Visible-light Activity Research Articles

Surfactants Modulating of BiVO4 on Photocatalytic Property as a Regulation of Surface Free Energy.

BiVO4 is a stable photocatalytic material but has poor photocatalytic activity in visible light. Herein, the surfactants were investigated to enhance the photocatalytic degradation of tetracycline (TC) of BiVO4 through a hydrothermal method. The different molecular structures and properties of surfactant-modified BiVO4 show clustered small spheres and stacked plate-like microcrystals. The N-hexadecyltrimethylammonium chloride (CTAC)-modified BiVO4 (BiVO4-CTAC) with stacked plate-like morphology increases the light absorption range and decreases the energy band gap. Surfactants with different hydrophilic groups and molecular structures affect the formation process of BiVO4, regulating the morphology, crystal structure, and crystalline surface exposure of BiVO4. BiVO4-CTAC has demonstrated superior TC degradation efficiency compared with the original BiVO4 (BiVO4-Blank). This enhancement is attributed to the observation in the Nyquist plot, where BiVO4-CTAC exhibits the smallest arc radius, indicative of reduced charge transfer resistance and improved charge separation. Furthermore, holes (h+) and superoxide radicals (•O2-) reactive species are the main active radicals for TC photocatalytic degradation. This study develops a novel method to synthesize monoclinic phase lamellar BiVO4 materials by simply changing the surfactant type. This study holds potential implications for advancing surfactant-assisted synthesis of high-efficiency photocatalysts.

Enhanced Visible-Light Photocatalysis Activity of TiO2/Ag Nanocomposites Prepared by the Ultrasound-Assisted Sol–Gel Method: Characterization and Degradation–Mineralization of Cationic and Anionic Dyes

Coupling TiO2 with various elements could enhance its photocatalytic activity. In this study, an innovative ultrasound-assisted sol–gel method was used to synthesize TiO2/Ag(x%) by varying Ag–support mass (x = 9.3, 17.1, and 23.6%), followed by calcination at 450 °C for 30 min. The aim was to demonstrate that Ag compositing improves photoactivity under visible light (>400 nm). The synthesized photocatalysts were assessed for their effectiveness in the degradation and mineralization of Methylene Blue (MB) and Acid Orange 7 (AO7) using visible lamps emitting in the range of 400–800 nm. Characterization of the prepared photocatalysts was performed by using Raman spectroscopy, SEM/EDS, pHpzc, and UV–visible spectroscopy. Raman spectroscopy confirmed the predominance of the anatase phase in all the photocatalysts. The photodegradation efficiencies of the selected dyes, MB and AO7, reached 99% (pH 6) and 95% (pH 3) after 180 min of irradiation, respectively. The best performance for the degradation of the two dyes was observed with TiO2/Ag9.3%, showing optimal kinetics at this doping concentration. The improved photoactivity of the TiO2/Ag composite is due to a decrease in the recombination rate of electron/hole (e−/h+) and a decrease in the band gap from 3.13 to 2.49 eV. The mineralization rate of both dyes under visible light is about 9.3%, indicating the presence of refractory by-products that resist complete degradation. Under UVA irradiation, complete mineralization is obtained. This study confirms the potential of TiO2/Ag composite as a high-performance and cost-effective photocatalyst for solar environmental remediation, highlighting the role of silver in extending light absorption into the visible region and improving charge separation.

Structural design of dual Z-scheme GCN/CdO/CaFe2O4 ternary heterojunction with high visible light activity: Photocatalytic performance and mechanism in the degradation of Congo red dye

Structural design of dual Z-scheme GCN/CdO/CaFe2O4 ternary heterojunction with high visible light activity: Photocatalytic performance and mechanism in the degradation of Congo red dye

Photocurrent switching effect and visible light activity of electrochemically synthesized bifunctional through oxide via TiO2/CuO composites

