We employed density functional theory (DFT) to investigate the effect of tungsten (W) doping on the crystal structure, electronic properties, and optical response of Bi2MoO6−xWxO6. The results show that W doping retains the Aurivillius orthorhombic lattice structure while inducing localized distortions. All doping systems retain semiconductor characteristics with a band gap ranging from 2.11 to 2.26 eV. The valence band is mainly composed of O-2p orbitals, while the conduction band consists of Mo-4d and W-5d states. As W doping increases, the influence of W-5d states near the conduction band edge intensifies, modulating the electronic structure. Optical calculations show that W doping shifts the absorption edge and allows for precise adjustment of the absorption threshold in the visible light range. These findings provide insight into how W doping affects the electronic and optical properties of γ-Bi2MoO6 and offer a theoretical basis for improving Bi2MoO6-based photocatalytic materials.

Active food packaging based on chitosan-gelatin nanocomposites functionalized with bioactive nanoparticles: fabrication, properties, and application in seafood preservation.

Constructing multimetal centers on carbon-based substrates is a promising strategy to enhance C-N coupling for efficient urea synthesis, while the underlying design principles, particularly how metal-metal and metal-substrate interactions govern reactant activation and reaction pathways, remain intangible. To address this gap, we developed a frontier orbital interaction-guided C-N coupling selectivity map based on the p-d asymmetric dual-atom models (DACs) through the synergistic integration of DFT calculations and machine learning classification. Specifically, efficient NOx reduction was found to require a narrow energy gap (ΔE1 < 3.38 eV) between the HOMO of p-block metals and the LUMO of the d@substrate (where d-block atoms are treated as integrated with substrates for simplification). In contrast, selective urea synthesis necessitates a larger energy gap (ΔE2 > 1.39 eV) between the LUMO of p-block metals and the HOMO of the d@substrate, signifying weaker p-d interactions. Moreover, such an asymmetric dual-atom structure enables a tunable bandgap while simultaneously optimizing the visible-light absorption range. As a result, the AlPd@PCN and GaPt@PCN systems stand out as exceptional candidates, exhibiting fully thermodynamically favorable energy profiles throughout the photocatalytic cycle. These insights not only extend frontier orbital theory to DACs systems but also establish a robust, generalizable framework for designing high-performance dual-atom urea synthesis catalysts.

The efficient and low-energy treatment of dye wastewater remains a significant challenge. Herein, a novel co-sensitized TiO2 photocatalyst (CS-TiO2) was constructed by combining ruthenium-based dye N719 with a laboratory-synthesized organic dye RA, aiming to extend the visible-light absorption range. The CS-TiO2 was subsequently embedded into poly(methyl methacrylate) micro–nano fibers via centrifugal spinning, yielding easily recyclable photocatalytic membranes. After deducting the 30% self-degradation contribution of methylene blue arising from its intrinsic photosensitizing effect, the as-prepared PMMA/CS-TiO2 membrane achieved a net MB degradation efficiency of 58.12%—significantly superior to that of single-dye sensitized counterparts. This enhanced performance is ascribed to efficient charge separation and boosted production of dominant ·OH radicals enabled by the synergistic co-sensitization effect. Notably, the membrane retained ∼80% of its initial net degradation efficiency after five consecutive cycles, demonstrating excellent reusability and structural stability. This work offers a promising approach for constructing efficient, sustainable, and recyclable photocatalytic systems for dye wastewater remediation.

