Search Results (19)

Bismuth oxyiodide (BiOI) microspheres were synthesized by a microwave-assisted solvothermal method at 126 °C in only 4 min, a significantly shorter reaction time than in previously reported works. The structural, surface, morphological, and optical properties of BiOI were analyzed and correlated with the photocatalytic activity during the degradation of gallic acid (GA) and the photo-oxidation of nitric oxide (NO) in the aqueous and gas phases, respectively. The BiOI microspheres exhibited higher first-order apparent rate constants for GA and NO (0.188 min⁻¹ and 0.230 min⁻¹) than the benchmark TiO₂ P25 (0.101 min⁻¹ and 0.066 min⁻¹). In addition, in steady-state reaction conditions (after 10 min), BiOI achieved 86% degradation of GA instead of the 63% degradation observed with TiO₂ P25. Furthermore, at the same point in the reaction, the BiOI microspheres showed up to 65% NO conversion, while TiO₂ P25 only achieved 15%. Accordingly, the results suggest that the microwave-assisted solvothermal method provides significant advantages for rapid, low-cost, and eco-friendly synthesis of BiOI microspheres for photocatalytic remediation of polluted water and air. Full article

Acid red 14 (AR14) is a widely used azo dye that belongs to a major family of commercial dyes employed extensively in the textile industry. The present study aimed to investigate the photocatalytic discoloration of AR14 using a visible-light-responsive catalyst. The composite catalyst was synthesized by integrating thermally modified MIL-101 (M-MIL) integrated into bismuth oxide. Thermal modification of MIL-101 produced octahedral α-Fe₂O₃ particles with a size of 1–2 μm, which were incorporated into bismuth oxyiodide (BiOI) featuring a nanosheet structure. BiOI@M-MIL composite exhibited an enhanced photocatalytic activity. The bandgap energy, E_g, of BiOI was reduced from 1.95 eV to 1.73 eV in the composite. Photocatalytic reactions were performed under visible-light irradiation using a 5 W cold LED lamp. The AR14 discoloration tests demonstrated that BiOI@M-MIL was 1.81-fold more efficient compared to pristine BiOI. Key parameters affecting AR14 discoloration —such as catalyst dosage, pH, dye concentration, and contact time, were investigated. The composite achieved almost a complete dye removal efficiency of 94.26% under experimental conditions. Radical trapping tests highlighted the crucial role of superoxide radicals, $O_2^{.-},$ in the dye discoloration process. BiOI@M-MIL takes advantage of simultaneous adsorption and photocatalysis with the highest adsorption capacity of 45.32 mg g⁻¹ and 32.2 mg g⁻¹, based on Sips and Langmuir models, respectively. The catalyst also showed good reusability and ~14% loss in removal efficiency after five consecutive cycles. In conclusion, the BiOI@M-MIL composite demonstrates excellent photocatalytic performance, combining low energy consumption with material stability, making it a promising candidate for AR14 discoloration. Full article

This work describes a novel method for converting bismuth triiodide (BiI₃) microplates into bismuth oxyiodide (BiOI) nanoflakes under ultrasonic irradiation. To produce BiOI nanoflakes with a high yield and high purity, the conversion process was carefully adjusted. Rapid reaction kinetics and increased mass transfer are benefits of the ultrasonic-assisted approach that result in well-defined converted BiOI nanostructures with superior characteristics. The produced BiOI nanoflakes were examined utilizing a range of analytical methods, such as Transmission Electron Microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD). The progress in the ultrasonic conversion process with time was monitored through diffuse reflectance spectroscopy (DRS). The outcomes demonstrated the effective conversion of BiI₃ microplates into crystalline, homogeneous, high-surface-area BiOI nanoflakes. Additionally, the degradation of organic dyes (methylene blue) under ultraviolet (UV) light irradiation was used to assess the photocatalytic efficacy of the produced BiOI nanoflakes. Because of their distinct morphology and electrical structure, the BiOI nanoflakes remarkably demonstrated remarkable photocatalytic activity, outperforming traditional photocatalysts. The ability of BiOI nanoflakes to effectively separate and utilize visible light photons makes them a viable option for environmental remediation applications. This work not only shows the promise of BiOI nanoflakes for sustainable photocatalytic applications but also demonstrates a simple and scalable approach to their manufacturing. The knowledge gathered from this work opens up new avenues for investigating ultrasonic-assisted techniques for creating sophisticated nanomaterials with customized characteristics for a range of technological uses. Full article