Photoelectrochemical conversion of solar energy into fuel products such as H2 or CH4 is an appealing, but technologically difficult process due to the simultaneous requirements for stability, efficiency and selectivity in the photoelectrode. One approach to design a photoelectrode with suitable properties is by using different materials that can complement each other. In this study, we introduce a novel approach by compositing TiO2 with CuO via electrodeposition of Cu into through-oxide vias/channels – a design that offers enhanced synergy between the materials. The Cu is then precisely transformed into Cu2O, CuO, or a mixture, based on annealing temperature, enabling tunable properties and optimized functionality. Unlike in traditional “sandwich” composites, this structuring reduces bulk charge carrier recombination through the formation of a depletion zone between TiO2 and CuO, allowing both materials to perform distinct functions. As a result, photocurrent switching is achieved by altering the applied potential, which is a functionality not previously demonstrated for photoactive composite materials. Our study also reports evidence of visible light sensitivity in TiO2/CuO composites when illuminated by a 4100K LED without UV components. Open circuit voltage decay measurements reveal that the improved charge carrier transport is due to the formation of a conductive Cu pathway—a novel finding that opens new possibilities for efficient photoexcitation. Although the charge carrier lifetimes were found to be shorter in TiO2/CuO electrodes compared to pure TiO2, we attribute this to the phenomenon of Cu "filling" the TiO2 channels and decreasing the available surface area, a trade-off that provides crucial insights into material design for future applications.

Water process/treatment by a S-scheme Fe2O3/TiO2 heterojunction photocatalyst for excellent antibiotic degradation/CO2 reduction/H2 production; process optimization and mechanistic insights

A facile synthesis approach was employed to fabricate a binary Fe2O3/TiO2 nanocomposite (FeTi4-400) for enhanced photocatalytic hydrogen (H2) production, cephalexin degradation and CO2 reduction under visible light irradiation. Compared to pristine TiO2, FeTi4-400 exhibited improved visible light absorption and promoted charge carrier separation, leading to increased H2 production rate and CO2 conversion into CH4 and CO. This improvement can be attributed to the formation of an S-scheme heterojunction, along with the desirable properties of FeTi4-400, including visible light activity, high surface area, and strong CO2 adsorption. The photocatalyst achieved a maximum H2 production rate of 649 μmol/g·h−1, exceeding that of pure TiO2. Similarly, the highest CO production rate of 16.44 μmol/g·h−1 was attained with FeTi4-400. Furthermore, FeTi4-400 achieved excellent cephalexin degradation (96 %) under optimal conditions, with a degradation rate constant of 0.01 min−1. A plausible cephalexin degradation pathway over FeTi4-400 is proposed. Transient photocurrent measurements and EIS analysis corroborated a significant enhancement in photocatalytic activity for FeTi4-400, attributed to the efficient separation of photogenerated electron-hole pairs. Stability studies demonstrated consistent cephalexin degradation by FeTi4-400 over five consecutive cycles without noticeable photocatalyst deactivation. This work presents a novel strategy for fabricating low-cost, efficient, and readily synthesized nanomaterials for applications in solar energy conversion and environmental remediation.

Design and Development of g-C3N4/ZnO/CdS Ternary Photocatalyst for the Removal of Environmentally Hazardous Organic Dyes under Visible Light

The processing of wastewater has emerged as a primary focus of research owing to the unavailability of clean water to satisfy the current population’s needs. In this work, a ternary nano-photocatalyst, g-C3N4/ZnO/CdS exhibiting visible light activity has been fabricated via a dual-step process that involved a pyrolytic transformation of urea to g-C3N4 subsequently followed by the solid state mechanochemical method to fabricate g-C3N4/ZnO/CdS. The synthesized nanomaterial underwent characterization using advanced techniques such as XRD, FTIR, FE-SEM/EDAX and UV-DRS techniques. The decomposition of Indigo Carmine dye was performed under the illumination of visible light, resulting in 99.6% degradation using a 50-mg photocatalytic dosage. Kinetic studies indicate that the photodegradation process followed pseudo-first-order where the phenomenon of adsorption adhered to the Langmuir–Hinshelwood model. This work attempted the generation of a multi pathway of electron migration by combining more than one Type-II heterojunction, which can effectively delay the electron-carrier recombination.

