Bi4Ti3O12 Research Articles

Enhanced visible-light photocatalytic performance of hollow Bi/Bi4Ti3O12 microspheres assembled with Bi4Ti3O12 nanosheets and Bi nanodots synthesized by hydrothermal method

Bi4Ti3O12 (BTO) microspheres were synthesized by a facile hydrothermal method, and 2-methoxyethanol was used as reductant for formation of Bi nanodots on BTO nanosheet surfaces. The morphology evolution and photocatalytic mechanism of Bi/BTO (B/BTO) composites were explored. As the B/BTO composite was synthesized at 200oC for 72h, the hollow B/BTO microspheres assembled with BTO nanosheets and Bi nanodots were formed due to the Ostwald-ripening mechanism. For the hollow B/BTO microsphere composites, the hollow-microsphere structure increased the surface area and the multiple internal reflections of light to enhance the light utilization efficiency, and the formation of B/BTO interfaces improved the separation efficiency of photogenerated carriers and efficient charge transfer. When the 2-methoxyethanol content in the Bi-Ti precursor was 2ml, the as-prepared hollow B/BTO microspheres exhibited excellent photocatalytic performance for TC degradation under visible-light irradiation due to the synergistic effect of hollow-microsphere structure and Bi nanodot decoration.

Enhancing ionic conductivity and controlling lithium dendrite growth via ferroelectric ceramic Bi4Ti3O12

BackgroundSolid polymer electrolytes (SPEs) have gained numerous research interest in the field of lithium metal batteries. Solid polymer electrolytes have improved safety compared to liquid electrolytes. Despite this, their low ionic conductivity remains a major barrier to practical applications. To overcome the challenge of low ionic conductivity in SPEs, our study introduces a novel approach that integrates ferroelectric ceramics with polymer solid electrolytes. MethodsWe used a one-step molten salt method to synthesize Bi4Ti3O12 (BIT), combined with a poly (vinylidene difluoride) matrix to form the composite solid-state electrolyte. Through various electrochemical characterizations and COMSOL Multiphysics simulations, we discovered that the ferroelectric properties of BIT significantly increase the dissociation of lithium salts, leading to a greater concentration of mobile lithium ions and more efficient ion transport. Significant findingsThis electrolyte showed a remarkable improvement in lithium-ion conductivity, reaching a value of 8.5 × 10−4 S cm−1 at room temperature. Batteries made with these composite electrolytes demonstrate superior cycling stability, the capacity retention rates for LFP/SPEs/Li cells remain high, reaching 95 % even after 1,000 cycles at room temperature (25 °C). These findings highlight the promising applications of ferroelectric ceramics in solid-state batteries.

Achieving high energy storage density and efficiency in (Na0.5Bi0.5)TiO3-based lead-free ceramics

Due to the demands of miniaturization, weight reduction and green development for electronic devices, development of lead-free dielectric ceramic capacitors with high recoverable energy density (Wrec) and energy storage efficiency (η) attracts much attention. To this end, (1-x)[0.75(Na0.5Bi0.5)TiO3-0.25SrTiO3]-xNdNbO4 (abbreviated as: NBST-xNN) ceramics were fabricated through a solid-state reaction method. After adding NN, the non-perovskite phase of Bi2Ti2O7 (BTO) with low dielectric constant (εr) and loss (tan δ) is generated. Finite element software (COMSOL) was used to explore the influence of the BTO phase on breakdown strength (Eb). The simulation result indicates that the BTO phase with a low εr concentrates a larger local electric field (LEF), and thus weakens the LEF loading in the main perovskite phase, which is beneficial for enhancing Eb. Moreover, NN doping significantly decreases the oxygen vacancy concentration in NBST ceramics, which plays a key role in improving Eb. On the other hand, as NN content increases, the hysteresis of the polarization (P)-electric field (E) loops is substantially suppressed, and the polarization saturation is delayed, which can be ascribed to the appearance of the BTO phase having a linear dielectric characteristic and to the enhanced fluctuations of composition and charge by NN doping. Benefitting from the above factors, the optimal energy storage performance (ESP) with a Wrec of 4.14 J/cm3 and an η of 90 % is obtained in NBST-0.08NN ceramics. Meanwhile, the ESP of NBST-0.08NN ceramics shows good charge-discharge properties and thermal stability. In conclusion, these results demonstrate that NBST-0.08NN ceramics are promising candidates as environment-friendly dielectric capacitor materials.

