Nanoscale transition metal catalysts anchored on perovskite oxide enabling enhanced kinetics of lithium polysulfide redox in lithium-sulfur batteries

To obtain high-performance lithium-sulfur(Li-S)batteries,it is necessary to rationally design electrocatalytic materials that can promote efficient sulfur electrochemical reactions.Herein,the robust heterostructured material of nanoscale transition metal anchored on perovskite oxide was designed for efficient catalytic kinetics of the oxidation and reduction reactions of lithium polysulphide(Li PSs),and verified by density functional theory(DFT)calculations and experimental characterizations.Due to the strong interaction of nanoscale transition metals with Li PSs through chemical coupling,heterostructured materials(STO@M)(M=Fe,Ni,Cu)exhibit excellent catalytic activity for redox reactions of Li PSs.The bifunctional heterostructure material STO@Fe exhibits good rate performance and cycling stability as the cathode host,realizing a high-performance Li-S battery that can maintain stable cycling under rapid charge-discharge cycling.This study presents a novel approach to designing electrocatalytic materials for redox reactions of Li PSs,which promotes the development of fast charge-discharge Li-S batteries.

Ultrathin two-dimensional bimetal NiCo-based MOF nanosheets as ultralight interlayer in lithium-sulfur batteries

Lithium-sulfur batteries as one of the most promising next-generation high-energy storage system, the shuttle effect, the expansion of cathode and the slow electrode redox kinetics limit its further development. Herein, we report a two-dimensional, ultrathin and ultra-light bimetal-Ni Co-organic framework as the interlayer for Li-S batteries. This kind of interlayer can effectively block polysulfides and accelerate the conversion with a thickness of only 1 μm and a load of 0.1 mg/cm^(2). Because the MOF nanosheets with a thickness of a few nanometers have a large specific surface and a large number of exposed accessible active sites. At the same time, the intrinsic activity of each site is enhanced and the catalytic performance is improved due to the synergistic effect of mixed metals and the unique coordination environment around the active sites. So, 2D NiCo MOF/CNT totally meets the requirements for the lightweight and effective interlayer. The initial discharge capacity of cell with 2D NiCo MOF/CNT interlayer can reach 1132.7 m Ah/g at 0.5 C. It remained 709.1 m Ah/g after 300 cycles, showing good cycling stability and rate performance.

Investigating aldehyde and ketone compounds produced from indoor cooking emissions and assessing their health risk to human beings

Aldehyde and ketone compounds are ubiquitous in the air and prone to adverse effects on human health.Cooking emission is one of the major indoor sources.Aiming to evaluate health risks associated with inhalation exposure to aldehyde and ketone compounds,13 carbonyl compounds(CCs)released from heating 5 edible oils,3 seasonings,and 2 dishes were investigated in a kitchen laboratory.For the scenarios of heating five types of oil,aldehydes accounted for 61.1%-78.0%of the total emission,mainly acetaldehyde,acrolein and hexanal.Comparatively,heating oil with added seasonings released greater concentrations of aldehyde and ketone compounds.The concentration enhancement of larger molecular aldehydes was significantly greater.The emission factors of aldehyde and ketone compounds for cooking the dish of chili friedmeatweremuch greater compared to that of tomato fried eggs.Therefore,food materials also had a great impact on the aldehyde and ketone emissions.Acetone and acetaldehyde were the most abundant CCs in the kitchen.Acrolein concentrations ranged from 235.18 to 498.71μg/m^(3),which was about 100 times greater compared to the guidelines provided by Office of Environmental Health Hazard Assessment(OEHHA).The acetaldehyde inhalation for adultswas 856.83-1515.55μg and 56.23-192.79μg from exposure to chili fried meat and tomato fried eggs,respectively.This exceeds the reference value of 90μg/day provided by OEHHA.The findings of this study provided scientific evidences for the roles of cooking emissions on indoor air quality and human health.

Enhancing electrochemical conversion of lithium polysulfide by 1T-rich MoSe_(2) nanosheets for high performance lithium-sulfur batteries

The sluggish conversion kinetics and shuttle effect of lithium polysulfides(LiPSs)severely hamper the commercialization of lithium-sulfur batteries.Numerous electrocatalysts have been used to address these issues,amongst which,transition metal dichalcogenides have shown excellent catalytic performance in the study of lithium-sulfur batteries.Note that dichalcogenides in different phases have different catalytic properties,and such catalytic materials in different phases have a prominent impact on the performance of lithium-sulfur batteries.Herein,1T-phase rich MoSe_(2)(T-MoSe_(2))nanosheets are synthesized and used to catalyze the conversion of LiPSs.Compared with the 2H-phase rich MoSe_(2)(H-MoSe_(2))nanosheets,the T-MoSe_(2) nanosheets significantly accelerate the liquid phase transformation of LiPSs and the nucleation process of Li2S.In-situ Raman and X-ray photoelectron spectroscopy(XPS)find that T-MoSe_(2) effectively captures LiPSs through the formation of Mo-S and Li-Se bonds,and simultaneously achieves fast catalytic conversion of LiPSs.The lithium-sulfur batteries with T-MoSe_(2) functionalized separators display a fantastic rate performance of 770.1 mAh/g at 3 C and wonderful cycling stability,with a capacity decay rate as low as 0.065%during 400 cycles at 1 C.This work offers a novel perspective for the rational design of selenide electrocatalysts in lithium-sulfur chemistry.