Visible light activation of permanganate by nitrogen vacancy-modified g-C3N4: Insight into the role of photo-generated electrons and holes

The photo-activation of permanganate (PM) for pollutant degradation in water has garnered significant interest due to its potential, yet it is impeded by efficiency constraints. In this study, the nitrogen-vacancy (NV) engineered graphitic carbon nitride (CN) catalysts with high light absorption, well photocarrier separation, and robust photoreduction capability were employed to activate PM under visible light irradiation (Vis) for sulfadiazine degradation. A high first-order rate constant of 0.185 min−1 was observed with the Vis/PM/NV-modified CN system, which was 25.2 and 7.1 times greater than those from Vis/PM and Vis/PM/CN system respectively. More interestingly, it was found that PM predominantly engaged with photo-generated holes as Lewis acid sites, elevating its oxidation potential and concurrently stimulating the production of photo-generated electrons. Meanwhile, dissolved oxygen (DO) was reduced by photo-generated electrons to form superoxide ions, singlet oxygen, and hydroxyl radicals. These produced reactive species through the synergistic activation of PM and DO, finally participated in the degradation of pollutants. Furthermore, the versatility and reusability of NV-CN catalysts were assessed under different reaction conditions, demonstrating promising prospects for practical applications. The results will contribute to a comprehensive understanding of the mechanism of photoactivation of PM for pollutant degradation.

Boosting of photocatalytic degradation of Malachite green dye on facile synthesized highly active Ca@TiO2@g-C3N4 photocatalyst: Photocatalytic mechanism and kinetics

The Ca@TiO2@g-C3N4 nanocomposite was synthesized using non-precious components via heat polymerization followed by an ultrasonic power technique. The nanocomposite was extensively characterized. The X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) investigations unequivocally demonstrated the successful synthesis of the Ca@TiO2@g-C3N4 nanostructures. By account of its small particle size of 6.1081 nm, narrow band gap energy of 2.82 eV, and visible light activity, it was able to photodegrade MG dye in an efficient manner, achieving a 99.9 % degradation rate. The photoluminescence measurement demonstrated efficient separation and transfer of charge carriers. The ternary photocatalyst’s activity can be attributed to the production of a S-scheme heterojunction at the interfaces of TiO2@g-C3N4, the generation of defects such as Ti3+ and Ovs through the surface interaction of Ca with TiO2, and the enlarged surface area of the photocatalyst. The ternary Ca@TiO2@g-C3N4 nanostructures demonstrated superior photodegradation of MG dye in comparison to pure g-C3N4 and binary TiO2@g-C3N4. A viable mechanism is also shown through active species trapping experiments using different scavengers, demonstrating that the photogenerated h+ and O2− are vital in the photodegradation reaction under visible light irradiation. Furthermore, the catalyst’s potential for industrial applications is enhanced by its utilization of inexpensive initial ingredients, straightforward synthesis process, and ability to harness solar light.

A modern approach to intermittent illumination for the characterization of chain-propagation in photoredox catalysis

Photoredox catalysis has become an invaluable tool for the construction of organic molecules, allowing for unparalleled control over radical intermediates enabled by the mild conditions achieved through visible-light activation of a photocatalyst. These reactions can be classified under two distinct mechanistic paradigms: closed photocatalytic cycles, and photoinitiated chain reactions. While optimization strategies for each of these classes of reaction differ significantly, organic chemists still lack a straightforward means for probing chain-propagation. In this work, we report a simple and accessible approach to performing intermittent illumination studies for characterizing chain reactions in photoredox catalysis. Using modern LED technologies to precisely control the rate of sample illumination, we were able to validate the presence or absence of product-forming chain reactions in four previously reported photoredox protocols. Furthermore, this technique also allows for the determination of chain-propagating lifetimes through a simple graphical analysis. Given the operational simplicity and ease of accessibility, we believe this intermittent illumination technique will be of great value to practitioners of the field moving forward.

