Highly Efficient Hydrogen Production using Bi2O3/TiO2 Nanostructured Photocatalysts Under Led Light Irradiation

Design, synthesis, and optimization of a novel ternary photocatalyst for degradation of cephalexin antibiotic in aqueous solutions

The widespread use of antibiotics in veterinary and medical applications has increased the possibility of water contamination, which causes adverse effects such as increased bacterial resistance in humans and other organisms. This study, investigates the efficient removal of cephalexin (CPX) using Fe doped TiO2-Bi2O3 nanocomposite, synthesized via the simple sol-gel method as a visible active photocatalyst. The weight fraction of Fe (3-7 wt%), and Bi2O3 (7-11 wt%) was optimized. The Fe-TiO2-Bi2O3 nanocomposite with a weight fraction of 3 and 11% for Fe and Bi2O3 has the best photocatalytic activity for Cephalexin degradation. The characteristics of photocatalyst with optimum composite (3 wt% of Fe and 11 wt% Bi2O3) were also investigated by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), diffuse reflectance spectra (DRS) and FTIR. The DRS spectra approved that the adsorption wavelength of Fe-doped TiO2-Bi2O3 is in the visible light range. The influence of amount of catalyst (0.5-1.5 g/L), Cephalexin concentration (5-15 mg/L) and initial pH of the solution (3-9) in on CPX photodegradation was modeled and optimized using central composite design based on response surface methodology. Maximum cephalexin degradation Under visible light irradiation (50 W LED, 395-400 nm) was achieved about 74% at 5 mg/L of CPX, 1.5 g/L catalyst loading and pH of 9 in 240 min. Moreover, using a 15W UV lamp under the same conditions increased the degradation efficiency to 96% at 120 min. Considering the high potential of Fe-TiO2/Bi2O3 nanocomposite in removing Cephalexin antibiotics, it can be considered a suitable candidate for removing antibiotics from contaminated water sources.

In Situ Growth of CuBi2O4/Bi2O3 Z-Scheme Heterostructures for Bifunctional Photocatalytic Applications

In this study, we present an in situ solvothermal approach for synthesizing a highly efficient bifunctional CuBi2O4/Bi2O3 composite catalyst for applications in H2 production and the removal of organic pollutants. Various characterization techniques, including XRD, UV-vis DRS, SEM, TEM, and EIS, were used to characterize the prepared catalyst. Density functional theory calculations confirmed a Z-scheme mechanism, revealing the charge transfer mechanism from the Bi2O3 surface to the CuBi2O4 surface. The composite exhibited a photocurrent of 2.83 × 104 A/cm2 and a hydrogen production rate of 526 μmolg-1h-1 under natural sunlight. Moreover, the catalyst demonstrated efficient degradation of RhB up to 58% in 120 min under 50 W LED illumination. Additionally, multiple recycling tests confirmed its high stability and recyclability, making it a promising candidate for various applications in the field of photocatalysis.

Polyaniline/g-C3N4/Bi2O3/Ti photoanode for visible light responsive photocatalytic fuel cell degradation of rhodamine B and electricity generation

In order to develop efficient photoanode to improve the performance of visible light responsive photocatalytic fuel cell (PFC), in this work, polyaniline/g-C₃N₄/Bi₂O₃/Ti photoanode was successfully prepared using silica-sol drop coating method, and assembled with Cu cathode to construct PFC to decompose rhodamine B and generate electricity simultaneously. The degradation rate, maximum photocurrent density and maximum power density of this PFC were 91.23%, 0.086 mA cm^-2 and 4.78 μW cm^-2, respectively, which were 1.4 and 1.8 times, 2.4 and 4.5 times, and 1.9 and 7.3 times those of the corresponding values of the PFCs with g-C₃N₄/Bi₂O₃/Ti and Bi₂O₃/Ti photoanodes, respectively. This is attributed to the type II heterojunction structure formed among polyaniline, g-C₃N₄ and Bi₂O₃ in the polyaniline/g-C₃N₄/Bi₂O₃/Ti photoanode. Among them, polyaniline has π-π conjugated structure, which can rapidly transfer the electronic charge between g-C₃N₄ and Bi₂O₃, thus enhancing the separation efficiency of photo-generated e^--h⁺ pairs spatially and reducing their recombination, extending the visible light response wavelength of the photocatalyst, and finally improving its photocatalytic properties. This study can provide significant reference for the research of Bi₂O₃-based visible light responsive PFC.

