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2.
Res Microbiol ; 171(7): 271-280, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32979473

RESUMO

The Kurokawa river flowing through the Aso Caldera in Southwest Japan is influenced by groundwater containing high concentration of dissolved metals (Fe2+ and Mn2+) and is associated with orange deposits in the upstream and thick black crusts on the wall of artificial waterway tunnel with several km lengths in the midstream regions. X-ray fluorescence analysis revealed that the orange deposits contained up to 34.4% Fe and black crusts comprised up to 25.4% and 10.6% Mn and Fe, respectively. Although naturally occurring Mn-oxides and crusts are considered biogenic in pH-neutral freshwater environments, the whole microbial community in Mn crust and their contribution to Mn crust formation in these environments remain unclear. High-throughput molecular sequencing for bacteria and eukaryotes including fungi revealed black Mn crusts had a high abundance of Sphingomonas, Hyphomicrobium, Bacillus, Pseudomonas, and Mortierella, previously reported genera including several species with Mn-oxidizing activity in Mn crusts or nodules of other marine and freshwater environments. In addition, one bacterial isolate and one fungal isolate with Mn-oxidizing activity were obtained from black Mn crust. These results suggest that multiple Mn-oxidizing bacteria including Pseudomonas and fungi are involved in Mn crust formation on the wall of dark waterway tunnel in the oligotrophic environment of the Kurokawa river.

3.
ACS Nano ; 2020 Apr 23.
Artigo em Inglês | MEDLINE | ID: mdl-32310638

RESUMO

Li metal anode has been considered as the ideal anode for next-generation batteries due to its ultrahigh capacity and lowest electrochemical potential. However, its practical application is still impeded by low Coulombic efficiency, huge volume change, and safety hazards arising from Li dendrite growth. In this work, a three-dimensional (3D) structured highly stable Li metal anode is designed and easily preapred. Benefiting from the in situ reaction between Li metal and AlN, highly Li+ conductive Li3N and lithiophilic LiAl alloy have been simultaneously formed and homogeneously distributed in the framework, in which Li metal is finely dispersed and embedded. The outstanding electron/ion mixed conductivity of Li3N/LiAl and 3D composite structure with enhanced interfacial area significantly improve the electrode kinetics and suppress the volume change on cycling, while a lithiophilic effect of LiAl alloy and uniform distribution of Li ion flux inside the electrode avoid dendritic Li deposition. As a result, the proposed Li metal electrode exhibits exceptional electrochemical reversibility in both carbonate and ether-based electrolytes. Paired with LiFePO4 and sulfurized polyacrylonitrile (S@pPAN) cathodes, the full cells deliver highly stable and long-term cycling performance. Therefore, the proposed strategy to fabricate Li metal anodes could promote the practical application of Li metal batteries.

4.
Med Gas Res ; 10(1): 47-49, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32189669

RESUMO

It has been revealed that the cause of senescence and diseases is associated with the reactive oxygen species "hydroxyl radicals" (·OH). Senescence and diseases may be overcome as long as we can scavenge •OH mostly produced in mitochondria. It is one and only one "molecular hydrogen" (H2) that can both penetrate into the mitochondria and scavenge the •OH. The H2 in the body can function in disease prevention and recovery. H2 gas is explosive so that a safe hydrogen inhaler has to be developed for home use. We would like to advocate the great use of H2.