Achieving high photocatalytic NOx removal activity using a Bi/BiOBr/TiO2 composite photocatalyst

Fossil fuel combustion generates nitrogen oxides (NO + NO2 = NOx), which pose threats to the environment and human health. Although commercial products containing titanium dioxide (TiO2) can remedy NOx pollution by photocatalysis, they only function in the ultraviolet (UV). On the other hand, bismuth oxybromide (BiOBr) is active in the visible. BiOBr is stable, affordable, and non-toxic, making it an appealing alternative. In addition, nanoparticulate Bi metal can further enhance visible light absorption through its surface plasmon properties and charge carrier lifetime by spatially separating charge. In this study, to enhance the visible-light activity of TiO2-based photocatalysts for NOx pollution, a composite of Bi-decorated BiOBr/TiO2 was synthesised using a solvothermal method across varying the Ti/Bi atomic ratio (0.2, 2.2, 4.4, and 6.6), and synthesis duration (6h, 12h, and 18h). The photocatalytic performance of the synthesised composites for NO gas removal was investigated using an adapted ISO method (22197–1:2016). Analysis showed that the preferential growth of the (010) crystal facet in BiOBr and the presence of Bi metal both play an important role in the superior photocatalytic activity seen in our Bi-decorated BiOBr/TiO2 composite. The composites were characterised using X-ray diffraction (XRD), attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), high-resolution scanning electron microscopy (HR-SEM), UV–Vis diffuse reflectance (DRS) spectroscopy, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), and diffuse reflectance transient absorption spectroscopy (DR-TAS). Our research shows that the Bi/BiOBr–TiO2 composite synthesised through a 12h solvothermal method with a Ti/Bi atomic ratio of 4.4 exhibits the highest photocatalytic performance towards both NO and NO2 oxidation; with 32.8% and 54.9% NO removal and 15.1% and 29.5% NO2 under visible and UV lamps, respectively.

Efficient Defect-Driven Cation Exchange beyond the Nanoscale Semiconductors toward Antibacterial Functionalization.

Defect engineering is an exciting tool for customizing semiconductors' structural and optoelectronic properties. Elaborating programmable methodologies to circumvent energy constraints in multievent inversions expands our understanding of the mechanisms governing the functionalization of nanomaterials. Herein, we introduce a novel strategy based on defect incorporation and solution rationalization, which triggers energetically unfavorable cation exchange reactions in extended solids. Using Sb2X3 + Ag (I) → Ag: Sb2X3 (X= S, Se) as a system to model, we demonstrate that incorporating chalcogen vacancies and AgSbVX complex defects into initial thin films (TFs) is crucial for activating long-range solid-state ion diffusion. Additional regulation of the Lewis acidity of auxiliary chemicals provides an exceptional conversion yield of the Ag precursor into a solid-state product up to 90%, simultaneously transforming upper matrix layers into AgSbX2. The proposed strategy enables tailoring radiative recombination processes, offers efficiency to invert TFs at moderate temperatures quickly, and yields structures of large areas with substantial antibacterial activity in visible light for a particular inversion system. Similar customization can be applied to most sulfides/selenides with controlled reaction yields.

Photocatalytic degradation of methylene blue using a Cu2+-modified bimetallic titanium-based metal organic framework (MIL-125) photocatalyst with enhanced visible light activity.

Cu-modified TiO2 nanoparticles derived from MIL-125 were prepared by solvothermal method for the photocatalytic degradation of methylene blue under visible light illumination. For boosting the photocatalytic performance as well as the physicochemical properties of bare sample, 2 wt % Cu2+ ions were integrated into the nodes of the MIL-125 framework. The results showed that incorporation of 2 wt % Cu2+ ions into the MOF framework had significant effects on the crystallographic structure and morphological and optical properties of photocatalytic samples, as well as catalytic activity for the methylene blue degradation reaction. The high activity profile of Cu-modified TiO2 nanoparticles derived from MIL-125 might be attributed to the increased thermal stability, lower band gap energy, and smaller crystallite size of the sample. Activity tests were carried out at five varying MB initial concentrations and four different pH values. According to the findings, an increase in initial dye concentration resulted in a decrease in degradation efficiency. It was observed that increasing the pH value in the range of 3-11 initially led to higher degradation rates until pH 7, after which the degradation rate began to decline.

