydroxide concentration, and titanium butoxide purity, were probed and perfected. Furthermore, the Cl doping process did not damage the intrinsic LTO morphology. The analysis, based on interpreting a compilation of SEM, XRD, XPS, and TEM-EDS results, was used to determine an optimized dopant concentration of Cl. Electrochemical tests demonstrated an increased capacity via cycling of 12 % for a Cl-doped sample as compared with pristine LTO. Moreover, the Cl-doped LTO sample described in this study exhibited the highest discharge capacity yet reported at an observed rate of 2C for this material at 143mAh g-1 . Overall, these data suggest that the Cl dopant likely enhances not only the ion transport capabilities, but also the overall electrical conductivity of our as-prepared structures. To help explain these favorable findings, theoretical DFT calculations were used to postulate that the electronic conductivity and Li diffusion were likely improved by the presence of increased Ti3+ ion concentration coupled with widening of the Li migration channel.

Effect of Cl doping on the electrochemical performance of Sr2Fe1.5Mo0.5O6−δ cathode material for solid oxide fuel cells

In this paper, a novel Cl− anion doping strategy is proposed to modify the electrochemical performance of Sr2Fe1.5Mo0.5O6−δ (SFM) cathode for solid oxide fuel cells. A series of Cl-doped Sr2Fe1.5Mo0.5O6−x−δClx (SFMClx, x = 0, 0.1, 0.2, 0.3, 0.4) materials is synthesized by the citric acid–glycine combustion method, and the effect of Cl doping on the crystal structure and electrochemical performance is systemically investigated. The doping of Cl into the SFM leads to the lattice expansion, and the electrochemical performance of Cl-doped SFMClx cathodes is effectively improved as a result of the enhanced mobility of lattice oxygen introduced by Cl doping. The optimal composition with x = 0.2 (sample Sr2Fe1.5Mo0.5O5.8−δCl0.2, noted as SFMCl0.2) exhibits a minimum polarization resistance Rp value of 1.987 Ωcm2 at 600 °C, reduced by 38.04% compared with the SFM cathode. These results suggest that Cl doping is an effective strategy to improve the electrochemical properties of cathode for solid oxide fuel cells.

Extrinsic dopants in quasi-one-dimensional photovoltaic semiconductor Sb2S3: A first-principles study

Extrinsic elements such as C, Zn, Sn, Bi, and Ti had been doped into Sb2S3 in order to increase the electrical conductivity and thus the photovoltaic efficiency. However, the influences of these dopants are so far unclear. Using the first-principles calculations, we show that (i) Zn and Sn doping can slightly increase the p-type conductivity of Sb2S3 through forming ZnSb2 and SnSb2 acceptors, explaining the observed increase in photocurrent and carrier concentration; (ii) in contrast, the formation energies of C dopants on different sites are high, which means C doping cannot increase the conductivity of Sb2S3 obviously, so the highly reduced resistivity of C-doped Sb2S3 in experiments cannot be explained and the effects of C doping should be revisited; (iii) Bii acts as the carrier recombination center, so the photocurrent of the Bi-doped Sb2S3 solar cells decreases; and (iv) the formation energies (concentration) of Tii and TiSb1 donors are extremely low (high), so the photocurrent of the Ti doped Sb2S3 solar cells increases significantly. Considering the influences on both electrical conductivity and carrier non-radiative recombination, we propose that Pb and Cl are relatively benign p-type and n-type dopants, respectively. Cl doping can make Sb2S3 show high n-type conductivity and long minority carrier lifetime, thus offering a promising method for overcoming the current efficiency bottleneck of Sb2S3 solar cells.

Meliorating the sodium storage properties of NaTi2(PO4)3/C by rational structural design

Sodium-ion battery is considered to be a potential replacement for lithium-ion battery due to abundant sodium reserve and low cost. NASICON-type NaTi2(PO4)3 possesses three-dimensional channels, which makes it show excellent sodium storage performance. And it is a prospective anode for sodium-ion battery. In this paper, sodium storage property of NaTi2(PO4)3/C was further improved by rational structural design. We prepared NaTi2(PO4)3-xCl3x/C (x = 0, 0.05, 0.1, 0.2) by sol-gel method and applied it to anode materials for sodium-ion battery. Cl doping on PO43− site has no significant effect on the crystalline structure and particle agglomeration of materials. It is clear that electrochemical performances of all Cl-doped samples are better than those of blank sample. As the doping amount increases, the performance first enhances and then declines. For the rate performance of all samples, NaTi2(PO4)2.9Cl0.3 (NC/Cl-30) delivers discharge capacities of 257.8, 212.7, 169.5, and 146.3 mAh g−1 at 0.1, 0.4, 2, and 4 A g−1, with marked enhancement of 133.7, 124.4, 113.2, and 112.2 mAh g−1 compared with NaTi2(PO4)3/C (NC). In addition, NC/Cl-30 also exhibits outstanding cycling performance. The discharge capacity of NC/Cl-30 at 1 A g−1 after 1000 cycles reaches up to 142.2 mAh g−1, 62.9 mAh g−1 larger than that of NC. NC/Cl-30 presents higher capacity resulting from proper Cl doping. Our work provides some references for optimizing performance of NaTi2(PO4)3 in sodium-ion battery through a method of anion doping.

