Iron‐nitrogen‐carbon materials are being intensively studied as the most promising substitutes for Pt‐based electrocatalysts for the oxygen reduction reaction (ORR). A rational design of the ...morphology and porous structure can promote the accessibility of the active site and the reactants/products transportation, accelerating the reaction kinetics. Herein, 1D porous iron/nitrogen‐doped carbon nanorods (Fe/N‐CNRs) with a hierarchically micro/mesoporous structure are prepared by pyrolyzing the in situ polymerized pyrrole on the surface of Fe‐MIL‐88B‐derived 1D Fe2O3 nanorods (MIL: Material Institut Lavoisier). The Fe2O3 nanorods not only partially dissolve to generate Fe3+ for initiating polymerization but serve as templates to form the 1D structure during polymerization. Furthermore, the pyrrole coated Fe2O3 nanorod architecture prevents the porous structure from collapsing and protects Fe from aggregation to yield atomic Fe‐N4 moieties during carbonization. The obtained Fe/N‐CNRs display exceptional ORR activities (E1/2 = 0.90 V) and satisfactory long‐term durabilities, exceeding those for Pt/C. Furthermore, the unprecedented Fe/N‐CNRs catalytic performance is demonstrated with Zn‐air batteries, including a superior maximum power density (181.8 mW cm−2), specific capacity (998.67 W h kg−1), and long‐term durability over 100 h. The prominent performance stems from the unique 1D structure, hierarchical pore system, high surface area, and homogeneously dispersed single‐atom Fe‐N4 moieties.
1D iron/nitrogen (Fe/N)‐doped hierarchically porous carbon nanorods (Fe/N‐CNRs) catalysts with atomically dispersed Fe‐N4 sites are prepared via an in situ polymerization strategy. The obtained Fe/N‐CNRs catalyst displays excellent catalytic performance towards oxygen reduction reaction and Zn‐air batteries, surpassing commercial Pt/C, which indicates that the prepared catalyst possesses the potential of practical application in electrochemical devices.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Gallic acid (3,4,5-trihydroxybenzoic acid, GA), a phenolic acid, is ubiquitous in almost all parts of the plant. In the present study, a neuroinflammatory rat model using intranigral infusion of ...lipopolysaccharides (LPS, 4 μg/μL) was employed to study the neuroprotective effect of GA which was orally administered daily. Compared with the vehicle-treated rats, systemic administration of GA (100 mg/kg) significantly attenuated LPS-induced increases in glial fibrillary acidic protein (a biomarker of activated astrocytes) and ED-1 (a biomarker of activated microglia), as well as inducible nitric oxide synthase (iNOS, a proinflammatory enzyme) and interleukin-1β (a proinflammatory cytokine), in the LPS-infused substantia nigra (SN) of rat brain. At the same time, GA attenuated LPS-induced elevation in heme oxygenase-1 level (a redox-regulated protein) and α-synuclein aggregation (a hallmark of CNS neurodegeneration), suggesting that GA is capable of inhibiting LPS-induced oxidative stress and protein conjugation. Furthermore, GA prevented LPS-induced caspase 3 activation (a biomarker of programmed cell death) and LPS-induced increases in receptor-interacting protein kinase (RIPK)-1 and RIPK-3 levels (biomarkers of necroptosis), indicating that GA inhibited LPS-induced apoptosis and necroptosis in the nigrostriatal dopaminergic system of rat brain. Moreover, an in vitro study was employed to investigate the anti-inflammatory effect of GA on BV2 microglial cells which were subjected to LPS (1 μg/mL) treatment. Consistently, co-incubation of GA diminished LPS-induced increases in
iNOS