Hypoxia-Active Iridium(III) Bis-terpyridine Complexes Bearing Oligothienyl Substituents: Synthesis, Photophysics, and Phototoxicity toward Cancer Cells.

In an effort to develop hypoxia-active iridium(III) complexes with long visible-light absorption, we synthesized and characterized five bis(terpyridine) Ir(III) complexes bearing oligothienyl substituents on one of the terpyridine ligands, i.e., nT-Ir (n = 0-4). The UV-vis absorption, emission, and transient absorption spectroscopy were employed to characterize the singlet and triplet excited states of these complexes and to explore the effects of varied number of thienyl units on the photophysical parameters of the complexes. In vitro photodynamic therapeutic activities of these complexes were assessed with respect to three melanoma cell lines (SKMEL28, A375, and B16F10) and two breast cancer cell lines (MDA-MB-231 and MCF-7) under normoxia (∼18.5% oxygen tension) and hypoxia (1% oxygen tension) upon broadband visible (400-700 nm), blue (453 nm), green (523 nm), and red (633 nm) light activation. It was revealed that the increased number of thienyl units bathochromically shifted the low-energy absorption bands to the green/orange spectral regions and the emission bands to the near-infrared (NIR) regions. The lowest triplet excited-state lifetimes and the singlet oxygen generation efficiency also increased from 0T to 2T substitution but decreased in 3T and 4T substitution. All complexes exhibited low dark cytotoxicity toward all cell lines, but 2T-Ir-4T-Ir manifested high photocytotoxicity for all cell lines upon visible, blue, and green light activation under normoxia, with 2T-Ir showing the strongest photocytotoxicity toward SKMEL28, MDA-MB-231, and MCF-7 cells, and 4T-Ir being the most photocytotoxic one for B16F10 and A375 cells. Singlet oxygen, superoxide anion radicals, and peroxynitrite anions were found to likely be involved in the photocytotoxicity exhibited by the complexes. 4T-Ir also showed strong photocytotoxicity upon red-light excitation toward all cell lines under normoxia and retained its photocytotoxicity under hypoxia toward all cell lines upon visible, blue, and green light excitation. The hypoxic activity of 4T-Ir along with its green to orange light absorption, NIR emission, and low dark cytotoxicity suggest its potential as a photosensitizer for photodynamic therapy applications.

Photocatalytic degradation of Diuron in water – Impact of Rh impregnation on P25 visible light activity

Significant efforts have lately been dedicated to the development of visible light activated photocatalysts for the degradation of emerging pollutants in water. This study shows the impact of Rh addition on the photocatalytic performance of TiO2 in Diuron degradation through various experimental approaches and modelling. Three samples with different Rh loading (0.5 %, 1 %, and 2 %) were synthesized, characterized, and their activities were evaluated. It was observed that the activity of RhP25 improved under white light irradiation with increasing Rh content. At low Rh loadings the Rh atoms interact with Ti and may be stabilized in the TiO2 lattice. At higher loadings Rh interacts with the O atoms forming two different clusters Rh3O4 and Rh4O6 on the TiO2 surface. This phenomenon was evidenced by DFT, XPS and XRD results. The addition of Rh induce new electronic states in the TiO2 enhancing the visible light absorption. Photocatalytic experiments revealed a threefold increase in Diuron removal under white light irradiation for 2%RhP25 compared to P25, achieving 23 % degradation in comparison with the 7 % observed for the P25 without the Rh addition. Furthermore, repeated experiments did not show significant deterioration of the activity.