Photocatalytic performance of Au/Bi4Ti3O12 composite improved by synergistic piezoelectric effect and exciton-plasmon

Bi4Ti3O12 (BiTO) is a typical bismuth-layered Aurivillius ferroelectric material for its potential application in photocatalysis. In this study, Au/BiTO hybrid was fabricated by precipitating Au nanoparticles onto BiTO nanoflake using a sodium citrate reduction route. This integration has led to a remarkable enhancement in the photocatalytic efficiency, which is attributed to the synergistic coupling of piezoelectric effect of BiTO with the localized surface plasmon resonance (LSPR) of Au nanoparticles. The incorporation of Au nanoparticles onto the BiTO matrix has significantly boosted the light absorption and charge carrier separation, thereby augmenting the photocatalytic activity. Notably, Au/BiTO-2 composite exhibits exceptional photocatalytic performance, demonstrating the complete degradation of RhB within 40 min under full-spectrum light irradiation. Moreover, Au/BiTO-2 displays a robust photocatalytic action against other organic pollutants, including methyl orange (MO), ofloxacin (OFLX) and tetracycline hydrochloride (TC). Further enhancement of photocatalytic process is achieved when combing light irradiation with ultrasonic excitation. The ultrasonic waves break the static spontaneous polarization through alternating piezoelectric potential, which accelerates the catalytic reaction. The photocatalytic action rate of Au/BiTO-2 toward RhB reaches a value as high as 0.0984 min−1, which is nearly 2.3 folds increasement compared to that of pristine BiTO. The possible synergistic mechanism caused by piezoelectric effect and exciton-plasmon effect is discussed in detail. The work not only enriches our understanding of the underlying principles but also supply a new strategy to design high-performance catalysts in the field of environmental remediation and energy conversion.

Enhanced energy storage performance in Bi4Ti3O12 thin films with oxygen depletion layers

The imprint effect in ferroelectric materials can significantly enhance the performance of energy storage devices. Bi4Ti3O12 (BTO) and oxygen-deficient Bi4Ti3O11.2 (DBTO) thin films were deposited on single-crystal Nb-doped SrTiO3 substrates using pulsed laser deposition. In stark contrast, multilayer DBTO/BTO thin films incorporating an oxygen-deficient layer were also fabricated, with the DBTO layers having thicknesses of 5 nm and 10 nm, respectively. Both BTO and DBTO thin films exhibited epitaxial growth and c-axis-oriented crystallinity. Regarding ferroelectric properties, DBTO/BTO capacitors with an oxygen-deficient layer demonstrated a pronounced imprint effect in their ferroelectric hysteresis loops, compared to the BTO and DBTO capacitors. This effect was particularly noticeable in the DBTO/BTO capacitor with a 10 nm oxygen-deficient layer, as opposed to the thin film with a 5 nm oxygen-deficient layer. We suggest that the imprint effect can be attributed to localized electric field variations and imbalances in charge transport at the interface between the oxygen-depleted layer and the remaining thin film. Consequently, the imprint effect observed in the DBTO/BTO capacitors contributed to an enhancement in energy storage density and efficiency, compared to BTO and DBTO capacitors. This study demonstrates the potential of multilayer DBTO/BTO thin films in advancing capacitive energy storage systems.

Piezoelectric Polymer Solid Electrolyte Integrating Electromechanical Coupling and Ferroelectric Polarization Effects.