Photocatalytic hydrogen production by ternary heterojunction composites of silver nanoparticles doped FCNT-TiO2

Silver nanoparticles doped with FCNT-TiO₂ heterogeneous catalyst was prepared via one-step chemical reduction process and their efficacy was tested for hydrogen production under solar simulator. Crystallinity, purity, optical properties, and morphologies of the catalysts were examined by X-Ray diffraction, Raman spectroscopy, UV-Visible diffuse reflectance spectra, and Transmission Electron Microscopy. The chemical states and interface interactions were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The optimized catalyst showed 19.2 mmol g^-1 h^-1 of hydrogen production, which is 28.5 and 7 times higher than the pristine TiO₂ nanoparticles and FCNT-TiO₂ nanocomposite, respectively. The optimized catalyst showed stability up to 50 h under the solar simulator irradiation. The natural solar light irradiated catalyst showed ~2.2 times higher hydrogen production rate than the solar simulator irradiation. A plausible reaction mechanism of Ag NPs/FCNT-TiO₂ photocatalyst was elucidated by investigating the beneficial co-catalytic role of Ag NPs and FCNTs for enhanced hydrogen production.

Enhanced Sulfamerazine Removal via Adsorption–Photocatalysis Using Bi2O3–TiO2/PAC Ternary Nanoparticles

The presence of sulfonamides (SAs) in water has received increasing attention due to the risk to ecosystems. The adsorption and photocatalysis performance for sulfamerazine (SMZ) of Bi2O3–TiO2 supported on powdered activated carbon (Bi2O3–TiO2/PAC) nanoparticles was evaluated. The amount of doped Bi2O3 not only influenced the photocatalytic performance but also impacted the adsorption capacity. The adsorption mass transfer mechanism of Bi2O3–TiO2/PAC was elucidated and is further discussed in combination with the photocatalytic mechanism. It was indicated that Bi2O3–TiO2/PAC(10%–700 °C) performed best, and the SMZ removal by the adsorption–photocatalysis of Bi2O3–TiO2/PAC(10%–700 °C) reached 95.5%. Adsorption onto active sites was a major adsorption step, and external diffusion was assisted. Superoxide radical (●O2−) and hole (h+) were identified as the major reactive oxygen species (ROS) for SMZ removal. Benzene ring fracture, SO2 extrusion and nitrogenated SMZ were proposed as the main pathways for photocatalysis. Meanwhile, alkaline conditions enhanced photocatalytic performance, while contrary effects were observed for adsorption. The adsorption–photocatalysis removal performance for SMZ in lake water was better than that for river water. It can be generalized for the potential application of photocatalysis coupling with adsorption to remove refractory antibiotics in water.

Hydrogen production from glycerol reforming: conventional and green production

The use of biomass to produce transportation and related fuels is of increasing interest. In the traditional approach of converting oils and fats to fuels, transesterification processes yield a very large coproduction of glycerol. Initially, this coproduct was largely ignored and then considered as a useful feedstock for conversion to various chemicals. However, because of the intrinsic large production, any chemical feedstock role would consume only a fraction of the glycerol produced, so other options had to be considered. The reforming of glycerol was examined for syngas production, but more recently the use of photocatalytic decomposition to hydrogen (H2) is of major concern and several approaches have been proposed. The subject of this review is this greener photocatalytic route, especially involving the use of solar energy and visible light. Several different catalyst designs are considered, together with a very wide range of secured rates of H2 production spanning several orders of magnitude, depending on the catalytic system and the process conditions employed. H2 production is especially high when used in glycerol-water mixtures.