Bi2O3 nanoparticles incorporated porous TiO2 films as an effective p‐n junction with enhanced photocatalytic activity

Porous TiO₂ films decorated with Bi₂O₃ nanoparticles are fabricated via alkali‐hydrothermal of titanium (Ti) plate by varying the reaction time. The amorphous TiO₂ is transformed into anatase after annealing the films at 500°C in air. The p‐type Bi₂O₃ nanoparticles are successfully assembled on the surface of porous n‐type TiO₂ films through the ultrasonic‐assisted successive ionic layer adsorption and reaction (SILAR) technique to form Bi₂O₃/TiO₂ nanostructure by the two cycles. The obtained Bi₂O₃/TiO₂ films are consisted of a well‐ordered and uniform porous structure with an average pore diameter of about 100‐200 nm containing homogeneously dispersed Bi₂O₃ nanoparticles of ~5 nm diameter. Moreover, the resultant composites present excellent photocatalytic performance toward methyl blue (MB) degradation under UV and visible light irradiation, which could be mainly ascribed to the enhanced light adsorption capacity of unique composite structure and the formation of p‐n heterojunctions in the porous Bi₂O₃/TiO₂ films. This research is helpful to design and construct the highly efficient heterogeneous semiconductor photocatalysts.     

Facile Synthesis of BiOBr/Bi2Sn2O7 Heterojunction Photocatalysts with Improved Photocatalytic Activities

BiOBr/Bi₂Sn₂O₇ heterojunction photocatalysts were successfully synthesized by treating hydrothermal as‐prepared Bi₂Sn₂O₇ nanoparticles with hydrobromic acid (HBr). Partial Bi₂Sn₂O₇ nanoparticles reacted with HBr to form the sheet‐like BiOBr, and Bi₂Sn₂O₇ nanoparticles distributed evenly on BiOBr sheets. BiOBr/Bi₂Sn₂O₇ photocatalysts treated with different concentrations of HBr solution were successfully obtained, and their structures, morphologies, optical, and visible light photocatalytic properties were characterized by XRD, DRS, PL, SEM, and TEM. The experimental results showed that the BiOBr/Bi₂Sn₂O₇ photocatalysts showed improved photocatalytic activity under visible light irradiation than pure Bi₂Sn₂O₇. The sample treated with 0.08 mol/L HBr solution shows the best visible light photodegradation performance of rhodamine B. In addition, the active species and photocatalytic mechanism were discussed in detail.     

On Structure,Optical Properties and Photodegradated Ability of Aurivillius‐Type Bi3TiNbO9 Nanoparticles

Bi₃TiNbO₉ nanoparticles with an acceptor dopant of Ni²⁺ ion were prepared by the conventional Pechini sol–gel synthesis. The X‐ray polycrystalline diffraction measurements (XRD) and the Rietveld refinements of Bi₃TiNbO₉ samples were completed. The surface property of Bi₃TiNbO₉ nanoparticles was investigated by transmission electron microscope, scanning electron microscope), and N₂ adsorption–desorption isotherms. Bi₃TiNbO₉ nanoparticles showed an optical band gap with energy of 3.1 eV in the UV region. While the Ni²⁺‐doping could greatly reduce the band energy of Bi₃TiNbO₉:xNi²⁺ nanoparticles to 2.79 eV (x = 0.05) and 2.61 eV (x = 0.1). This indicates that the Ni‐doped samples could be excited by UV–visible light. The photocatalytic abilities were tested by the photodegradation on methylene blue solution (MB) and phenol solutions excited by visible light. Accordingly, the photocatalytic activity was improved by the Ni‐doping in B‐sites in this Aurivillius‐type structure. The results concluded that Bi₃TiNbO₉:Ni²⁺ would be a possible candidate as a visible light‐driven photocatalyst. The effective photocatalysis was discussed on the structure characteristic and experiment such as polarized Aurivillius (Bi₂O₂)²⁺ layers, luminescence, and decay lifetimes, etc.     

