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Highly Strong, Tough, and Cryogenically Adaptive Hydrogel Ionic Conductors via Coordination Interactions.

Despite the promise of high flexibility and conformability of hydrogel ionic conductors, existing polymeric conductive hydrogels have long suffered from compromises in mechanical, electrical, and cryoadaptive properties due to monotonous functional improvement strategies, leading to lingering challenges. Here, we propose an all-in-one strategy for the preparation of poly(acrylic acid)/cellulose (PAA/Cel) hydrogel ionic conductors in a facile yet effective manner combining acrylic acid and salt-dissolved cellulose, in which abundant zinc ions simultaneously form strong coordination interactions with the two polymers, while free solute salts contribute to ionic conductivity and bind water molecules to prevent freezing. Therefore, the developed PAA/Cel hydrogel simultaneously achieved excellent mechanical, conductive, and cryogenically adaptive properties, with performances of 42.5 MPa for compressive strength, 1.6 MPa for tensile strength, 896.9% for stretchability, 9.2 MJ m-3 for toughness, 59.5 kJ m-2 for fracture energy, and 13.9 and 6.2 mS cm-1 for ionic conductivity at 25 and -70 °C, respectively. Enabled by these features, the resultant hydrogel ionic conductor is further demonstrated to be assembled as a self-powered electronic skin (e-skin) with high signal-to-noise ratio for use in monitoring movement and physiological signals regardless of cold temperatures, with hinting that could go beyond high-performance hydrogel ionic conductors.

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Open Access
Catalytic valorization of biomass carbohydrates into levulinic acid/ester by using bifunctional catalysts

Methyl levulinate (ML) and levulinic acid (LA), important platform chemicals derived from biomass carbohydrates, are potential candidates for use as fuel additives and chemicals. In this work, bifunctional solid acid catalysts were prepared by impregnation via an environmentally friendly method and used for the conversion of glucose to ML and LA. In the conversion of glucose to levulinate, the isomeric conversion of glucose into fructose mainly utilized the Lewis acid sites properties exhibited by chromium, and the dehydration of fructose to 5-hydroxymethylfurfural and its degradation to levulinate mainly exploited the Brønsted acid sites properties exhibited by A15. The yield of ML and LA was 43.1 % and 1.2 %, respectively, and glucose was completely transformed into methanol within 2.0 h at 200 °C. The excellent activity of the best catalyst may be due to the sufficient total acidity and suitable ratio of the number of Lewis acid sites to that of Brønsted acid sites. The results for five catalysis cycles proved that the catalyst has good stability and reusability. In addition, the catalyst prepared was effective for the conversion of other carbohydrates, namely, sucrose, cellobiose, and 5-hydroxymethylfurfural to ML with yields of 83.3 %, 77.7 %, and 57.4 %, respectively.

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Insights into novel lignin-based magnetic carbon enabling peroxymonosulfate activation for tetracycline removal: Performance, mechanism and application

Excellent and recyclable catalysts are essential for wastewater treatment by peroxymonosulfate (PMS)-based advanced oxidation processes. Herein, a novel lignin-based magnetic carbon Fe@CCL was fabricated as a heterogeneous catalyst to boost PMS activation in tetracycline (TC) degradation. Experiments collectively suggested that the TC removal efficiency could be achieved as 95.9% by Fe@CCL/PMS system in a wide value of pH 3–11. Among sundry reactive oxygen species (•OH, SO4•–, O2•– and 1O2) in reaction system, singlet oxygen 1O2 could be selectively generated and played a major contribution for TC degradation. Theoretical simulations demonstrated that the valence state transformation of Fe species distributed in carbon skeleton is the main reason for the generation of 1O2, while the Fe(Ⅱ)/Fe(Ⅲ) redox cycle and the electron transfer in Fe@CCL were evidently beneficial to the effective activation of PMS. In addition, Fe@CCL could be easily recovered by an external magnet from the reaction system, and the catalytic performance in TC removal could be well maintained after regeneration. This work proposes an approach in the construction of high-performance and sustainable magnetic catalysts for organic pollutants removal.

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Skin‐Like Transparent, High Resilience, Low Hysteresis, Fatigue‐Resistant Cellulose‐Based Eutectogel for Self‐Powered E‐Skin and Human–Machine Interaction

AbstractArtificial electronic skin (E‐skin), a class of promising materials mimicking the physical‐chemical and sensory performance of the human skin, has gained extensive interest in the field of human health‐monitoring and robotic skins. However, developing E‐skin simultaneously achieving high resilience, hysteresis‐free, and absent external power is always a formidable challenge. Herein, a liquid‐free eutectic gel‐based self‐powered E‐skin with high resilience, fatigue resistance, and conductivity is prepared by introducing hydroxypropyl cellulose (HPC) into metal salt‐based deep eutectic solvents (MDES). The unique structural design of cellulose‐anchored permanent entangled poly(acrylic acid) (PAA) chain, in combination with rapid broken/reconstruction of the dense dynamic sacrificial bonds, realizes the fabrication of high‐elastic E‐skin with negligible hysteresis. This further demonstrates the promising practical application of the cellulose‐based eutectogel with high transmittance (92%), high conductivity (36.6 mS m−1), and high resilience (98.1%), and excellent environment stability in robust triboelectric nanogenerator for energy harvesting and high resilience, self‐powered E‐skin for human health‐caring and human‐machine interaction.

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Enhancing coking resistance of ZSM-5 in the conversion of pine sawdust into oxygen-free bio-aromatic hydrocarbons through tandem catalytic hydropyrolysis/vapor-phase hydrotreatment

The conversion of biomass into bio-aromatic hydrocarbons is a crucial aspect of achieving sustainable development. However, inadequate deoxygenation not only reduces the yield of aromatics but also causes instability in the produced biofuels. In this study, a tandem hydropyrolysis/vapor phase hydrotreatment process was conducted in a two-stage pressurized fixed-bed reactor to produce oxygen-free bio-aromatic hydrocarbons from pine sawdust under 0.15 MPa H2 with ZSM-5. The experimental results indicated that oxygen-containing compounds generated during the hydropyrolysis of pine sawdust in the first-stage reactor, were completely hydrodeoxygenated in the second-stage reactor over ZSM-5. This resulted in a total bio-aromatic hydrocarbons yield of 109.6 mg/g, with 81.5% selectivity to monoaromatic hydrocarbons, including benzene, toluene, ethylbenzene, and xylenes (BTEXs). The optimization study revealed that the hydropyrolysis temperature, hydrodeoxygenation temperature, and catalyst-to-biomass mass ratio could be controlled at 550 °C, 450 °C, and 8:1, respectively. The tandem process, conducted under pressurized H2, showed the capability to inhibit the deactivation of ZSM-5, as the low deactivation rate (35.1%) was observed in 15 sequential experiments of pine sawdust with an accumulated catalyst-to-biomass mass ratio of 0.5. The catalytic tandem vapor-phase hydrotreatment strategy offers a promising approach to effectively produce bio-aromatic hydrocarbons from biomass.

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