The unsatisfactory lithium-ion conductivity (σ) and limited mechanical strength of polymer solid electrolytes hinder their wide applications in solid-state lithium metal batteries (SSLMBs). Here, a thin piezoelectric polymer solid electrolyte integrating electromechanical coupling and ferroelectric polarization effects has been designed and prepared to achieve long-term stable cycling of SSLMBs. The ferroelectric Bi4Ti3O12 nanoparticle (BIT NPs) loaded poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) piezoelectric nanofibers (B-P NFs) membranes are introduced into the poly(ethylene oxide) (PEO) matrix, endowing the composite electrolyte with unique polarization and piezoelectric effects. The piezoelectric nanofiber membrane with a 3D network structure not only promotes the dissociation of lithium (Li) salts through the polarization effect but also cleverly utilizes the coupling effect of a mechanical stress-local electric field to achieve dynamic regulation of the Li electroplating process. Through the corresponding experimental tests and density functional theory calculations, the intrinsic mechanism of piezoelectric electrolytes improving σ and suppressing Li dendrites is fully revealed. The obtained piezoelectric electrolyte has achieved stable cycling of LiFePO4 batteries over 2000 cycles and has also shown good practical application potential in flexible pouch batteries.

In situ regulation of the oxygen vacancy concentration of Bi4Ti3O12 by β-particles to activate peroxydisulfate

The key to enhancing the activation efficiency of peroxydisulfate (PDS) lies in facilitating the adsorption of PDS and accelerating the rate of electron transfer at the interface. In this work, the oxygen vacancy (Ovs) concentration of ultrathin Bi4Ti3O12 (BTO) was controlled in situ by high-energy electron beam bombardment. BTOV-300 exhibited a significant activation effect on PDS. The degradation rate constant (kobs) for the removal of ciprofloxacin (CIP) was measured to be 0.2080 min−1 under visible light irradiation, which was 3.71 times greater than that of the original BTO. Density functional theory calculations uncovered the principal role of oxygen vacancies as active sites for PDS activation. Introducing OVs significantly boosted the adsorption energy of PDS on BTO and lengthened the OO bond of PDS. This study represents the potential mechanism behind the activation of PDS by BTOV and provides valuable insights for enhancing the photoactivation efficiency of PDS.

Effect of the template particles size on structure and piezoelectric properties of 〈0 0 1〉‐textured BNT‐based ceramics

AbstractThis research investigated the effect of Bi4Ti3O12 (BiT) template particles size on the structure and piezoelectric properties of 〈001〉‐textured (Bi0.5Na0.5)TiO3 (BNT)‐based lead‐free piezoelectric ceramics. Results of X‐ray diffractometer analyses and scanning electron microscopy observations showed that high purity BiT template particles could be obtained with the KCl as the molten salt system. Highly 〈001〉‐textured (~87%) BNT‐based ceramics prepared with large size BiT templates (7.75 µm) exhibited a high inverse piezoelectric constant d33* (1100 pm/N), which was ∼3.38‐fold larger than that with 1.91 µm (325 pm/N). In addition, we have found that too small the template size can make it difficult to align the orientation of the template during the casting process, whereas too large the size can create problems such as too much hysteresis (∆S/Smax = 67%). This study has demonstrated that the use of high purity large size BiT template particles could provide a feasible route to fabricate BNT‐based textured ceramics with desired electro‐strain properties.

Bi2Ti2O7/PbCdS2/PbS solar cells with NiS@rGO Electrocatalyst: A strategy for enhancing light absorption and polysulfide reduction

