Bi Doping Research Articles

Structural and Optical Properties of Bismuth-doped Cerium Oxide Prepared at a Low Temperature

Cerium oxide (CeO2) is a functional material with excellent physicochemical properties. Its properties can be modified by doping with different elements, including bismuth, which can be done through various synthesis methods. The precipitation method combined with ultrasonic radiation was used to synthesize bismuth-doped cerium oxide (CeO2:Bi) at a low temperature of 200oC. In this study, we investigate the alteration of structural and optical properties of as-prepared CeO2:Bi by subjecting it to additional calcination at a high temperature of 500oC. The structural and optical properties of CeO2:Bi were characterized using thermal gravimetric analysis, X-ray diffraction, Scanning Electron Microscope-Energy Dispersive X-Ray, Fourier Transform Infrared spectroscopy, and UV-Visible spectroscopy. The additional calcination produced a less significant weight-loss percentage than the as-prepared CeO2:Bi observed from the gravimetric curve. The Fourier transform infrared spectrum revealed the loss of a small number of hydroxyl molecules trapped on the CeO2:Bi surface when additional calcination was subjected. Based on the X-ray diffraction spectra, additional calcination results in the smallest crystallite size and compressive strain without the changed cubic crystal structure of CeO2:Bi. The successful doping of Bi in CeO2 was confirmed by the composition analysis from Energy Dispersive X-Ray measurement. Scanning electron microscope image showed spherical and agglomerated particles of calcined CeO2:Bi. The optical properties of both CeO2:Bi possessed similar trend absorption spectra and almost the same band gap energy. The results indicated that the calcination of as-prepared CeO2:Bi at a temperature of 500oC did not affect its structural and optical properties significantly. Thus, combining ultrasonic radiation with precipitation is an advantageous method to synthesize at a low temperature of stable CeO2:Bi crystalline.

Li3Bi/Li2O layer with uniform built-in electric field distribution for dendrite free lithium metal batteries

Lithium metal batteries have garnered significant attention as a promising energy storage technology, offering high energy density and potential applications across various industries. However, the formation of lithium dendrites during battery cycling poses a considerable challenge, leading to performance degradation and safety hazards. This study aims to address this issue by investigating the effectiveness of a protective layer on the lithium metal surface in inhibiting dendrite growth.The hypothesis is that continuous lithium consumption during battery cycling is a primary contributor to dendrite formation. To test this hypothesis, a protective layer of Li3Bi/Li2O was applied to the lithium foil through immersion in a BiN3O9 solution. Experimental techniques including kelvin probe force microscopy (KPFM) and density functional theory (DFT) calculations were employed to analyze the structural and electronic properties of the Li3Bi/Li2O layer.The findings demonstrate successful doping of Bi into the Li coating, forming Bi-Bi and Bi-O bonds. KPFM measurements reveal a higher work function of Li3Bi/Li2O, indicating its potential as an effective protective layer. DFT calculations further support this observation by revealing a greater adsorption energy of lithium on the Li3Bi/Li2O layer compared to the bulk material. Charge density analysis suggests that the adsorption of Li atoms onto the Li3Bi/Li2O layer induces a redistribution of charge, resulting in increased electron availability on the surface and preventing electrode–electrolyte contact.This study provides insights into the role of the Li3Bi/Li2O protective layer in inhibiting dendrite growth in lithium metal batteries. By mitigating dendrite formation, the protective layer holds promise for enhancing battery performance and longevity. These findings contribute to the development of strategies for improving the stability and reliability of lithium metal batteries, facilitating their wider adoption in energy storage applications.