5.
Oxid Med Cell Longev ; 2020: 6978784, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32104537

RESUMO

Neonatal hypoxic-ischemic encephalopathy (HIE) is a leading cause of death in neonates with no effective treatments. Recent advancements in hydrogen (H2) gas offer a promising therapeutic approach for ischemia reperfusion injury; however, the impact of this approach for HIE remains a subject of debate. We assessed the therapeutic effects of H2 gas on HIE and the underlying molecular mechanisms in a rat model of neonatal hypoxic-ischemic brain injury (HIBI). H2 inhalation significantly attenuated neuronal injury and effectively improved early neurological outcomes in neonatal HIBI rats as well as learning and memory in adults. This protective effect was associated with initiation time and duration of sustained H2 inhalation. Furthermore, H2 inhalation reduced the expression of Bcl-2-associated X protein (BAX) and caspase-3 while promoting the expression of Bcl-2, nuclear factor erythroid-2-related factor 2, and heme oxygenase-1 (HO-1). H2 activated extracellular signal-regulated kinase and c-Jun N-terminal protein kinase and dephosphorylated p38 mitogen-activated protein kinase (MAPK) in oxygen-glucose deprivation/reperfusion (OGD/R) nerve growth factor-differentiated PC12 cells. Inhibitors of MAPKs blocked H2-induced HO-1 expression. HO-1 small interfering RNA decreased the expression of peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) and sirtuin 1 (SIRT1) and reversed the protectivity of H2 against OGD/R-induced cell death. These findings suggest that H2 augments cellular antioxidant defense capacity through activation of MAPK signaling pathways, leading to HO-1 expression and subsequent upregulation of PGC-1α and SIRT-1 expression. Thus, upregulation protects NGF-differentiated PC12 cells from OGD/R-induced oxidative cytotoxicity. In conclusion, H2 inhalation exerted protective effects on neonatal rats with HIBI. Early initiation and prolonged H2 inhalation had better protective effects on HIBI. These effects of H2 may be related to antioxidant, antiapoptotic, and anti-inflammatory responses. HO-1 plays an important role in H2-mediated protection through the MAPK/HO-1/PGC-1α pathway. Our results support further assessment of H2 as a potential therapeutic for neurological conditions in which oxidative stress and apoptosis are implicated.


Assuntos
Heme Oxigenase-1/metabolismo , Hidrogênio/farmacologia , Hipóxia-Isquemia Encefálica/tratamento farmacológico , Sistema de Sinalização das MAP Quinases , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/metabolismo , Animais , Animais Recém-Nascidos , Antioxidantes/farmacologia , Apoptose/efeitos dos fármacos , Apoptose/genética , Caspase 3/metabolismo , Feminino , Heme Oxigenase-1/genética , Hidrogênio/uso terapêutico , Hipóxia-Isquemia Encefálica/metabolismo , Hipóxia-Isquemia Encefálica/patologia , Hipóxia-Isquemia Encefálica/fisiopatologia , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Aprendizagem/efeitos dos fármacos , Sistema de Sinalização das MAP Quinases/efeitos dos fármacos , Masculino , Memória/efeitos dos fármacos , Quinases de Proteína Quinase Ativadas por Mitógeno/antagonistas & inibidores , Quinases de Proteína Quinase Ativadas por Mitógeno/metabolismo , Neurônios/efeitos dos fármacos , Neurônios/metabolismo , Fármacos Neuroprotetores/farmacologia , Estresse Oxidativo/efeitos dos fármacos , Células PC12 , Coativador 1-alfa do Receptor gama Ativado por Proliferador de Peroxissomo/genética , Ratos , Ratos Sprague-Dawley , Sirtuína 1/metabolismo , Proteína X Associada a bcl-2/metabolismo , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo
6.
J Thorac Cardiovasc Surg ; 159(5): 2110-2118, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31780065

