Search

The fabrication of the flexible devices with excellent photovoltaic performance and stability is critical for the commercialization of organic solar cells (OSCs). Herein, the conjugated dimer acceptor DY‐TVCl and the non‐conjugated dimer acceptor DY‐3T based on the monomer MY‐BO are synthesized to regulate the molecular glass transition temperatures (Tg) for improving the morphology stability of active layer films. And the crack onset strain values for the blend films based on dimer acceptors are superior than that of small molecule, which are beneficial for the preparation of flexible devices. Accordingly, the binary device based on PM6:DY‐TVCl achieves a maximum power conversion efficiency (PCE) of 18.01%. Meanwhile, the extrapolated T80 (time to reach 80% of initial PCE) lifetimes of the PM6:DY‐TVCl‐based device and PM6:DY‐3T‐based device are 3091 and 2227 h under 1‐sun illumination, respectively, which are better than that of the PM6:MY‐BO‐based device (809 h). Furthermore, the flexible devices based on DY‐TVCl and DY‐3T exhibit the efficiencies of 15.23% and 14.34%, respectively. This work affords a valid approach to improve the stability and mechanical robustness of OSCs, as well as ensuring the reproducibility of organic semiconductors during mass production. [ABSTRACT FROM AUTHOR]

Salinispirillum sp. LH 10-3-1 was newly isolated from the alkali lake water samples collected in Inner Mongolia. In this study, a gene coding for D-lactate dehydrogenase from the strain LH 10-3-1 (SaLDH) was cloned and characterized. The recombinant enzyme was a tetramer with a native molecular mass of 146.2 kDa. The optimal conditions for SaLDH to reduce pyruvate and oxidize D-lactic acid were pH 8.0 and pH 5.0, at 25 °C. Cu2+ and Ca2+ slightly promoted the oxidation and reduction activities of SaLDH, respectively. To improve the stability of SaLDH, the enzyme was immobilized on Cu3(PO4)2-based inorganic hybrid nanoflowers. The results showed that the reduction activity of the hybrid nanoflowers disappeared, and the optimum temperature, specific activity, thermostability, and storage stability of the immobilized SaLDH were significantly improved. In addition, the biotransformation of D-lactic acid to pyruvate catalyzed by SaLDH and the hybrid nanoflowers was investigated. The maximum conversion of D-lactic acid catalyzed by the immobilized SaLDH was 25.7% higher than by free enzymes, and the immobilized SaLDH could maintain 84% of its initial activity after six cycles. [ABSTRACT FROM AUTHOR]

Gallium oxide (Ga2O3), with an ultrawide bandgap corresponding to the deep ultraviolet (DUV) range, has attracted significant attention in optical filter‐free photodetectors. In practical terms, DUV photodetectors employed in extreme conditions, for example, flame detection and space exploration, face the challenges of performance degradation caused by high/low‐temperature transformation. Here, DUV photodetectors are tailored with high durability and stability by one‐step‐grown β‐Ga2O3 films via pulsed laser deposition. A high‐oxygen‐pressure scheme effectively addresses the issue of film‐free deposition at specifically high temperatures, facilitating the formation of polycrystalline high‐resistivity β‐Ga2O3 films. As a result, the devices exhibit outstanding performance, including a low dark current (4.4 pA @30 V), high photoresponsivity (147.36 A W−1), and fast response time (3.1/22.6 ms). Additionally, the photoresponse performance shows minimal degradation at high temperatures up to 300 °C and even improves at low temperatures down to −100 °C, ranking it among the most robust DUV photodetectors. The mechanism of photoresponse, involving the exciton formation, bandgap evolution, carrier‐phonon scatter, etc., is also elucidated in a wide temperature range. This work provides an efficient solution for developing robust Ga2O3 DUV photodetectors with excellent performance for extreme‐condition applications. [ABSTRACT FROM AUTHOR]

With the rapid development of modern communication technology, it has become a core problem in the field of communication to find new ways to effectively modulate signals and to classify and recognize the results of automatic modulation. To further improve the communication quality and system processing efficiency, this study combines two different neural network algorithms to optimize the traditional signal automatic modulation classification method. In this paper, the basic technology involved in the communication process, including automatic signal modulation technology and signal classification technology, is discussed. Then, combining parallel convolution and simple cyclic unit network, three different connection paths of automatic signal modulation classification model are constructed. The performance test results show that the classification model can achieve a stable training and verification state when the two networks are connected. After 20 and 29 iterations, the loss values are 0.13 and 0.18, respectively. In addition, when the signal-to-noise ratio (SNR) is 25dB, the classification accuracy of parallel convolutional neural network and simple cyclic unit network model is as high as 0.99. Finally, the classification models of parallel convolutional neural networks and simple cyclic unit networks have stable correct classification probabilities when Doppler shift conditions are introduced as interference in practical application environment. In summary, the neural network fusion classification model designed can significantly improve the shortcomings of traditional automatic modulation classification methods, and further improve the classification accuracy of modulated signals. [ABSTRACT FROM AUTHOR]