Surface Reconstruction of Lead-Free Perovskite Cs2Ag0.6Na0.4InCl6:Bi by Hydroxylation with Blue-Light-Excited Performance

Molecular surface reconfiguration strategies have been instrumental to performance improvements of halide perovskite photovoltaic applications in recent years. However, research into the optical properties of the lead-free double perovskite Cs2AgInCl6 on the complex reconstructed surface is still lacking. Here, blue-light excitation in double perovskite Cs2Na0.4Ag0.6InCl6 with Bi doping has been successfully achieved by excess KBr coating and ethanol-driven structural reconstruction. Ethanol drives the formation of hydroxylated Cs2-yKyAg0.6Na0.4In0.8Bi0.2Cl6-yBry in the Cs2Ag0.6Na0.4In0.8Bi0.2Cl6@xKBr interface layer. The hydroxyl group adsorbed on the interstitial sites of the double perovskite structure induces a transfer of local space electrons to the [AgCl6] and [InCl6] octahedral regions, enabling them to be excited with blue light (467 nm). The passivation of KBr shell reduces the non-radiative transition probability of excitons. Blue-light-excited flexible photoluminescence devices based on hydroxylated Cs2Ag0.6Na0.4In0.8Bi0.2Cl6@16KBr are fabricated. The application of hydroxylated Cs2Ag0.6Na0.4In0.8Bi0.2Cl6@16KBr as down-shift layer in GaAs photovoltaic cell module can increase its power conversion efficiency by 3.34%. The surface reconstruction strategy provides a new way to optimize the performance of lead-free double perovskite.

Solar-driven wastewater treatment coupled with hydrogen and electricity production via a bismuth-doped TiO2 nanorod array

An ingenious and unassisted solar-driven wastewater resourcezation system (SDWRS) was designed by connecting a silicon cell (SC) to the back of a bismuth-doped TiO2 nanorod array (BTNR) for efficient water treatment accompanying hydrogen and electricity generation. Doping of Bi effectively improved the charge-transfer property and donor density of the BTNR. In addition, the introduction of SC provided an inner bias much higher than conventional photocatalytic fuel cells (PFCs) to drive efficient electron transfer from the photoanode to cathode by absorbing the transmitted longer wavelength photons. Therefore, compared with pure TNR, the photocurrent density of BTNR at 0.8 V vs Ag/AgCl is greatly increased to ∼2.81 mA cm−2. Due to the enhanced light utilization and charge transfer, which derived from the synergistic effect between the BTNR and SC, the assembled SDWRS displayed the outstanding tetracycline (TC) degradation together with hydrogen and electricity production. A TC removal ratio of nearly 100% after 2.5 h of operation, an average hydrogen generation rate of ∼29.08 μmol h−1 cm−2, and an electricity output with a maximum power output of ∼632.8 μW cm−2 were achieved. The results also manifested that SDWRS had great application potential for degrading various refractory pollutants from wastewater for clean energy production.

Bi(Ⅲ) and Ce(Ⅳ) functionalized carbon nitride photocatalyst for antibiotic degradation: Synthesis, toxicity, and mechanism investigations

Graphite-phase carbon nitride (g-C3N4) has shown great potential for antibiotic wastewater treatment due to its unique electronic structure and corresponding to visible light. In this study, a series of Bi/Ce/g-C3N4 photocatalysts with different doping amount were developed by direct calcination method for Rhodamine B and sulfamethoxazole photocatalytic degradation. The experiment result shows that the photocatalytic performance of Bi/Ce/g-C3N4 catalysts were better than that of single component samples. Under the optimal experimental conditions, the degradation rates of RhB (20 min) and SMX (120 min) by 3Bi/Ce/g-C3N4 reached 98.3% and 70.5%, respectively. The theoretical calculation results of DFT show that after Bi and Ce doping modification, the band-gap width of g-C3N4 is reduced to 1.215 eV and carrier migration rate is greatly improved. The enhanced photocatalytic activity was mainly attributed to the capture of electrons after doping modification, which inhibition of photogenerated carriers recombination and reduced the gap width. The cyclic treatment experiment of sulfamethoxazole showed that Bi/Ce/g-C3N4 catalysts had good stability. Ecosar evaluation and leaching toxicity test showed that Bi/Ce/g-C3N4 can be safely used for wastewater treatment. This study provides a perfect strategy for modifying g-C3N4 and a new way to improve the photocatalytic performance.

Fully 3D Printed Tin Selenide (SnSe) Thermoelectric Generators with Alternating n-Type and p-Type Legs.