Bismuth-based nanocomposites as potential materials for indoor air treatment

Air pollution is a worldwide health hazard; thus, improving air quality is a demanding need. Photocatalysis is a robust strategy for air treatment. The boosted activity of the photocatalytic system depends on tuning their properties for the particular application. BiOX (X: Cl, I) compounds are emergent photocatalytic systems with numerous advantages for air treatment. However, their optical properties (Eg) and fast recombination of active species (e−/h+) limit their practical applications. In this study, we remark on the properties of BiOX-GO systems for indoor air purification. We use a microwave-activated solvothermal technique to synthesize the nanomaterials (NMs). BiOX NMs exhibit hierarchical 3D structures, crystallinity, and tunable optical absorption properties. BiOX-GO composites present an enhanced visible-light photocatalytic activity due to the electron acceptor capacity of GO and modification of Eg. The indoor air disinfection capacity of the NMs ranked as follows: BiOCl-GO (96.7%) > BiOI-GO (96.2%) > BiOI (89.2%) > BiOCl (79%). The higher efficiency under visible light of BiOCl-GO can be related to the presence of oxygen vacancies, strong oxidation potential, and single crystalline phase of the materials. Due to the abundance and biocompatibility of bismuth-containing compounds, together with their enhanced visible light activity, BiOX become potent candidates for environmentally sustainable remediation technologies.

Visible-light assisted peroxymonosulfate process for efficient water treatment via Fe-O embedded ZIF-62

The development of efficient and environmentally friendly water treatment technologies is essential for the treatment of emerging pollutants. In this study, a ZIF-62 catalyst embedded with Fe-O was prepared for the visible-light assisted activation of peroxymonosulfate (PMS) to achieve the removal of bisphenol A by coupling photogenerated carriers with the non-radical pathway. The embedding of Fe-O narrowed the bandgap width (reduced from 3.07 eV to 2.37 eV), enhanced the overall photoresponse performance, and improved the segregation of photogenerated carriers. The upward shift of the d-band center contributes to the adsorption of PMS. The embedding of Fe-O improves the BPA removal kinetics by a factor of 15.4 (increased from 0.00391 min−1 to 0.06005 min−1). Surface-activated complexes played a dominant role in the removal of BPA in this system, and photogenerated holes (h+) and singlet oxygen (1O2) were also involved in the removal of BPA. In addition, the system has good pH adaptability (pH = 3 ∼ 11) and good environmental suitability. Toxicity assessment showed that the overall toxicity of the intermediates tended to decrease. This study provides new insights into visible-light assisted activation of PMS.

Synthesis and design strategies of codoped titanium dioxide with band alignment and multiple reflections of incident light for efficient visible light activity

To increase the visible-light photocatalytic performance of Titania, it was codoped with specific elements and was effectively synthesized. The goal of enhancing visible-light photocatalytic performance was achieved by broadening its absorption spectrum in the visible light range and enhancing the quantum efficiency of the photocatalytic reaction toward the degradation of the hazardous dye methyl orange. Mixed phase photocatalyst with different percentage hierarchical secondary nanostructure has been synthesized by the combination of chemical bath deposition methods and hydrothermal. The density of the sprout-like branches changes from the concentration levels of titanium butoxide in the precursor solution. Based on the experimental analysis, a mechanism was proposed to interpret the evolution of the secondary growth. The band edge difference between anatase and TiO2(B) phases induces transfer of charge at the interface. The result revealed that in the TiO2 crystal some O-sites were substituted by N and S anions resulting in band mixing and incorporation of extra energy states in between the valence band maxima and conduction band minimum, which caused a shift towards longer wavelengths in the absorption edge. Compared with pure TiO2 nanobelt, the surface modified doped samples exhibited good visible light activity. The combined effect of fast charge transfer in the atomic level contact between two phases and localized N 2p and S 3p band above valence-band edge in the same material makes titanium dioxide suitable for use in the presence of visible light.

CdWO4 Sub-1 nm Nanowires for Visible-Light CO2 Photoreduction.

