Lixia Li

The electrocatalytic reduction of nitrate to ammonia (NH₃) under mild environmental conditions is attracting increasing attention, in which efficient and inexpensive transition metal catalysts, with the advantages of abundancy and low cost, play a key role. However, synergistic activity and selectivity promotion are still highly challenging. Herein, we developed a hydrogel-assisted strategy to prepare FeNi nanoparticles via the in situ adsorption and reduction of Fe/Ni precursors on a polypyrrole hydrogel. After optimization, the maximum NH₃ yield reached 0.166 mmol h⁻¹ cm⁻², with a Faradaic efficiency of 88.9% and a selectivity of 86.6%. This excellent electrochemical performance was attributed to the mesoporous hydrophilic structure of the polypyrrole hydrogel, which facilitates the homogeneous loading of FeNi nanoparticles and provides a channel for both charge and mass transfer during nitrate reduction, which is important for the conversion of NO₃⁻ to NH₃. Electrochemical active surface area determination and impedance spectroscopy showed that the introduction of hydrogel increased the active sites and improved the charge transfer. This study provides an effective strategy for improving the selectivity and yield of NH₃ in transition metal electrocatalysts by utilizing the three-dimensional hydrogel network and electrical conductivity.

The manipulation of trap states plays a crucial role in the development of efficient photocatalysts. An ultrathin-shelled Zn-AgIn₅S₈/ZnS quantum dots (QDs) photocatalyst was synthesized via in situ growth using a low-temperature hydrothermal method. The optical properties of the samples coated with ZnS shell were studied vis UV-vis absorption and fluorescence spectra. The ultrathin ZnS shell plays an important role in the Zn-AgIn₅S₈/ZnS core–shell heterostructure photocatalytic water splitting system, which could reduce surface defects, prolong the carrier lifetime and improve the photo-generated electron–hole pair separation effectively, resulting in the improved photocatalytic efficiency and enhanced stability of the catalyst. The results provide an effective guideline for shell thickness design in future constructions of the core–shell heterostructure photocatalyst.

Economic development is often accompanied by a variety of production safety accidents. Currently, human factors have become the main constraint on safety for enterprises, especially small and medium-sized. Establishing corporate safety culture is an important approach to addressing that issue and improving the intrinsic safety level of enterprises. In this paper, an element system for safety culture construction, containing eight primary elements and 32 secondary elements, for medium and small enterprises was put forward according to the actual situation of safety production in enterprises in industrial parks using an expert survey method. This system integrated the construction of safety culture into the existing management system and specific safety work so that it had good implementability. Then, using SPSSAU online analysis software, expert surveys, and analytic hierarchy process (AHP), as well as the expert survey method, weights and rankings of every element of this safety culture element construction system were determined, which could provide a reference for the efficient of the safety culture construction. It is very important to evaluate the enterprise safety culture construction. Here, a set of quantitative evaluation methods was proposed, which combined a direct quantitative evaluation for secondary elements and a fuzzy comprehensive evaluation method for the primary elements and the whole safety culture construction. This method can be used to evaluate the effectiveness of enterprise safety culture construction, identify weaknesses and continuously improve, and could also serve as a reference for government regulatory agencies, insurance companies, or third-party organizations to assess enterprise security.

The creation of junctions between 0D and 2D materials can be an efficient strategy to enhance charge separation for solar hydrogen production. In this study, a simple in situ growth method has been used to synthesize a series of 0D/2D Zn-Ag-In-S quantum dots/reduced graphene oxide (ZAIS QDs/RGO) heterojunctions. The developed heterojunctions were characterized for structural characteristics, morphology, and photocatalytic performance, while varying the content of RGO. We observed that photocatalytic hydrogen production reached a maximum at an RGO content of 30 μL (342.34 µmol g⁻¹ h⁻¹), surpassing that of pure ZAIS QDs (110.38 µmol g⁻¹ h⁻¹) by 3.1 times, while maintaining excellent stability. To understand this enhancement, we performed time-resolved fluorescence and electrochemical impedance spectroscopy. The fluorescence lifetime of RGO loaded at 30 μL (417.76 ns) was significantly higher than that of pure ZAIS QDs (294.10 ns) and had the fastest charge transfer, which can be attributed to the charge transfer and storage capacity of RGO to extend the lifetime of photogenerated carriers and improve the charge separation efficiency. This study offers a simple synthesis method for constructing 0D/2D QDs/RGO heterojunction structures and provides a valuable reference for further enhancing the activity and stability of I-III-VI sulfide QDs.

Silica aerogels are considered as the distinguished materials of the future due to their extremely low thermal conductivity, low density, and high surface area. They are widely used in construction engineering, aeronautical domains, environmental protection, heat storage, etc. However, their fragile mechanical properties are the bottleneck restricting the engineering application of silica aerogels. This review briefly introduces the synthesis of silica aerogels, including the processes of sol–gel chemistry, aging, and drying. The effects of different silicon sources on the mechanical properties of silica aerogels are summarized. Moreover, the reaction mechanism of the three stages is also described. Then, five types of polymers that are commonly used to enhance the mechanical properties of silica aerogels are listed, and the current research progress is introduced. Finally, the outlook and prospects of the silica aerogels are proposed, and this paper further summarizes the methods of different polymers to enhance silica aerogels.

The thermal safety problem of lithium-ion batteries (LIB) in use requires an excellent thermal management system to preserve it. In the paper, an expansion flame-retardant composed of APP and CFA and kaolinite is used to enhance the flame-retardant property of phase change materials (PCM). The performances of PCM and their property in the thermal management of LIB were studied. The results indicate that the kaolinite can improve the long-term thermostability of PCM. The addition of flame retardant can make the flame-retardant property of PCM reach V0 level. The synergistic action of expansion flame-retardant and kaolinite can increase the residual carbon and enhance the thermal reliability of flame-retardant PCM (RPCM). The RPCM has an obvious cooling effect on the surface temperature of the battery. The RPCM can reduce the maximum temperature of the cell to 37.4 °C at 3 C, which is 12 °C lower than pure PA. The peak temperature of the battery pack at 3 C is also reduced to 50.28 °C by the flame-retardant PCM, and the temperature difference is kept within 5 °C.

This study proposed a method for identifying traffic accident (TA) hotspots. The method combines kernel density estimation (KDE) with network kernel density estimation (NKDE). The hotspots identified through NKDE can be overlaid on the high-risk areas (hot zones) identified using planar KDE, resulting in accurate hotspot identification. The research site was Zhenjiang City in Jiangsu Province, China; data on 410 fatal traffic accidents from 2017 to 2020 were collected. An average nearest neighbour (ANN) ratio (0.563) was obtained using the global auto nearest neighbour distance method; thus, the fatal TAs had a cluster-type distribution in the city. Subsequently, the maximum clustering distance (7812.842591 m) in the research site was analysed using Ripley’s K-function, which yielded a reasonable KDE bandwidth and enabled identifying the distribution of hot zones for fatal TAs. Precise hotspot identification was achieved by overlaying the results of NKDE-based analysis in these hot zones. The proposed method was verified using data on 131 fatal TAs during January to July 2021. The results revealed that, in Zhenjiang City, the identification rate for hot zones and hotspots in hot zones was 71.75% and 38.29%, respectively, and the overall hotspot identification rate was 27.48%, demonstrating the method’s ability to relatively accurately identify hotspot locations, information that can help traffic authorities implement preventive measures.