Tin selenide (SnSe) has attracted much attention in the field of thermoelectrics since the discovery of the record figure of merit (zT) of 2.6 ± 0.3. While there have been many publications on p-type SnSe, to manufacture efficient SnSe thermoelectric generators, ann-type is also required. Publications on n-type SnSe, however, are limited. This paper reports a pseudo-3D-printing technique to fabricate bulk n-type SnSe elements, by utilizing Bi as a dopant. Various Bi doping levels are investigated and characterized over a wide range of temperatures and through multiple thermal cycles. Stable n-type SnSe elements are then combined with printed p-type SnSe elements to fabricate a fully printed alternating n- and p-type thermoelectric generator, which is shown to produce 145 μW at 774 K.

Carrier Relaxation and Multiplication in Bi Doped Graphene (Small 18/2023)

Bi Doped Graphene In article number 2206218, Xianyang Lu, Thomas Frauenheim, Yongbing Xu, and co-workers investigate femtosecond laser excitation induced electronic dynamic in Bi doped graphene, using time resolved and angular resolved photoemission spectrum. The Fermi surface in Dirac cone and carrier concentration is modulated by adatoms' content. This effectively tailors the competition between auger combination and impact excitation, tuning the carrier multiplication in graphene.

Tripling in coercivity (Hc) for the thermal and structural highly stabilized MnAlBi-C rare earth free permanent magnet via Bi doping

The limited coercivity (Hc) and metastability of the ferromagnetic τ phase MnAl-C magnet have constrained its magnetic performance and application potential. Bi was doped into the Mn54Al44-xBixC2 alloy system in this study. The doped Bi could effectively stabilize the metastable τ phase and inhibit the non-magnetic Al-rich phase formation. The ferromagnetic τ phase ratio increased dramatically as the doped Bi increase, with a peak Ms of 81 emu/g was achieved for the post-annealed Mn54Al43.6Bi0.4C2 alloy at 19 kOe. High Hc ferromagnetic LTP MnBi phase forms within the Mn54Al44-xBixC2 (x = 0.2, 0.4, 0.6) alloys when it been annealed at 300℃ for 24 h, the samples tripled or even quadrupled in Hc compared with the initial synthesized alloy. The doped Bi dissolved within lattice caused the τ phase thermally stability, structural stability improves substantially; 0.4 Bi doped Mn54Al43.6Bi0.4C2 alloy exhibited a combination of high Ms and Hc even after been ball milled for a long period of 15 and 20 h. The (Ms, Hc) achieved a value of (59.6 emu/g, 3526 Oe) for the 15 h milled sample and (51.5 emu/g, 4546 Oe) for the 20 h milled sample at 19 kOe, respectively; which is desirable for its application as a high-performance rare earth free permanent magnet.

Ultralow Lattice Thermal Conductivity and High Thermoelectric Performance in Ge1–x–yBixCayTe with Ultrafine Ferroelectric Domain Structure

GeTe and its derivatives emerging as a promising lead-free thermoelectric candidate have received extensive attention. Here, a new route was proposed that the minimization of κL in GeTe through considerable enhancement of acoustic phonon scattering by introducing ultrafine ferroelectric domain structure. We found that Bi and Ca dopants induce strong atomic strain disturbance in the GeTe matrix because of large differences in atom radius with host elements, leading to the formation of ultrafine ferroelectric domain structure. Furthermore, large strain field and mass fluctuation induced by Bi and Ca codoping result in further reduced κL by effectively shortening the phonon relaxation time. The co-existence of ultrafine ferroelectric domain structure, large strain field, and mass fluctuation contribute to an ultralow lattice thermal conductivity of 0.48 W m-1 K-1 at 823 K. Bi and Ca codoping significantly enhances the Seebeck coefficient and power factor through reducing the energy offset between light and heavy valence bands of GeTe. The modified band structure boosts the power factor up to 47 μW cm-1 K-2 in Ge0.85Bi0.09Ca0.06Te. Ultimately, a high ZT of ∼2.2 can be attained. This work demonstrates a new design paradigm for developing high-performance thermoelectric materials.

