Department of Chemistry and Material Sciences

Accurate prediction of algal blooms is often hindered by the scarcity of high-frequency water quality data, as field monitoring typically provides only discontinuous and sparse measurements. While machine learning (ML) models require large training data sets and process-based models demand extensive parametrization, we develop a hybrid framework that leverages the complementary strengths of both to provide a practical decision support framework. Using a Random Forest algorithm to identify key algal bloom drivers from sparse monthly observations in the Lam Tsuen River, Hong Kong, we then reconstruct physically consistent, daily time-series for these drivers by Soil and Water Assessment Tool (SWAT). An ML model trained solely on these SWAT-reconstructed inputs achieves reliable chlorophyll-a predictions (test R2 = 0.58, Kling-Gupta Efficiency = 0.56, and root-mean-square error = 0.109 μg/L), demonstrating that accurate daily predictions can be obtained with a minimal set of variables. This study presents a parsimonious, transferable workflow that transforms limited monitoring data into an operational prediction tool, enabling cost-effective algal bloom management in data-limited watersheds.

The electrochemicalCO2 reduction (ECO2R)on copper (Cu) remains one of the most promising pathways to convertCO2 into value-added products. However, it suffers fromsevere restructuring, resulting in the unknown structural identityof the ECO2R active catalyst. Here, we show that dissolution–redepositionis the universal early-stage restructuring mechanism in ECO2R, occurring across all the tested Cu morphologies, including foils,nanoparticles, oxide-derived films, and gas diffusion electrodes.Using identical location scanning electron microscopy, we directlyvisualize and confirm that this transformation begins at the reactiononset, reshaping catalyst morphology and complicating structure–activityinterpretations. Our findings demonstrate that all the Cu catalystsact as precursors to their true, in situ-formed activephase, generated through the reduction of Cu oxides and electrolyte-drivendissolution-redeposition. Recognizing the universality of this transformationis essential for accurate mechanistic understanding and the rationaldesign of future Cu-based ECO2R catalysts.

Fast charging of lithium-ion batteries (LIBs) is currently crucial for the widespread use of electric vehicles and consumer electronics, but this process is challenged by the rapid consumption of liquid electrolytes. Commercial Al2O3 ceramic-based separators show low electrolyte absorption, so they cannot meet the future demands of fast charging. In this study, a sponge-like membrane composed of nanoporous SiO2 and a polyethylene substrate was developed as a separator for LIBs. The as-prepared SiO2-coated separator (S-CS) exhibits an excellent performance, including a high swelling degree (362%), ionic conductivity (7.8 × 10–3 S/cm at 25 °C), and a wide electrochemical stabilization window (5.1 V). The NMC523/S-CS/graphite pouch cell exhibits a discharge capacity retention of 88.9% and a Coulombic efficiency of 99.7% over 500 cycles at a fast-charging rate of 2 C and 25 °C. Furthermore, the cell does not show any lithium plating and a lower surface temperature (33.6 °C) after cycling, which significantly improves the safety of the fast charging of LIBs. Therefore, this study offers useful insights into the effect of separators on fast charging and strategic suggestions for the safe fast-charging of LIBs.

Abstract Novel substituted chromenopyrrolidinones were synthesized from natural amino acid derivatives through an unprecedented route involving a Knoevenagel/transesterification sequence and an allylative palladium-catalyzed cyclization reaction. The products were nature-inspired heterocycles derived from natural amino acids. The targets were synthesized with varying degrees of stereoselectivity: racemization is a known issue with amino acids, and this provided a formidable challenge to our method development. In total, six derivatives were synthesized in moderate to good yields.

Complex salts composed of cationic Au(i) and anionic Cu(i) species were synthesized by utilizing bis(diphenylarsino)methane (dpam) and bis(diphenylphosphino)methane (dppm) ligands. The discrete tetranuclear complexes were obtained as crystals, and the four-metal chain, CuAuAuCu, was linked through homo- and hetero-metallophilic interactions. Three crystal polymorphs were obtained for the dpam- and dppm-complexes, depending on the recrystallization solvent. All the crystals exhibited intense phosphorescence (quantum yields up to 0.97) at room temperature, and the emission color of each crystal was significantly different. The crystals could be interconverted by exposure to solvent vapor, and this was accompanied by a drastic change in the emission color.

Exodo-metallofullerene microcrystals of C60(SnI4)2 were produced by utilizing the “coffee-ring” effect during a simple drop-drying process.

Mesoporous carbon fibers, a kind of light weight microwave absorbing material, are prepared by electrospinning, through which the pore structure and microwave absorbing properties are influenced by the addition of tetraethyl orthosilicate.

Organogel formation was observed for isobutyl-substituted cage octasilsesquioxane (T8) in the main-chain type polyazomethines, while precipitates instead of gel formation were observed for phenyl-substituted double-decker-shaped silsesquioxanes (DDSQ)-poly(azomethine)s.

An interesting effect was observed when studying explosive and non-explosive crystalline ionic materials at high pressures. A wide benchmark set of 76 crystals of different families was studied using the state-of-the-art methods at ambient pressure and in extremes (at 20, 50 and 100 GPa). It was found that hydrostatic compression leads to an electron transfer from the anion to the cation, which was carried out with different efficiencies for explosive and non-explosive salts. The measure of this electron transfer is reflected in the Hirshfeld charges (q) on cations, which decreased with the rise of pressure. Non-explosive materials are generally resistant to this effect, while explosives are much more susceptible. Thus, at 100 GPa, all the studied energetic salts demonstrate qcat < +0.1e, while for the non-explosive salts qcat > +0.1e. This value can be considered as a conditional boundary between explosive and non-explosive salts. The observed effect is in accord with the Szigeti's dielectric theory as well as with the electrophilicity/electronegativity equalization principle. In the present paper, we develop a mechanism of the explosive decomposition based on the assumption about formation of a radical pair as a result of the following reaction: . The study of such radicals revealed their intrinsic instability, which generally reflects either in a dissociative structure or in the presence of strongly weakened trigger bonds.