The ubiquitous accumulation of antibiotics and synthetic dyes in aquatic environments has emerged as a critical threat to the ecological integrity and human health. Visible-light-driven photocatalysis represents a sustainable strategy for decontaminating such pollutants; yet, its practical efficacy is often hampered by narrow light-harvesting ranges and rapid photogenerated carrier recombination. Herein, a ternary photocatalyst, namely, CDs/UiO-66-NH2/BiOCl (CUCl), was rationally constructed by integrating carbon dots (CDs) into a UiO-66-NH2/BiOCl Z-scheme heterojunction. Serving as an efficient electron reservoir, the introduced CDs not only significantly extended the visible-light absorption range but also effectively suppressed carrier recombination. Under visible-light irradiation, the optimized CUCl catalyst achieved remarkable degradation efficiencies of 87.2% and 98.8% for tetracycline and rhodamine B, respectively, outperforming the binary UiO-66-NH2/BiOCl heterojunction and pristine BiOCl. Radical trapping experiments and photocatalytic mechanism investigations revealed that photogenerated holes (h+) and superoxide radicals (·O2-) were the dominant active species responsible for pollutant degradation. Moreover, the CUCl catalyst exhibited excellent structural stability and reusability, retaining more than 85% of its initial catalytic activity after four consecutive reuse cycles. This work provides a novel and viable strategy for fabricating high-efficiency, stable environmental photocatalysts via the synergistic integration of Z-scheme heterojunctions and carbon dot functionalization.

The underwater light environment is important for lake ecosystem function and structure. In the summer of 2023, the Yangtze River basin suffered an extreme drought, and Poyang Lake experienced its lowest water level since 1951. However, there remainsa gap in understanding the impact of extreme drought on the underwater light environment. In this study, the underwater light environment in Poyang Lake was quantitatively investigated in late July 2023, and its influencing factors were explored. The results showed that the underwater light environment in Poyang Lake attenuated most drastically within the 0-0.4m depth range, where the underwater spectrum changes significantly, especially in the visible light range (400-700nm). With increasing depth, the proportion of red and green light increased, whereas that of blue light decreased rapidly. However, in regions with high Secchi depth (SD), even at 1.2m depth, blue light still accounted for 2.03-9.15%, forming a distinct underwater light environment. In other regions with low SD and high suspended solids (SS), blue light attenuated severely and red light became dominat. Although the red-to-blue lightratio varied across Poyang Lake, its maximum values were consistently distributed in the west. Attenuation of blue, green, and red light, as well as photosynthetically active radiation, in the four lake regions followed the order: northern > western > southern > eastern, with blue light attenuating the most rapidly. In contrast to previous findings, SD was the key factor driving changes in the underwater light environment of Poyang Lake, followed by SS. Future efforts should prioritize enhanced monitoring of SD and the underwater light environment in Poyang Lake.

In this study, we have investigated heterostructural TiO2/BiVO4 anodes to determine the effect of the amount and form of BiVO4 nanoparticles on TiO2 on the response of photoanodes under UV and visible illumination. BiVO4 nanopowders were prepared and annealed at temperatures ranging from 200 to 500 °C. Structural and optical characterization indicates that as the annealing temperature is increased, a phase transition from a weakly ordered to a dominant monoclinic BiVO4 phase is observed, which is accompanied by an increase in visible light absorption. Subsequently, the most crystalline powder was utilized to deposit BiVO4 on nanostructured TiO2 either as a compact overlayer (drop-casting) or as a progressively grown nanoparticle (TiO2@S series) in the successive ionic layer adsorption and reaction process (SILAR). Photoelectrochemical measurements were performed, revealing a morphology-dependent photocurrent response under UV and visible illumination. A further increase in the number of cycles systematically increases the photocurrent in the visible light range while limiting the response to UV radiation. The TiO2@d photoanode demonstrates the highest relative activity within the visible range; however, it also generates the lowest absolute photocurrent, indicating the presence of significant transport and recombination losses within the thick BiVO4 layer. The results demonstrate that the presence of BiVO4 nanoparticles on TiO2 exerts a substantial influence on the separation of charge between semiconductors and the synergistic utilization of photons from the UV and visible ranges. This research yielded a proposed scheme of mutual band arrangement and charge carrier transfer mechanism in TiO2@BiVO4 heterostructures.

