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Platinum (Pt)–group metals, which are scarce and expensive, are used for the demanding oxygen reduction reaction (ORR) in hydrogen fuel cells. One competing approach for reducing their use is to create nanoparticles with earth-abundant metals to increase their activity and surface area; another is to replace them with metals such as cobalt (Co) in carbide or nitride sites. Chong et al. thermally activated a Co metal-organic framework compound to create ORR-active Co sites and then grew PtCo alloy nanoparticles on this substrate. The resulting catalyst had high activity and durability, despite its relatively low Pt content. Science , this issue p. 1276 Active cobalt sites and platinum-cobalt nanoparticles are combined in a highly active and durable oxygen reduction catalyst. Achieving high catalytic performance with the lowest possible amount of platinum is critical for fuel cell cost reduction. Here we describe a method of preparing highly active yet stable electrocatalysts containing ultralow-loading platinum content by using cobalt or bimetallic cobalt and zinc zeolitic imidazolate frameworks as precursors. Synergistic catalysis between strained platinum-cobalt core-shell nanoparticles over a platinum-group metal (PGM)–free catalytic substrate led to excellent fuel cell performance under 1 atmosphere of O 2 or air at both high-voltage and high-current domains. Two catalysts achieved oxygen reduction reaction (ORR) mass activities of 1.08 amperes per milligram of platinum (A mg Pt −1 ) and 1.77 A mg Pt −1 and retained 64% and 15% of initial values after 30,000 voltage cycles in a fuel cell. Computational modeling reveals that the interaction between platinum-cobalt nanoparticles and PGM-free sites improves ORR activity and durability.

HighlightsGraphene-like 2D V2O5 nanosheets rich in oxygen vacancies are designed as multi-functional catalysts to fabricate MgH2-H-V2O5 composites.Hydrogen release starts from 185 °C and capacity retention is as high as 99% after 100 cycles at 275 °C.The composites present rapid kinetics and impressive hydrogen absorption capability at near room temperature.The oxygen vacancies could directly enhance kinetics of MgH2 while indirectly exciting “hydrogen pump” effect of VH2/V.MgH2 is a promising high-capacity solid-state hydrogen storage material, while its application is greatly hindered by the high desorption temperature and sluggish kinetics. Herein, intertwined 2D oxygen vacancy-rich V2O5 nanosheets (H-V2O5) are specifically designed and used as catalysts to improve the hydrogen storage properties of MgH2. The as-prepared MgH2-H-V2O5 composites exhibit low desorption temperatures (Tonset = 185 °C) with a hydrogen capacity of 6.54 wt%, fast kinetics (Ea = 84.55 ± 1.37 kJ mol−1 H2 for desorption), and long cycling stability. Impressively, hydrogen absorption can be achieved at a temperature as low as 30 °C with a capacity of 2.38 wt% within 60 min. Moreover, the composites maintain a capacity retention rate of ~ 99% after 100 cycles at 275 °C. Experimental studies and theoretical calculations demonstrate that the in-situ formed VH2/V catalysts, unique 2D structure of H-V2O5 nanosheets, and abundant oxygen vacancies positively contribute to the improved hydrogen sorption properties. Notably, the existence of oxygen vacancies plays a double role, which could not only directly accelerate the hydrogen ab/de-sorption rate of MgH2, but also indirectly affect the activity of the catalytic phase VH2/V, thereby further boosting the hydrogen storage performance of MgH2. This work highlights an oxygen vacancy excited “hydrogen pump” effect of VH2/V on the hydrogen sorption of Mg/MgH2. The strategy developed here may pave a new way toward the development of oxygen vacancy-rich transition metal oxides catalyzed hydride systems.

HighlightsA comprehensive discussion of the recent advances in the nanostructure engineering of Mg-based hydrogen storage materials is presented.The fundamental theories of hydrogen storage in nanostructured Mg-based hydrogen storage materials and their practical applications are reviewed.The challenges and recommendations of current nanostructured hydrogen storage materials are pointed out.With the depletion of fossil fuels and global warming, there is an urgent demand to seek green, low-cost, and high-efficiency energy resources. Hydrogen has been considered as a potential candidate to replace fossil fuels, due to its high gravimetric energy density (142 MJ kg−1), high abundance (H2O), and environmental-friendliness. However, due to its low volume density, effective and safe hydrogen storage techniques are now becoming the bottleneck for the \"hydrogen economy\". Under such a circumstance, Mg-based hydrogen storage materials garnered tremendous interests due to their high hydrogen storage capacity (~ 7.6 wt% for MgH2), low cost, and excellent reversibility. However, the high thermodynamic stability (ΔH =  − 74.7 kJ mol−1 H2) and sluggish kinetics result in a relatively high desorption temperature (> 300 °C), which severely restricts widespread applications of MgH2. Nano-structuring has been proven to be an effective strategy that can simultaneously enhance the ab/de-sorption thermodynamic and kinetic properties of MgH2, possibly meeting the demand for rapid hydrogen desorption, economic viability, and effective thermal management in practical applications. Herein, the fundamental theories, recent advances, and practical applications of the nanostructured Mg-based hydrogen storage materials are discussed. The synthetic strategies are classified into four categories: free-standing nano-sized Mg/MgH2 through electrochemical/vapor-transport/ultrasonic methods, nanostructured Mg-based composites via mechanical milling methods, construction of core-shell nano-structured Mg-based composites by chemical reduction approaches, and multi-dimensional nano-sized Mg-based heterostructure by nanoconfinement strategy. Through applying these strategies, near room temperature ab/de-sorption (< 100 °C) with considerable high capacity (> 6 wt%) has been achieved in nano Mg/MgH2 systems. Some perspectives on the future research and development of nanostructured hydrogen storage materials are also provided.