Ultralow Thermal Conductivity and Thermoelectric Properties of Rb2Bi8Se13

Complex bismuth chalcogenides are narrow band gap semiconductors with intrinsic low thermal conductivity, which exhibit high potential as highly efficient thermoelectric materials. Here, we assess the basic thermoelectric properties of polycrystalline Rb2Bi8Se13 in the temperature range 300–823 K as well as performance-optimizing strategies. We find that the as-made bulk samples are single phase with the monoclinic crystal structure (P21/m) and crystallize in layer morphology. The pristine sample exhibits an exceedingly low lattice thermal conductivity of 0.6–0.46 W·m–1·K–1 at 300–823 K, which derives from strong lattice anharmonicity, large Grüneisen parameters, and low phonon velocities induced by the complex crystal structure with heavy atom Bi and a large unit cell. The Cl doping successfully enhances the carrier concentration in Rb2Bi8Se13 with a negligible impact on the electronic band structure, displaying common doping behaviors. Se vacancy, on the contrary, leads to n-type doping and enhances the effective mass and power factors more significantly. Consequently, a maximum ZT of ∼0.75 at 823 K for the 0.3% Se-vacancy-doped sample is obtained.

Fabricating Surface-Functionalized CsPbBr3/Cs4PbBr6 Nanosheets for Visible-Light Photocatalytic Oxidation of Styrene.

The halide perovskite (PVSK) material, an excellent light absorber with fast carrier kinetics, has received increased attention as a potential photocatalyst for organic synthesis. Herein, we report a straightforward synthesis of chemically modified halide perovskite and its application as an efficient photocatalyst to convert styrene into benzaldehyde. A simple method is employed to synthesize the chemically modified CsPbBr3/Cs4PbBr6 nanosheets by using ZrCl4 to simultaneously achieve the Cl doping and the surface modification with Zr species. The photocatalytic oxidation rate of styrene to benzaldehyde catalyzed by surface-modified CsPbBr3/Cs4PbBr6 nanosheets under visible light can reach 1,098 μmol g−1 h−1, 2.9 times higher than that of pristine CsPbBr3/Cs4PbBr6 nanosheets (372 μmol g−1 h−1). The enhanced photocatalytic performance may originate from the modified band structure induced by the synergistic effect of Cl doping and surface modification, whereby the same methodology can be applied to MAPbBr3. This work demonstrates the surface modification of PVSK materials and their potential as efficient photocatalyst toward organic synthesis.

Visible light photocatalysis of amorphous Cl-Ta2O5−x microspheres for stabilized hydrogen generation

Harvesting broad spectral absorption and visible light photocatalysis of ultrawide bandgap semiconductors are one of most significative topics in the solar energy conversion and utilization fields. In this work, amorphous Cl-Ta2O5−x microspheres were prepared by facile solvothermal method for stabilized visible light photocatalytic hydrogen generation. The acetone absorbed on the interfaces of Ta2O5 nanoparticles induced the formation of oxygen vacancies, enhanced visible light absorption, and formation of Ta2O5−x microspheres with preferred orientations as well as Cl doping. The Cl-Ta2O5−x microspheres showed typical amorphous characteristics and obvious visible light absorption in comparison to those of commercial Ta2O5. More importantly, the prepared Cl-Ta2O5−x microspheres also showed stabilized visible light photocatalytic hydrogen generation performance in the spectral regions of 400 nm ≤ λ ≤ 600 nm mainly because of the introduction of oxygen vacancy defects and Cl doping, which might significantly expand the application of tantalum oxide semiconductors in the broad spectral photocatalytic water splitting.