Anti-diabetic effects of linarin from Chrysanthemi Indici Flos via AMPK activation

Objective:The purpose of this study is to investigate the anti-diabetic effects of linarin,a flavonoid extracted from Chrysanthemi Indici Flos(CIF),and its potential mechanisms.Methods:The effects of linarin on cell viability and glucose consumption in Hep G2 cells were measured.Meanwhile,monosodium glutamate(MSG) mouse model was constructed to monitor the changes of insulin tolerance,glucose tolerance,triglyceride and cholesterol.The protein expression levels of pAMPK,p-ACC,PEPCK and p-GS were detected by Western blot.Results:Linarin could increase the relative glucose consumption of Hep G2 cells,improve insulin tolerance and glucose tolerance,and decrease the levels of triglyceride and cholesterol of MSG mice.Simultaneously,the expression levels of p-AMPK and p-ACC in Hep G2 cells and the liver tissue of MSG mice were increased,while the expression levels of PEPCK and p-GS were decreased after treatment with linarin.Conclusion:Insulin resistance could be ameliorated by linarin in type 2 diabetes,and its mechanism may be related to AMPK signaling pathway.

Antioxidation and active constituents analysis of flower residue of Rosa damascena

Objective:To make full usage of resource and turn waste into treasure,the chemical constituents and bioactivity were firstly investigated on Damask rose(Rosa damascena)flower residue(DRFR).Methods:DPPH and ABTS experiments were applied to assess the antioxidant activity of DRFR.Then,column chromatography was used to purify compounds from an antioxidation extract(DRFR-A),and the chemical structure was identified using NMR.The total phenolic acid content was measured by FolinCiocalteu colorimetric method,and the content of gallic acid of the indicator ingredient was detected by HPLC.Results:DRFR-A was found to show a high activity both on DPPH(IC5o:2.760μg/mL)and ABTS(ICso:2.258μg/mL)compared to positive control Vc,Ten compounds were isolated and identified as quercetin(1),kaempferol(2),gallic acid(3),protocatechuic acid(4),pyrogallic acid(5),2-phenylethyl 3,4,5-trihydroxybenzoate(6),methyl gallate(7),p-hydroxybenzoic acid(8),p-hydroxyphenethyl alcohol(9)and astragalin(10)from DRFR-A.Among them,pyrogallic acid,2-phenylethyl-3,4,5-trihydroxybenzoate,p-hydroxybenzoic acid and p-hydroxyphenethyl alcohol are obtained from the plant for the first time.The content of total phenolic acids and gallic acid,main ingredient in DRFR-A was determined as 63.73%and 24.67%,respectively.Conclusion:This study provides a reliable data and lays the foundation for the development and utilization of rose residue,and hence for the full utilization of rose resources.

Spinel-type bimetal sulfides derived from Prussian blue analogues as efficient polysulfides mediators for lithium-sulfur batteries

More and more attentions have been attracted by lithium-sulfur batteries(Li-S), owing to the high energy density for the increasingly advanced energy storage system. While the poor cycling stability, due to the inherent polysulfide shuttle, seriously hampered their practical application. Recently, some polar hosts,like single metal oxides and sulfides, have been employed as hosts to interact with polysulfide intermediates. However, due to the inherent poor electrical conductivity of these polar hosts, a relatively low specific capacity is obtained. Herein, a spinel-type bimetal sulfide NiCo_(2)S_(4)through a Prussian blue analogue derived methodology is reported as the novel host of polysulfide, which enables highperformance sulfur cathode with high Coulombic efficiency and low capacity decay. Notably, the Li-S battery with NiCo_(2)S_(4)-S composites cathode still maintains a capacity of 667 m Ah/g at 0.5 Cafter 300 cycles, and 399 m Ah/g at 1 C after 300 cycles. Even after 300 cycles at the current density of 0.5C, the capacity decays by 0.138% per cycle at high sulfur loading about 3 mg/cm;. And the capacity decays by0.026% per cycle after 1000 cycles, when the rate is 1C. More importantly, the cathode of Ni Co_(2)S_(4)-S composite shows the outstanding discharge capacity, owing to its good conduction, high catalytic ability and the strong confinement of polysulfides.