The Sar-e-Sang lapis lazuli deposit has a mining history exceeding 5000 years, producing the world’s finest lapis lazuli. Recently, gem-quality forsterite has been discovered in the marble containing spinel, dolomite, and phlogopite at the periphery of the lapis lazuli ore body at the Pitawak mine, located east of the Sar-e-Sang deposit. The mineral assemblage indicates that the protolith of this marble is dolomite with aluminous and siliceous components. These forsterite crystals occur as colorless, transparent anhedral grains, exhibiting distinct red fluorescence under 365 nm ultraviolet light. To investigate the gemological and spectroscopic characteristics of the Pitawak mine forsterite, this study conducted and analyzed data from basic gemological analysis, electron probe microanalysis (EPMA), Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), ultraviolet–visible absorption spectroscopy (UV-VIS), Fourier-transform infrared spectroscopy (FTIR), laser Raman spectroscopy (RAMAN), and photoluminescence spectroscopy (PL) on four forsterite samples from the Pitawak mine. The analysis results reveal that the samples indicate a composition close to ideal forsterite with a crystal chemical formula of (Mg2.00Fe0.02)Σ2.02Si0.99O4. The trace elements present include Fe, Mn, Ca, and minor amounts of Cr and Ni. The UV-VIS spectroscopy results show that the samples possess high transmittance across the visible light range with very weak absorption bands, contributing to the colorless and transparent appearance of Pitawak mine forsterite. This phenomenon is attributed to the extremely low content of chromophoric elements, which have a negligible effect on the forsterite’s color. PL spectroscopy indicates that the red fluorescence of the samples is caused by an emission peak near 642 nm. This emission peak arises from the spin-forbidden 4T1 → 6A1 transition of Mn2+ ions situated in octahedral sites within the forsterite structure.

In this work, the effects of intrinsic point defects on the electronic and optical properties of both pristine and p-type-doped AlxGa1-xAs nanowires are investigated through first-principles calculations. The formation energy, band structure, charge density difference, density of states, work function, and optical absorption coefficient are analyzed. Results indicate that defects are more prone to formation in the surface layer of nanowires, with a gradual increase in formation energy as defects migrate toward the core region. Band structure and charge density difference analysis reveal that defects such as Gain, Alin, VAs, AsGa, and AsAl introduce donor impurity within the bandgap. In contrast, defects such as Asin, VGa, VAl, GaAs, and AlAs exhibit acceptor impurity characteristics, leading to an elevated work function and hindered electron emission. The former effectively reduces the electron escape barrier, while the latter increases the work function and hinders electron emission. Moreover, p-type doping promotes the formation of antisite defects while suppressing the generation of interstitial defects and vacancy defects. Notably, as the AsGa defect moves away from the p-type doping center, the local electron compensation efficiency diminishes, and the defect-induced donor energy level continuously shifts toward lower energy, resulting in a gradient reduction of bandgap. Furthermore, all defects can enhance the optical absorption capacity of AlxGa1-xAs nanowire photocathodes in the visible light range, especially for p-type doping nanowires.

Two-dimensional graphitic carbon nitride (g-C3N4) is a promising photocatalyst, though its efficiency is hindered by fast charge recombination and limited visible-light absorption. In this work, we investigated the influence of stress applied along the armchair (X-axis) and zigzag (Y-axis) directions on the electronic structure and optical properties of monolayer g-C3N4 using first-principles calculations. The results show that applied stress effectively tunes the C─N bond lengths and significantly modulates the bandgap: compressive stress substantially reduces the bandgap from 2.64eV (pristine) to 2.04eV (-9GPa, Y-axis) and 2.13eV (-9GPa, X-axis), while tensile stress leads to a slight widening. Moreover, a technologically critical indirect-to-direct bandgap transition occurs at specific critical strains-under Y-axis tensile stress exceeding +4GPa or X-axis compressive stress beyond -6GPa. This transition promotes direct electron excitation. Density of states analysis reveals the underlying mechanism: compressive stress lowers the conduction band minimum by enhancing the hybridization of C/N-2p orbitals, while tensile stress increases the contribution of s-orbitals. Modifications in optical properties under specific stress conditions significantly extend the visible-light absorption range (380-760nm). This work establishes stress engineering as an effective strategy for optimizing g-C3N4 for optoelectronic and photocatalytic applications.

