The development of electromagnetic wave absorbing materials with wideband absorption and thin thickness confronts huge challenges in addressing the aggravating problem of electromagnetic pollution. Herein, hollow core–shell Fe₃O₄@MoS₂ microspheres with controllable interior and tunable shell are constructed to precisely regulate the electromagnetic wave attenuation. The results demonstrate that hollow Fe₃O₄ microspheres exhibit strong absorption in C–X bands owing to their strong ferromagnetic resonance. By structural regulation, hollow core–shell Fe₃O₄@MoS₂ microspheres not only ensure superior electromagnetic wave absorption intensity at thin thickness, but also endow wideband absorption. Benefiting from the cooperative merits of manipulated Fe₃O₄ interior and controllable MoS₂ shells, the as-synthesized microspheres display obvious interface polarization, defect/dipole polarization, and multiple scatterings, thereby resulting in ameliorated impedance matching and outstanding attenuation performance. Especially for Fe₃O₄@MoS₂-2, the minimum reflection loss is − 69.01 dB at 2.66 mm and the effective absorption bandwidth reaches 8.40 GHz when the thickness is 3.0 mm. This study systematically investigates the balance relationships between core–shell structures and absorption attenuation, and simultaneously provides a referable strategy to modulate the electromagnetic wave absorption by structural optimization.

Levulinic acid (LA) is a promising renewable platform compound derived from biomass for the manufacture of various valuable chemicals, among which levulinate esters have been demonstrated to be good fuel additives. Many previous studies have focused on the production of short-chain levulinates for biofuels such as methyl and ethyl levulinates, but these esters suffer from some essential issues including a high oxygen content, low energy density (or heating value) and water solubility. Long-chain levulinate esters have similar structures to biodiesel. The long carbon chain may provide a higher carbon content and strong hydrophobicity, therefore improving the energy density and water insolubility. In this work, the synthesis of a long-chain levulinate ester, n-hexyl levulinate (HL), has been fast and efficiently achieved by the catalytic esterification of LA and 1-hexanol at low temperature. Tungsten hexachloride (WCl₆) showed the most superior activity among the tested metal salt catalysts under mild conditions. A HL yield of ∼85% with almost complete LA conversion could be obtained at 50 °C after only 30 min. Other hexanols that have larger steric hindrances, such as 2-ethyl-1-butanol, 2-hexanol, 3-hexanol and cyclohexanol, could also promote efficient esterification with LA over the WCl₆ catalyst, resulting in excellent product yields of ∼82–91%. The strategy applies to the efficient synthesis of longer chain levulinate esters such as n-octyl levulinate (OL) as well. The WCl₆ catalyst was reusable several times in a consecutive batch reaction mode. The method reported herein offers a strategy for the efficient production of liquid fuels from LA, potentially bridging raw biomass feedstocks and terminal utilization of biobased products.

The introduction of Al ₂ O ₃ increased the number of weak acid sites, altered the copper chemical state and improved the catalytic performance and stability consequently.

An easy access to a series of previously unreported heterodinuclear Pd-Ln compounds, Pd-bpydc-La, Pd-bpydc-Ce and Pd-bpydc-Nd (bpydc = 2,2′-bipyridine-5,5′-dicarboxylate) has been developed. The Pd-Ln hybrid networks were effectively applied as catalysts in Suzuki–Miyaura C-C cross-coupling reactions of 4-bromoanisole and 4-bromobenzonitrile with phenylboronic acid, under mild conditions. A systematic investigation revealed Pd-bpydc-Nd as the most active catalyst. In all cases, reaction yields varied with the base, catalyst loading and substantially augmented with temperature (from 30 to 60 °C). Substituent effects were operative when changing from 4-bromoanisole to 4-bromobenzonitrile. The key role played by the lanthanides, aromatic substrate and base, in modulating the Pd-catalytic cycle has been highlighted. Importantly, the new catalysts proved to be stable in air and vs. functionalities and are quite efficient in Suzuki–Miyaura carbon-carbon bond formation conducted in protic solvents.

A series of Ni/SiO₂ catalysts with different Ni content were prepared by sol‐gel method for application in the synthesis of 2‐methyltetrahydrofuran (2‐MTHF) by hydrogenation of 2‐methylfuran (2‐MF). The catalyst structure was investigated by X‐ray diffraction (XRD), transmission electron microscopy (TEM), X‐ray photoelectron spectroscopy (XPS), and temperature programmed reduction (TPR). It is found that structures and catalytic performance of the catalysts were highly affected by the Ni content. The catalyst with a 25% Ni content had an appropriate size of the Ni species and larger BET surface area and produced a higher 2‐MF conversion with enhanced selectivity in 2‐MTHF.