The pyrochlore structure of bismuth titanate (Bi2Ti2O7) has been used as a photo-anode to fabricate PbCdS2 sensitized solar cells. The ternary PbCdS2 alloy has been coated with the thin Bi2Ti2O7 (BTO) films by optimizing the successive ionic layer adsorption and reaction (SILAR) cycles. The structure and chemical composition have been identified through X-ray diffraction and X-ray photoelectron spectral analysis. The nanorods-like morphology has been observed from the morphological analysis. J-V results demonstrate that the BTO/3PbCdS2 with NiS counter electrode (CE) cell has a better power conversion efficiency (PCE) of 1.03 % with a JSC of 4.56 mA cm−2, VOC of 49 mV, and FF of 0.39, which is superior to other BTO/PbCdS2 combinations and pristine CdS and PbS. Furthermore, the PCE is increased by sandwiching the NiS-rGO CE with the BTO/3PbCdS2/Sn2-/S2- and attaining a maximum JSC of 5.65 mA cm−2, VOC of 539 mV, FF of 0.56, and PCE of 2 %. The obtained FF and are 43 % and 94 % higher than the BTO/3PbCdS2/Sn2-/S2-/NiS cell, respectively. The improvement is owing to increased light absorption, perhaps due to a favorable band position, lower carrier recombination, and the effective polysulfide reduction of NiS-rGO. The results suggest that optimized SILAR cycles are not the only approach to attaining a superior PCE; implanting an effective electrocatalyst is also a viable option.

Coupling photothermal and piezoelectric effect in Bi4Ti3O12 for enhanced photodegradation of tetracycline hydrochloride

Semiconductor photocatalysis is an effective way to remove antibiotic pollution. However, recombination of photogenerated carriers limits the efficiency of photocatalytic degradation of antibiotic. In this work, Bi4Ti3O12 (BTO) with micro-hollow spheres (HS-BTO) was successfully self-assembled by BTO nano-sheets. The microstructure of HS-BTO can serve as a guarantee for its good adsorption capability. Assisted by photothermal effect, HS-BTO shows efficient photodegradation of tetracycline hydrochloride (TC) solution. This work reveals that heat can effectively reduce the charge transfer resistance, accelerate the charge transfer, thus promoting the charge separation and improving the photocatalytic performance. In addition, through ultrasound vibration, polarization charges and built-in polarization fields may be generated in HS-BTO. They can accelerate photogenerated charge carriers separation and greatly suppress recombination rate of electron/hole pairs, and is helpful to achieve piezoelectric catalytic degradation of TC. Consequently, a developed photocatalytic degradation of TC assisted by photothermal and piezoelectric effect is achieved. Thus, this work proposes an innovative approach to coupling optical, photothermal and mechanical energy to advance photocatalysis.

Preparation and Optical Properties of Nd:Bi2Ti2O7 Laser Crystal with Disordered Structure and Attractive Multiwavelength Emission Characteristics.

Laser crystals with multiwavelength emission characteristics are potential light sources for terahertz radiation. Herein, the pure and Nd-doped Bi2Ti2O7 (BTO) laser crystals with sizes up to 16 × 13 × 5 mm3 were successfully grown using the flux method in the KF-B2O3-CaBi4Ti4O15 growth system. The crystal structure, ideal morphology, chemical, mechanical, and thermal properties, optical transmission and Raman spectra, refractive index, absorption, and fluorescence spectra, as well as fluorescence lifetimes, were systematically studied. Besides, the spectral parameters of Nd3+ ions in the BTO crystal were systematically calculated based on the Judd-Ofelt theory. The Nd:BTO crystal has a wide transmittance range (0.44-7.30 μm), a small coefficient of thermal expansion (5.80 × 10-6 K-1), and a large absorption full width at half-maximum (fwhm) (31.2 nm) at around ∼804 nm, making it more potential for use in high-power laser systems. Moreover, fluorescence spectra show four emission peaks at 1054, 1062, 1104, and 1112 nm. The strong multiwavelength emission property makes Nd:BTO a promising laser crystal, serving as a potential light source for terahertz radiation.