One-step synthesis of ZnO and Ag/ZnO heterostructures and their photocatalytic activity

By following a one-step, novel methodology, ZnO and Ag/ZnO heterostructures were successfully synthesized at room-temperature. This route is simple, effective, high yield (91%), environmentally friendly (green synthesis) and consists of a mechanically assisted metathesis reaction. The metathesis reaction used in this investigation showed two results: the in-situ generation of alkaline nitrates, LiNO₃/NaNO₃, and the direct crystallization of the desired Zn-based compounds in milling media; revealing a true mechanochemical synthesis of ZnO and Ag/ZnO (1.25, 2.50 and 4.50 mol% of Ag) heterostructures. Particles showed spherical-like morphologies and sizes smaller than 20 nm. The Ag/ZnO heterostructures exhibited higher photocatalytic activity than ZnO for degrading methylene blue (MB) dye. It was also shown that the presence of Ag (up to 1.25 mol%) nanoparticles (NPs) in ZnO accelerates the photodegradation reaction and then slows down with further increases in Ag contents. The 1.25-Ag/ZnO sample (10 mg) showed the highest photocatalytic activity (96%) for degrading MB (100 ml, 10 mg L^?1) within 100 min under UV–Vis light irradiation (λ = 310 nm).     

A novel nano-sized MoS2 decorated Bi2O3 heterojunction with enhanced photocatalytic performance for methylene blue and tetracycline degradation

In this paper, MoS₂ was used as a band-suitable semiconductor to construct the Bi₂O₃/MoS₂ heterostructured photocatalysts for the first time via a deposition-hydrothermal method. The XRD, SEM and HRTEM analysis indicated that the surface of Bi₂O₃ was decorated with MoS₂ nanoparticles and Bi₂O₃/MoS₂ heterojunctions were formed. The performances on photocatalytic degradation of methylene blue (MB) and tetracycline (TC) were evaluated under visible light irradiation. The results demonstrated that the Bi₂O₃/MoS₂ heterojunctions displayed remarkably improved photocatalytic activity for both MB and TC degradation, compared to the base material (Bi₂O₃). Specifically, as the molar ratio of MoS₂ was 23.81%, the obtained Bi₂O₃/MoS₂-23.81 heterojunctions exhibited promising photocatalytic activities, and approximately 100% MB and 97% TC were degraded within 100 min, respectively. The superior photocatalytic activity was mainly attributed to its large surface area, high visible-light harvesting and the efficient separation of photogenerated electrons and holes caused by the unique heterojunction architecture. Notably, the Bi₂O₃/MoS₂ heterojunctions showed remarkable stability in recycling photocatatlytic experiments. The active species trapping and terephthalic acid (TA) fluorescence experiments indicated that the •OH was the major reactive oxidizing species for MB degradation. Furthermore, the intermediates were detected by UPLC-MS spectrometry and the possible degradation pathways for MB and TC were proposed. Finally, a possible reaction mechanism of Bi₂O₃/MoS₂ heterojunctions for the photodegradation MB was also proposed. This interesting interfacial architecture strategy will provide useful insights for designing and fabricating new class of binary heterojunctions with high-efficient photocatalytic activity towards practical application.     

Construction of a novel Ca2Bi2O5/α-Bi2O3 semiconductor heterojunction for enhanced visible photocatalytic application