First Principles Research on the Magnetic Properties of Na and Cl doped ZnO

ZnO is considered as a wide bandgap material because it has a 3.4 eV direct bandgap. This wide bandgap characteristic causes good transparency, high electron mobility and luminescence at room temperature.The unique and tuneable properties of nanostructured ZnO shows excellent stability in chemically as well as thermally stable n-type semiconducting material with wide applications such as in luminescent material, supercapacitors, battery and solar cells. To be applied to a variety of needs, price control bandgap is needed. Likewise, control over the magnetic nature. Therefore we need a study related to bandgap modification, one of them is by giving impurity atoms. Atom Na and Cl were chosen as representatives of donors and acceptors. Atomistic calculations use the Functional Density Theory method which is implemented in ABINIT software. Relaxation and convergence research results are used to find the most stable energy value of ZnO.. The results showed Magnetic Properties in ZnO doping Na obtained magnetization values of 1.4802 𝜇𝐵 greater than pure ZnO that is 0.9394 𝜇𝐵 while ZnO doping Cl obtained magnetization values of 0.8593 𝜇𝐵 smaller than pure ZnO. In conclusion the ZnO doping magnetic properties of Na increase magnetization and Cl doping also change the magnetic properties by decreasing ZnO magnetization.

Tailoring all-inorganic cesium lead halide perovskites for robust triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) have attracted considerable interests because of their high conversion efficiency from low-frequent mechanical energy to electricity. Robust dielectric materials are critical in enhancing the contact electrification charge density of TENGs. Herein, all-inorganic cesium lead halide (CsPbX3, X = I, Br, Cl) perovskites with tunable morphologies and dielectric properties are synthesized through a facile solvent etching method and applied as the triboelectric materials in perovskite TENGs. The influences of effective contact area and the dielectric properties associated with electron donating capacity of perovskite films are systematically investigated through solvent and compositional engineering. Compared with the all-inorganic perovskite free of etching, the crystal growth conditions are well controlled. In addition, the doping of Cl− or I− ions is in favor of regulating the polarity and electronic structure of the [PbBr6]4- octahedral. Benefitting from the physical surface engineering approaches for enhancing the triboelectric charge density and the chemical doping for regulating dielectric property, an open-circuit voltage of 192 V, a short-circuit current of 16.7 μA and maximum power density of 1.2 W m−2 at a contact frequency of 0.5 Hz are achieved in the champion CsPbBr2.6I0.4 TENG. The discovery of extraordinary dielectric behavior of the perovskite halides may pave the way of perovskite TENGs with boosting triboelectric charge density for mechanical energy harvesting.

Tunable high workfunction contacts: Doped graphene

Contact electrodes with high work functions can enable significant enhancement in optoelectronic device performance due to their important role in efficient extracting/injecting carriers especially from optically active materials with high electron affinity or deep valence band edge, such as CdTe and some perovskites. With such materials becoming increasingly important in emerging solar cell technologies, the need for high work function electrodes has become of timely importance. In this work, p-doped graphene is investigated using first principle calculations, as a potential high work function contact electrode material for optoelectronic device applications. We found that chemical doping based on the adsorption of different non-metallic adatoms on graphene allows tuning the work function which can reach as high as 5.76 eV. A range of p-dopant adatoms, with varying doping concentrations, was investigated and we showed that the largest change of the work function is caused by chlorine and bromine dopants: a 4% concentration of Cl and Br dopants results in an increase of the work function of graphene from 4.38 eV to 5.76 eV and 5.71 eV, respectively. Furthermore, the calculations show that this significant increase in graphene’s work function is mainly due to the charge transfer from graphene to p-dopant adatoms, which increases the concentration of holes at the graphene surface, and hence, increases its work function. We also analyzed the stability conditions for absorbed halogen adatoms on graphite. In particular, we found that halogen molecules formation process should be significantly inhibited by electrostatic repulsion between charged adatoms which provides additional barrier for them to get closer to react. These findings provide valuable guidance to experimental efforts towards the realization of tunable high work function graphene-based electrodes.

First principles investigation on energetics, structure, and mechanical properties of amorphous carbon films doped with B, N, and Cl

Amorphous carbon (a-C) films have received significant attention due to their reliable structures and superior mechanical, chemical and electronic properties, making them a strong candidate as a hard mask material. We investigated the energetics, structure, and electronic and mechanical properties of the B, N, and Cl doped a-C films based on density functional theory (DFT) calculation. Our DFT calculated results clearly show that introducing B and N atoms into a-C films makes the bulk modulus slightly reduced as a function of the concentration increases. Interestingly, it is noted that introducing Cl atom into a-C films makes the bulk modulus is drastically reduced, which suggests that the films softened by Cl doping would relieve residual stress of the individual layers within the overall stacks in integrated semiconductor devices. These requirements become more important and increasingly more challenging to meet as the device integrity grows. In the perspective of F blocking nature, B doping into a-C films pulls in and captures the F atom due to the strong bonding nature of B‒F bond than C-F bond. Unlike the B doping, for the N doped a-C film, F atom has extremely large diffusion barrier of 4.92 eV. This large diffusion barrier is attributed to the electrostatically repulsive force between both atoms. The Cl doped a-C film shows consistently the similar results with the N doped a-C film because both N and Cl atoms have large electro-negativity, which causes F atom to push out. If one notes the optimized designing with the suitable doped characteristics, our results could provide a new straightforward strategy to tailor the a-C films with excellent mechanical and other novel physical and chemical properties.