RESUMO

BACKGROUND: Molecular hydrogen can reduce the oxidative stress of ischemia-reperfusion injury in various organs for transplantation and potentially improve survival rates in recipients. This study aimed to evaluate the protective effects of a hydrogen-rich preservation solution against ischemia-reperfusion injury after cold ischemia in rat lung transplantation. METHODS: Lewis rats were divided into a nontransplant group (n = 3), minimum-ischemia group (n = 3), cold ischemia group (n = 6), and cold ischemia with hydrogen-rich (more than 1.0 ppm) preservation solution group (n = 6). The rats in the nontransplant group underwent simple thoracotomy, and the rats in the remaining 3 groups underwent orthotopic left lung transplantation. The ischemic time was <30 minutes in the minimum-ischemia group and 6 hours in the cold ischemia groups. After 2-hour reperfusion, we evaluated arterial blood gas levels, pulmonary function, lung wet-to-dry weight ratio, and histologic features of the lung tissue. The expression of proinflammatory cytokines was measured using quantitative polymerase chain reaction assays, and 8-hydroxydeoxyguanosine levels were evaluated using enzyme-linked immunosorbent assays. RESULTS: When compared with the nontransplant and minimum-ischemia groups, the cold ischemia group had lower dynamic compliance, lower oxygenation levels, and higher wet-to-dry weight ratios. However, these variables were significantly improved in the cold ischemia with hydrogen-rich preservation solution group. This group also had fewer signs of perivascular edema, lower interleukin-1ß messenger RNA expression, and lower 8-hydroxydeoxyguanosine levels than the cold ischemia group. CONCLUSIONS: The use of a hydrogen-rich preservation solution attenuates ischemia-reperfusion injury in rat lungs during cold ischemia through antioxidant and anti-inflammatory effects.

7.
Gen Thorac Cardiovasc Surg ; 68(2): 158-163, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31468277

RESUMO

OBJECTIVE: Bronchiolitis obliterans syndrome arising from chronic airway inflammation is a leading cause of death following lung transplantation. Several studies have suggested that inhaled hydrogen can protect lung grafts from ischemia-reperfusion injury via anti-inflammatory and -oxidative mechanisms. We investigated whether molecular hydrogen-saturated water can preserve lung allograft function in a heterotopic tracheal allograft mouse model of obliterative airway disease METHODS: Obliterative airway disease was induced by heterotopically transplanting tracheal allografts from BALB/c donor mice into C57BL/6 recipient mice, which were subsequently administered hydrogen water (10 ppm) or tap water (control group) (n = 6 each) daily without any immunosuppressive treatment. Histological and immunohistochemical analyses were performed on days 7, 14, and 21. RESULTS: Hydrogen water decreased airway occlusion on day 14. No significant histological differences were observed on days 7 or 21. The cluster of differentiation 4/cluster of differentiation 3 ratio in tracheal allografts on day 14 was higher in the hydrogen water group than in control mice. Enzyme-linked immunosorbent assay performed on day 7 revealed that hydrogen water reduced the level of the pro-inflammatory cytokine interleukin-6 and increased that of forkhead box P3 transcription factor, suggesting an enhancement of regulatory T cell activity. CONCLUSIONS: Hydrogen water suppressed the development of mid-term obliterative airway disease in a mouse tracheal allograft model via anti-oxidant and -inflammatory mechanisms and through the activation of Tregs. Thus, hydrogen water is a potential treatment strategy for BOS that can improve the outcome of lung transplant patients.

8.
Med Gas Res ; 9(3): 160-162, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31552881

RESUMO

Production and excretion of hydrogen (H2) gas in human was reported in 1969, since then it has been regarded as non-toxic molecule. For preventive and therapeutic medical uses, a possible treatment for cancer was reported and another article was published on how H2 acts as a therapeutic antioxidant by selectively reducing cytotoxic oxygen radicals. A variety of H2 gas inhalers have been available in the market for hospital and home uses. However, H2 is odorless and flammable or explosive ignited by static electricity. We have examined the safety of a variety of H2 gas concentrations from the viewpoint of flammability and explosion. We have also measured concentrations of H2 gas inhalers in the market respectively. This paper also details how to control H2 gas concentration for preventing explosions.