A type-II heterojunction photodetector based on MnPSe 3 /MoS 2 with a vertical stacking sequence exhibits self-powered photodetection capability ranging from near-ultraviolet to the visible light range.

Polyhedral oligomeric silsesquioxane (POSS) polyimide is promising for sealing flexible photoelectronic devices for space applications. However, atomic oxygen interaction with POSS polyimide results in a porous SiOx passivating layer, ultraviolet interaction results in bonding degradation, both causing the transmittance decrease in the visible light range. In this study, the atomic oxygen exposure-induced transmittance decrease of POSS polyimide is explained and simulated by Rayleigh scattering. Ultrathin oxide films and ultraviolet absorbent are introduced to POSS polyimide by surface- and bulk-phase modifications to improve atomic oxygen and ultraviolet resistance, which achieves ≈0wt% mass loss upon an eight-year long-term atomic oxygen exposure and is deduced by molecular dynamics. The atomic oxygen exposure effect on the sheet resistance of flexible conductive indium tin oxide-POSS polyimide is explained by band structure calculation. The SiO2-POSS polyimide sealed triple-junction GaAs thin-film solar cell exhibits beginning of life (BOL) and end of life (EOL) efficiencies of 27.67% and 23.38% upon an eight-year long-term to atomic oxygen. The atomic oxygen reactions with polyimide-based films are explained by zero- and first-order reactions, and predictive formulas are created for the film mass loss and sealed solar cell performance under the long-term atomic oxygen exposure. This study suggests a POSS polyimide composite as a packaging film for flexible photoelectronic devices in low Earth orbit.

The artificial light-harvesting system (LHS) based on the cascade fluorescence resonance energy transfer (FRET) mechanism has ability to widely regulate the luminescent performance, however, it still faces significant challenges to achieve full-color luminescent regulation covering the entire visible spectrum in a single LHS system. In this study, we designed and constructed an artificial LHS with a three-step cascade energy transfer mechanism, achieving effective emission of white light and multicolor fluorescence within the visible light range. A cationic 6-bromobenzo[de]isochromene-1,3-dione derivative (BNI) was prepared, which was able to generate a supramolecular complex with sulfobutylether-β-cyclodextrin (SBE-β-CD) via electrostatic interactions. Given that this complex has excellent dark blue fluorescence performance, it was selected as the energy donor and sequentially participated in FRET process with commercial dyes Fluorescein (Flu), Rhodamine B (RhB) and Sulforhodamine 101 (SR101), thereby constructing an artificial LHS with three-step sequential energy transfer. By precisely regulating the ratios of acceptor molecules, multicolor fluorescence emissions ranging from blue to red bands and white light emission were achieved. Ultimately, the synthesized supramolecular LHS was effectively utilized in the development of multicolor fluorescent light-emitting devices and demonstrated its potential application in information storage.

An updated review on the modifications and food preservation applications of chitosan.

(COOH, NH2)-modified defective MOF-808(Zr) for enhancing photocatalytic oxidation of tetracycline and structural feature determination by Pearson correlation analysis.

Cs3Bi2Br9/Bi19Br3S27Z-scheme heterojunction for visible-to-near-infrared light-driven photocatalytic CO2 reduction.