HighlightsA MgH2/TiO2 heterostructure with nano MgH2 assembled on oxygen vacancy-rich 2D TiO2 nanosheets was successfully fabricated via a simple solvothermal strategy.The MgH2/TiO2 heterostructure shows rapid desorption kinetics, low dehydrogenation temperature, and excellent cycling stability.In situ HRTEM observations and ex situ XPS analyses reveal that multi-valance of Ti species, presence of abundant oxygen vacancies, formation of catalytic Mg-Ti oxides, and confinement of TiO2 nanosheets, contribute to the high stability and kinetically accelerated hydrogen sorption performances of Mg.MgH2 has attracted intensive interests as one of the most promising hydrogen storage materials. Nevertheless, the high desorption temperature, sluggish kinetics, and rapid capacity decay hamper its commercial application. Herein, 2D TiO2 nanosheets with abundant oxygen vacancies are used to fabricate a flower-like MgH2/TiO2 heterostructure with enhanced hydrogen storage performances. Particularly, the onset hydrogen desorption temperature of the MgH2/TiO2 heterostructure is lowered down to 180 °C (295 °C for blank MgH2). The initial desorption rate of MgH2/TiO2 reaches 2.116 wt% min−1 at 300 °C, 35 times of the blank MgH2 under the same conditions. Moreover, the capacity retention is as high as 98.5% after 100 cycles at 300 °C, remarkably higher than those of the previously reported MgH2-TiO2 composites. Both in situ HRTEM observations and ex situ XPS analyses confirm that the synergistic effects from multi-valance of Ti species, accelerated electron transportation caused by oxygen vacancies, formation of catalytic Mg-Ti oxides, and stabilized MgH2 NPs confined by TiO2 nanosheets contribute to the high stability and kinetically accelerated hydrogen storage performances of the composite. The strategy of using 2D substrates with abundant defects to support nano-sized energy storage materials to build heterostructure is therefore promising for the design of high-performance energy materials.

Panoramic imaging is increasingly critical in UAVs and high-altitude surveillance applications. In addressing the challenges of detecting small targets within wide-area, high-resolution panoramic images, particularly issues concerning accuracy and real-time performance, we have proposed an improved lightweight network model based on YOLOv8. This model maintains the original detection speed, while enhancing precision, and reducing the model size and parameter count by 10.6% and 11.69%, respectively. It achieves a 2.9% increase in the overall mAP@0.5 and a 20% improvement in small target detection accuracy. Furthermore, to address the scarcity of reflective panoramic image training samples, we have introduced a panorama copy–paste data augmentation technique, significantly boosting the detection of small targets, with a 0.6% increase in the overall mAP@0.5 and a 21.3% rise in small target detection accuracy. By implementing an unfolding, cutting, and stitching process for panoramic images, we further enhanced the detection accuracy, evidenced by a 4.2% increase in the mAP@0.5 and a 12.3% decrease in the box loss value, validating the efficacy of our approach for detecting small targets in complex panoramic scenarios.

In recent years, photovoltaic/thermal (PV/T) systems have played a crucial role in reducing energy consumption and environmental degradation, nonetheless, the low energy conversion efficiency presents a considerable obstacle for PV/T systems. Therefore, improving heat conversion efficiency is essential to enhance energy efficiency. In this paper, the PV/T system with the Tesla valve is proposed to solve this problem. Firstly, the cooling effect is simulated and analyzed in the system with four different flow channel structures: semicircle, rectangle, triangle and Tesla valve. The results indicate that the system with the Tesla valve exhibits superior cooling performance. Subsequently, several factors including angle, valve number, valve type, and pipe diameter ratio for the Tesla valve are further studied through numerical and simulation analysis. The results reveal that Tesla valves demonstrate optimal cooling performance when possessing the following structural parameters: complete symmetry, more valves, a 30-degree angle and a pipe diameter ratio of 1. Finally, four different types of fluid are selected to explore the Tesla valve. The conclusion shows that nanofluids with high density, low specific heat, and high thermal conductivity also improve the cooling performance. Thus, the PV/T system with the Tesla valve exhibits good heat dissipation and energy storage efficiency, electrical efficiency can reach 16.32% and thermal efficiency reach 59.65%.