The work presented an electrochemical anode method with different electrolyte concentrations and heat posttreatment to control the stoichiometry and structure of Cu2−xS electrocatalysts. X‐ray diffraction, X‐ray photoelectron spectroscopy, and scanning electron microscopy were employed to characterize the composition and morphology, whereas the electrocatalytic activity was evaluated by linear scanning voltammetry and electrochemical impedance spectroscopy. The results showed that the electrochemical method successfully synthesized thin flake‐shaped Cu7S4, which exhibited optimal performance at the electrolyte concentration of 0.45 mol L1 with maximum turnover frequency of 0.786 s−1, maximum mass activity of 0.539 A g−1, minimum charge transfer resistance of 0.156 Ω cm−2, and minimum overpotential of 154 mV at a current density of 10 mA cm−2. In the Cu7S4 structure, Cu2+ and S2− were coordinated in a CuS4 tetrahedral structure, whereas Cu+ and S2− were coordinated in a CuS3 triangular structure. Heat posttreatment could change the stoichiometry from 1.75 to 1.8 and improve the electrochemical performance. In the Cu9S5 structure, the CuS3 triangular structure had disappeared. Under the same conditions, the overvoltage was only 128 mV. [ABSTRACT FROM AUTHOR]

A numerical simulation model of a natural ventilation greenhouse is helpful for improving the production and quality of greenhouse crops in tropical areas. Field experiments show that the mean coefficient of variation of indoor light intensity in four seasons was lower than 10.0%. The highest indoor temperature reached 39.3 °C during summer, while the average indoor temperature ranged from 24 °C to 26 °C in the other three seasons. The average relative humidity in the greenhouse ranged from 76% to 87% annually, which was higher and more stable than that in the external environment. A three-dimensional steady-state numerical model of the greenhouse was established based on computational fluid dynamics. Under natural ventilation conditions, the maximum error between the simulated value and the measured value of the temperature in each measuring point was 5.90%. And the average relative error between the simulated and measured values was 3.0% in the range of 0.7−1.5 m of crop cultivation height. Finally, a numerical simulation of adding side windows and expanding the vents was carried out. The results show that these methods can homogenize the airflow distribution in the greenhouse and improve the utilization efficiency of natural ventilation without more mechanical system operations. [ABSTRACT FROM AUTHOR]

2D metal-organic frameworks (MOFs) have emerged as potential candidates for electrocatalytic oxygen evolution reactions (OER) due to their inherent properties like abundant coordination unsaturated active sites and efficient charge transfer. Herein, a versatile and massively synthesizable self-etching assembly strategy wherein nickel-iron foam (NFF) acts as a substrate and a metal ion source. Specifically, by etching the nickel-iron foam (NFF) surface using ligands and solvents, Ni/Fe metal ions are activated and subsequently reacted under hydrothermal conditions, resulting in the formation of self-supporting nanosheet arrays, eliminating the need for external metal salts. The obtained 33 % NiFeMOF/NFF exhibits remarkable OER performance with ultra-low overpotentials of 188/231 mV at 10/100 mA cm -2 , respectively, outperforming most recently reported catalysts. Besides, the built 33 % NiFeMOF/NFF (+) ||Pt/C (-) electrolyzer presents low cell voltages of 1.55/1.83 V at 10/100 mA cm -2 , superior to the benchmark RuO 2 (+) ||Pt/C (-) , implying good industrialization prospects. The excellent catalytic activity stems from the modulation of the electronic spin state of the Ni active site by the introduction of Fe, which facilitates the adsorption process of oxygen-containing intermediates and thus enhances the OER activity. This innovative approach offers a promising pathway for commercial-scale sustainable energy solutions., (© 2024 Wiley-VCH GmbH.)

Doping metals and constructing heterostructures are pivotal strategies to enhance the electrocatalytic activity of metal-organic frameworks (MOFs). Nevertheless, effectively designing MOF-based catalysts that incorporate both doping and multiphase interfaces poses a significant challenge. In this study, a one-step Co-doped and Co 3 O 4 -modified Ni-MOF catalyst (named Ni NDC-Co/CP) with a thickness of approximately 5.0 nm was synthesized by a solvothermal-assisted etching growth strategy. Studies indicate that the formation of the Co-O-Ni-O-Co bond in Ni NDC-Co/CP was found to facilitate charge density redistribution more effectively than the Co-O-Ni bimetallic synergistic effect in NiCo NDC/CP. The designating Ni NDC-Co/CP achieved superior oxygen evolution reaction (OER) activity (245 mV @ 10 mA cm -2 ) and robust long stability (100 h @ 100 mA cm -2 ) in 1.0 M KOH. Furthermore, the Ni NDC-Co/CP (+) ||Pt/C/CP (-) displays pregnant overall water splitting performance, achieving a current density of 10 mA cm -2 at an ultralow voltage of 1.52 V, which is significantly lower than that of commercial electrolyzer using Pt/C and IrO 2 electrode materials. In situ Raman spectroscopy elucidated the transformation of Ni NDC-Co to Ni(Co)OOH under an electric field. This study introduces a novel approach for the rational design of MOF-based OER electrocatalysts.