Impact of Chlorine Doping on the Performance of Perovskite Solar Cells

In this paper the effect of Cl doping on optical, photovoltaic and morphological properties of mixed halide perovskite (CH3NH3PbI3-xClx) structure in a solar cell has been reported. The perovskite layer was spin-coated by employing sequential deposition method over a PEDOT-PSS hole transport layer. Lastly, the device was finished by coating Al via thermal evaporation. The addition of 10% methylammonium chloride (MACl) by weight into the methylammonium iodide (MAI) solution as additive was improved the photovoltaic performance of the solar cell, since the Cl doping has positive effect on the growth of perovskite crystals in the final film. Furthermore, addition of MACl enables the formation of smoother films and thus reduces photocurrent leakage due to pinholes or incomplete surface coverage. The Cl doping also increases reproducibility of planar devices for consistent device results.

Comparative study of Cl,N-Cdots and N-Cdots and application for trinitrophenol and ClO− sensor and cell-imaging

To understand the effect of Cl doping in carbon dots, nitrogen-doped carbon dots (N-Cdots) and nitrogen and chlorine dual-doped carbon dots (Cl,N-Cdots) were fabricated by high-temperature carbonization and low-temperature concentrated acid (HCl) acidification of dried shaddock peel, respectively. The quantum yield of Cl,N-Cdots is about four times of that of N-Cdots and the size of Cl,N-Cdots is smaller than that of N-Cdots. Furthermore, since trinitrophenol (PA) and ClO− could effectively quench the fluorescence of Cl,N-Cdots, the fluorescence sensors for determining PA and ClO− was constructed, respectively. The linear range of PA and ClO− are 0.9–90 μM and 3.24–216 μM with the limit of detection of 37.1 nM and 2.88 μM, respectively. The proposed sensor was used to detect PA in Taiyuan tap water, Wutai tap water, Wutai rain water and Wutai river water samples with encouraging results. The as-constructed sensor was also used to detect ClO− in Taiyuan tap water and commercial disinfectants. Last but not least, Cl,N-Cdots was employed as an agent for A549 and HeLa cell-imaging, possessing optimal imaging effect and ultra-low cytotoxicity. Our results suggested that Cl,N-Cdots has promising applications in sensing, water monitoring, commodity supervision and cell-imaging.

A novel and low-cost iron source for synthesizing Cl-doped LiFePO4/C cathode materials for lithium-ion batteries

The optimal experimental conditions (sintering time is 4 h, the sintering temperature is 650 °C, and the mass percentage of citric acid and pickled iron oxide red is 80.25%) for the synthesis of LFP/C cathode materials were determined by orthogonal experiments. To further improve electrochemical performance, Cl-doped LiFePO4/C cathode material was successfully synthesized by high-temperature solid phase method using pickling iron oxide red and citric acid as the iron source and carbon source, respectively. The experimental results reveal that it is a practical method to prepare LiFePO4/C cathode material by pickling iron oxide red as raw material to reduce production cost. It is also proved that Cl doping can effectively change the microstructure, improve the structural stability and improve its rate performance, cycle performance and ion diffusion rate of LiFePO4. The initial capacity of Cl-doped LiFePO4/C electrode achieves 164.1 mAh g−1 at 0.1C, which is about 96.53% of the theoretical capacity (170 mAh g−1). The Cl-doped LiFePO4/C electrode material can achieve the reversible capacity of 105.3 mAh g−1 with the capacity retention rate of 91.5% after 500 cycles at 10C, which is much higher than that of undoped LiFePO4/C (62.7%) electrode materials.

Engineering anion defect in LaFeO2.85Cl0.15 perovskite for boosting oxygen evolution reaction

Development of cost-effective, highly-active and durable catalysts for oxygen evolution reaction (OER) is critical to sustainable energy conversion and storage devices. Perovskite oxides are exploited as a research frontier on OER, however, their activity and stability are still far from desirable. Herein, we highlight a paradigm shift in the design of highly efficient perovskite-type catalysts for OER by engineering anion defect. The Cl-doped LaFeO2.85Cl0.15 perovskite demonstrates an enhanced OER activity, which is attributed to the abundant surface oxygen vacancies and low adsorption energy of H2O molecule after Cl doping. Moreover, the LaFeO2.85Cl0.15 catalyst also delivers an improved electrocatalytic durability, in contrast to the pristine LaFeO3 catalyst.

