Photocatalytic Activity Of Bi Research Articles

Visible-LEDs-induced photocatalytic activity of Bi2WO6/BiVO4 heterojunctions prepared by a novel and green methodology

Coupling Bi2WO6/BiVO4 semiconductors to construct heterostructures improves charge transfer and restricts the recombination of photogenerated electron–hole pairs, boosting photocatalytic activity.

Hierarchical Bi2WO6/BiFeWO6 n-n heterojunction as an efficient photocatalyst for water splitting under visible light

A hierarchical Bi 2 WO 6 /BiFeWO 6 architectures were synthesized by a facile and low-cost hydrothermal approach using Bi 2 WO 6 flower structure as an efficient backbone for the growth of layered BiFeWO 6 sheets. The conduction band offset and bandgap of flower like Bi 2 WO 6 were tailored strategically as active photocatalyst under visible light and suitable for water reduction. By developing n-n heterojunction between Bi 2 WO 6 and BiFeWO 6 , the active surface area as well as number of free charge carriers have been enhanced which may boost the catalytic redox reactions. The physicochemical properties of the heterojunction was characterized to investigate the phase, morphology, thermal stability, light absorption and oxidation states of the elements. The photocatalytic activity of Bi 2 WO 6 /BiFeWO 6 heterojunction was investigated through H 2 generation via water splitting under visible light, where four-fold enhanced activity achieved for heterojunction compared to bare Bi 2 WO 6 . Further, photoelectrochemical properties were studied to determine the band edge potentials and illustrate the enhanced photoresponse for heterojunction. The Bi 2 WO 6 /BiFeWO 6 heterojunction showed lower charge transfer resistance compared to Bi 2 WO 6 , owing to efficient charge separation at electrode-electrolyte interface. The synergistic effect of high surface area, lower recombination rate and the suitable band edge potentials led to high catalytic activity, good cycling stability and superior photoelectrochemical response of heterojunction. This work provide insight into the synergistic effect of hierarchical n-n heterojunction and opens up an avenue for rational design of photocatalyst for water splitting and H 2 generation. • The n-n Bi 2 WO 6 /BiFeWO 6 heterojunction has been developed • The photocatalytic H 2 generation of n-n Bi 2 WO 6 /BiFeWO 6 heterojunction is greatly enhanced. • The charge transfer mechanism are confirmed from Mott-Schottky analysis. • The synergistic effect of high surface area, lower recombination and suitable band edges led to high catalytic activity.

Photocatalytic Activity of Bi2O3 Enhanced by the Addition of Ce3+/Ce4+ Synthesized by Ethylene Glycol‐assisted Solvothermal Method

AbstractThe photocatalysts Bi2O3:Ce3+/Ce4+ (cerium content 0.2, 0.5, 0.8, and 1.1 wt. %) were prepared via one‐pot ethylene glycol‐assisted solvothermal method. The prepared x Ce‐Bi2O3 (x=0.5, 0.8, 1.1) samples present δ‐Bi2O3 phase with space group of Fm‐3 m at room temperature, which indicates that the high‐temperature cubic phase could be stabilized via Ce doping in Bi2O3 lattices. Moreover, the addition of Ce3+/Ce4+ could change the amount of oxygen vacancies (OVs) and adsorbed oxygen on the surface of photocatalysts. The existence of oxygen vacancies and adsorbed oxygen facilitated the generation of superoxide radicals () and hydroxide radicals (), which were the dominant reactive oxygen species for phenol degradation. The photocatalyst containing 0.8 wt. % cerium presented the highest photoactivity than the other synthesized samples. A photodegradation mechanism is proposed based on scavenger and electron spin resonance studies.

Influence of BiOI content on the photocatalytic activity of Bi 2 WO 6 /BiOI/allophane composites and molecular modeling studies of acetaldehyde adsorption

Abstract As a major indoor volatile organic compound, acetaldehyde is considered to be toxic when applied externally for prolonged periods; it is an irritant and a probable carcinogen. In this work, Bi2WO6/BiOI/allophane (BW/BI/A) composites with different molar ratios of Bi2WO6:BiOI were prepared by either mechanical mixing or a hydrothermal synthesis. The adsorption capacity and photocatalytic activity of the prepared composites were evaluated for the adsorption and photodegradation of gaseous acetaldehyde in the dark and under visible light irradiation, respectively. SEM revealed that with increasing BiOI content, the overall morphology of the BW/BI/A composite was altered because BiOI nanoparticles gradually occupied the surfaces of the nanosheets, which formed flower-like structures, and eventually covered the surfaces of the Bi2WO6 particles. Adsorption affinities and preferential adsorption sites of acetaldehyde molecules on the Bi2WO6, BiOI, and allophane components of the BW/BI/A composite were also predicted using molecular dynamics simulations. The BW/0.5BI/A composite exhibited high adsorption capacity, excellent photocatalytic performance and good stability owing to its large specific surface area, greater number of easily accessible active sites, facilitated diffusion of reactants, multiple scattering of incident light, and formed p–n heterojunction, which suggest that it can be used in environmental remediation in the future.

Photocatalytic Degradation of Methyl Orange on Bi2O3 and Ag2O-Bi2O3 Nano Photocatalysts

The photocatalytic activity of Bi2O3 and Ag2O-Bi2O3 was evaluated by degradation of aqueous methyl orange as a model dye effluent. Bi2O3 was synthesized using chemical precipitation method. Structural analysis revealed that Bi2O3 contain a unique well-crystallized phase and the average crystallite size of 22.4 nm. The SEM analysis showed that the size of Bi2O3 particles was mainly in the range of 16-22 nm. The most important variables affecting the photocatalytic degradation of dyes, namely reaction time, initial pH and catalyst dosage were studied, and their optimal amounts were found at 60 min, 5.58 and 0.025 g, respectively. A good correlation was found between experimental and predicted responses, confirming the reliability of the model. Incorporation of Ag2O in the structure of composite caused decreasing band gap and its response to visible light. Because a high percentage of sunlight is visible light, hence Ag2O-Bi2O3 nano-composite could be used as an efficient visible light driven photocatalyst for degradation of dye effluents by sunlight.

