Search Results (9)

Ethanolamine (EA) is a widely used yet toxic volatile organic compound (VOC). However, existing gas sensors for EA detection face persistent challenges in achieving exceptional sensitivity and low detection limits at room temperature (RT). In this study, a novel and high-performance EA sensor based on the MoO₃/BiOI composite was prefabricated using hydrothermal and cyclic impregnation methods. The response value toward 100 ppm EA reached 861.3, which was 3.5-times higher compared to that of pure MoO₃. In addition, the MoO₃/BiOI composite exhibited a low detection limit (0.13 ppm), excellent selectivity, short response/recovery times, exceptional repeatability and long-term stability. The outstanding gas sensing performance of the MoO₃/BiOI is attributed to the formation of a p-n heterojunction, synergistic effects between the two materials, abundant adsorbed oxygen species and superior charge transfer efficiency. The sensor developed in this work effectively addresses the long-standing challenges, demonstrating unprecedented practical application potential for EA gas detection. Simultaneously, this study provides a novel strategy, a new approach and a promising material for the subsequent development of advanced amine sensors. Full article

Water pollution is a global problem that severely impacts human and environmental health, water recycling, and the economy. In Mexico, due to water scarcity, potable water contains significant amounts of heavy metals (i.e., arsenic (As)); thus, there is a need for efficient and sustainable water treatment strategies. Bismuth oxyhalides, BiOX (X = Cl, Br, I), exhibit three-dimensional (3D) porous structures suitable for efficient adsorption activity. In addition, bismuth is an abundant and biocompatible element appropriate for fabricating sustainable environmental remediation technologies, such as adsorptive BiOX nanomaterials (NMs). In this study, we examine the adsorption capacity of BiOX (X = Cl, I), BiOX-GO (GO: graphene oxide) and GO NMs to remove methylene blue (MB), methyl orange (MO) and arsenite (AsO₃³⁻) from aqueous solution. BiOCl-GO 10%, BiOI, BiOI-GO 1%, BiOI-GO 10% and GO have an enhanced adsorption capacity, removing MB (20 ppm) within one hour using a low dose of NMs (1 mg/mL). In addition, BiOX-GO NMs can be easily separated from the solution and regenerated upon visible light activation due to the photocatalytic activity of the materials. The efficiency of the NMs under study for MO removal decreases, with the GO material having the highest efficiency (96%), followed by BiOX-GO 10% (78%). BiOCl-GO 1% removes arsenic from aqueous solution at low doses and short treatment times; 5 mg As/g adsorbent takes five hours; however, at longer adsorption times (24 h), BiOI-GO 1% excels in its arsenic removal capacity. Perlite-supported BiOCl NMs exhibit a weak capacity for water treatment due to the poor mechanical strength of perlite and the amount of surface-exposed BiOCl material. For the photocatalytic removal of arsenic (oxidation–adsorption), BiOI-GO 1% excels in arsenic removal with efficiencies > 70%. Full article

Orthorhombic molybdenum trioxide (α-MoO₃) is well known as a photocatalyst, adsorbent, and inhibitor during methyl orange photocatalytic degradation via TiO₂. Therefore, besides the latter, other active photocatalysts, such as AgBr, ZnO, BiOI, and Cu₂O, were assessed via the degradation of methyl orange and phenol in the presence of α-MoO₃ using UV-A- and visible-light irradiation. Even though α-MoO₃ could be used as a visible-light-driven photocatalyst, our results demonstrated that its presence in the reaction medium strongly inhibits the photocatalytic activity of TiO₂, BiOI, Cu₂O, and ZnO, while only the activity AgBr is not affected. Therefore, α-MoO₃ might be an effective and stable inhibitor for photocatalytic processes to evaluate the newly explored photocatalysts. Quenching the photocatalytic reactions can offer information about the reaction mechanism. Moreover, the absence of photocatalytic inhibition suggests that besides photocatalytic processes, parallel reactions take place. Full article

With the growing population, access to clean water is one of the 21st-century world’s challenges. For this reason, different strategies to reduce pollutants in water using renewable energy sources should be exploited. Photocatalysts with extended visible light harvesting are an interesting route to degrade harmful molecules utilized in plastics, as is the case of Bisphenol A (BPA). This work uses a microwave-assisted route for the synthesis of two photocatalysts (BiOI and Bi₂MoO₆). Then, BiOI/Bi₂MoO₆ heterostructures of varied ratios were produced using the same synthetic routes. The BiOI/Bi₂MoO₆ with a flower-like shape exhibited high photocatalytic activity for BPA degradation compared to the individual BiOI and Bi₂MoO₆. The high photocatalytic activity was attributed to the matching electronic band structures and the interfacial contact between BiOI and Bi₂MoO₆, which could enhance the separation of photo-generated charges. Electrochemical, optical, structural, and chemical characterization demonstrated that it forms a BiOI/Bi₂MoO₆ p-n heterojunction. The free radical scavenging studies showed that superoxide radicals (O₂•⁻) and holes (h⁺) were the main reactive species, while hydroxyl radical (•OH) generation was negligible during the photocatalytic degradation of BPA. The results can potentiate the application of the microwave synthesis of photocatalytic materials. Full article

