Search

Utilizing the reactive molecular dynamics (ReaxFF MD) simulation, we conducted a comprehensive study on the impact of basicity (OH−/Al3+ ratio), concentration, and temperature on the hydrolysis and polymerization reactions of Al3+‐solvated molecules. Through simulations, we analyzed the structural changes, energy fluctuations of the system, and the evolution patterns of reaction products under different parameters, which were subsequently validated by experimental data. The research results indicate that hydroxide ions in the solution directly influence the breakage of OH bonds in the coordinating water molecules of solvated aluminum ions. This, in turn, affects the number of H2O and OH− ions coordinated with Al3+, leading to changes in hydrolysis products. Additionally, the number of OH− ions surrounding Al3+ affects the electrostatic repulsion, making it easier for polymerization reactions to occur as the system approaches the point of zero charge. On the other hand, an increase in concentration and temperature enhances the frequency of cluster collisions, thus contributing to an increase in polymerization degree. The experimental results align closely with our simulated predictions. As the pH value increases, the particle size exhibits a trend of first increasing and then decreasing, reaching a maximum at the point of zero charge. Simultaneously, an increase in concentration also prompts an increase in particle size. The combination of these empirical results with simulations enhances the credibility and reliability of our model's predictive capabilities. This study not only expands our understanding of the relevant chemical reaction processes but also provides important theoretical support for practical applications in related fields. [ABSTRACT FROM AUTHOR]

Recognizing the essential factor governing interfacial hydrogen/oxygen evolution reactions (HER/OER) is central to electrocatalytic water‐splitting. Traditional strategies aiming at enhancing electrocatalytic activities have mainly focused on manipulating active site valencies or coordination environments. Herein, the role of interfacial adsorption is probed and modulated by the topological construct of the electrocatalyst, a frequently underestimated non‐Faradaic mechanism in the dynamics of electrocatalysis. The engineered Co0.75Fe0.25P nanorods, anchored with FeOx clusters, manifest a marked amplification of the surface electric field, thus delivering a substantially improved bifunctional electrocatalytic performance. In alkaline water splitting anion exchange membrane (AEM) electrolyzer, the current density of 1.0 A cm−2 can be achieved at a cell voltage of only 1.73 V for the FeOx@Co0.75Fe0.25P|| FeOx@Co0.75Fe0.25P pairs for 120 h of continuous operation at 1.0 A cm−2. Detailed investigations of electronic structures, combined with valence state and coordination geometry assessments, reveal that the enhancement of catalytic behavior in FeOx@Co0.75Fe0.25P is chiefly attributed to the strengthened adsorptive interactions prompted by the intensified electric field at the surface. The congruent effects observed in FeOx‐cluster‐decorated Co0.75Fe0.25P nanosheets underscore the ubiquity of this effect. The results put forth a compelling proposition for leveraging interfacial charge densification via deliberate cluster supplementation. [ABSTRACT FROM AUTHOR]

Electrochromic devices have gained great attention owing to their potential application in fields such as smart windows, glassware, and low-cost displays. Recent investigations have shown that the nickel phosphate films (NiHPO4·3H2O, NiHP films) are highly promising for the fabrication of large-area smart windows with large optical modulation. However, the performances such as the color switching time, coloration efficiency and cycling stability of such films are not ideal and need further investigations. In this study, we propose a layer-by-layer electrodeposition method for the fabrication of a composite metal phosphate film. A CoHPO4 layer is first deposited on the ITO glass as the frame, and then NiHPO4 is further electrodeposited on the CoHPO4 frame as an electrochromic active layer. The resulting film with NiHPO4 on CoHPO4 (CoHP/NiHP film) exhibits an optical modulation of 65.55%, a fast color switching time (tc/tb 2.0/8.5 s, the coloring time is three times faster than that of the pure NiHPO4 film), a high charge capacity (81.36 mF cm−2), excellent memory effect (10.53% attenuation after 5000 s), a high coloration efficiency (140.37 cm2 C−1, it is twice that of the pure NiHPO4 film) and 5 times improved outstanding cycling stability compared with the pure NiHPO4 film (1400 cycles with retained performance). The uniform nanosheet morphology of CoHPO4 provides a large active area for the electrochromic response. Meanwhile, the electrochemical investigations indicate that, compared with the pure NiHPO4 film, the NiHPO4 on CoHPO4 composite structure shows much faster electrical dynamics with diffusion coefficient values of OH− increased by an order of magnitude. The larger active area and much faster electrical dynamics promote the electrochromic performances of the metal phosphate films. Our findings may help in the development of metal phosphate films with high electrochromic performances. The layer-by-layer electrodeposition strategy may help to develop new types of electrochromic materials. [ABSTRACT FROM AUTHOR]