Bi³⁺-containing compounds have been intensively investigated for their potential application as photocatalysts for degrading pollutants and splitting water. In this work, a Ca₂Bi₂O₅/α-Bi₂O₃ heterojunction photocatalyst was successfully prepared via the facile sol–gel method. The excess of the initial Bi raw material can result in the Ca₂Bi₂O₅/α-Bi₂O₃ heterojunction of the final products. The as-synthesized nanoparticles were investigated via X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive spectrometry, UV–Vis optical absorption, and X-ray photoelectron spectroscopy. The band energy of the Ca₂Bi₂O₅ substrate semiconductor was 2.49 eV and characterized with a direct transition nature. The photocatalytic effect on the photodegradation of Rhodamine B solutions was evaluated. Ca₂Bi₂O₅/α-Bi₂O₃ heterojunctions showed improved photocatalytic abilities compared with single Ca₂Bi₂O₅ and α-Bi₂O₃ under viable light irradiation. The mechanism was discussed in terms of the microstructure, luminescence intensities, and decay curves (lifetimes). The photo-produced electrons and holes can be adequately separated in Ca₂Bi₂O₅/α-Bi₂O₃ heterojunctions ensuring its photocatalytic activities. The present results can serve as reference for investigating the optical properties of Bi semiconductors.     

Controlled synthesis of Bi2O3/BiOBr/Zn2GeO4 heterojunction photocatalysts with enhanced photocatalytic activity

BiOBr/Zn₂GeO₄ heterojunctions decorated by Bi₂O₃ quantum dots (QDs; named as Bi₂O₃/BiOBr/Zn₂GeO₄ hereafter) with intriguing micro/nanostructures have been constructed via a two‐step hydrothermal route. The compositions, phases, and morphologies of Bi₂O₃/BiOBr/Zn₂GeO₄ were investigated in detail. The light absorption ability, photocurrent responses, and photocatalytic degradation of methylene blue (MB) experiments were performed to evaluate the photocatalytic activity of the micro/nanoheterostructured Bi₂O₃/BiOBr/Zn₂GeO₄, which present a degradation efficiency of 88% after 240 minutes under light irradiation (λ = 300‐600 nm) over 100 mg Bi₂O₃/BiOBr/Zn₂GeO₄ in a 100 mL, 4 mg/L MB solution. The photocatalytic performance could be retained for at least four runs, indicating its excellent reusability for the degradation of MB in aqueous solution. It is found that the photodegradation of MB over Bi₂O₃/BiOBr/Zn₂GeO₄ is mainly ascribed to a hole oxidation mechanism in combination with a superoxide oxidation process. The high photocatalytic performance of Bi₂O₃/BiOBr/Zn₂GeO₄ upon UV light irradiation can be attributed to the effective charge separation and smoothly transferring of the photogenerated charge carriers throughout the heterojunction. The feasible strategy of preparing Bi₂O₃/BiOBr/Zn₂GeO₄ ternary composites is also of benefit to fabricate other efficient heterojunction catalysts with specific morphologies and properties.     

Visible Light Photocatalytic Activity of Bismuth Ferrites Tuned by Bi/Fe Ratio

Pure perovskite BiFeO₃, sillenite Bi₂Fe₄O₉, and BiFeO₃/Bi₂Fe₄O₉ were synthesized facilely by controlling the precursor Bi/Fe ion ratio through a hydrothermal method. The phase composition, morphology, optical properties, and photocatalytic activity of as‐prepared samples were investigated in detail. Our results indicate that the morphology and properties of products strongly dependent on the precursor Bi/Fe ion ratio. Photocatalysis of Congo Red reveals that sillenite Bi₂Fe₄O₉ shows superior activity to perovskite BiFeO₃, and BiFeO₃/Bi₂Fe₄O₉ exhibited higher activity with 71.45% degradation rate in 90 min. It provides an easy and efficient way to tune the composition and photocatalytic activity of Bi‐based oxides.     

Generation of hydrogen under visible light irradiation with enhanced photocatalytic activity of Bi2WO6/Cu1.8Se for organic pollutants under Vis‐NIR light reign