9.
FEMS Microbiol Ecol ; 95(8)2019 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-31281924

RESUMO

Community compositional changes and the corrosion of carbon steel in the presence of different electron donor and acceptor combinations were examined with a methanogenic consortium enriched for its ability to mineralize paraffins. Despite cultivation in the absence of sulfate, metagenomic analysis revealed the persistence of several sulfate-reducing bacterial taxa. Upon sulfate amendment, the consortium was able to couple C28H58 biodegradation with sulfate reduction. Comparative analysis suggested that Desulforhabdus and/or Desulfovibrio likely supplanted methanogens as syntrophic partners needed for C28H58 mineralization. Further enrichment in the absence of a paraffin revealed that the consortium could also utilize carbon steel as a source of electrons. The severity of both general and localized corrosion increased in the presence of sulfate, regardless of the electron donor utilized. With carbon steel as an electron donor, Desulfobulbus dominated in the consortium and electrons from iron accounted for ∼92% of that required for sulfate reduction. An isolated Desulfovibrio spp. was able to extract electrons from iron and accelerate corrosion. Thus, hydrogenotrophic partner microorganisms required for syntrophic paraffin metabolism can be readily substituted depending on the availability of an external electron acceptor and a single paraffin-degrading consortium harbored microbes capable of both chemical and electrical microbially influenced iron corrosion.

11.
Chem Commun (Camb) ; 55(27): 3971-3974, 2019 Apr 07.
Artigo em Inglês | MEDLINE | ID: mdl-30874700

RESUMO

We described an effective way to generate a Co3O4 mesocrystal array with well-developed porosity, simply by uniting a coupled interface with hydrazine treatment. Due to the fast electron transfer and sufficient active sites, the Ti mesh-supported Co3O4 nanoneedles electrode could provide a current density of 49.9 mA cm-2 at 570 mV OER overpotential and has exceptionally high stability.

12.
Int J Mol Sci ; 20(2)2019 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-30669692

RESUMO

Bacteria inhabiting the human gut metabolize microbiota-accessible carbohydrates (MAC) contained in plant fibers and subsequently release metabolic products. Gut bacteria produce hydrogen (H2), which scavenges the hydroxyl radical (•OH). Because H2 diffuses within the cell, it is hypothesized that H2 scavenges cytoplasmic •OH (cyto •OH) and suppresses cellular senescence. However, the mechanisms of cyto •OH-induced cellular senescence and the physiological role of gut bacteria-secreted H2 have not been elucidated. Based on the pyocyanin-stimulated cyto •OH-induced cellular senescence model, the mechanism by which cyto •OH causes cellular senescence was investigated by adding a supersaturated concentration of H2 into the cell culture medium. Cyto •OH-generated lipid peroxide caused glutathione (GSH) and heme shortage, increased hydrogen peroxide (H2O2), and induced cellular senescence via the phosphorylation of ataxia telangiectasia mutated kinase serine 1981 (p-ATMser1981)/p53 serine 15 (p-p53ser15)/p21 and phosphorylation of heme-regulated inhibitor (p-HRI)/phospho-eukaryotic translation initiation factor 2 subunit alpha serine 51 (p-eIF2α)/activating transcription factor 4 (ATF4)/p16 pathways. Further, H2 suppressed increased H2O2 by suppressing cyto •OH-mediated lipid peroxide formation and cellular senescence induction via two pathways. H2 produced by gut bacteria diffuses throughout the body to scavenge cyto •OH in cells. Therefore, it is highly likely that gut bacteria-produced H2 is involved in intracellular maintenance of the redox state, thereby suppressing cellular senescence and individual aging. Hence, H2 produced by intestinal bacteria may be involved in the suppression of aging.


Assuntos
Senescência Celular , Citoplasma/metabolismo , Peróxido de Hidrogênio/metabolismo , Hidrogênio/metabolismo , Radical Hidroxila/metabolismo , Fator 4 Ativador da Transcrição/metabolismo , Senescência Celular/efeitos dos fármacos , Inibidor p16 de Quinase Dependente de Ciclina/genética , Inibidor de Quinase Dependente de Ciclina p21/genética , Dano ao DNA , Fator de Iniciação 2 em Eucariotos/metabolismo , Fibroblastos/efeitos dos fármacos , Fibroblastos/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Glutationa/metabolismo , Humanos , Hidrogênio/farmacologia , Peróxido de Hidrogênio/farmacologia , Peroxidação de Lipídeos , Masculino , Estresse Oxidativo , Transdução de Sinais/efeitos dos fármacos
13.
Angew Chem Int Ed Engl ; 57(38): 12563-12566, 2018 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-30070752