Designing reasonable atomic structures is essential in modulating the selectivity of the valuable products produced in the electrochemical CO2 reduction. Herein, a CuSn diatomic sites electrocatalyst stabilized by double oxygen vacancies on CeO2‐x is constructed, which exhibits superior electrochemical selectivity toward formate, achieving a 90.0% Faradaic efficiency at formate partial current density of 216.8 mA cm−2 with the applied bias of −1.2 V versus REH. The experimental characterizations and theoretical calculations highlight the significance of the synergistic effect of Cu and Sn diatoms on reducing the activation energy and promoting the formation of intermediate *OCHO, which accounts for its high selectivity toward formate. Meanwhile, the oxygen vacancies on the CeO2‐x also play a pivotal role in manipulating the electrochemical performance and stability, which underlines the importance of regulating the electronic metal‐support interaction between CuSn diatoms and CeO2‐x. This work demonstrates an effective method to design efficient electrochemical CO2 reduction catalysts by modulating the surface structures of single‐atoms anchored support. [ABSTRACT FROM AUTHOR]

Accurate determination of crop phenology information is essential for effective field management and decision-making processes. Remote sensing time series analyses are widely employed to extract the phenological stages. Each crop's phenological stage has its unique characteristic on the crop plant, while the satellite-derived crop phenology refers to some key transition dates in time series satellite observations. Current techniques primarily estimate specific phenological stages by detecting points with distinctive features on the remote sensing time series curve. But these stages may be different from the Biologische Bundesanstalt, Bundessortenamt and CHemical Industry (BBCH) scale, which is commonly used to identify the phenological development stages of crops. Moreover, when aiming to extract various phenological stages concurrently, it becomes necessary to adjust the extraction strategy for each unique feature. This need for distinct strategies at each stage heightens the complexity of simultaneous extraction. In this study, we utilize the Sentinel-2 Normalized Difference Vegetation Index (NDVI) time series data and propose a phenology extraction framework based on the Derivative Dynamic Time Warping (DDTW) algorithm. This method is capable of simultaneously extracting complete phenological stages, and the results demonstrate that the Root Mean Square Errors (RMSEs, days) of detected phenology on the BBCH scale for corn were less than 6 days overall. [ABSTRACT FROM AUTHOR]

Fiber reinforcement is an effective method to improve the inherent brittleness of conventional aerogels. However, high-density and complex preparation processes plague fiber-reinforced aerogel composites (FACs). For example, they are usually prepared using costly supercritical drying, freeze-drying, and time-consuming atmospheric drying, limiting the further development in applications and technologies of the material. Herein, a straightforward route to FACs is proposed. Namely, electrostatically spun nanofibers are used as reinforcement materials for aerogels. The nanofiber composite silica gel precursors are produced using chemical swelling and sol–gel techniques. Direct calcination is then used to prepare FACs with distinct nanoporous structures. As a result, FACs have a thermal conductivity as low as 0.029 W m–1 K–1 at room temperature, a high porosity of up to 99.55%, and excellent temperature resistance, maintaining a stable porous structure even at 1400 °C. Therefore, FACs have greater potential for thermal insulation applications. The route described in this study will contribute to the opening of a pathway for the simple preparation of FACs with ultralow density and high temperature resistance, thereby promoting the application and development of nanofiber-reinforced aerogel materials. [ABSTRACT FROM AUTHOR]