Nanostructured MoS2 with Interlayer Controllably Regulated by Ionic Liquids/Cellulose for High-Capacity and Durable Sodium Storage Properties.

Low intrinsic conductivity and structural instability of MoS2 as an anode of sodium-ion batteries limit the liberation of its theoretical capacity. Herein, density functional theory simulations for the first time optimize MoS2 interlayer distance between 0.80 and 1.01 nm for sodium storage. 1-Butyl-3-methyl-imidazolium acetate ([BMIm]Ac) induces cellulose oligomers to intercalate MoS2 interlayers for achieving controllable distance by changing the mass ratio of cellulose to [BMIm]Ac. Based on these findings, porous carbon loading the interlayer-expanded MoS2 allowing Na+ to insert with fast kinetics is synthesized. A carbon layer derived from [BMIm]Ac and cellulose coating the composite prevents the MoS2 from contacting electrolytes, leading to less sulfur loss for a more reversible specific capacity. Meanwhile, MoS2 and carbon have a strong interfacial connection through MoN binding, contributing to enhanced structural stability. As expected, while cycling 250 times at 0.1 A g-1 , the MoS2 -porous carbon composite displays an optimal reversible capacity at 517.79 mAh g-1 as a sodium-ion batteries anode. The cyclic test of 1.0 A g-1 also shows considerable stability (310.74 mAh g-1 after 1000 cycles with 86.26% retentive capacity). This study will open up new possibilities of modifying MoS2 that serves as an applicable material as sodium-ion battery anode.

Synergistic citric acid-surfactant catalyzed hydrothermal liquefaction of pomelo peel for production of hydrocarbon-rich bio-oil.

Citric acid showed good performance of hydrothermal liquefaction (HTL) of biomass waste via promoting the depolymerization of macromolecules. The synergistic effects of citric acid-surfactants/solid catalysts in the low-temperature (200 °C) catalytic hydrothermal liquefaction of pomelo peel (PP) were studied for the first time. It turned out that citric acid-surfactants promoted the conversion of pomelo peel to bio-oil with a higher yield (26.10-67.72 wt%), higher heating value (17.79-24.77 MJ/kg) and energy yield (33.53-114.11 %), while citric acid-solid catalysts were more conducive to the formation of gas and other products. FT-IR and GC-MS analysis testified that citric acid-surfactants increased the selectivity of hydrocarbons from 49.99 % to 74.19 %. Additionally, the chemical functional groups of bio-oil were characterized by 1H NMR and 13C NMR, indicating that the highest aliphatic content of bio-oils was 89.67 %. Moreover, citric acid-surfactant more environmentally friendly for low temperature liquefaction of biomass.

Low-temperature hydrothermal liquefaction of pomelo peel for production of 5-hydroxymethylfurfural-rich bio-oil using ionic liquid loaded ZSM-5.

Ionic liquid loaded ZSM-5 with high stability and catalytic performance was used for hydrothermal liquefaction (HTL) of pomelo peel for the first time. Bio-oil obtained at 200 °C had the highest yield (29.21 wt%) and high heating value (21.41 MJ/kg), with main constituents of 5-hydroxymethylfurfural (5-HMF, 50.10%), 3-Pyridinol (19.8%) and pentanoic acid (5.35%). The higher 5-hydroxymethylfurfural yield obtained using ionic liquid loaded ZSM-5 was further compared to other studies (0-50%). In comparison to high-temperature HTL, catalytic HTL with ionic liquid loaded ZSM-5 led to lower activation energy requirements (31.93 kJ·mol-1) for the conversion of glucose into 5-HMF. Additionally, the catalysts showed excellent recyclability, with 19.68 wt% of bio-oil containing 59.6% of light oil obtained after 5 cycles. Hence, this study presents a novel approach for the catalytic conversion of lignocellulosic biomass into 5-HMF-rich bio-oil for energy and green chemistry applications.

Structural Evolution of Graphitic Carbon Derived from Ionic Liquids-Dissolved Cellulose and Its Application as Lithium-Ion Battery Anodes.

With an attempt to replace petroleum-derived commercial graphite (CG) with biomass-derived carbon, microcrystalline cellulose (MCC) dissolved in 1-butyl-3-methylimidazolium acetate (BMIMAcO) was facilely carbonized to prepare cellulose-derived carbon under a low-temperature range of 250-1600 °C. TEM and AFM results revealed structural evolution of carbon nanosheets starting from carbon dots. The XRD and Raman results showed that the degree of crystallinity of the MCC-derived carbon was apparently enhanced as the temperature was increased to 93.02% at 1600 °C, while the XPS results revealed that the nitrogen content was greatly reduced with increasing temperature. BMIMAcO not only induced low-temperature graphitization of MCC-derived carbon but also provided nitrogen doping for the carbon. Used as an anode of lithium-ion batteries (LIBs), the carbon synthesized at 750 °C showed the best cyclic stability and reversible capacity (1052.22 mAh g-1 at 0.5 A g-1 after 100 cycles and 1017.46 mAh g-1 at 1 A g-1 after 1000 cycles) compared to other MCC-derived carbon and CG. In addition, the costs of cellulose-derived carbon are much lower than those of the petroleum-derived graphite, showing environmental and economical merits for LIB anode production.

Synthesis of biocompatible and highly fluorescent N-doped silicon quantum dots from wheat straw and ionic liquids for heavy metal detection and cell imaging.

Silane-based precursors for the synthesis of water-dispersible silicon quantum dots (SiQDs) present harmful effects on both researchers and the environment, due to their high toxicity. Though waste wheat straw is an abundant source of natural silicon, its application towards the synthesis of biocompatible SiQDs for metal detection has not yet been explored. In this study, N-doped SiQDs demonstrating uniform spherical morphologies, excellent water dispersity and strong fluorescence emission with a quantum yield of 28.9% were facilely synthesized by using wheat straw (WS) as silicon source and allyl-3-methylimidazolium chloride (AMIMCl) as nitrogen source. The wheat straw based SiQDs (WS-SiQDs) showed linear fluorescence quenching ((F0-F)/F) with Cr(VI) and Fe(III) concentration in the range of 0-6 × 10-4 M. Following immobilization on hydrophilic silica hydrogels, WS-SiQDs@silica hydrogels demonstrated enhanced fluorescence emission which can selectively detect Cr(VI) and Fe (III) to the limits of 142 and 175 nM, respectively. Moreover, cell imaging results reflected that WS-SiQDs can penetrate the membranes of dental pulp stem cells and react with the nucleuses of the stem cells. The stem cells maintained high viability under the conditions of 24 h incubation and SiQD concentration below 50 mg·L-1, thus indicating low cytotoxicity of WS-SiQDs. The as-prepared SiQDs demonstrated notable structural and fluorescent properties, therefore representing promising biocompatible fluorescent nanomaterials for metal detection and cell imaging.