Adsorption is a low-energy, economical, and efficient method for pollutant removal from water. Because of their unique structure, large specific surface area (SSA), and non-toxicity, bismuth-based semiconductors, usually researched for the photodegradation of organic molecules, are also excellent for dark adsorption processes. Here, a three-dimensional adsorbent with a heterostructure with a hydrangea-like shape made of Bi₂MoO₆ (BMO) and BiOI (BOI) was synthesized by a one-pot solvothermal process and investigated for the adsorption of toxic dyes. BOI/BMO with an I-to-Mo ratio of 2.0 adsorbed 98.9% of the model pollutant rhodamine B (RhB) within 5 min with a maximum adsorption capacity of 72.72 mg/g in the dark at room temperature. When compared to pure BMO, the BOI₂/BMO heterostructure was 14.1 times more performant because of its flower-like morphology with multiple planes, an SSA that was 1.6-fold larger, increased porosity, the formation of heterojunctions, and a negative surface charge attracting RhB. Further investigation indicated that adsorption by BOI₂/BMO fitted the pseudo-second-order kinetic and the Langmuir isotherm models. In addition, the thermodynamic analysis showed that it was a spontaneous exothermic process probably relying on physisorption. Thus, the BOI/BMO adsorbent developed here is promising for the fast removal of toxic dyes from industrial wastewater. Full article

A novel 1D/2D Bi₂O₂CO₃–BiOI heterojunction photocatalyst with high-quality interfaces was synthesized through a hydrothermal method by using Bi₂O₂CO₃ nanorods and KI as raw materials. Two-dimensional (2D) BiOI nanosheets uniformly and vertically grow on the 1D porous Bi₂O₂CO₃ rods. Bi₂O₂CO₃–BiOI heterojunctions exhibit better photocatalytic activity than pure Bi₂O₂CO₃ nanorods and BiOI nanosheets. Cr(VI) (30 mg/L), MO (20 mg/L) and BPA (20 mg/L) can be completely degraded in 8–15 min. The superior photocatalytic performance of 1D/2D Bi₂O₂CO₃–BiOI heterojunction is ascribed to the synergistic effects: (a) vertical 2D on 1D multidimensional structure; (b) the formation of the Bi₂O₂CO₃–BiOI p–n heterojunction; (c) high-quality interfaces between Bi₂O₂CO₃ and BiOI. Full article

A new type of I-deficient bismuth oxyiodide Bi₃O₅I₂ with a hollow morphology was prepared by the solvothermal process. The structure, composition, morphology, optical property and photoelectric property of the as prepared photocatalyst were investigated through some characterization methods. Those characterization results showed that Bi₃O₅I₂ displayed a larger specific surface area, promising band structure and lower recombination of photoinduced carriers than pure BiOI. Bi₃O₅I₂ had a higher photocatalytic activity than BiOI on the decomposition of methyl orange (MO) under simulated solar light irradiation. The superoxide (·O₂⁻) and hole (h⁺) were the dominating active species during the degradation of MO. Its stability and reusability performance showed its great promising application in the degradation of organic pollutant. Full article

Three-dimensional flower-like BiOI/BiOX (X = Br or Cl) hybrids were synthesized via a facile one-pot solvothermal approach. With systematic characterizations by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), the Brunauer-Emmett-Teller (BET)specific surface area, X-ray photoelectron spectroscopy (XPS), and the UV-Vis diffuse reflectance spectra (DRS), the BiOI/BiOCl composites showed a fluffy and porous 3-D architecture with a large specific surface area (SSA) and high capability for light absorption. Among all the BiOX (X = Cl, Br, I) and BiOI/BiOX (X = Cl or Br) composites, BiOI/BiOCl stands out as the most efficient photocatalyst under both visible and UV light irradiations for methyl orange (MO) oxidation. The reaction rate of MO degradation on BiOI/BiOCl was 2.1 times higher than that on pure BiOI under visible light. Moreover, BiOI/BiOCl exhibited enhanced water oxidation efficiency for O₂ evolution which was 1.5 times higher than BiOI. The enhancement of photocatalytic activity could be attributed to the formation of a heterojunction between BiOI and BiOCl, with a nanoporous structure, a larger SSA, and a stronger light absorbance capacity especially in the visible-light region. The in situ electron paramagnetic resonance (EPR) revealed that BiOI/BiOCl composites could effectively evolve superoxide radicals and hydroxyl radicals for photodegradation, and the superoxide radicals are the dominant reactive species. The superb photocatalytic activity of BiOI/BiOCl could be utilized for the degradation of various industrial dyes under natural sunlight irradiation which is of high significance for the remediation of industrial wastewater in the future. Full article

Developing efficient visible-light-driven (VLD) photocatalysts for environmental decontamination has drawn significant attention in recent years. Herein, we have reported a novel heterostructure of multiwalled carbon nanotubes (MWCNTs) coated with BiOI nanosheets as an efficient VLD photocatalyst, which was prepared via a simple solvothermal method. The morphology and structure were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectroscopy (DRS), and specific surface area measurements. The results showed that BiOI nanosheets were well deposited on MWCNTs. The MWCNTs/BiOI composites exhibited remarkably enhanced photocatalytic activity for the degradation of rhodamine B (RhB), methyl orange (MO), and para-chlorophenol (4-CP) under visible-light, compared with pure BiOI. When the MWCNTs content is 3 wt %, the MWCNTs/BiOI composite (3%M-Bi) achieves the highest activity, which is even higher than that of a mechanical mixture (3 wt % MWCNTs + 97 wt % BiOI). The superior photocatalytic activity is predominantly due to the strong coupling interface between MWCNTs and BiOI, which significantly promotes the efficient electron-hole separation. The photo-induced holes (h⁺) and superoxide radicals (O₂⁻) mainly contribute to the photocatalytic degradation of RhB over 3%M-Bi. Therefore, the MWCNTs/BiOI composite is expected to be an efficient VLD photocatalyst for environmental purification. Full article