Improved thermoelectric performance by microwave wet chemical synthesis of low thermal conductivity SnTe

SnTe is a promising replacement for PbTe due to its non-toxicity and high thermoelectric conversion efficiency. However, it suffers from poor performance caused by the presence of tin vacancies and a wide energy gap between the light and heavy valence bands, as well as high thermal conductivity that inhibits its thermoelectric properties. In this work, complexes of in situ grown SnTe with Bi doping were synthesized by microwave wet chemical synthesis. The complex morphology of the micro-nanoparticles and the formation of holes after spark plasma sintering suppress phonon scattering and greatly reduce the lattice thermal conductivity of the system. The band structure and phonon dispersion of Bi doped SnTe were calculated by first principles, and the reasons for the improvement of electric transport properties and the decrease of thermal conductivity of SnTe were investigated, combined with mechanical properties and sound speed reduction. The effects of various mechanisms such as polycrystalline interfaces, point defects, complex morphologies, and phonon dispersion flat bands on phonon scattering are discussed in detail and the obtaining mechanism of low lattice thermal conductivity is understood.

Broadband Optical Amplification in Bi‐Doped Multicomponent Glass Fiber

AbstractBismuth(Bi)‐doped photonic materials with broadband near‐infrared luminescence can be used in applications such as high‐capacity fiber communication, fiber laser, and biological imaging. The scalable fabrication of Bi‐doped fibers with high dopant solubility, high optical activity, and broadband optical response still remains a significant challenge. In this study, the comprehensive studies on the physical, chemical, mechanical, and optical responses of a Bi‐doped glass system are performed and a Bi‐doped germanate multicomponent glass system is proposed to be the promising candidate. The deactivation mechanism of Bi in a glass matrix is investigated and prevented by controlling the fiber drawing. In addition, a Bi‐doped multicomponent germanate glass fiber with a high level of Bi doping is successfully constructed. Finally, a principle compact fiber amplifier device is fabricated for broadband optical amplification. This device can be potentially used for increasing the capacity of telecommunication systems.

Lanthanum–bismuth mixed oxide catalyst with improved activity for carbonyl sulfide hydrolysis

The presence of carbonyl sulfide (COS) in industrial tail gas poses considerable risks to human health and ecosystems. Catalytic hydrolysis is efficient in COS removal, yet developing high-performance catalysts at low temperatures remains challenging. In this work, we designed novel nanorod-like lanthanum-bismuth (La-Bi) mixed oxides for the catalytic hydrolysis of COS. The COS hydrolysis activity of the Bi-doped catalyst was significantly improved as compared to the bare La oxide. The catalysts with various La/Bi ratios were thoroughly analyzed by microscopic and spectroscopic techniques to elucidate their structural and chemical properties. The results indicated that the Bi doping into the La oxide enhanced the basicity and electron transfer of the catalyst, leading to improved hydrolysis activity. A reaction pathway for the COS catalytic hydrolysis on La-Bi mixed oxide was proposed, in which COS adsorption was significantly strengthened due to enhanced basicity, and thereby the formation of intermediates such as HCO3− and HSCO2- was facilitated. In addition, the La-Bi mixed oxide catalyst demonstrated excellent sulfur tolerance and stability in long-term testing using simulated industrial gas.

Experimental and theoretical research on improving the gas sensitivity of ethanol based on Bi-doped ZnSn(OH)6

The wider band gap of ZnSn(OH)6 (ZHS) leads to higher resistance and low sensitivity to gases, and doping is one important way of reducing resistance and improving gas sensitivity. In this paper, cubic ZHS and Bi-doped ZHS were successfully prepared by hydrothermal method and analyzed by XRD, SEM, TEM and XPS, respectively. The results are as following: XRD pattern of the samples are consistent with ZHS standard card, and the XRD characteristic peak shifts to the left after Bi doping; the size of the cubic particle decreases greatly; Zn, Sn, O and Bi elements are evenly distributed. The replacement of Sn with Bi will form a displacement impurity, and insert a shallow donor impurity level at the bottom of the conduction band. As a result, the carrier concentration increases while the band gap width and material resistance decreases. Therefore, the performance of the sensor is greatly improved.

