The layer‐structured MoS2 is a typical hydrogen evolution reaction (HER) electrocatalyst but it possesses poor activity for the oxygen evolution reaction (OER). In this work, a cobalt covalent doping ...approach capable of inducing HER and OER bifunctionality into MoS2 for efficient overall water splitting is reported. The results demonstrate that covalently doping cobalt into MoS2 can lead to dramatically enhanced HER activity while simultaneously inducing remarkable OER activity. The catalyst with optimal cobalt doping density can readily achieve HER and OER onset potentials of −0.02 and 1.45 V (vs reversible hydrogen electrode (RHE)) in 1.0 m KOH. Importantly, it can deliver high current densities of 10, 100, and 200 mA cm−2 at low HER and OER overpotentials of 48, 132, 165 mV and 260, 350, 390 mV, respectively. The reported catalyst activation approach can be adapted for bifunctionalization of other transition metal dichalcogenides.
A cobalt covalent doping catalyst activation approach to induce hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) bifunctionality of MoS2 is proposed and experimentally validated, demonstrating superior bifunctional electrocatalytic activities with great application potential for overall water splitting in alkaline media.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
The vast majority of the reported hydrogen evolution reaction (HER) electrocatalysts perform poorly under alkaline conditions due to the sluggish water dissociation kinetics. Herein, a hybridization ...catalyst construction concept is presented to dramatically enhance the alkaline HER activities of catalysts based on 2D transition metal dichalcogenides (TMDs) (MoS2 and WS2). A series of ultrathin 2D‐hybrids are synthesized via facile controllable growth of 3d metal (Ni, Co, Fe, Mn) hydroxides on the monolayer 2D‐TMD nanosheets. The resultant Ni(OH)2 and Co(OH)2 hybridized ultrathin MoS2 and WS2 nanosheet catalysts exhibit significantly enhanced alkaline HER activity and stability compared to their bare counterparts. The 2D‐MoS2/Co(OH)2 hybrid achieves an extremely low overpotential of ≈128 mV at 10 mA cm−2 in 1 m KOH. The combined theoretical and experimental studies confirm that the formation of the heterostructured boundaries by suitable hybridization of the TMD and 3d metal hydroxides is responsible for the improved alkaline HER activities because of the enhanced water dissociation step and lowers the corresponding kinetic energy barrier by the hybridized 3d metal hydroxides.
Ultrathin 2D hybrids are designed and prepared via surface modification of monolayer MoS2 and WS2 nanosheets by metal (Ni, Co, Fe, Mn) hydroxides, which form a new class of alkaline hydrogen evolution reaction (HER) electrocatalysts. The surface introduction of metal hydroxides can effectively reduce the kinetic barrier of the prior water dissociation step of the alkaline HER reaction.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Studies have explored the influence of DNA damage in assisted reproductive technology (ART), but the outcome remains controversial. To determine whether sperm DNA fragmentation index (DFI) has any ...effect on ART outcomes, we collected detailed data regarding 1,333 IVF cycles performed at our centre, and the data of our retrospective cohort study were extracted for this meta‐analysis. We searched PubMed, Web of Science, EMBASE and Google Scholar and performed a systemic review and meta‐analysis. Primary meta‐analysis of 10 studies comprising 1,785 couples showed that live birth rate was no significantly different between low‐DFI group and high‐DFI group (p > 0.05). Secondary meta‐analysis of 25 studies comprising 3,992 couples showed a higher miscarriage rate in high‐DFI group than in low‐DFI group (RR=1.57 1.18, 2.09, p < 0.01). Meta‐analysis of eight studies comprising 17,879 embryos revealed a lower good‐quality embryo rate (RR=0.65 0.62, 0.68, p < 0.01). Meta‐analysis of 23 studies comprising 6,771 cycles showed that the high‐DFI group had a lower clinical pregnancy rate than low‐DFI group (RR=0.85 0.75, 0.96, p < 0.01). Heterogeneity of included studies weakened our conclusions. Our study showed that DFI has adverse effects on ART outcome. More well‐designed studies exploring the association between DFI and ART outcome are desired.