mRNA and iNOS protein expression in the treated BV-2 cells as well as NO production in the culture medium. The anti-oxidative activity of GA was evaluated using iron-induced lipid peroxidation of brain homogenates. After 3-h incubation at 37 °C, GA was more potent than glutathione and less potent than trolox in inhibiting iron-induced lipid peroxidation. Conclusively, the present study suggests that GA is anti-inflammatory via attenuating LPS-induced neuroinflammation, oxidative stress, and protein conjugation. Furthermore, GA prevented LPS-induced programmed cell deaths of nigrostriatal dopaminergic neurons of the rat brain, suggesting that GA may be neuroprotective by attenuating neuroinflammation in CNS neurodegenerative diseases.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The rational design of catalytically active sites in porous materials is essential in electrocatalysis. Herein, atomically dispersed Fe‐Nx sites supported by hierarchically porous carbon membranes ...are designed to electrocatalyze the hydrazine oxidation reaction (HzOR), one of the key techniques in electrochemical nitrogen transformation. The high intrinsic catalytic activity of the Fe‐Nx single‐atom catalyst together with the uniquely mixed micro‐/macroporous membrane support positions such an electrode among the best‐known heteroatom‐based carbon anodes for hydrazine fuel cells. Combined with advanced characterization techniques, electrochemical probe experiments, and density functional theory calculation, the pyrrole‐type FeN4 structure is identified as the real catalytic site in HzOR.
Hierarchically porous carbon membrane‐supported atomically dispersed pyrrole‐type FeN4 sites are proposed and verified as real active sites for the hydrazine oxidation reaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Iron‐nitrogen‐carbon materials are being intensively studied as the most promising substitutes for Pt‐based electrocatalysts for the oxygen reduction reaction (ORR). A rational design of the ...morphology and porous structure can promote the accessibility of the active site and the reactants/products transportation, accelerating the reaction kinetics. Herein, 1D porous iron/nitrogen‐doped carbon nanorods (Fe/N‐CNRs) with a hierarchically micro/mesoporous structure are prepared by pyrolyzing the in situ polymerized pyrrole on the surface of Fe‐MIL‐88B‐derived 1D Fe
2
O
3
nanorods (MIL: Material Institut Lavoisier). The Fe
2
O
3
nanorods not only partially dissolve to generate Fe
3+
for initiating polymerization but serve as templates to form the 1D structure during polymerization. Furthermore, the pyrrole coated Fe
2
O
3
nanorod architecture prevents the porous structure from collapsing and protects Fe from aggregation to yield atomic Fe‐N
4
moieties during carbonization. The obtained Fe/N‐CNRs display exceptional ORR activities (
E
1/2
= 0.90 V) and satisfactory long‐term durabilities, exceeding those for Pt/C. Furthermore, the unprecedented Fe/N‐CNRs catalytic performance is demonstrated with Zn‐air batteries, including a superior maximum power density (181.8 mW cm
−2
), specific capacity (998.67 W h kg
−1
), and long‐term durability over 100 h. The prominent performance stems from the unique 1D structure, hierarchical pore system, high surface area, and homogeneously dispersed single‐atom Fe‐N
4
moieties.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Owing to the wide range and low cost of sodium resources, sodium-ion batteries (SIBs) have received extensive attention and research. Metal sulfides with high theoretical capacity are used as ...promising anode materials for SIBs. This paper presents the electrochemical performance of the binder-free NiS
2
nanosheet arrays grown on stainless steel (SS) substrate (NiS
2
/SS) using an in situ growth and sulfidation strategy as anode for sodium ion batteries. Owing to the close connection between the NiS
2
nanosheet arrays and the SS current collector, the NiS
2
/SS anode demonstrates high rate capability with a reversible capacity of 492.5 mAh·g
−1
at 5.0C rate. Such rate capability is superior to that of NiS
2
nanoparticles (NiS
2
/CMC: 41.7 mAh·g
−1
at 5.0C, NiS
2
/PVDF: 7.3 mAh·g
−1
at 5.0C) and other Ni sulfides (100–450 mAh·g
−1
at 5.0C) reported. Furthermore, the initial reversible specific capacity and Coulombic efficiency of NiS
2
/SS are 786.5 mAh·g
−1
and 81%, respectively, demonstrating a better sodium storage ability than those of most NiS
2
anodes reported for SIBs. In addition, the amorphization and conversion mechanism during the sodiation/desodiation process of NiS
2
are proposed after investigation by in situ X-ray diffraction (XRD) measurements of intermediate products at successive charge/discharge stages.
