Developing efficient and stable electrocatalysts is crucial for the electrochemical production of pure and clean hydrogen. For practical applications, an economical and facile method of producing ...catalysts for the hydrogen evolution reaction (HER) is essential. Here, we report ruthenium (Ru) nanoparticles uniformly deposited on multi-walled carbon nanotubes (MWCNTs) as an efficient HER catalyst. The catalyst exhibits the small overpotentials of 13 and 17 mV at a current density of 10 mA cm
in 0.5 M aq. H
SO
and 1.0 M aq. KOH, respectively, surpassing the commercial Pt/C (16 mV and 33 mV). Moreover, the catalyst has excellent stability in both media, showing almost "zeroloss" during cycling. In a real device, the catalyst produces 15.4% more hydrogen per power consumed, and shows a higher Faradaic efficiency (92.28%) than the benchmark Pt/C (85.97%). Density functional theory calculations suggest that Ru-C bonding is the most plausible active site for the HER.
Abstract
The one-step electrochemical synthesis of H
2
O
2
is an on-site method that reduces dependence on the energy-intensive anthraquinone process. Oxidized carbon materials have proven to be ...promising catalysts due to their low cost and facile synthetic procedures. However, the nature of the active sites is still controversial, and direct experimental evidence is presently lacking. Here, we activate a carbon material with dangling edge sites and then decorate them with targeted functional groups. We show that quinone-enriched samples exhibit high selectivity and activity with a H
2
O
2
yield ratio of up to 97.8 % at 0.75 V vs. RHE. Using density functional theory calculations, we identify the activity trends of different possible quinone functional groups in the edge and basal plane of the carbon nanostructure and determine the most active motif. Our findings provide guidelines for designing carbon-based catalysts, which have simultaneous high selectivity and activity for H
2
O
2
synthesis.
Mitochondrial dysfunction is associated with aging‐mediated inflammatory responses, leading to metabolic deterioration, development of insulin resistance, and type 2 diabetes. Growth differentiation ...factor 15 (GDF15) is an important mitokine generated in response to mitochondrial stress and dysfunction; however, the implications of GDF15 to the aging process are poorly understood in mammals. In this study, we identified a link between mitochondrial stress‐induced GDF15 production and protection from tissue inflammation on aging in humans and mice. We observed an increase in serum levels and hepatic expression of GDF15 as well as pro‐inflammatory cytokines in elderly subjects. Circulating levels of cell‐free mitochondrial DNA were significantly higher in elderly subjects with elevated serum levels of GDF15. In the BXD mouse reference population, mice with metabolic impairments and shorter survival were found to exhibit higher hepatic Gdf15 expression. Mendelian randomization links reduced GDF15 expression in human blood to increased body weight and inflammation. GDF15 deficiency promotes tissue inflammation by increasing the activation of resident immune cells in metabolic organs, such as in the liver and adipose tissues of 20‐month‐old mice. Aging also results in more severe liver injury and hepatic fat deposition in Gdf15‐deficient mice. Although GDF15 is not required for Th17 cell differentiation and IL‐17 production in Th17 cells, GDF15 contributes to regulatory T‐cell‐mediated suppression of conventional T‐cell activation and inflammatory cytokines. Taken together, these data reveal that GDF15 is indispensable for attenuating aging‐mediated local and systemic inflammation, thereby maintaining glucose homeostasis and insulin sensitivity in humans and mice.
Aging‐induced GDF15 production is observed in humans and mice, which is positively correlated with systemic inflammation and mitochondrial stress. GDF15 deficiency promotes glucose intolerance as well as hepatic and adipose inflammation in old mice. GDF15 contributes to regulatory T cells‐mediated suppression of conventional T cell activation, but senescent T cells were resistant to regulatory T cells‐mediated suppression compared to conventional T cells.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Single atom catalysts (SACs) are of great importance for oxygen reduction, a critical process in renewable energy technologies. The catalytic performance of SACs largely depends on the structure of ...their active sites, but explorations of highly active structures for SAC active sites are still limited. Herein, we demonstrate a combined experimental and theoretical study of oxygen reduction catalysis on SACs, which incorporate M−N3C1 site structure, composed of atomically dispersed transition metals (e.g., Fe, Co, and Cu) in nitrogenated carbon nanosheets. The resulting SACs with M−N3C1 sites exhibited prominent oxygen reduction catalytic activities in both acidic and alkaline media, following the trend Fe−N3C1 > Co−N3C1 > Cu−N3C1. Theoretical calculations suggest the C atoms in these structures behave as collaborative adsorption sites to M atoms, thanks to interactions between the d/p orbitals of the M/C atoms in the M−N3C1 sites, enabling dual site oxygen reduction.