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DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Surface engineering has been shown critical for the success of perovskite solar cells by passivating the surface enriched defects and mobile species. The discovery of surface modulators with superior ...interaction strength to perovskite is of paramount importance since they can retain reliable passivation under various environments. Here, we report a chelation strategy for surface engineering of CsPbI
Br perovskite, in which dithiocarbamate molecules can be coordinate to surface Pb sites via strong bidentate chelating bonding. Such chelated CsPbI
Br perovskite can realize excellent passivation of surface under-coordinated defects, reaching a champion power conversion efficiency of 17.03% and an open-circuit voltage of 1.37 V of CsPbI
Br solar cells. More importantly, our chelation strategy enabled excellent device stability by maintaining 98% of their initial efficiency for over 1400 h in ambient condition. Our findings provide scientific insights on the surface engineering of perovskite that can facilitate the further development and application of perovskite optoelectronics.
Efficient and durable electrocatalysts from earth-abundant elements play a vital role in the key renewable energy technologies including overall water splitting and hydrogen fuel cells. Here, ...generally used CoFe based layered double hydroxides (LDHs) were first delaminated and exfoliated in the DMF-ethanol solvent (CoFe LDH-F), with enhancement both in oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The exfoliation process creates more coordinatively unsaturated metals and improves the intrinsic electronic conductivity, which is important in water electrolyzer reactions. In the basic solution, the CoFe LDH-F catalyst outperforms the commercial iridium dioxide (IrO2) electrocatalyst in activity and stability for OER and approaches the performance of platinum (Pt) for HER. The bifunctional electrocatalysts can be further used for overall water splitting, with a current density of ∼10 mA/cm2 at the applied voltage of 1.63 V for long-term electrolysis test, rivalling the performance of Pt and IrO2 combination as benchmarks. Our findings demonstrate the promising catalytic activity of LDHs for scale-up alkaline water splitting.
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IJS, KILJ, NUK, PNG, UL, UM
The size effect on the cellular uptake of nanoparticles (NPs) has been extensively studied, but it is still not well understood. Herein, a reductionist approach is used to minimize all influencing ...factors except the particle size, and co‐exposure of different‐sized silica nanoparticles (SNPs) is adopted instead of the common single exposure. SNPs are found being internalized by Hela cells in serum‐free medium mainly via clathrin‐dependent endocytosis, thus simplifying the data analysis for reliable attribution to size effects. Remarkably, even though at conditions that the size effects seem very small or even undetectable in the common single exposure experiments, the co‐exposure experiments reveal significant size effects due to an unexpected interplay between two different‐sized SNPs. Namely, the bigger SNPs significantly promote the cellular uptake of the smaller ones, while the smaller SNPs inhibit the internalization of the bigger ones, with a total uptake increase of the particle number of SNPs in the cells. This strong interplay between different‐sized NPs might unavoidably exist within most “single‐sized” NP products, whose sizes actually distribute in certain ranges, thus urging reconsideration of the size effect on the cellular uptake of NPs, for the benefits of both bioapplications and safety assessment of nanomaterials.
An unexpected interplay between different‐sized silica nanoparticles (SNPs) in their cellular uptake is revealed by co‐exposure experiments. It is found that the bigger SNPs significantly promote the cellular uptake of the smaller ones, while the smaller SNPs inhibit the internalization of the bigger ones, resulting in an increase of the total number uptake of SNPs.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Considerable effort has been made to develop efficient water-splitting photocatalysts, which are generally composed of light-absorbing semiconductors and so-called cocatalysts that play a key role in ...accelerating the reaction kinetics of water splitting. Platinum (Pt)-based catalysts have been widely regarded as excellent cocatalysts for photocatalytic water splitting, but the relationship between their valence state and reaction activity for photocatalytic water splitting had never been summarized. This review presents positively charged Pt nanoparticles, clusters and even single atoms that can boost the reaction activity dramatically, and summarises several strategies and techniques to tailor the positive valence states of Pt-based cocatalysts such as by using oxygen atoms. By tailoring the valence states of Pt-based cocatalysts, the capacities of these cocatalysts for water splitting can be significantly enhanced. Moreover, the
operando
analyses that can determine the real structures of this type of cocatalyst under working conditions are also discussed. These developments suggest that positively charged Pt-based cocatalysts could determine the direction and efficiency of photocatalytic water splitting, which may provide an ideal orientation to design state-of-the-art catalysts for achieving efficient photocatalytic water splitting.