To make better use of solar light, a new Bi₂WO₆/Cu_1.8Se photocatalyst active to visible and near‐infrared light has been synthesized by a facile hydrothermal method. The composites were characterized by X‐ray diffractometry (XRD), scanning electron microscopy (SEM), UV‐vis diffuse reflectance spectroscopy (DRS), and photoluminescene (PL). The photocatalytic activities of Bi₂WO₆/Cu_1.8Se are evaluated by degrading Congo red solution and hydrogen generation from water. It was found that the molar percentage of Cu_1.8Se had great effects on the morphology and photocatalytic property of the Bi₂WO₆/Cu_1.8Se heterojunctions, and the composite with suitable molar amount of Cu_1.8Se exhibits much enhanced photocatalytic activity for Congo red degradation under visible and near‐infrared light irradiation and for hydrogen generation under visible light compared to Bi₂WO₆. The significant improvement photocatalytic activity of the composite could be attributed to its good light absorption, suitable band gap structure, and effective separation of photogenerated electron‐hole pairs of Bi₂WO₆/Cu_1.8Se heterojunction. This work presents an efficient multifunction photocatalyst owning the activity both for water splitting under visible light and for organic contaminants decomposition under visible‐near‐infrared light.     

BiOCl nanosheet/Bi4Ti3O12 nanofiber heterostructures with enhanced photocatalytic activity

Aurivillius oxide semiconductors are important photocatalyst because of their unique electronic structure and layered crystal. In this paper, two kinds of Aurivillius oxide semiconductors heterostructures based on Bi₄Ti₃O₁₂ nanofibers frameworks and BiOCl nanosheets are successfully synthesized by combining the electrospinning technique and solvothermal method. The high-resolution transmission electron microscopy results reveal that an intimate interface between Bi₄Ti₃O₁₂ nanofibers and BiOCl nanosheets forms in the heterojunctions. Photocatalytic tests show that the BiOCl/Bi₄Ti₃O₁₂ heterostructures exhibit enhanced photocatalytic activity than bare Bi₄Ti₃O₁₂ and BiOCl, mainly owing to the photoinduced interfacial charge transfer based on the photosynergistic effect of the BiOCl/Bi₄Ti₃O₁₂ heterojunction. At the end, the photocatalytic mechanism with O₂⁻ production was studied.     

Synthesis and characterization of CeO2/Bi2O3/gC3N4 ternary Z-scheme nanocomposite

An effective and facile phytogenic method was used to prepare CeO₂/Bi₂O₃ and CeO₂/Bi₂O₃/gC₃N₄ composites using Eichhornia crassipes phytoextract. The synthesized catalysts were characterized using techniques such as XRD, FTIR, UV-DRS, PL, SEM-EDAX, XPS, zeta potential, and TGA. These catalysts showed diverse photocatalytic and optical properties due to the alteration in the bandgap. The synthesized composites exhibited good photocatalytic activity by degrading Malachite green (MG) dye. The increase in the photocatalytic activity could be attributed to the p-n heterojunction of the catalysts with efficient charge separation and strong oxidative ability. The modified photocatalysts showed excellent catalytic activity and reusability under visible light. The superior efficiency and its applications in environmental remediation make these catalysts a potential candidate for photocatalysis.     

Preparation and electrochemical performance of nanosized Bi compounds-modified ZnO for Zn/Ni secondary cell

Surface-modified ZnO with nanosized Bi compounds was prepared on the basis of the hydrolysis of Bi(NO₃)₃. Transmission electron microscopy images revealed that some nanoparticles with about 40 nm in diameter were modified on ZnO. X-ray diffraction indicated that Bi compounds consisted of Bi₂O₃ and BiO. Electrochemical performances of the surface-modified ZnO were analyzed by charge/discharge cycle test and slow rate cyclic voltammetry (CV). Compared with Bi₂O₃–physically mixed ZnO, nanosized Bi compounds-modified ZnO showed the improved cycle performance, higher discharge capacity and utilization ratio of ZnO. The discharge capacity of the modified ZnO with 9.3 wt.% Bi was the most stable among all tested electrode material and maintained 450 mAh g⁻¹. In comparison with the average utilization ratio (53%) of the physically mixed ZnO, the average utilization ratio of the modified ZnO could reach 80%. The improvement of electrochemical performance resulted from the fact that surface modification with Bi compounds slowed dissolution of ZnO in the electrolyte and maintained the electrochemical activity of ZnO. Cyclic voltammograms clearly illuminated that the modifying agent could decrease polarization, maintain the electrochemical activity, and enhance the discharge capacity of ZnO.     