Multimodal energy harvesting and catalysis of piezoelectric nanosheets for efficient and round-the-clock wastewater treatment

Solar-driven pollutants degradation is an important way for green wastewater treatment, but it is still limited by the intermittent solar flux. Here, we have prepared piezoelectric Bi4Ti3O12 (BTO) nanosheets with abundant physical properties, which can convert extensive solar energy, mechanical energy and temperature variation energy into electrical and chemical energy. It can be used for round-the-clock wastewater treatment by harvesting multi-modal energy. More importantly, the degradation rate of piezoelectric nanosheets can reach 153.4 × 10-3 min−1, and nanosheets can degrade many organic pollutants. In addition, we fabricate porous foam catalysts based on BTO-polydimethylsiloxane (PDMS) composite to prevent secondary contamination. Our results suggest that BTO nanosheets with photoelectric, piezoelectric and pyroelectric catalysis offer a potential approach for round-the-clock wastewater degradation by harvesting solar energy, ambient mechanical energy, and cyclic thermal energy.

Photodegradation behaviour of sol–gel synthesized Bi4Ti3O12 for water pollution disinfection

Minimization of water consumption and effective recycling of water by choosing the appropriate water treatment technique in industry are the most essential in this modern era. Nowadays, the usage of sol–gel synthesized nanomaterial to study the photo degradation behavior of disinfected water pollution is a promising way. Phase purity analysis, reusability test, photoarate constant of photo-catalytic and rate constant of photolysis reaction were examined. X-ray diffraction (XRD) results confirm the formation of Bi4Ti3O12 (BTO) with an orthorhombic structure. The phase purity of the catalyst is also analyzed using the Jana2006 refinement. The FESEM image revealed a hexagonally structured particle with an indistinguishable grain boundary. The degradation behaviour of Rhodamine-B (RhB) in sunlight is investigated under the influence of BTO nanoparticles. The rate constant of the photo-catalytic and photolysis reaction is found to be 0.0198 and 0.0008. Degradation efficiencies are found to be 91.3% for RhB. Overall results revealed that the sol–gel synthesized bismuth titanium oxide (Bi4Ti3O12) is best choice for water pollution disinfection.

Selective Exposure of Robust Perovskite Layer of Aurivillius-Type Compounds for Stable Photocatalytic Overall Water Splitting.

Aurivillius-type compounds ((Bi2 O2 )2+ (An -1 Bn O3 n +1 )2- ) with alternately stacked layers of bismuth oxide (Bi2 O2 )2+ and perovskite (An -1 Bn O3 n +1 )2- are promising photocatalysts for overall water splitting due to their suitable band structures and adjustable layered characteristics. However, the self-reduction of Bi3+ at the top (Bi2 O2 )2+ layers induced by photogenerated electrons during photocatalytic processes causes inactivation of the compounds as photocatalysts. Here, using Bi3 TiNbO9 as a model photocatalyst, its surface termination is modulated by acid etching, which well suppresses the self-corrosion phenomenon. A combination of comprehensive experimental investigations together with theoretical calculations reveals the transition of the material surface from the self-reduction-sensitive (Bi2 O2 )2+ layer to the robust (BiTiNbO7 )2- perovskite layer, enabling effective electron transfer through surface trapping and effective hole transfer through surface electric field, and also efficient transfer of the electrons to the cocatalyst for greatly enhanced photocatalytic overall water splitting. Moreover, this facile modification strategy can be readily extended to other Aurivillius compounds (e.g., SrBi2 Nb2 O9 , Bi4 Ti3 O12 , and SrBi4 Ti4 O15 ) and therefore justify its usefulness in rationally tailoring surface structures of layered photocatalysts for high photocatalytic overall water-splitting activity and stability.

Studies of structural, dielectric and impedance characteristics of Gd modified Bi4Ti3O12 Aurivillius ceramic

The synthesis and characterization (structure, dielectric, electrical properties) of ceramic technology prepared gadolinium modified bismuth titanate of a composition Bi4-x GdxTi3O12 (x = 0, 0.1) have been reported in this paper. The development of a single-phase orthorhombic structure with a space group Aba2 has been confirmed by analysing room temperature X-rays diffraction (XRD) patterns. The plate-like microstructures of the samples are revealed by scanning electron microscope, which confirmed the layered perovskite structure of Bi4-x GdxTi3O12 (x = 0,0.1). The crystallite size (D) and strain (ε), calculated from the W–H (Williamson-Hall) plots, are found to be 64 nm, 0.001, respectively for BIT (bismuth titanate, Bi4Ti3O12) and 53 nm, 0.009, respectively for Gd modified BIT. Some obtained electrical parameters (dielectric constant, conductivity, electrical impedance, and modulus) of BIT and Gd modified BIT have provided useful data on the conduction mechanism, structure-properties relationship, etc. The Nyquist plots confirm the contribution of grain boundary and the bulk effect to the properties (physical) of the materials.