CuCo2O4, as a spinel-structured transition metal oxide, has drawn significant attention in photocatalytic hydrogen evolution due to its excellent redox properties, chemical stability, and cost-effectiveness. However, its high charge carrier recombination rate, limited conductivity, and insufficient visible-light absorption hinder its catalytic efficiency in water splitting. Therefore, addressing these limitations and further enhancing its photocatalytic activity remains a critical research challenge. Sulfide-based materials have been widely utilized in hydrogen evolution due to their narrow bandgap, high charge mobility, and superior visible-light absorption capabilities. Typical sulfides, such as CdS, MoS2, and other transition metal sulfides, have demonstrated high activity and selectivity in photocatalysis. However, CdS suffers from severe photocorrosion, while MoS2 exhibits limited catalytic performance due to the restricted exposure of active sites in its layered structure. Despite these challenges, sulfide modification has shown potential in improving charge separation and enhancing light absorption, making it a promising approach for optimizing photocatalytic efficiency. In this study, CuCo2O4 was synthesized via a hydrothermal method followed by an annealing process to obtain the spinel-structured material. The SEM image (Figure 1a) reveals that CuCo2O4 forms microspheres with an average diameter of approximately 1 μm, composed of needle-like structures around 30 nm in diameter. The XRD pattern (Figure 1b) confirms that the synthesized CuCo2O4 matches well with the reference pattern (PDF#01-1115). Furthermore, EDS mapping (Figure 1c) demonstrates the homogeneous distribution of Cu, Co, and O within the material, validating the successful synthesis of CuCo2O4. To further enhance its photocatalytic activity, CuCo2O4 is modified with sulfides to improve charge separation and transfer efficiency while expanding its visible-light response range. The formation of a heterostructure between sulfides and CuCo2O4 facilitates effective charge carrier separation at the interface, reducing recombination rates and enhancing hydrogen evolution efficiency. Additionally, the incorporation of sulfides modulates the surface chemistry of CuCo2O4, further boosting its catalytic activity. Future research will focus on optimizing the interfacial engineering between sulfides and CuCo2O4, tuning the band structure, and systematically evaluating the photocatalytic hydrogen evolution performance under different reaction conditions. These efforts aim to further enhance the efficiency and stability of sulfide-modified CuCo2O4 for practical solar-driven hydrogen production. Figure 1

Photocatalysis is a promising method for splitting water molecules into green oxygen and hydrogen gas via direct sunlight. However, gas evolution rates are limited due to the necessity of high-bandgap materials with low absorptance in the visible light range to overcome the energetic barriers of the redox reaction. The Z-scheme reactor design circumvents this limitation by separating the reaction into two distinct steps mediated by a charge-exchanging redox shuttle reaction. This design allows for more efficient use of the visible light spectrum via reduced bandgap catalysts, and individual optimization of the oxygen evolving (OER) and hydrogen evolving (HER) half-reactions. In this work, we demonstrate a scaled type-III Z-scheme reactor design which separates the OER and HER half-reactions into separate chambers between which the redox shuttle electrolyte is exchanged. While semiconductor nanoparticle sheets are the dominant design for large-scale photocatalytic demonstrations, semiconductor-coated ceramic photocatalysts show potential for improved flow design, optical absorption, reaction surface area, and mass transport. Additionally, optical concentrators are a relatively cost-effective method of enhancing reaction rates by increasing incident light intensity. Here, we experimentally compare large-scale reaction rates and feasibility of each photocatalyst design under varying illumination intensity via optical concentration, flow distribution design, redox shuttle concentration, electrolyte pH, and material composition. The photocatalytic materials tested include TiO2 and SrTiO3 nanoparticle sheets, as well as AlO3 foams coated in TiO2 and BiVO4. Results emphasize the importance of demonstrating photocatalytic water splitting at scale to determine the practical limitations and the potential for novel methods of reaction rate enhancement.