Development of a lead‐free copper co‐fired BNT‐based piezoceramic sintered at low temperature

Compatibility of Bi‐based piezoelectric ceramic and copper electrodes is demonstrated by co‐firing 0.88Bi_1/2Na_1/2TiO₃–0.08Bi_1/2K_1/2TiO₃–0.04BaTiO₃ (BNKBT88) with copper. A combination of Bi₂O₃, CuO, ZnO, Li₂CO₃, and B₂O₃ are used as additives to reduce firing temperature to 900°C with minimal effect on the electromechanical properties compared to sintering at 1150°C without additives. Co‐firing with copper electrodes requires controlled oxygen sintering at low temperature. The atmosphere is controlled using carbon dioxide and hydrogen gas to maintain an oxygen partial pressure of 6.1 × 10^?8 atm, which is necessary for the coexistence of Cu metal and Bi₂O₃. The thermodynamic activity of bismuth oxide in BNKBT88 is calculated to be 0.38. BNKBT88 ceramics were successfully co‐fired with internal as well as surface Cu metal electrodes. The copper co‐fired ceramics were successfully polarized and the dielectric and piezoelectric properties are evaluated.     

Synthesis,optical, and magnetic properties of six-layered Aurivillius bismuth ferrititanate

This work reports on the preparation, structure, photochemical, and magnetic properties of six-layered Aurivillius bismuth ferrititanates, that is, Bi₇Ti₃Fe₃O₂₁, Bi₇(Ti₂Nb)Fe₃O_21+δ, and Bi₇(Ti₂Mg)Fe₃O_21−δ nanoparticles. The samples were prepared through the modified citrate complexation and precursor film process. The XRD Rietveld refinements were conducted to study the phase formations and crystal structure. The morphological and chemical component characteristics were investigated using SEM, TEM, and EDX analyses. Bi₇Ti₃Fe₃O₂₁, Bi₇(Ti₂Nb)Fe₃O_21+δ, and Bi₇(Ti₂Mg)Fe₃O_21−δ nanoparticles present an indirect allowed transitions with band energies of 2.04, 2.03, and 2.02 eV, respectively. The hybridized (O2p+Fet_2g+Bi6s) formed the valence band (VB) and electronic components of (Ti–3d+Fe–e_g) formed the conduction band (CB) of this six-layered Aurivillius bismuth ferrititanate. The three samples showed efficient photocatalytic degradation of Rhodamine B (RhB) dyes with the excitation wavelength λ > 420 nm. The optical absorption, photodegradation, and magnetic abilities were improved through microstructural modification on “B” site via partial substitution of Mg²⁺ and Nb⁵⁺ for Ti⁴⁺. The photocatalytic results were discussed based on the layer structure and multivalent Fe ions. Fe^3+/2+ in the perovskite slabs (Bi₅Fe₃Ti₃O₁₉)²⁻ could act as the catalytic mediators in the photocatalysis process. As a photocatalyst, Aurivillius Bi₇(Ti₂Mg)Fe₃O_21−δ nanoparticle is advantageous due to its photocatalytic and magnetically recoverable abilities.     

Improved photocatalytic activity of Bi4TaO8Cl by Gd3+ doping

Bi₄TaO₈Cl and Bi₄TaO₈Cl:Gd³⁺ photocatalysts were synthesized by the solvothermal technique. The phase, microstructure, optical properties, and photocatalytic activities were investigated. Both Bi₄TaO₈Cl and Bi₄TaO₈Cl:Gd³⁺ have the singly orthorhombic phase and the flower-like hierarchical structure. The Bi₄TaO₈Cl:Gd³⁺ has higher photocatalytic activity of MB than that of Bi₄TaO₈Cl under visible light irradiation. The higher photocatalytic activity of Bi₄TaO₈Cl:Gd³⁺ is induced by its lower band gap energy, the higher efficiency charge separation, and transfer process, as well as the photogenerated charge carriers with a longer time, which are confirmed by the longer absorption band edge, lower emission intensity, and higher photocurrent under visible light irradiation. The trapping experiments and electron spin resonance results suggest that ˙O₂⁻ is the predominant active species for the photocatalysis of MB by Bi₄TaO₈Cl and Bi₄TaO₈Cl:Gd³⁺ under visible light irradiation.     