Graphical abstract
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
To obtain environmentally friendly, integrated and miniaturized gas sensors for the increasing request for the Internet of Things industry and other relative areas, the ultra-thin CoO
x
/ZnO ...heterogeneous film with active interfacial sites was in-situ deposited on micro-electro-mechanical systems (MEMS) as H
2
S sensor. Atomic layer deposition (ALD) was employed to in-situ fabricate the uniform ZnO thin film. ALD CoO
x
was deposited on ZnO surface to obtain CoO
x
/ZnO heterojunction and active interfacial sites. The ultra-thin film (20 nm) with 50 ALD CoO
x
decorated on 250 ALD ZnO displays excellent sensing performance, including very high response (4.45@200 × 10
−9
) and selectivity to H
2
S with a limit of detection (LOD) of 0.38 × 10
−9
, long-term sensing stability, high response/recovery performance (7.5 s/15.7 s) and mechanical strength at 230 °C. Reasons for the high sensing performance of CoO
x
/ZnO have been confirmed by series of characterizations and density functional theory (DFT) calculation. Heterojunction film thickness with Debye length, the oxygen vacancies and the synergistic effect of active interfacial sites are main reasons for the high sensing performance. The strategy by fabrication of CoO
x
/ZnO heterogeneous film within Debye length and employing synergistic effect of active interfacial sites offers a promising route for the design of environmentally friendly gas sensors. Furthermore, the ALD technique offers a facile in-situ strategy and high-throughput fabrication of MEMS gas sensors.
Graphical Abstract
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
CO poisoning is one of the obstacles for platinum catalysts toward the electro-catalysis process for proton exchange membrane fuel cell (PEMFC) or direct methanol fuel cell (DMFC). Herein, we aim to ...weaken the CO poisoning on Pt by varying the cluster sizes and supports via doping graphene with B and N based on DFT + D3 calculations. Energetically, the most favorable Pt
n
/X-graphene (X = C, B, N;
n
= 1–6, 13) structures are obtained, and the calculated binding energies between Pt
n
and X-graphene are size- and support-dependent on a sequence: Pt
n
/B-g > Pt
n
/N-g > Pt
n
/C-g. The low-coordinated and protruded Pt atoms are identified as the active sites. The medium-sized clusters (
n
= 4–6) display CO poisoning-free properties with an excellent CO oxidation performance, resulting from the moderate locations of d-band center and electronic transfer via the interface. Furthermore, E-R mechanism is revealed to dominate the reaction route with a rate-limiting step of the second CO
2
desorption. The corresponding activation energy barriers are 0.53, 0.61 and 0.56 eV for Pt
n
/B-g (
n
= 4, 5, 6), respectively. This work provides insights into the theoretical design of CO poisoning-free catalyst Pt
n
/X-g in the applications of DMFC/PEMFC.