Pt-based cocatalysts with positive valence states achieve efficient photocatalytic water splitting.
Significance Alzheimer’s disease (AD) is a devastating disease that results in the progressive cognitive deficits of elderly and has become one of major social and economic burdens worldwide. There ...is no effective drug or therapy to prevent or halt the progressive cognitive dysfunctions due to the complex mechanisms such as accumulation of amyloid-β (Aβ), increase in oxidative stress, and formation of neurofibrillary tangle that drive the development of the disease. We found here that Edaravone, a drug that has been used for ischemic stroke, is able to prevent and treat AD by targeting multiple pathways of AD pathogenesis and rescuing the cognitive deficits of a mouse model of AD. Our study suggests Edaravone is a promising drug candidate for AD.
Alzheimer’s disease (AD) is one of most devastating diseases affecting elderly people. Amyloid-β (Aβ) accumulation and the downstream pathological events such as oxidative stress play critical roles in pathogenesis of AD. Lessons from failures of current clinical trials suggest that targeting multiple key pathways of the AD pathogenesis is necessary to halt the disease progression. Here we show that Edaravone, a free radical scavenger that is marketed for acute ischemic stroke, has a potent capacity of inhibiting Aβ aggregation and attenuating Aβ-induced oxidation in vitro. When given before or after the onset of Aβ deposition via i.p. injection, Edaravone substantially reduces Aβ deposition, alleviates oxidative stress, attenuates the downstream pathologies including Tau hyperphosphorylation, glial activation, neuroinflammation, neuronal loss, synaptic dysfunction, and rescues the behavioral deficits of APPswe/PS1 mice. Oral administration of Edaravone also ameliorates the AD-like pathologies and memory deficits of the mice. These findings suggest that Edaravone holds a promise as a therapeutic agent for AD by targeting multiple key pathways of the disease pathogenesis.
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BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK
Electrocatalysts featuring high activity, selectivity and stability are urgently needed in solar-electricity powered energy-conversion technologies. In the past decade, various electrocatalysts have ...been demonstrated to be electrocatalytically active toward the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Despite the significant progress, catalyst discovery is still dominated by "trial-and-error" practice due to the lack of understanding of the origin of electrocatalytic activity, active site structures and key factors determining the
operando
electrocatalytic performance. Therefore, this critical review focuses on summarizing effective catalyst activation strategies to enable efficient catalyst discovery, on the basis of understanding real active sites for the HER and OER. Meanwhile, theory prediction and
operando
characterization techniques have also been introduced to identify the origin of electrocatalytic activity and active site structures. Moreover, catalyst atomic structure reconstruction/rearrangement under working conditions and the accompanying catalyst activation strategies have been discussed to address the negative impacts of reaction media. Finally, a brief perspective on the challenges and future directions for predicting, characterizing and understanding
operando
active sites to discover efficient activation strategies will also be presented.
This review summarizes recent progress in calculation prediction,
operando
characterization and advanced synthesis to extract and illustrate electrocatalyst activation principles that are widely applicable to guide new catalyst discovery.
Hydrogen production through electrochemical process is at the heart of key renewable energy technologies including water splitting and hydrogen fuel cells. Despite tremendous efforts, exploring ...cheap, efficient and durable electrocatalysts for hydrogen evolution still remains as a great challenge. Here we synthesize a nickel-carbon-based catalyst, from carbonization of metal-organic frameworks, to replace currently best-known platinum-based materials for electrocatalytic hydrogen evolution. This nickel-carbon-based catalyst can be activated to obtain isolated nickel atoms on the graphitic carbon support when applying electrochemical potential, exhibiting highly efficient hydrogen evolution performance with high exchange current density of 1.2 mA cm(-2) and impressive durability. This work may enable new opportunities for designing and tuning properties of electrocatalysts at atomic scale for large-scale water electrolysis.
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