RESUMO

The exploitation of metal-free organic polymers as electrodes for water splitting reactions is limited by their presumably low activity and poor stability, especially for the oxygen evolution reaction (OER) under more critical conditions. Now, the thickness of a cheap and robust polymer, poly(p-phenylene pyromellitimide) (PPPI) was rationally engineered by an in situ polymerization method to make the metal-free polymer available for the first time as flexible, tailorable, efficient, and ultra-stable electrodes for water oxidation over a wide pH range. The PPPI electrode with an optimized thickness of about 200 nm provided a current density of 32.8 mA cm-2 at an overpotential of 510 mV in 0.1 mol L-1 KOH, which is even higher than that (31.5 mA cm-2 ) of commercial IrO2 OER catalyst. The PPPI electrodes are scalable and stable, maintaining 92 % of its activity after a 48-h chronoamperometric stability test.

14.
ChemSusChem ; 11(14): 2306-2309, 2018 Jul 20.
Artigo em Inglês | MEDLINE | ID: mdl-29851293

RESUMO

Electrochemical gas evolution and activation reactions are complicated processes, involving not only active electrocatalysts but also the interaction among solid electrodes, electrolyte, and gas-phase products and reactants. In this study, multiphase interfaces of superadsorbing graphene-based electrodes were controlled without changing the active centers to significantly facilitate mass diffusion kinetics for superior performance. The achieved in-depth understanding of how to regulate the interfacial properties to promote the electrochemical performance could provide valuable clues for electrode manufacture and for the design of more active electrocatalysts.

15.
Shock ; 50(6): 640-647, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-29293174

RESUMO

Bacterial translocation is a major cause of multiple organ dysfunction syndrome in critical illness, and its management is an important therapeutic strategy. In this study, we focused on the key factors responsible for bacterial translocation including the intestinal microbiome and investigated the impact of molecular hydrogen therapy as a countermeasure against bacterial translocation in a murine model of sepsis. The experimental protocols were divided into the sham, saline treatment (control), and hydrogen treatment (H2) groups. In the H2 group, 15 mL/kg of hydrogen-rich saline (7 ppm) was gavaged daily for 7 days following cecal ligation and puncture (CLP). In the control group, normal saline was gavaged in the same way. In the results, the 7-day survival rate was significantly improved in the H2 group versus the control group (69% vs. 31%, P < 0.05). The incidence of bacterial translocation at 24 h after CLP as assessed by cultivation of mesenteric lymph nodes and blood was significantly decreased in the H2 group versus the control group. Administration of hydrogen-rich saline also prevented the expansion of facultative anaerobic Enterobacteriaceae and ameliorated intestinal hyperpermeability at 24 h after CLP. Intestinal tissue levels of inflammatory mediators such as inducible nitric oxide synthases, tumor necrosis factor α, interleukin (IL)-1ß, IL-6, and oxidative stress marker malondialdehyde at 6 h after CLP were down-regulated in the H2 group. These results suggest luminal administration of hydrogen-rich saline, which prevents intestinal dysbiosis, hyperpermeability, and bacterial translocation, could potentially be a new therapeutic strategy in critical illness.