Area-selective atomic layer deposition (AS-ALD) is a promising technique for advanced nanofabrication processes. This allows for the simple bottom-up creation of intricate nanostructures essential for advanced optoelectronic and sensor applications.1 Due to the flexibility of ALD, the method can be used alongside its organic counterpart, molecular layer deposition (MLD).2 The combined atomic/molecular layer deposition (ALD/MLD) enables tuning of material properties by incorporating organic linkers into the film while maintaining the nanoscale control.3 Area-selective ALD and MLD separately have been demonstrated previously, but these processes typically rely on utilization of inhibitors and lithography steps to achieve the area-selectivity, which complicates the process.4,5 While there are examples of AS-ALD being used on two-dimensional materials (2DM), AS-MLD on them is still mostly unexplored. Due to the inherent 2D nature, the surface of 2DM does not provide sufficient reactive sites for the chemisorption of ALD/MLD precursors compared with traditional microelectronics. Surface functionalization can provide the selective 3D growth of desired materials. Recently, we have overcome the chemical inertness of graphene to ALD precursors by local activation using direct femtosecond laser two-photon oxidation (TPO)6 for selective ZnO deposition.7 In this study, we guided the growth of Europium-terephthalate thin films on top of single-layer graphene via TPO.8 We achieved high homogeneity and more than 90% selectivity in locally activated predefined regions for thicknesses up to 11 nm. The deposited thin films exhibited intriguing photoluminescent properties, broadening the material's characteristic excitation wavelength from ultraviolet to the visible light range. The work function, Raman spectroscopy, and fluorescence lifetime imaging data confirmed electronic interactions and n-type doping of TPO graphene after ALD/MLD. The demonstrated approach provides a path forward for integrating 2DM-based heterostructures into optoelectronic, photonic, and energy-harvesting devices. Sub-micron precision achieved in this work expands the design possibilities for multifunctional devices on a single chip. References Parsons G. N., Clark R. D., Chemistry of Materials. 2020, Volume 32, Issue 12, Multia J., Karppinen M., Advanced Materials Interfaces. 2022, Volume 9, Issue 15, Safdar M., Ghazy A., Tuomisto M., Lastusaari M, Karppinen M., Journal of Materials Science. 2021, Volume 56, 12634.Mackus A. J. M., Bol A. A., Kessles W. M. M., 2014 , Volume 6, Issue 9, 10941.Prasittichai C., Zhou H., Bent S. F., ACS Applied Materials & Interfaces. 2013 , Volume 5, Issue 24, Aumanen, A. Johansson, J. Koivistoinen, P. Myllyperkiö, M. Pettersson, Nanoscale 7, 2851 (2015).K. Mentel, A. V. Emelianov, A. Philip, A. Johansson, M. Karppinen, M. Pettersson, Adv. Mater. Interfaces 9, 2201110 (2022).A. V. Emelianov, K. K. Mentel, A. Ghazy, Yu-H. Wang, A. Johansson, M. Karppinen, M. Pettersson, submitted (2025). DOI: 10.26434/chemrxiv-2024-81qv0

Abstract Achieving efficient and long‐lasting afterglow that can be activated by visible light remains challenging. In this work, a melt‐injection strategy is proposed for the synthesis of afterglow materials. Excitingly, the afterglow materials can be excited by visible light with a wavelength of up to 500 nm, achieving a photoluminescence quantum yield of 25.6%. The efficient and visible light‐excited afterglow is attributed to a matrix‐stabilized dimers mechanism. Specifically, injection of formaldehyde into melt urea initiated the formation of urea‐formaldehyde (UF) matrix. Phenanthroline is incorporated into this matrix in the form of dimers, which caused a red‐shift in the absorption and excitation spectra of phenanthroline into the visible light range. Aided by hydrogen and chemical bonding, cross‐linking networks are established between the UF matrix and the phenanthroline dimers. These networks further reduce the energy gaps between the singlet and triplet states, promote the intersystem crossing processes, and stabilize the excitons from quenching. This research offers novel insights into the design of visible‐light‐activated afterglow materials, which show great potential in information security and bio‐imaging.