Quantum size effect usually causes energy level splitting and band broadening as material size decreases. However, this may change again by the surface adsorbents, doping and defects, which rarely attracts much attention. Herein, CdWO4 sub-1 nm nanowires (SNWs) with oleylamine adsorption, PO4 3--doping and oxygen defects are synthesized by combining Cd(CH3COO)2, H3PW12O40 (PW12) and oleylamine (abbreviated as PO4 3--CdWO4-X SNWs). Compared with bulk CdWO4, they exhibit unexpected absorption spectra (extended from 292 nm to 453 nm) and band gap (reduced from 4.25 eV to 2.74 eV), thus bringing remarkable visible-light CO2 photoreduction activity. Under 410 nm LED light irradiation, PO4 3--CdWO4-40 SNWs exhibit the highest photocatalytic performance with a CO2-to-CO generation rate of 1685 μmol g-1 h-1. Density functional theory (DFT) calculations demonstrate the adsorbed oleylamine raises the valence band and enhances the adsorption of reaction substrate and intermediates, thus decreasing their reduction energy barriers. Furthermore, PO4 3--doping and oxygen defects will generate defect energy band below the conduction band of PO4 3--CdWO4-40 SNWs, resulting in remarkable visible light absorption and superior photocatalytic CO2 reduction performance. This work highlights the significant impacts of surface adsorbents, doping and defects on the physicochemical and catalytic properties of sub-nano materials.

Bismuth oxyiodide-based composites for advanced visible-light activation of peroxymonosulfate in pharmaceutical mineralization

The presence of pharmaceutical pollutants in water bodies represents a significant environmental and public health concern, largely due to their inherent persistence and potential to induce antibiotic resistance. Advanced oxidation processes (AOPs) that employ peroxymonosulfate (PMS) activation have emerged as an effective means of degrading these contaminants. Bismuth oxyiodides (BiOI), which are known for their visible-light photocatalytic properties, demonstrate considerable potential for removal of pharmaceutical pollutants. This study examines the synthesis and performance of BiOI-based composites with barium ferrite (BFO) nanoparticles for enhanced PMS activation under visible light. BiOI and Bi5O7I were synthesized via solvothermal and electrodeposition methods, respectively, and their morphologies and crystalline structures were observed to exhibit distinctive characteristics following annealing. The formation of the composite with BFO resulted in an improvement in the catalytic properties, which in turn enhanced the surface area and availability of active sites. The objective of the photocatalytic studies was to evaluate the degradation and mineralization of tetracycline (TC) under visible light, PMS, and combined conditions. The Bi5O7I(ED)-BFO catalyst was identified as the optimal candidate, achieving up to 99.8% TC degradation and 99.4% mineralization within 90 min at room temperature. The synergistic effect of BFO in BiOI-based composites significantly enhanced performance across all conditions, indicating their potential for efficient remediation of pharmaceutical pollutant. The material's performance was further evaluated in tap water, where the degradation efficiency decreased to 56.4% and mineralization to 38.2%. These results reflect the challenges posed by complex water matrices. However, doubling the PMS concentration to 5 mM led to improved outcomes, with 93.8% degradation and 81.4% mineralization achieved. These findings demonstrate the material's robust potential for treating pharmaceutical pollutants in real-world conditions, advancing sustainable water treatment technologies.

Photoactive Conjugated Polyelectrolyte‐Ionomer Composite Coatings for Versatile Photoreactors

AbstractConjugated polymers are promising photoactive materials for heterogeneous photocatalysis, but their limited solubility hinders the scalability in practical use. Herein, we develop polymer composites using processable conjugated polyelectrolytes and ionomers to fabricate photocatalytic thin films with visible light activity. The composite of conjugated polyelectrolytes and ionomers with identical counter anions in their side chains enables compatibility in solvents and stabilized charged states within the composite. This facilitates the development of stable coatings on diverse substrates and enhances charge separation and transport. The resulting photocatalytic thin films exhibited a 1.5‐fold increase in photocurrent response and a 7.0‐fold increase in mechanical strength compared to the pristine conjugated polymer. Photoactive coatings with polymer composites showcase the potential for synergistic photocatalytic oxidation of NADH, organic dye, and sulfide under visible light irradiation. The photocatalytic thin films are stable, versatile, and scalable for various photocatalytic reactions, showing promise for developing upscaled photoreactors.