Assuntos
Disbiose/metabolismo , Mucosa Intestinal/metabolismo , Animais , Translocação Bacteriana/efeitos dos fármacos , Modelos Animais de Doenças , Enterobacteriaceae/genética , Hidrogênio/farmacologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Microbiota/efeitos dos fármacos , Microbiota/genética , Estresse Oxidativo/efeitos dos fármacos , Estresse Oxidativo/genética , RNA Mensageiro/genética , RNA Ribossômico 16S/genética , Sepse , Proteínas de Junções Íntimas/genética , Proteínas de Junções Íntimas/metabolismo
16.
Bioresour Technol ; 249: 809-817, 2018 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29136936

RESUMO

A bio-electrochemical system packed with supporting material can promote anaerobic digestion for several types of organic waste. To expand the target organic matters of a BES, tomato plant residues (TPRs), generated year-round as agricultural and cellulosic waste, were treated using three methanogenic reactors: a continuous stirred tank reactor (CSTR), a carbon fiber textile (CFT) reactor, and a bio-electrochemical reactor (BER) including CFT with electrochemical regulation (BER + CFT). CFT had positive effects on methane fermentation and methanogen abundance. The microbial population stimulated by electrochemical regulation, including hydrogenotrophic methanogens, cellulose-degrading bacteria, and acetate-degrading bacteria, suppressed acetate accumulation, as evidenced by the low acetate concentration in the suspended fraction in the BER + CFT. These results indicated that the microbial community in the BER + CFT facilitated the efficient decomposition of TPR and its intermediates such as acetate to methane.


Assuntos
Reatores Biológicos , Carbono , Anaerobiose , Bactérias Anaeróbias , Fibra de Carbono , Lycopersicon esculentum , Metano , Têxteis
17.
Biochem Biophys Res Commun ; 492(1): 74-81, 2017 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-28807355

RESUMO

Chronic obstructive pulmonary disease (COPD) is predominantly a cigarette smoke (CS)-triggered disease with features of chronic systemic inflammation. Oxidants derived from CS can induce DNA damage and stress-induced premature cellular senescence in the respiratory system, which play significant roles in COPD. Therefore, antioxidants should provide benefits for the treatment of COPD; however, their therapeutic potential remains limited owing to the complexity of this disease. Recently, molecular hydrogen (H2) has been reported as a preventive and therapeutic antioxidant. Molecular H2 can selectively reduce hydroxyl radical accumulation with no known side effects, showing potential applications in managing oxidative stress, inflammation, apoptosis, and lipid metabolism. However, there have been no reports on the efficacy of molecular H2 in COPD patients. In the present study, we used a mouse model of COPD to investigate whether CS-induced histological damage in the lungs could be attenuated by administration of molecular H2. We administered H2-rich pure water to senescence marker protein 30 knockout (SMP30-KO) mice exposed to CS for 8 weeks. Administration of H2-rich water attenuated the CS-induced lung damage in the SMP30-KO mice and reduced the mean linear intercept and destructive index of the lungs. Moreover, H2-rich water significantly restored the static lung compliance in the CS-exposed mice compared with that in the CS-exposed H2-untreated mice. Moreover, treatment with H2-rich water decreased the levels of oxidative DNA damage markers such as phosphorylated histone H2AX and 8-hydroxy-2'-deoxyguanosine, and senescence markers such as cyclin-dependent kinase inhibitor 2A, cyclin-dependent kinase inhibitor 1, and ß-galactosidase in the CS-exposed mice. These results demonstrated that H2-rich pure water attenuated CS-induced emphysema in SMP30-KO mice by reducing CS-induced oxidative DNA damage and premature cell senescence in the lungs. Our study suggests that administration of molecular H2 may be a novel preventive and therapeutic strategy for COPD.


Assuntos
Proteínas de Ligação ao Cálcio/deficiência , Hidrogênio/administração & dosagem , Hidrogênio/farmacologia , Peptídeos e Proteínas de Sinalização Intracelular/deficiência , Enfisema Pulmonar/prevenção & controle , Fumar/efeitos adversos , Água/administração & dosagem , Água/química , Animais , Proteínas de Ligação ao Cálcio/genética , Proteínas de Ligação ao Cálcio/metabolismo , Hidrogênio/química , Peptídeos e Proteínas de Sinalização Intracelular/genética , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Enfisema Pulmonar/genética , Enfisema Pulmonar/metabolismo , Água/farmacologia
18.
ChemSusChem ; 10(24): 4845-4850, 2017 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-28718226