Investigations on Bi Doped Cu2Se Prepared by Solid State Reaction Technique for Thermoelectric Applications

The influence of Bi doping on the structural and thermoelectric properties of Cu2Se is presented in this work. Cu2−xBixSe (x = 0.00, 0.004, 0.008, 0.012) samples were prepared using conventional solid-state reaction techniques. According to room temperature XRD results, Cu2−xBixSe samples have a monoclinic crystal structure. Doping Bi to the Cu site acts as a donor, lowering the hole concentration, except for the sample with x = 0.004. The resistivity of the Cu2−xBixSe sample increases with an increase in Bi content. Seebeck coefficient data confirm that the holes are the charge carriers in Cu2−xBixSe samples. At 700 K, the Cu1.988Bi0.012Se sample has the highest power factor of 1474 μWm−1K−2, showing great potential in developing high-performance Cu2Se based thermoelectric materials.

Tuning superconductivity in highly crystalline Pb1−xBix alloy ultrathin films at atomic level

Achieving highly crystalline superconductors with reduced dimensionality and fine-tuning their superconductivity have been daunting challenges in condensed matter physics. Here, we have successfully grown two-monolayer highly crystalline ${\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}$(111) films with controllable Bi concentrations $x$ by molecular beam epitaxy and systematically studied their structural and superconducting properties by scanning tunneling microscopy. We first show that the superconducting transition temperatures of ${\mathrm{Pb}}_{1\ensuremath{-}x}{\mathrm{Bi}}_{x}$ films exhibit a domelike behavior with increasing Bi concentration $x$. Our first-principles calculations reveal that Bi doping can promote the electronic states and the electron-phonon coupling strength at lower $x$ and suppress the electron-phonon coupling strength and superconductivity with largely Bi electronic states when Bi doping increases over a critical ratio. Our findings not only demonstrate a quantum phenomenon of superconductivity in highly crystalline alloyed films but also provide a practical pathway to tune the superconductivity at the atomic level.

Unraveling the synergistic effect on ionic transport of ceria via the surface engineering for low-temperature ceramic fuel cells

Recently, the multifunctional semiconductor CeO2 realized high ionic conductivity via surface conduction and delivered higher fuel cell performance. This indicates a promising strategy for the design of an electrolyte for the low-temperature ceramic fuel cell. In this study, we develop a ceria-based electrolyte by surface doping Bi into CeO2 to attain the CeBiO2 (BDC) electrolyte. The designed electrolyte is facilitated with an enriched O-vacancy surface layer, enabling high ionic conduction (0.20 S/cm) and excellent power density (1057 mW/cm2) at 530 °C. The difference in the Fermi level of BDC and CeO2 arises due to the surface doping, which entails the band alignment and establishes the space charge region, thereby constituting a built-in field enhancing the charge transportation and minimizing e-conduction. In order to assist the formation of O-vacancies in the design, the BDC electrolyte density functional theory calculation was also made. These findings suggest surface doping is the best approach to attaining excellent performance and designing electrolytes and electrodes for advanced low-temperature fuel cell technology.

Greatly boosted photocatalytic N2-to-NH3 conversion by bismuth doping in CdMoO4: Band structure engineering and N2 adsorption modification

This work enhances the photocatalytic N2 immobilization performance of CdMoO4 through Bi doping. The doped Bi element exists in the presence of Bi3+ and substitutes the position of Cd2+. The particle size of CdMoO4 is greatly decreased due to Bi doping. Additionally, it narrowed the band gap, reduced the work function, and elevated the conduction band, which endowed the Bi-doped CdMoO4 with a stronger ability in generating and separating charge carriers than CdMoO4. Density function theory (DFT) calculations further indicated that N2 has stronger adsorption at the unsaturated Mo sites of Bi-doped CdMoO4 due to the interactions between the 2π* orbital of N2 with the d orbital of Mo. The combination of these changes allows Bi-CdMoO4 to exhibit excellent photocatalytic N2-to-NH3 performance. The NH3 generation rate of optimal Bi-CdMoO4 reaches 7.2 times that of CdMoO4. This work may show some light on the preparation of novel photocatalysts for N2-to-NH3 conversion.