Ferroelectric and photocatalytic properties of Aurivillius phase Ca2Bi4Ti5O18

Aurivillius phase Ca₂Bi₄Ti₅O₁₈ powders with micrometer size were produced by solid-state reaction. X-ray diffraction revealed that the powders had polar orthorhombic structure with space group of B2cb. Ca₂Bi₄Ti₅O₁₈ ceramic exhibited frequency independent dielectric anomaly at 774°C. The piezoelectric coefficient d₃₃ value of poled Ca₂Bi₄Ti₅O₁₈ pellets was 0.7 ± 0.2 pC/N. Both frequency independent dielectric anomaly and detectable d₃₃ value clearly indicated that Ca₂Bi₄Ti₅O₁₈ is a ferroelectric material with Curie point of 774 ℃. UV–vis absorption spectra revealed that Ca₂Bi₄Ti₅O₁₈ had a direct band gap of 3.2 eV. Photocatalytic activity of the Ca₂Bi₄Ti₅O₁₈ powders was examined by degradation of rhodamine B (RhB) under simulated solar light. 16% of RhB solution was degraded by Ca₂Bi₄Ti₅O₁₈ powders after 4 hours UV-vis irradiation. With Ag nanoparticles deposited on the Ca₂Bi₄Ti₅O₁₈ powders surface, 50% of RhB was degraded under the same irradiation condition. The fitted degradation rate constant of Ag decorated Ca₂Bi₄Ti₅O₁₈ was 4 times higher than that of bare Ca₂Bi₄Ti₅O₁₈. This work suggested that the Aurivillius ferroelectric Ca₂Bi₄Ti₅O₁₈ is a promising candidate for photocatalytic applications.     

In-situ room-temperature synthesis of amorphous/crystalline contact Bi2S3/Bi2WO6 heterostructures for improved photocatalytic ability

We developed a facile in-situ growth method to construct amorphous-based Bi₂S₃/Bi₂WO₆ heterostructures at room temperature. As demonstrated by HRTEM, XPS and EDX-mapping, amorphous state Bi₂S₃ dispersed uniformly on the surface of crystalline Bi₂WO₆ hollow spheres. The photocatalytic activities of prepared Bi₂S₃/Bi₂WO₆ heterostructures were evaluated by the photodegradation of RhB and TC under visible light irradiation, indicating that the introduction of appropriate amorphous Bi₂S₃ significantly improved the photocatalytic activity of Bi₂WO₆. The amorphous/crystalline contact in Bi₂S₃/Bi₂WO₆ heterostructures played a crucial role in the enhancement of photocatalytic efficiency. Based on DRS, photoluminescence spectra, photocurrent intensity, electrochemical impedance spectroscopy and OCVD measurements, it was proposed that the enhanced performance could be ascribed to increased visible light utilization, promoted separation efficiency and prolonged life time of photogenerated electron-hole pairs by the introduction of amorphous Bi₂S₃. This work may provide new insights into the construction of amorphous-based composited heterostructures for improving photocatalytic activity.     