Regulating the Electronic Structure of Bismuth Nanosheets by Titanium Doping to Boost CO2 Electroreduction and Zn-CO2 Batteries.

The electrochemical carbon dioxide reduction reaction (E-CO2 RR) to formate is a promising strategy for mitigating greenhouse gas emissions and addressing the global energy crisis. Developing low-cost and environmentally friendly electrocatalysts with high selectivity and industrial current densities for formate production is an ideal but challenging goal in the field of electrocatalysis. Herein, novel titanium-doped bismuth nanosheets (TiBi NSs) with enhanced E-CO2 RR performance are synthesized through one-step electrochemical reduction of bismuth titanate (Bi4 Ti3 O12 ).We comprehensively evaluated TiBi NSs using in situ Raman spectra, finite element method, and density functional theory. The results indicate that the ultrathin nanosheet structure of TiBi NSs can accelerate mass transfer, while the electron-rich properties can accelerate the production of *CO2 - and enhance the adsorption strength of *OCHO intermediate. The TiBi NSs deliver a high formate Faradaic efficiency (FEformate ) of 96.3% and a formate production rate of 4032µmolh-1 cm-2 at -1.01V versus RHE. An ultra-high current density of -338.3mA cm-2 is achieved at -1.25versus RHE, and simultaneously FEformate still reaches more than 90%. Furthermore, the rechargeable Zn-CO2 battery using TiBi NSs as a cathode catalyst achieves a maximum power density of 1.05mW cm-2 and excellent charging/discharging stability of 27 h.

Novel strategies to tune the color emission of Bi2Ti2-xZrxO7:Er3+,Yb+3 upconversion phosphors: Substituting Ti by Zr and annealing at high temperatures

Bi2Ti2-xZrxO7:Er3+,Yb3+ phosphors were synthesized with different content of Zr (X = 0–1.5) by combustion method at 550 °C, producing a mixture of Bi2Ti2O7/Bi4Ti3O12 phases. After increasing the synthesis temperature to 1000 °C, a pure Bi2Ti2O7 (BiTiO) phase was obtained as well as porous coalesced microparticles (2–10 µm) with pore sizes of 110–420 nm. Those samples produced green (548 nm)/red (655 nm) and NIR (1530 nm) emission bands after excitation with 980 nm and their color emission was tuned from green to yellow–red or viceversa using two strategies: i) by increasing the Zr content in the Bi2Ti2-xZrxO7:Er3+,Yb3+ host (from X = 0 to 1) or ii) by increasing the synthesis temperature from 550 to 1000 °C. Interestingly, the intensity of the NIR and red emission bands was enhanced with the content of OH groups on the surface of the BiTiO:Yb,Er phosphors.

Controllable fabrication of Bi4Ti3O12/C/Bi2S3/MoS2 heterojunction with effective suppression of Bi2S3 assisted by amorphous carbon interlayer for significantly enhanced photocatalysis