Isolated M−N3C1 active sites were engineered into the single atom catalysts for efficient oxygen reduction catalysis. Theoretical calculations proposed that the M/C atoms in the active sites served as dual adsorption sites, enabling more efficient collaborative catalysis.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Single-atom catalysts have recently attracted considerable attention because of their highly efficient metal utilization and unique properties. Finding a green, facile method to synthesize them is ...key to their widespread commercialization. Here we show that single-atom catalysts (including iron, cobalt, nickel and copper) can be prepared via a top-down abrasion method, in which the bulk metal is directly atomized onto different supports, such as carbon frameworks, oxides and nitrides. The level of metal loading can be easily tuned by changing the abrasion rate. No synthetic chemicals, solvents or even water were used in the process and no by-products or waste were generated. The underlying reaction mechanism involves the mechanochemical force in situ generating defects on the supports, then trapping and stably sequestering atomized metals.
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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
Recently, studies of 2D organic layered materials with unique electronic properties have generated considerable interest in the research community. However, the development of organic materials with ...functional electrical transport properties is still needed. Here, a 2D fused aromatic network (FAN) structure with a C5N basal plane stoichiometry is designed and synthesized, and thin films are cast from C5N solution onto silicon dioxide substrates. Then field‐effect transistors are fabricated using C5N thin flakes as the active layer in a bottom‐gate top‐contact configuration to characterize their electrical properties. The C5N thin flakes, isolated by polydimethylsiloxane stamping, exhibit ambipolar charge transport and extraordinarily high electron (996 cm2 V−1 s−1) and hole (501 cm2 V−1 s−1) mobilities, surpassing the performance of most pristine organic materials without doping. These results demonstrate their vast potential for applications in thin‐film optoelectronic devices.
A crystalline fused aromatic network with a basal plane stoichiometry of C5N exhibits exceptionally high carrier mobility. The thin flakes of C5N, obtained by poly(dimethylsiloxane) stamping, show ambipolar charge transport and remarkably high electron and hole mobilities, demonstrating their huge potential for applications in thin‐film electronics.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Flexoelectricity can play an important role in the reversal of the self‐polarization direction in epitaxial BiFeO3 thin films. The flexoelectric and interfacial effects compete with each other to ...determine the self‐polarization state. In Region I, the self‐polarization is downward because the interfacial effect is more dominant than the flexoelectric effect. In Region II, the self‐polarization is upward, because the flexoelectric effect becomes more dominant than the interfacial effect.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Flexoelectric control of defect formation and associated electronic function is demonstrated in ferroelectric BiFeO3 thin films. An intriguing, so far never demonstrated, effect of internal electric ...field (Eint) on defect formation is explored by a means of flexoelectricity. Our study provides novel insight into defect engineering, as well as allows a pathway to design defect configuration and associated electronic function.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
The direct conversion of biorenewable alcohols into value‐added graphene and pure hydrogen (H2) at benign conditions is an important challenge, especially, considering the open carbon‐reduced cycle. ...In this study, it is demonstrated that inexpensive calcium oxide (CaO, from eggshells) can transform alcohols into bulky nanoporous graphene and pure hydrogen (≈99%) with robust selectivity at the temperature as low as 500 °C. Consequently, the growth of graphene can follow the direction of alcohol flow and uniformly penetrate into bulky nanoporous CaO platelets longer than 1 m without clogging. The experimental results and density functional theory calculations demonstrate that alcohol molecules can be catalytically carbonized on the surface of CaO at low temperature. The concept of the comprehensive utilization of biomass‐derived alcohols offers a carbon‐negative cycle for mitigating global warming and the energy demand.
The cheaply available CaO can simultaneously transform renewable alcohols into pure hydrogen (≈99%) and high‐value graphene at a temperature as low as 500 °C. The concept on the comprehensive utilization of biomass with a carbon‐negative cycle offers a new way to mitigate global warming and the world's energy demands.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Microglial hyperactivation and neuroinflammation are known to induce neuronal death, which is one of the main causes of neurodegenerative disorders. We previously found that Aquilariae Lignum extract ...attenuated both neuronal excitotoxicity and neuroinflammation in vivo and in vitro. For further analysis, we extracted the methylene chloride fraction of Aquilariae Lignum to determine the bioactive compounds. In this study, we investigated the anti-neuroinflammatory effects and underlying mechanisms of the Aquilariae Lignum fraction (ALF) using lipopolysaccharide (LPS)-stimulated BV2 microglial cells. BV2 cells were pretreated with ALF (0.5, 1, and 2.5 μg/mL) before treatment with LPS (1 μg/mL). Pretreatment with ALF significantly attenuated the LPS-induced overproductions of nitric oxide (NO), cyclooxygenase-2 (COX-2), prostaglandin E
(PGE
), and interleukin (IL)-1β. These anti-inflammatory effects were supported by ALF-mediated modulation of the nuclear factor-kappa B (NF-κB) pathway. Furthermore, ALF exerted strong anti-inflammasome effects, as shown by IL-1β-specific inhibitory activity, but not activity against tumor necrosis factor (TNF)-α, along with inhibition of caspase-1 activity and NACHT, LRR, and PYD domain-containing protein 3 (NLRP3)-related molecules. These results indicate the potent anti-neuroinflammatory activity of ALF and that its underlying mechanism may involve the regulation of NLRP3 inflammasome-derived neuroinflammation in microglial cells.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
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