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Chlorophyll-a (Chl-a) concentration is a key indicator for assessing the eutrophication level in water bodies. However, accurately inverting Chl-a concentrations in optically complex coastal waters presents a significant challenge for traditional models. To address this, we employed Sentinel-2 MSI sensor data and leveraged the power of five machine learning models, including a convolutional neural network (CNN), to enhance the inversion process in the coastal waters near Hong Kong. The CNN model demonstrated superior performance with on-site data validation, outperforming the other four models (R2 = 0.810, RMSE = 1.165 μg/L, MRE = 35.578%). The CNN model was employed to estimate Chl-a concentrations from images captured over the study area in April and October 2022, resulting in the creation of a thematic map illustrating the spatial distribution of Chl-a levels. The map indicated high Chl-a concentrations in the northeast and southwest areas of Hong Kong Island and low Chl-a concentrations in the southeast facing the open sea. Analysis of patch size effects on CNN model accuracy indicated that 7 × 7 and 9 × 9 patches yielded the most optimal results across the tested sizes. Shapley additive explanations were employed to provide post-hoc interpretations for the best-performing CNN model, highlighting that features B6, B12, and B8 were the most important during the inversion process. This study can serve as a reference for developing machine learning models to invert water quality parameters. [ABSTRACT FROM AUTHOR]

Aqueous zinc-ion batteries (ZIBs) have attracted significant attention as alternatives to lithium-ion batteries. In this case, vanadium pentoxide is a promising cathode material for aqueous zinc ion batteries. However, the small interlayer spacing of traditional vanadium oxide cathodes results in poor electrochemical performances, while their complex preparation steps also limit their applications. Herein, a simple and effective hydrothermal method was developed for the synthesis of K+ and H2O intercalated vanadium pentoxide (KVOH), which was realized by hydrogen peroxide-induced conversion from the vanadium oxide phase to a hydrated vanadium oxide phase. This bi-intercalated structure possesses a large interlayer spacing (10.2 Å), promoting the embedding and detachment of Zn2+. The enhanced diffusion kinetics was explained by the fact that the intercalated water shields the electrostatic interactions between Zn2+ and the vanadium oxide skeleton, which was demonstrated by the bonding distribution in the molecular structure of KVOH. The strong electronegativity of K+, strong K–O bonding, and the pillar interaction of K+ synergistically enhanced the structural stability and ionic diffusion kinetics (6.13 × 10−14 cm2 s−1, which is two orders of magnitude higher compared with V2O5). KVOH showed excellent capacity and rate performance, with a discharge specific capacity of up to 414.7 mA h g−1 (95.9%) at a current density of 0.1 A g−1 and up to 284 mA h g−1 (76.4%) after 800 cycles at a high current density of 1 A g−1. The present work provides an effective solution for the construction of vanadium-based cathode materials for ZIBs as well as for the development of high-efficiency aqueous energy storage devices. [ABSTRACT FROM AUTHOR]

To meet the increasing demand for energy storage, it is urgent to develop high-voltage lithium-ion batteries. The electrolyte’s electrochemical window is a crucial factor that directly impacts its electrochemical performance at high-voltage. Currently, the most common high-voltage cathode material is LiNi0.5Mn1.5O4 (LNMO). This paper aims to match LNMO cathode material to develop an electrolyte with stable electrochemical performance under high-voltage. Fluoroethylene carbonate (FEC) and lithium difluoro(oxalato)borate (LiDFOB) are studied as co-solvent and additive components in LiNi0.5Mn1.5O4 (LNMO) high-voltage electrolyte, respectively. This paper reports an increase in the electrochemical window from the original 4.3 to 5.5 V through the synergistic effect of two additives. The two additives also promote the formation of CEI layers on the cathode surfaces. This film acts as a protective barrier, safeguarding the electrode material’s structure from potential damage. After undergoing 100 cycles at a temperature of 25 °C, the rate of capacity retention can achieve a value of 75.1%; after 50 cycles at 40 °C, it can reach 78.2%. Our work offers guidance for the commercial production of high-performance, high-voltage lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Catalytic cracking of low-value oil fractions over ZSM-5 zeolites is a vital processing method for the manufacture of light olefins as critical building blocks in the petrochemical industry. Exploring novel zeolite engineering technologies that allow for better access to active sites and an optimized flow regime has long been one of the most important issues among scientific topics as well as in industrial practices. Herein, a monolith zeolitic catalyst with highly accessible active sites for enhanced catalytic cracking was fabricated by in situ crystal engineering on a digital light processing (DLP) 3D-printed woodpile scaffold. By anchoring crystal seeds onto the scaffold, a thick layer of ZSM-5 nanocrystals (ca. 60 μm) was in situ created on the monolith surface with the assistance of hydrothermal treatment, forming monolith zeolitic catalysts (MC-Z) with a high crystallinity of 41.2%. Such a high ZSM-5 loading on the 3D-printed scaffold surface enabled more acid sites to be accessible in catalytic reactions. In addition, a remarkable mass transfer advantage was revealed in the fabricated monolith zeolitic catalysts owing to their radial interconnected channels. The monolith zeolitic catalyst demonstrated superior activity in 1,3,5-triisopropylbenzene (TIPB) and n-octane cracking reactions. This strategy can be extended to other catalytic systems requiring highly accessible active sites to achieve further catalytic efficiency improvement as well as process intensification. [ABSTRACT FROM AUTHOR]