BackgroundFabricating heterojunctions by combining with MoS2 is efficient to boost the visible light photocatalytic activity of Bi4Ti3O12 (BTO) but limited by the concurrent formation of Bi2S3 nanorods by in-situ ion exchange reaction. MethodsAn amorphous carbon interlayer that can effectively protect the BTO fibrous structure and suppress the Bi2S3 generation was introduced to construct Bi4Ti3O12/C/Bi2S3/MoS2 (BCBM) composites with enhanced photocatalytic activity. The BCBM fibers were fabricated by electrospinning and subsequent hydrothermal growth of carbon and MoS2. Significant findingsOwing to the important roles of carbon interlayer to keep the integrity of the BTO fibrous structure and provide charge transfer channel, fast separation of photoinduced carriers happens on the semiconductor interface between BTO and MoS2 to improve the visible light photocatalytic activity. The optimum BCBM displays a photocatalytic efficiency of 88.4% and apparent constant of 0.0148 min−1 towards degrading RhB, which are much higher relative to the Bi4Ti3O12/Bi2S3/MoS2 composites prepared without the carbon interlayer. Moreover, it is demonstrated that the thickness of carbon interlayer is crucial for fabricating high-performance BTO heterojunctions with MoS2. The design and results in this work may broaden the horizon to construct the Bi-based semiconductor photocatalyst with high photocatalytic performance.

Facile synthesis, novel structure, multicolor luminescence, and potential applications of lanthanide ions doped bismuth titanate phosphors

A variety of lanthanide ions doped bismuth titanate (Bi4Ti3O12) luminescent materials with eminent down-conversion (DC) and up-conversion (UC) luminescence performance have been fabricated via a facile sol-gel approach. The XRD, XPS, and EDX elemental mapping results confirm the phase structure of orthorhombic Bi4Ti3O12 (BTO), and the lanthanide activator ions occupy the Bi3+ lattice sites in the BTO crystal. Under UV or NIR excitation, the Eu3+, Yb3+/Ln3+ (Ln = Er, Tm, and Ho) doped Bi4Ti3O12 samples exhibit characteristic red, green, blue, and green emissions. The luminescent mechanisms of the BTO:Eu3+ and BTO:Yb3+/Ln3+ samples are discussed based on the energy level diagrams. The doping concentrations of Eu3+, Yb3+, Er3+, Tm3+, Ho3+ ions and annealing temperature and time are optimized, whose optimal values are determined to be 14, 8, 1, 0.4, 1 mol% and 800 oC, 4 h. The as-obtained LED devices fabricated by Bi4Ti3O12:Eu3+ and Yb3+/Ln3+ phosphors exhibit dazzling multicolor visible light emissions from different Ln3+ ions. The results indicate that the as-obtained Ln3+ doped BTO phosphors may be potentially utilized in LED devices and solid-state lighting. Furthermore, the Eu3+ and Er3+ co-doped BTO samples exhibit different DC and UC luminescence spectral profiles when excited at various UV, visible, or NIR wavelengths, revealing their eminent feasibility and great potential in anti-counterfeiting applications.

D-π-A array structure of Bi4Ti3O12-triazine-aldehyde group benzene skeleton for enhanced photocatalytic uranium (VI) reduction

Photocatalytic reduction of UVI to UIV can help remove U from the environment and thus reduce the harmful impacts of radiation emitted by uranium isotopes. Herein, we first synthesized Bi4Ti3O12 (B1) particles, then B1 was crosslinked with 6-chloro-1,3,5-triazine-diamine (DCT) to afford B2. Finally, B3 was formed using B2 and 4-formylbenzaldehyde (BA-CHO) to investigate the utility of the D-π-A array structure for photocatalytic UVI removal from rare earth tailings wastewater. B1 lacked adsorption sites and displayed a wide band gap. The grafted triazine moiety in B2 introduced active sites and narrowed the band gap. Notably, B3, a Bi4Ti3O12 (donor)-triazine unit (π-electron bridge)-aldehyde benzene (acceptor) molecule, effectively formed the D-π-A array structure, which formed multiple polarization fields and further narrowed the band gap. Therefore, UVI was more likely to capture electrons at the adsorption site of B3 and be reduced to UIV due to energy level matching effects. UVI removal capacity of B3 under simulated sunlight was 684.9 mg g−1, 2.5 times greater than B1 and 1.8 times greater than B2. B3 was still active after multiple reaction cycles, and UVI removal from tailings wastewater reached 90.8%. Overall, B3 provides an alternative design scheme for enhancing photocatalytic performance.