Multiple-site Ag doping in Bi[formula omitted]Se[formula omitted]: Compositional crossover from substitution to intercalation as revealed by photoelectron diffraction and X-ray fluorescence holography

The local structure around Ag atoms in Ag-doped Bi2Se3 (AgxBi2−ySe3) was investigated by photoelectron diffraction and X-ray fluorescence holography to understand the manner of Ag atom doping. At a low Ag concentration (x=0.05), photoelectron diffraction indicated that Ag atoms occupied Bi substitution sites. However, a mere accumulation of holes via Ag substitution for Bi fails to explain the observed variation previously reported in the transport properties of Ag-doped Bi2Se3 with different x values. In particular, simple Ag substitution for Bi fails to explain the pinning of the Fermi level at the bottom of conduction band, as suggested by the observed transport properties. In the case of a high Ag concentration (x=0.2), photoelectron diffraction suggested that the Ag atoms occupied not only the substitutional Bi site but also multiple interstitial sites, namely, the octahedral site in the van der Waals interlayer and the interstitial site in the Se layer. Ag 3d photoelectron spectra revealed that the Ag atoms had the same oxidation state, +1, regardless of the type of occupied site. Furthermore, X-ray fluorescence holography was employed for a model-free local structural analysis that refined the exact locations of Ag atoms in the Bi2Se3 crystal lattice. The behavioral crossover documented herein from hole doping at the substitutional site to electron doping at multiple sites reasonably explains the dependence of electronic structures and transport properties of Ag-doped Bi2Se3 on dopant concentration.

Highly active cobalt-free perovskites with Bi doping as bifunctional oxygen electrodes for solid oxide cells

Cobalt-containing perovskite materials have been intensively investigated as bifunctional oxygen electrodes for solid oxide cells because of their mixed ionic-electronic conducting nature. However, the direct application of these materials to the most widely used zirconia-based electrolytes has been limited because of their thermo-chemical incompatibility. Herein, we introduce a cobalt-free manganite-perovskite with significantly improved electrocatalytic activity by doping with Bi which possesses stereochemically active lone pair electrons. Replacing Bi with Pr in Pr0.8Sr0.2MnO3−δ increases the oxygen vacancy concentration and promotes oxygen ion incorporation and charge transfer processes at the electrode. Consequently, we apply Pr0.5Bi0.3Sr0.2MnO3−δ, to the interlayer-free yttria-stabilized zirconia electrolyte-based cells, which exhibits record high performance in the fuel cell (1.91 W∙cm−2) as well as electrolysis (1.90 A∙cm−2) modes at 700 °C along with remarkable long-term stability (450 h). Thus, our findings demonstrate that Pr0.5Bi0.3Sr0.2MnO3−δ is a highly promising bifunctional catalyst for solid-state energy storage and conversion applications.

High-performance self-biased photodetectors based on Bi-incorporated ReSe2 ternary alloys

Transition Metal Dichalcogenides (TMDCs) have recently been the focus because of their unique physical properties. Bi-incorporated ReSe2 (Bi: ReSe2) is a new member of the TMDC family with a triclinic structure that is optically biaxial and strongly anisotropic. In this work, we reported the effect of Bi doping in layered ReSe2 crystals synthesized by the Direct Vapour Transport (DVT) method and studied the structural and optoelectronic properties in detail. The layered surface of the single crystals, the stoichiometric proportion of elements and the triclinic structure and phase purity of the material has been observed using Scanning electron microscopy (SEM), Energy dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD) respectively. The shifting in vibrational Raman modes has been observed by Raman spectroscopy at room temperature. The dynamic I-t characteristics of BixRe1-xSe2 (x = 0.1, 0.5) ternary alloy-based photodetectors were studied successively. The photodetector parameters were calculated under different biasing voltages and different wavelengths. The anisotropy in the dynamic I-t characteristics of transition metal chalcogenides was studied due to their layered structure. The device showed higher photoresponse for the perpendicular to c-axis configuration than for the parallel. Our results showed that the ternary alloys based single crystals have great potential for application in photosensitive devices.