Bi(1-x)Ni(x)VO(4-y) Solid Solution with a High Visible-Light Photocatalytic Activity for Degradation Methyl Orange.

Particulate solid solutions Bi(1-x)Ni(x)VO(4-y) were synthesized by solid-state reaction at high temperature. The samples were characterized by X-ray Diffraction (XRD), Field-Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectrometer (EDS), Brunauer-Emmett-Teller (BET) surface area and Ultraviolet-Visible spectroscopy (UV-Vis). The photocatalytic activity of BiVO4 for photocatalytic degradation of organic contaminants ability in visible light region could be improved by doping of Ni(2+). The high visible light photocatalytic activity of Bi(1-x)Ni(x)VO(4-y) solid solution might be due to the generation of a new band gap and expanding the range of visible light response. It was suggested that the Ni(2+) doping was beneficial to effective charge separation of Bi(1-x)Ni(x)VO(4-y) solid solution, thus improved the photocatalytic activity.

SYNTHESIS OF Bi2WO6 MICROSPHERES WITH VISIBLE-LIGHT-DRIVEN PHOTOCATALYTIC PROPERTIES

Bi 2 WO 6 microspheres constructed from nanosheets have been synthesized by a controllable solvothermal route in a large scale. The structure characterizations of the microspheres were investigated in detail by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM). On the basis of XRD analysis and SEM observation of the products at different reaction time periods, a growth mechanism of Bi 2 WO 6 microspheres was proposed. UV-Visible diffuse reflectance (DR) spectrum of the prepared Bi 2 WO 6 microspheres demonstrates that they have absorption in the visible light region. The photocatalytic activity of Bi 2 WO 6 microspheres toward Rhodamine-B ( RhB ) degradation was investigated and the as-prepared products exhibited good photocatalytic activity in degradation of RhB under 300 W Xe lamp light irradiation.

Preparation of a novel Bi 3.64Mo 0.36O 6.55 nanophotocatalyst by molten salt method and evaluation for photocatalytic decomposition of rhodamine B

Bismuth molybdate (Bi 3.64Mo 0.36O 6.55) powders as a novel photocatalyst was prepared using Bi(NO 3) 3·5H 2O and Na 2MoO 4·2H 2O as raw materials by a simple low temperature molten salt method at 160 °C for 2 h. The as-prepared samples were characterized with X-ray diffraction (XRD), transmission electron microscopy (TEM) and UV–visible (UV–vis) absorption spectra. The photocatalytic activity of Bi 3.64Mo 0.36O 6.55(BMO) nanocrystals was evaluated using the photocatalytic oxidation of rhodamine B (RhB) at room temperature under ultraviolet irradiation. The factors affecting the photocatalytic activity, such as photocatalysts concentration, RhB concentration and compressed air as the assisted oxidant species additives, had been studied.

Carbon-modified Bi2WO6 nanostructures with improved photocatalytic activity under visible light

Carbon-modified Bi(2)WO(6) (C-Bi(2)WO(6)) nanostructures were synthesized via a hydrothermal process in the presence of glucose followed by the calcination in Ar gas at 500 degrees C. The morphologies and crystallinity of Bi(2)WO(6) and the nature of carbon in the composites obtained with different glucose amounts were characterized. Raman spectrum analysis, electron microscopy results and light absorption of C-Bi(2)WO(6) at wavelengths larger than 450 nm clearly confirmed the carbon modification. Further results indicated that glucose did not affect the final crystalline structure or the band gap of Bi(2)WO(6), but it had great influences on the photocatalytic activity of Bi(2)WO(6) towards rhodamine-B (RhB) degradation. When the glucose amount was less than 0.04 g, the photoactivity was enhanced step by step with an increase in the glucose amount. The improved photocatalytic performance could be ascribed to the enhanced photogenerated electron-hole separation and more RhB adsorption associated with carbon. However, when the glucose amount was higher than 0.04 g, the photocatalytic property dramatically decreased due to the severe absorption of almost incident light by carbon, which hindered the accessibility of light to Bi(2)WO(6). Our work provides an alternative way to improve the photoactivity of Bi(2)WO(6) nanomaterials.

Bi2WO6 Nano‐ and Microstructures: Shape Control and Associated Visible‐Light‐Driven Photocatalytic Activities

The shape-controlled synthesis of nano- and microstructured materials has opened up new possibilities to improve their physical and chemical properties. In this work, new types of Bi(2)WO(6) with complex morphologies, namely, flowerlike, tyre- and helixlike, and platelike shapes, have been controllably synthesized by a facile hydrothermal process. The benefits of the present work also stem from the first report on the transformation of Bi(2)WO(6) from three-dimensional (3D) flowerlike superstructures to 2D platelike structures, and on the formation of tyre- and helixlike Bi(2)WO(6) superstructures. UV/Vis absorption spectra show that the optical properties of Bi(2)WO(6) samples are relevant to their size and shape. More importantly, the photocatalytic activities of Bi(2)WO(6) nano- and microstructures are strongly dependent on their shape, size, and structure for the degradation of Rhodamine B (RhB) under visible-light irradiation. The reasons for the differences in the photocatalytic activities of these Bi(2)WO(6) nano- and microstructures are further investigated.