RESUMO

Although Li-rich layered oxides (LLOs) have the highest capacity of any cathodes used, the rate capability of LLOs falls short of meeting the requirements of electric vehicles and smart grids. Herein, a layered-spinel microsphere/reduced graphene oxide heterostructured cathode (LS@rGO) is prepared in situ. This cathode is composed of a spinel phase, two layered structures, and a small amount of reduced graphene oxide (1.08 wt % of carbon). The assembly delivers a considerable charge capacity (145 mA h g-1 ) at an ultrahigh charge- discharge rate of 60 C (12 A g-1 ). The rate capability of LS@rGO is influenced by the introduced spinel phase and rGO. X-ray absorption and X-ray photoelectron spectroscopy data indicate that Cr ions move from octahedral lattice sites to tetrahedral lattice sites, and that Mn ions do not participate in the oxidation reaction during the initial charge process.


Assuntos
Fontes de Energia Elétrica , Eletrodos , Grafite/química , Lítio/química , Microesferas , Microscopia Eletrônica de Varredura , Microscopia Eletrônica de Transmissão , Óxidos/química , Espectroscopia Fotoeletrônica
19.
ChemSusChem ; 10(14): 2875-2879, 2017 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-28612461

RESUMO

Oxygen vacancies can help to capture oxygen-containing species and act as active centers for oxygen evolution reaction (OER). Unfortunately, effective methods for generating a high amount of oxygen vacancies on the surface of various nanocatalysts are rather limited. Here, we described an effective way to generate oxygen-vacancy-rich surface of transition metal oxides, exemplified with Co3 O4 , simply by constructing highly coupled interface of ultrafine Co3 O4 nanocrystals and metallic Ti. Impressively, the amounts of oxygen vacancy on the surface of Co3 O4 /Ti surpassed the reported values of the Co3 O4 modified even under highly critical conditions. The Co3 O4 /Ti electrode could provide a current density of 23 mA cm-2 at an OER overpotential of 570 mV, low Tafel slope, and excellent durability in neutral medium. Because of the formation of a large amount of oxygen vacancies as the active centers for OER on the surface, the TOF value of the Co3 O4 @Ti electrode was optimized to be 3238 h-1 at an OER overpotential of 570 mV, which is 380 times that of the state-of-the-art non-noble nanocatalysts in the literature.


Assuntos
Cobalto/química , Nanopartículas/química , Nanotecnologia , Óxidos/química , Oxigênio/química , Titânio/química , Água/química , Animais , Eletroquímica , Eletrodos , Engenharia , Oxirredução
20.
Chem Commun (Camb) ; 53(55): 7800-7803, 2017 Jul 06.
Artigo em Inglês | MEDLINE | ID: mdl-28653063

RESUMO

∼1 V lithium intercalation materials are promising anodes for lithium-ion batteries, because such materials give consideration to both the tolerance of lithium plating (e.g., graphite with ∼0.1 V versus Li+/Li easily results in lithium plating due to a too low potential) and the energy density of the batteries (e.g., Li4Ti5O12 with ∼1.55 V decreases the battery voltage, and thus reduces the energy density). Herein, the layered perovskite compound LiEuTiO4 with a 0.8 V lithium intercalation/deintercalation potential plateau was successfully synthesized by the ion-exchange reaction with NaEuTiO4 prepared via a sol-gel method. LiEuTiO4 can deliver a high capacity of 219.2 mA h g-1 (2nd discharge) at a rate of 100 mA g-1. Even after 500 cycles, the discharge capacity remains at ∼217 mA h g-1 and the Coulombic efficiency is 99.2%. To our knowledge, the cycle stability of LiEuTiO4 exceeds all previous ∼1 V electrodes. Different from the common lithium intercalation Ti-based electrodes (such as Li4Ti5O12) based on the reduction of the Ti4+ to Ti3+, electrochemical lithium intercalation into LiEuTiO4 leads to the reduction of the Eu3+ to Eu2+.

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