Facile synthesis of Br-doped g-C3N4 nanosheets via one-step exfoliation using ammonium bromide for photodegradation of oxytetracycline antibiotics

Graphitic carbon nitride (g-C3N4) was suggested since it enables the oxidation process under visible light irradiation. To enhance the photocatalytic activity of g-C3N4 (BCN) it is essential to exfoliate bulk g-C3N4 to the nanosheets form via a one-step exfoliation method, which was used to prepare g-C3N4 nanosheets with Br (CNN-Br) or Cl (CNN-Cl) doping by using melamine and ammonium salts. The final production yield reached 52% and the specific volume of CNN-Br was eight times compared to BCN. The Cl and Br doping of g-C3N4 was changed to increase the light absorbance in the visible-light region and to slightly decrease the bandgap energy of the samples. Additionally, the photocurrent densities of the CNN samples were enhanced compared with that of BCN. We evaluated the photocatalytic performance of the resultant nanosheets for the photodegradation of oxytetracycline under visible-light irradiation. The results showed that the Br or Cl doping of g-C3N4 and the nanosheet structure had synergetic effects, namely enhancing the absorbance in the visible-light region, the efficiency of photoinduced charge carriers, and the charge-separation capability. These improvements are useful for the photocatalytic degradation of antibiotics.

Cl-doping effect in ZnTe1-xOx highly mismatched alloys for intermediate band solar cells

Cl doping in highly mismatched ZnTe1-xOx (ZnTeO) alloys was achieved by molecular beam epitaxy using ZnCl2 as a dopant source. The temperature dependence of the bandgap energies for both upper and lower subbands, E+ and E−, of ZnTeO was determined by photoreflectance, and it was found to vary in accordance with those expected by the band anticrossing model. Secondary ion mass spectroscopy indicates that the Cl concentration increases with increasing ZnCl2 cell temperature. Low temperature photoluminescence (PL) spectra show the broad PL peak near the E− band. Intermediate band solar cells (IBSCs) fabricated using ZnTeO:Cl exhibit improved short circuit current and open circuit voltage. The results suggest that the Cl doping can effectively improve the PV properties of ZnTeO-based IBSCs and, therefore, is potentially useful for the realization of high efficiency IBSCs.

Low-Cost One-Step Fabrication of Highly Conductive ZnO:Cl Transparent Thin Films with Tunable Photocatalytic Properties via Aerosol-Assisted Chemical Vapor Deposition.

Low-cost, high-efficiency, and high quality Cl-doped ZnO (ZnO:Cl) thin films that can simultaneously function as transparent conducting oxides (TCOs) and photocatalysts are described. The films have been fabricated by a facile and inexpensive solution-source aerosol-assisted chemical vapor deposition technique using NH4Cl as an effective, cheap, and abundant source of Cl. Successful ClO substitutional doping in the ZnO films was evident from powder X-ray diffraction, X-ray photoelectron spectroscopy, and time-of-flight secondary ion mass spectrometry results, while scanning electron microscopy reveals the impact of Cl doping on the ZnO thin film morphology. All ZnO:Cl films deposited were transparent and uncolored; optical transmittance in the visible region (400–700 nm) exceeded 80% for depositions using 5–20 mol % Cl. Optimal electrical properties were achieved when using 5 mol % Cl with a minimum measured resistivity of (2.72 ± 0.04) × 10–3 Ω·cm, in which the charge carrier concentration and mobility were measured at (8.58 ± 0.16) × 1019 cm–3 and 26.7 ± 0.1 cm2 V–1 s–1 respectively, corresponding to a sheet resistance (Rsh) of 41.9 Ω□–1 at a thickness of 650 nm. In addition to transparent conducting properties, photocatalytic behavior of stearic acid degradation in the ZnO:Cl films was also observed with an optimal Cl concentration of 7 mol % Cl, with the highest formal quantum efficiency (ξ) measured at (1.63 ± 0.03) × 10–4 molecule/photon, while retaining a visible transparency of 80% and resistivity ρ = (9.23 ± 0.13) × 10–3 Ω·cm. The dual functionality of ZnO:Cl as both a transparent conductor and an efficient photocatalyst is a unique combination of properties making this a particularly unusual material.