A Z-scheme heterojunction photo(electro)catalyst was fabricated by coupling sulfonic acid-modified graphitic carbon nitride (SA-g-CN) with bismuth oxyiodide (BiOI). The SA-g-CN component was prepared via wet-impregnation, while BiOI was synthesized through a hydrothermal method. Comprehensive characterization elucidated the structural and morphological properties of the resulting composite. The SA-g-CN/BiOI exhibited exceptional performance in both photocatalytic degradation of tartrazine (TTZ) and photoelectrochemical oxygen evolution reaction (OER). Notably, 98.26% TTZ removal was achieved within 60 min of irradiation, while an OER onset potential of 0.94 V (vs. Ag/AgCl) and a high photocurrent density of 6.04 mA were recorded under AM 1.5G illumination. Band energy calculations based on Mott–Schottky measurements confirmed the formation of a Z-scheme heterojunction, which facilitated efficient charge separation and transfer, thereby enhancing catalytic activity. These findings establish the SA-g-CN/BiOI composite as a promising candidate for sustainable energy generation and environmental remediation applications. Full article

In environmental chemistry, photocatalysts for eliminating organic contaminants in water have gained significant interest. Our study introduces a unique heterostructure combining MIL-101(Cr) and bismuth oxyiodide (Bi₅O₇I). We evaluated this nanostructure’s efficiency in adsorbing and degrading tetracycline (TC) under visible light. The Bi₅O₇I@MIL-101(Cr) composite, with a surface area of 637 m²/g, prevents self-aggregation seen in its components, enhancing visible light absorption. Its photocatalytic efficiency surpassed Bi₅O₇I and MIL-101(Cr) by 33.4 and 9.2 times, respectively. Comprehensive analyses, including scanning electron microscopy (SEM) and transmission electron microscopy (TEM), confirmed the successful formation of the heterostructure with defined morphological characteristics. BET analysis demonstrated its high surface area, while X-ray diffraction (XRD) confirmed its crystallinity. Electron spin resonance (ESR) tests showed significant generation of reactive oxygen species (ROS) like h⁺ and·•O₂⁻ under light, crucial for TC degradation. The material maintained exceptional durability over five cycles. Density functional theory (DFT) simulations and empirical investigations revealed a type I heterojunction between Bi₅O₇I and MIL-101(Cr), facilitating efficient electron–hole pair separation. This study underscores the superior photocatalytic activity and stability of Bi₅O₇I@MIL-101(Cr), offering insights into designing innovative photocatalysts for water purification. Full article

Activated carbon/BiOI nanocomposites were successfully synthesized through a simplistic method. The produced composites were then characterized using XRD, TEM, SEM-EDX, and XPS. The results showed that BiOI with a tetragonal crystal structure had been formed. The interaction between activated carbon and BiOI was confirmed via all the mentioned tools. The obtained nanocomposites’ electrical conductivity, dielectric properties, and Ac impedance were studied at 59 KHz−1.29 MHz. AC and dc conductivities were studied at temperatures between 303 and 573 K within the frequency range of 59 KHz–1.29 MHz. The 10% activated carbon/BiOI nanocomposite possessed dc and AC conductivity values of 5.56 × 10⁻⁴ and 2.86 × 10⁻⁴ Ω⁻¹.cm⁻¹, respectively, which were higher than BiOI and the other nanocomposites. Every sample exhibited increased electrical conductivity values as the temperature and frequency rose, suggesting that all samples had semiconducting behavior. The loss and dielectric constants (ε′ and ε″) also dropped as the frequency increased, leading to higher dielectric loss. The Nyquist plot unraveled single semicircle arcs and a decreased bulk resistance, indicating decreased grain boundary resistance. Consequently, the electrical characteristics of BiOI, 1C/BiOI, 5C/BiOI, and 10C/BiOI implied their applicability as dielectric absorbers, charge-stored capacitors, and high-frequency microwave devices. Full article

Developing catalysts with superior activity to hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) is equally important to the overall photoelectrochemical water splitting to produce hydrogen. In this work, bismuth oxyiodide (BiOI), iron-modified bismuth iodide Fe/BiOI, and the sulfurized S-Fe/BiOI were prepared using the solvothermal method. The three materials all have good absorption ability for visible light. The photoelectrochemical catalytic activity of BiOI to oxygen evolution reaction (OER) is significantly enhanced after iron modification, while the sulfurized product S-Fe/BiOI exhibits better catalytic activity to hydrogen evolution reaction (HER). Hence, OER and HER can be simultaneously catalyzed by using Fe/BiOI and S-Fe/BiOI as anodic and cathodic catalysts to facilitate the overall photoelectrochemical water splitting process. Full article