Graphical abstract
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Aim： To investigate the immunomodulatory effects of andrographolide on both innate and adaptive immune responses. Methods： Andrographolide （10 pg/mL in vitro or 1 mg/kg in vivo） was used to modulate ...LPS-induced classical activated （M1） or IL-4- induced alternative activated （M2） macrophages in vitro and humor immune response to HBsAg in vivo. Cytokine gene expression profile （M1 vs M2） was measured by real-time PCR, IL-12/IL-10 level was detected by ELISA, and surface antigen expression was evaluated by flow cytometry, whereas phosphorylation level of ERK 1/2 and AKT was determined by Western blot. The level of anti-HBs antibodies in HBsAg immunized mice was detected by ELISA, and the number of HBsAg specific IL-4-producing splenocyte was enumerated by ELISPOT. Results： Andrographolide treatment in vitro attenuated either LPS or IL-4 induced macrophage activation, inhibited both M1 and M2 cytokines expression and decreased IL-12/IL-10 ratio （the ratio of M1/M2 polarization）. Andrographolide down-regulated the expression of mannose receptor （CD206） in IL-4 induced macrophages and major histocompability complex/costimulatory molecules （MHC I, CD40, CD80, CD86） in LPS-induced macrophages. Correspondingly, anti-HBs antibody production and the number of IL-4-producing splenocytes were reduced by in vivo administration of andrographolide. Reduced phosphorylation levels of ERK1/2 and AKT were observed in macrophages treated with andrographolide. Conclusion： Andrographolide can modulate the innate and adaptive immune responses by regulating macrophage phenotypic polarization and Ag-specific antibody production. MAPK and PI3K signaling pathways may participate in the mechanisms of andrographolide regulating macrophage activation and polarization.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
G4 DNA structure highly localized to functionally important sites within the human genome, has been identified as a biomarker for regulation of multiple biological processes. Identification ...G4-responsive fluorescence probes has broad application prospects for addressing G4 biological functions, as well as developing of new families of anticancer drugs. However, some currently designed G4 DNA probes may suffer from serious solvent-dependent effect, and cause unspecific fluorescence that masks the specific signal from G4 DNA. Herein, with a bulky imidazole-cored molecular rotor fusing in D-A building block of carbazole-pyridinium, we constructed a new probe ACPS. This new probe with desirable environmentally insensitive property exhibited a “fluorescence-off” state in various polarity solvents. In the presence of G4 DNA, the intra-molecular rotations would be restricted, triggering intense fluorescence enhancement. Especially, probe ACPS bound to G4 DNA structures with superior selectivity, exhibiting much weaker fluorescence response in the presence of non-G4 DNA structures. This probe was also able to realize fluorescence visualization in cell imaging. Collectively, the probe design strategy eliminates the background fluorescence caused by uncontrollable environmental polarity change, thereby achieving high-fidelity sensing G4 DNA structures in complicated systems.
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•An environmentally insensitive D-A type fluorescence probe ACPS was designed.•This probe with desirably always initial “fluorescence-off” state in various solvents.•Selective fluorescence lighting-up recognition of G4 DNA was presented.•The mechanism by which the probe recognized G4 DNA was revealed.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The oxygen reduction reaction (ORR) activity of the Fe/N/Carbon catalysts derived from the pyrolysis of zeolitic-imidazolate-framework-8 (ZIF-8) has been still lower than that of commercial Pt-based ...catalysts utilized in the proton exchange membrane fuel cells (PEMFCs) due to low density of accessible active sites. In this study, an efficient carbon-supporting strategy is developed to enhance the ORR efficiency of the ZIF-derived Fe/N/Carbon catalysts by increasing the accessible active site density. The enhancement lies in (i) improving the accessibility of active sites via converting dodecahedral particles to graphene-like layered materials and (ii) enhancing the density of FeNx active sites via suppressing the formation of nanoparticles as well as providing extra spaces to host active sites. The optimized and efficient Fe/N/Carbon catalyst shows a half-wave potential (E 1/2) of 0.834 V versus reversible hydrogen electrode in acidic media and produces a peak power density of 0.66 W cm–2 in an air-fed PEMFC at 2 bar backpressure, outperforming most previously reported Pt-free ORR catalysts. Finally, the general applicability of the carbon-supporting strategy is confirmed using five different commercial carbon blacks. This work provides an effective route to derive Fe/N/Carbon catalysts exhibiting a higher power density in PEMFCs.
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IJS, KILJ, NUK, PNG, UL, UM
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