Magnesium hydride (MgH 2 ) is a promising solid-state hydrogen source with high storage capacity (7.6 wt%). Although it is recently established that MgH 2 has potential applications in medicine because it sustainably supplies hydrogen gas (H 2 ), the biological functions of MgH 2 in plants have not been observed yet. Also, the slow reaction kinetics restricts its practical applications. In this report, MgH 2 (98% purity; 0.5–25 μm size) was firstly used as a hydrogen generation source for postharvest preservation of flowers. Compared with the direct hydrolysis of MgH 2 in water, the efficiency of hydrogen production from MgH 2 hydrolysis could be greatly improved when the citrate buffer solution is introduced. These results were further confirmed in the flower vase experiment by showing higher efficiency in increasing the production and the residence time of H 2 in solution, compared with hydrogen-rich water. Mimicking the response of hydrogen-rich water and sodium hydrosulfide (a hydrogen sulfide donor), subsequent experiments discovered that MgH 2 -citrate buffer solution not only stimulated hydrogen sulfide (H 2 S) synthesis but also significantly prolonged the vase life of cut carnation flowers. Meanwhile, redox homeostasis was reestablished, and the increased transcripts of representative senescence-associated genes, including DcbGal and DcGST1 , were partly abolished. By contrast, the discussed responses were obviously blocked by the inhibition of endogenous H 2 S with hypotaurine, an H 2 S scavenger. These results clearly revealed that MgH 2 -supplying H 2 could prolong the vase life of cut carnation flowers via H 2 S signaling, and our results, therefore, open a new window for the possible application of hydrogen-releasing materials in agriculture.

Aqueous zinc batteries are attractive for large-scale energy storage due to their inherent safety and sustainability. However, their widespread application has been constrained by limited energy density, underscoring a high demand of advanced cathodes with large capacity and high redox potential. Here, we report a reversible high-capacity six-electron-conversion Se cathode undergoing a ZnSe↔Se↔SeCl 4 reaction, with Br − /Br n − redox couple effectively stabilizes the Zn | |Se cell. This Se conversion, initiated in a ZnCl 2 -based hydrogel electrolyte, presents rapid capacity decay (from 1937.3 to 394.1 mAh g Se −1 after only 50 cycles at 0.5 A g Se −1 ) primarily due to the dissolution of SeCl 4 and its subsequent migration to the Zn anode, resulting in dead Se passivation. To address this, we incorporate the Br − /Br n − redox couple into the Zn | |Se cell by introducing bromide salt as an electrolyte additive. The generated Br n − species acts as a dead-Se revitalizer by reacting with Se passivation on the Zn anode and regenerating active Se for the cathode reaction. Consequently, the cycling stability of the Zn | |Se cell is improved, maintaining 1246.8 mAh g Se −1 after 50 cycles. Moreover, the Zn | |Se cell exhibits a specific capacity of 2077.6 mAh g Se −1 and specific energy of 404.2 Wh kg −1 based on the overall cell reaction. Developing chemistries for positive electrodes with large specific capacities and high operating potentials is highly desirable for aqueous zinc batteries. Here, authors report a reversible Se electrode that undergoes ZnSe↔Se↔SeCl 4 reaction, combined with Br − /Br n – redox couple as Se revitalizer to enhance cycling performance.

With the challenge of increasing global carbon emissions and climate change, the importance of solar energy as a clean energy source is becoming more pronounced. Accurate solar radiation prediction is crucial for planning and operating solar energy systems. However, the accurate measurement of solar radiation faces challenges due to the high cost of instruments, strict maintenance, and technical complexity. Therefore, this paper proposes a deep learning approach that integrates the Sparrow Search Algorithm (SSA), Convolutional Neural Networks (CNN), and Long Short-Term Memory (LSTM) networks for solar radiation forecasting. The study utilizes solar radiation data from Songjiang District, Shanghai, China, from 2019 to 2020 for empirical analysis. Initially, a correlation analysis was conducted to identify the main factors affecting the intensity of solar radiation, including temperature, clear-sky GHI, solar zenith angle, and relative humidity. Subsequently, the forecasting effectiveness of the model was compared on datasets of 10 min, 30 min, and 60 min, revealing that the model performed best on the 60 min dataset, with a determination coefficient (R2) of 0.96221, root mean square error (RMSE) of 65.9691, and mean absolute error (MAE) of 37.9306. Moreover, comparative experimental results show that the SSA-CNN-LSTM model outperforms traditional LSTM, BiLSTM, and CNN-LSTM models in forecasting accuracy, confirming the effectiveness of SSA in parameter optimization. Thus, the SSA-CNN-LSTM model provides a new and efficient tool for solar radiation forecasting, which is of significant importance for the design and management of solar energy systems.