Active photocatalysts with an efficiency of 99% were prepared for the degradation of the industrial dye, methylene blue (MB), under visible light irradiation. These photocatalysts comprised Co/Ni-metal–organic frameworks (MOFs), to which bismuth oxyiodide (BiOI) was added as a filler to prepare Co/Ni-MOF@BiOI composites. The composites exhibited remarkable photocatalytic degradation of MB in aqueous solutions. The effects of various parameters, including the pH, reaction time, catalyst dose, and MB concentration, on the photocatalytic activity of the prepared catalysts were also evaluated. We believe that these composites are promising photocatalysts for the removal of MB from aqueous solutions under visible light. Full article

The use of visible-light-driven photocatalysts in wastewater treatment, photoreduction of CO₂, green solar fuels, and solar cells has elicited substantial research attention. Bismuth oxyhalide and its derivatives are a group of visible-light photocatalysts that can diminish electron–hole recombination in layered structures and boost photocatalytic activity. The energy bandgap of these photocatalysts lies in the range of visible light. A simple hydrothermal method was applied to fabricate a series of bismuth oxychloride/bismuth oxyiodide/grafted graphitic carbon nitride (BiO_mCl_n/BiO_pI_q/g-C₃N₄) sheets with different contents of g-C₃N₄. The fabricated sheets were characterized through XRD, TEM, SEM-EDS, XPS, UV-vis DRS, PL, and BET. The conversion efficiency of CO₂ reduction to CH₄ of BiO_mCl_n/BiO_pI_q of 4.09 μmol g⁻¹ can be increased to 39.43 μmol g⁻¹ by compositing with g-C₃N₄. It had an approximately 9.64 times improvement. The photodegradation rate constant for crystal violet (CV) dye of BiO_mCl_n/BiO_pI_q of k = 0.0684 can be increased to 0.2456 by compositing with g-C₃N₄. It had an approximately 3.6 times improvement. The electron paramagnetic resonance results and the quenching effects indicated that ¹O₂, •OH, h⁺, and •O₂⁻ were active species in the aforementioned photocatalytic degradation. Because of their heterojunction, the prepared ternary nanocomposites possessed the characteristics of a heterojunction of type II band alignment. Full article

In this study, multiple heterojunction structures of anatase–rutile/Bismuth oxyiodide (BiOI) composite fibers are designed by the combined method of electrospinning and hydrothermal techniques. The influence of different Ti/Bi atomic ratios ([Ti/Bi]) on the nanostructures and photocatalytic properties are investigated. It is found that the morphology of BiOI covered on the TiO₂ fiber surface changed with [Ti/Bi] from nanosheets to submicron spheres structures. Additionally, the crystallization of the composite fibers including the phases of anatase, rutile, and BiOI is identified, theses phases are in close contact with each other, and the interfacial effects are helpful to form the multiple heterojunctions which lead to blue shifts on the chemical state of Ti. The absorption of visible light has been improved by compositing BiOI on TiO₂, while the band gap values of the composite fibers are significantly reduced, which can enhance the generation and separation of electrons and holes. For the case of [Ti/Bi] = 1.57, the photodegradation rate of anatase–rutile/BiOI composite fibers is about 12 times that of pure TiO₂. For the photocatalytic mechanism, the synergistic s-type heterojunctions increase the content of active oxides which have a positive effect on the degradation rate. Full article

Bismuth oxyiodide (BiOI) is a targeted material for its relative safety and photocatalytic activity under visible light. In this study, a successful simple and energy-saving route was applied to prepare BiOI through a sonochemical process at room temperature. The characterization of the prepared BiOI was conducted by physical means. The transmission electron microscope (TEM) image showed that the BiOI comprises nanoparticles of about 20 nm. Also, the surface area of the BiOI was found to be 34.03 m² g⁻¹ with an energy gap of 1.835 eV. The adsorption and photocatalytic capacities of the BiOI were examined for the indigo carmine dye (IC) as a model water-pollutant via the batch experiment methodology. The solution parameters were optimized, including pH, contact time, IC concentration, and temperature. Worth mentioning that an adsorption capacity of 185 mg·g⁻¹ was obtained from 100 mg L⁻¹ IC solution at 25 °C within 60 min as an equilibrium time. In addition, the BiOI showed a high degradation efficiency towards IC under tungsten lamb (80 W), where 93% was removed within 180 min, and the complete degradation was accomplished in 240 min. The fabricated BiOI nanoparticles completely mineralized the IC under artificial visible light, as indicated by the total organic carbon analysis. Full article

