Xiaoshu Qu

Zinc oxide quantum dots (ZnO QDs) are promising for photodetectors but are limited by surface oxygen vacancies that impair photocurrent and stability. This study addresses this by incorporating the polyoxometalate {Mo ₁₃₂ } into ZnO QDs to modify their electronic properties. {Mo ₁₃₂ } broadens the light absorption range and its multiple redox‐active metal centers facilitate efficient multielectron transport. Crucially, this process passivates surface traps and suppresses oxygen vacancy formation, thereby enhancing charge separation and transport. Experimental results confirm that {Mo ₁₃₂ } doping significantly enhances the device performance. The photocurrent increased from 2100 to 2700 μA in I‐T tests. Under an illumination intensity of 80 mW·cm ⁻² and a bias voltage of 5 V, the responsivity ( R ) reaches 18.35 mA·W ⁻¹ . Furthermore, device stability was substantially improved, with the photocurrent retaining 81.08% of its initial value after 96 h. XPS measurements verified a significant (11.4%) reduction in the oxygen vacancy concentration. This work demonstrates that the unique molecular‐level electronic properties of polyoxometalates offer a novel and effective strategy for developing high‐performance, stable photodetectors, broadening their application in optoelectronics.

Three new inorganic-organic hybrid compounds, (H₃DIBA)₂·SiMo₁₂O₄₀·H₂O (1), (H₃DIBA)₂·SiW₁₂O₄₀·H₂O (2), and [(H₂DIBA)(H₃DIBA)]·PMo₁₂O₄₀·2H₂O (3) (HDIBA = 3,5-di(1H-imidazol-1-yl)benzoic acid) were synthesized by the hydrothermal method. The structures were characterized by single-crystal X-ray diffraction, elemental analysis, powder X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. These three compounds are all 3D supramolecular structures formed by Keggin-type polyoxometalate anions and HDIBA through intermolecular weak interactions, which have been studied via Hirshfeld surface analysis. The electrochemistry properties of 1 and 3 have been studied, including cyclic voltammetric behaviors and electrocatalytic properties. The study on the removal of organic dye pollutants in water showed that compounds 1 and 3 had an adsorption effect on cationic dye RhB, and the adsorption process conforms to the Langmuir isotherm model. Compound 2 can photocatalytically degrade cationic organic dyes RhB, MB, and CV, and the photocatalytic mechanism study indicates that h⁺ plays a major role in the photocatalytic process.

A bimetallic organic gel (MOG-Fe/Al) was synthesized through the solvothermal method. The gel state of the product obtained under optimized gel formation conditions is sufficient to carry 2 g of weight for a long time. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Brunauer–Emmett–Teller (BET) technique, and X-ray photoelectron spectroscopy (XPS) analysis confirmed the structures and morphologies of the synthesized materials. MOG-Fe/Al, with good stability, excellent durability, and wide applicability, exhibited efficient MO adsorption capacity as high as 335.88 mg/g at 25 °C. Adsorption-influencing factors including solution pH, contact time, and temperature were investigated. The adsorption performance of the bimetallic organic gel was better than that of the monometallic organic gels (MOG-Fe and MOG-Al), and its adsorption processes were in accordance with the pseudo-second-order kinetic and Langmuir isothermal models. The excellent adsorption capacity of the MOG-Fe/Al is due to its surface structure, pore volume, π-π interactions, hydrogen bonds, and electrostatic interactions.

A multicolor electrochromic material based on polyoxometalate and a dye with pH and voltage dual-adjustment was studied. The material (PEI/[PEI/P₂W₁₈/PEI/AR]₃₀/PEI (P₂W₁₈-AR) film) was prepared by a simple layer-by-layer method and tested in several solutions of different pH (pH 2.00, pH 4.00, and pH 6.00), referred to as F1, F2, and F3, respectively. By applying different voltages, the color of the film could change from yellow to blue-green (F1), pink-orange to blue-violet (F2), and dark pink to violet (F3), while maintaining good electrochromic performance and stability. Among them, F1 showed the best optical contrast up to 39.71%, and the optical contrast retention rate of F3 was 90.71% after 1000 cycles. Simultaneously, the fabricated electrochromic devices also showed color adjustments. This film was controlled by pH and voltage, providing a new method for the preparation of multicolor electrochromic composite materials.

Photocatalyst is the core of photocatalysis and directly determines photocatalytic performance. However, low quantum efficiency and low utilization of solar energy are important technical problems in the application of photocatalysis. In this work, a series of polyoxometalates (POMs) [H₃PW₁₂O₄₀] (PW₁₂)-doped titanium dioxide (TiO₂) nanofibers modified with various amount of silver (Ag) nanoparticles (NPs) were prepared by utilizing electrospinning/photoreduction strategy, and were labelled as x wt% Ag/PW₁₂/TiO₂ (abbr. x% Ag/PT, x = 5, 10, and 15, respectively). The as-prepared materials were characterized with a series of techniques and exhibited remarkable catalytic activities for visible-light degradation tetracycline (TC), enrofloxacin (ENR), and methyl orange (MO). Particularly, the 10% Ag/PT catalyst with a specific surface area of 155.09 m²/g and an average aperture of 4.61 nm possessed the optimal photodegradation performance, with efficiencies reaching 78.19% for TC, 93.65% for ENR, and 99.29% for MO, which were significantly higher than those of PW₁₂-free Ag/TiO₂ and PT nanofibers. Additionally, various parameters (the pH of the solution, catalyst usage, and TC concentration) influencing the degradation process were investigated in detail. The optimal conditions are as follows: catalyst usage: 20 mg; TC: 20 mL of 20 ppm; pH = 7. Furthermore, the photodegradation intermediates and pathways were demonstrated by HPLC-MS measurement. We also investigated the toxicity of products generated during TC removal by employing quantitative structure-activity relationship (QSAR) prediction through a toxicity estimation software tool (T.E.S.T. Version 5.1.2.). The mechanism study showed that the doping of PW₁₂ and the modification of Ag NPs on TiO₂ broadened the visible-light absorption, accelerating the effective separation of photogenerated carriers, therefore resulting in an enhanced photocatalytic performance. The research provided some new thoughts for exploiting efficient and durable photocatalysts for environmental remediation.

The key challenge in the practical application of electrochromic energy storage devices (EESDs) is the fabrication of high-performance electrode materials. Herein, we deposited K₇[La(H₂O)_x(α₂-P₂W₁₇O₆₁)] (P₂W₁₇La) onto TiO₂ nanowires (NW) to construct an NW–P₂W₁₇La nanocomposite using a layer-by-layer self-assembly method. In contrast to the pure P₂W₁₇La films, the nanocomposite exhibits enhanced electrochromic and electrochemical performance owing to the 3D sea-cucumber-like microstructure. An EESD using the NW–P₂W₁₇La film as the cathode exhibited outstanding electrochromic and energy storage properties, with high optical modulation (48.6% at 605 nm), high switching speeds (t_coloring = 15 s, t_bleaching = 4 s), and high area capacitance (5.72 mF cm⁻² at 0.15 mA cm⁻²). The device can reversibly switch between transparent and dark blue during the charge/discharge process, indicating that electrochromic contrast can be used as a quantitative indicator of the energy storage status.