Microwave-assisted synthesis of α-Fe2O3/ZnFe2O4/ZnO ternary hybrid nanostructures for photocatalytic applications

Solar-driven highly efficient photocatalytic decomposition of toxic organic contaminants using magnetically separable α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid nanodiscs is reported. α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid nanostructures were synthesized by microwave-assisted co-precipitation and simple co-precipitation methods and well characterized by XRD, micro-Raman, FESEM and UV–vis spectroscopy. FESEM micrographs revealed nanodiscs in case of microwave-assisted co-precipitation whereas nanoparticles and their aggregates were formed under co-precipitation combined with calcination. XRD and Raman studies confirmed the hybrid nature of prepared α-Fe₂O₃/ZnFe₂O₄/ZnO nanostructures. Photocatalytic performance of α-Fe₂O₃/ZnFe₂O₄/ZnO hybrid nanostructures was investigated by carrying out the photodegradation of organic dyes MB and MG under solar light illumination. The prepared α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid magnetic nanodiscs decomposed MB and MG dyes in only 32 and 24 min, respectively. α-Fe₂O₃/ZnFe₂O₄/ZnO hybrid nanodiscs showed excellent photocatalytic performance together with reusability and easy magnetic separation demonstrating its suitability for solar-driven photocatalytic water purification applications. In-situ scavenger studies showed ?OH radicals are the main active radicals in solar-driven photocatalysis by α-Fe₂O₃/ZnFe₂O₄/ZnO nanodiscs. The tentative mechanism of growth of α-Fe₂O₃/ZnFe₂O₄/ZnO ternary hybrid nanodiscs and the photocatalytic mechanism are discussed.     

Partial chemical conversion strategy for the synthesis of novel Ag-Bi7O9I3-Bi25VO40 heterostructure with improved photocatalytic activity

The rational design of two-dimensional (2D) heterogeneous photocatalysts is considered to be one of the effective methods to achieve high-efficiency migration and separation of photo-excited electrons and holes. Nevertheless, if these separated photo-excited electrons fail to be removed as soon as possible, they tend to recombine with photo-generated holes due to their own instability, losing its excellent photocatalytic activity. Therefore, by means of the combination of 2D semiconductor heterostructures and noble metal modifying technology, we reported the preparation of novel 2D Ag-Bi₇O₉I₃-Bi₂₅VO₄₀ composite photocatalyst through a facile partial chemical conversion strategy coupling with photo-reduction method, employing the pre-prepared Bi₂₅VO₄₀ microcubes as starting materials. The resulted Ag-Bi₇O₉I₃-Bi₂₅VO₄₀ ternary heterostructure exhibited outstanding photo-degradation ability by comparison of pure Bi₇O₉I₃, Bi₂₅VO₄₀ as well as Bi₇O₉I₃-Bi₂₅VO₄₀. In addition, some active species produced during the photocatalytic reaction process were identified by the introduction of corresponding trapping agents. The improved photodegradation efficiency might be attributable to the effective separation of photo-induced electrons and holes derived from the energy level difference between two heterogeneous components, unique 2D layered structure, strong internal electric field and the famous "electronic sink effect" of Ag nanoparticles.     

The Influence of the Precursor on the Formation of Bi2O3 Polymorphs in CSD‐Derived Thin Films

This work examines the synthesis and characterization of crack‐free, β‐Bi₂O₃ thin films prepared on Pt/TiO₂/SiO₂/Si or corundum substrates using the sol‐gel method. We observed that the Bi‐based precursor has a pronounced influence on the β‐Bi₂O₃ phase formation. Well‐crystallized, single β‐Bi₂O₃ thin films were obtained from Bi‐2ethylhexanoate at a temperature of 400°C. In contrast, thin films deposited from Bi‐nitrate and Bi‐acetate resulted in non‐single Bi₂O₃ phase formation. TEOS was used for the stabilization of the β‐Bi₂O₃ phase. The phase composition of the thin films was characterized by means of X‐ray diffraction (XRD), whereas the morphology and thickness of the thin films were studied using scanning electron microscopy (SEM). The β‐Bi₂O₃ films' dielectric properties were characterized utilizing microwave‐frequency measurement techniques: (1) the split‐post dielectric resonator method (15 GHz) and (2) the planar capacitor configuration (1–5 GHz). The dielectric constant and dielectric loss measured at 15 GHz were 257 and 7.5 × 10^?3, respectively.