Recently, bismuth oxyiodide (BiOI) is an attractive semiconductor to use in heterogeneous photocatalysis processes. Unfortunately, BiOI individually shows limited photocatalytic efficiency, instability, and a quick recombination of electron/holes. Considering the practical application of this semiconductor, some studies show that synthetic zeolites provide good support for this photocatalyst. This support material permits a better photocatalytic efficiency because it prevents the quick recombination of photogenerated pairs. However, the optimal conditions (time and temperature) to obtain composites (BiOI/ synthetic zeolite) with high photocatalytic efficiency using a coprecipitation-solvothermal growth method have not yet been reported. In this study, a response surface methodology (RSM) based on a central composite design (CCD) was applied to optimize the synthesis conditions of BiOI/mordenite composites. For this purpose, eleven BiOI/mordenite composites were synthesized using a combined coprecipitation-solvothermal method under different time and temperature conditions. The photocatalytic activities of the synthesized composites were evaluated after 20 min of photocatalytic oxidation of caffeic acid, a typical organic pollutant found in agro-industrial wastewater. Moreover, BiOI/mordenite composites with the highest and lowest photocatalytic activity were physically and chemically characterized using nitrogen adsorption isotherms, scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and diffuse reflectance spectroscopy (DRS). The optimal synthesis conditions prove to be 187 °C and 9 h. In addition, the changes applied to the experimental conditions led to surface property modifications that influenced the photocatalytic degradation efficiency of the BiOI/mordenite composite toward caffeic acid photodegradation. Full article

Heterogeneous photocatalysis under visible light irradiation allows performing of selective oxofunctionalization of hydrocarbons at ambient temperature and pressure, using molecular oxygen as a sacrificial reagent and potential use of sunlight as a sustainable and low-cost energy source. In the present work, a photocatalytic material based on heterojunction of titanium dioxide and bismuth oxyiodide was used as photocatalyst on selective oxofunctionalization of cyclohexane and benzyl alcohol. The selective oxidation reactions were performed in a homemade photoreactor equipped with a metal halide lamp and injected air as a source of molecular oxygen. The identified oxidized products obtained from oxofunctionalization of cyclohexane were cyclohexanol and cyclohexanone. On the other hand, the product obtained from oxofunctionalization of benzyl alcohol was benzaldehyde. The yield obtained with BiOI/TiO₂ photocatalysts was higher than that obtained with pure bismuth oxyiodide. The higher performance of this material with respect to pure BiOI was attributed to its higher specific area. Full article

A bismuth oxyiodide (BiOI) photocatalyst with excellent sunlight-driven performance was synthesized by a solvothermal route without the addition of surfactants or capping agents. The prepared photocatalyst exhibited a tetragonal phase with an energy band gap of 2.15 eV. The efficiency of the photocatalyst was elucidated by monitoring the photodegradation of organic dyes and antibiotics. The BiOI photocatalyst provided a 95% removal of norfloxacin (NOR) antibiotics under visible light illumination. Interestingly, the complete removal of Rhodamine B (RhB) dye was achieved after 80 min of natural sunlight irradiation. The photodegradation reaction followed the first-order reaction. Both photo-generated holes and electrons play vital roles in the photodegradation of the pollutant. The BiOI photocatalyst remains stable and still shows a high efficiency even after the fifth run. This confirms the great cycling ability and high structural stability of the photocatalyst. The prepared BiOI catalyst, with a high surface area of 118 m² g⁻¹, can act as an excellent adsorbent as well. The synergistic effect based on both adsorption and photocatalysis is a key factor in achieving a very high removal efficiency. The photoactivity under sunlight is higher than that observed under visible light, supporting the practical use of the BiOI photocatalyst for the removal of organic pollutants in wastewater through the utilization of abundant solar energy. Full article

In the present work, visible light active bismuth oxyiodide (BiOI) was immobilized on a commercial, non-conductive support (an Al₂O₃ based ceramic paper) using a novel two-step spray coating technique and investigated with different characterization methods (e.g., SEM, Raman, XPS). Our main goal was to eliminate the separation costs after the photocatalytic measurement and investigate the chemical relevance and opportunity to use this technique in the industry. Our as-prepared uniform BiOI layer had similar properties to the well-known reference BiOI powder. The Raman and XPS measurements confirmed that the enriched amount of the surface iodine defined the color and as well the band gap of the BiOI layer. The durable BiOI layers have prominent photocatalytic activity under UV and visible light irradiation as well. The scale-up procedure proved that the designed BiOI coated paper was reusable and potentially applicable in the industry by straightforward scale-up, which is due to the elaborated non-conventional BiOI coverage estimation method. This immobilization technique could open several opportunities for immobilizing many other visible light active photocatalysts with simple materials and low cost. Full article