Electrochemically converting nitrate, a widespread water pollutant, back to valuable ammonia is a green and delocalized route for ammonia synthesis, and can be an appealing and supplementary ...alternative to the Haber-Bosch process. However, as there are other nitrate reduction pathways present, selectively guiding the reaction pathway towards ammonia is currently challenged by the lack of efficient catalysts. Here we report a selective and active nitrate reduction to ammonia on Fe single atom catalyst, with a maximal ammonia Faradaic efficiency of ~ 75% and a yield rate of up to ~ 20,000 μg h
mg
(0.46 mmol h
cm
). Our Fe single atom catalyst can effectively prevent the N-N coupling step required for N
due to the lack of neighboring metal sites, promoting ammonia product selectivity. Density functional theory calculations reveal the reaction mechanisms and the potential limiting steps for nitrate reduction on atomically dispersed Fe sites.
The electrochemical synthesis of chemicals and fuel feedstocks has been demonstrated to be a sustainable and “green” alternative to traditional chemical engineering, where oxygen evolution reaction ...(OER) plays a vital role in coupling with various cathodic reactions. While tremendous attention, involving both research and review topics, has been focused on pushing the limit of OER catalysts’ activity, the long-term stability of OER catalysts, which may play an even more important role in large-scale electrolysis industrialization, has been much less emphasized. Until this point, few systematic strategies for developing OER catalysts with industrially relevant durability have been reported. In this review, critical mechanisms that could influence OER stability are summarized, including surface reconstruction, lattice oxygen evolution, and the dissolution-redeposition process of catalysts. Moreover, to bridge the gap between lab-scale OER tests and large-scale electrocatalysis applications, stability considerations in electrolyzer design for long-term operation are also discussed in detail. This review provides catalyst and reactor design principles for overcoming OER stability challenges and will focus more attention from the field on the great importance of OER stability as well as future large-scale electrocatalysis applications.
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Recently, clean energy conversion through electrocatalysis is evolving rapidly as a promising alternative to fossil-fuel energy systems. However, electrolyzers have always suffered from long-term stability challenges, especially for the anodic oxygen evolution reaction catalysts. So far, other than high-cost noble-metal catalysts such as IrO2, no catalysts with industrially relevant stability for oxygen evolution process in acidic and neutral conditions have been demonstrated. Thus, mechanisms that lead to catalytic instability require further investigation and deep understanding to guide future catalyst design.
In order to explore both the origins of and solutions to the stability challenges, this review provides a comprehensive overview and analysis on mechanistic studies of OER catalytic stability. Surface reconstruction of catalysts under oxidation potential during oxygen evolution is one of the causes of catalyst degradation. In addition, lattice oxygen can sometimes participate in the reaction pathway and induce structural instability of catalysts. In addition, redeposition of dissolved ions onto the catalyst surface is a process that gains less attention but can greatly influence the catalytic stability. Besides the catalyst consideration, critical elements of electrolyzers are also discussed in this review to provide insights in electrolysis operation under more realistic conditions. Based on the studies summarized in this article, we also provide potential strategies to design stable OER catalysts. By appropriately tuning the components, structures, dissolution, and redeposition rates of catalysts, we believe that the development of catalysts with long-term stability for oxygen evolution reaction can be achieved in the near future.
Oxygen evolution reaction (OER) plays a vital role in clean energy conversion through electrochemical synthesis of chemicals and fuel feedstocks. However, OER catalysts have always suffered from long-term stability challenges. This review timely summarizes critical reaction mechanisms that could influence OER stability, discusses stability considerations for reactor designs, and proposes future perspectives and potential strategies for designing stable OER catalysts to overcome these challenges.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
2D transition metal carbides and nitrides (MXenes) have gained extensive attention recently due to their versatile surface chemistry, layered structure, and intriguing properties. The assembly of ...MXene sheets into macroscopic architectures is an important approach to harness their extraordinary properties. However, it is difficult to construct a freestanding, mechanically flexible, and 3D framework of MXene sheets owing to their weak intersheet interactions. Herein, an interfacial enhancement strategy to construct multifunctional, superelastic, and lightweight 3D MXene architectures by bridging individual MXene sheets with polyimide macromolecules is developed. The resulting lightweight aerogel exhibits superelasticity with large reversible compressibility, excellent fatigue resistance (1000 cycles at 50% strain), 20% reversible stretchability, and high electrical conductivity of ≈4.0 S m−1. The outstanding mechanical flexibility and electrical conductivity make the aerogel promising for damping, microwave absorption coating, and flexible strain sensor. More interestingly, an exceptional microwave absorption performance with a maximum reflection loss of −45.4 dB at 9.59 GHz and a wide effective absorption bandwidth of 5.1 GHz are achieved.
A 3D, electrically conductive, mechanically strong, and flexible MXene‐based aerogel reinforced with polyimide is fabricated for the first time. The conductive MXene/polyimide aerogel shows superelasticity, excellent resistance to fatigue for 1000 compression cycles under 50% strain, and thermal stability and fire retardancy, demonstrating its potential applications as multifunctional strain sensors and high‐performance microwave absorption coatings.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Oxygen reduction reaction towards hydrogen peroxide (H
2
O
2
) provides a green alternative route for H
2
O
2
production, but it lacks efficient catalysts to achieve high selectivity and ...activity simultaneously under industrial-relevant production rates. Here we report a boron-doped carbon (B-C) catalyst which can overcome this activity-selectivity dilemma. Compared to the state-of-the-art oxidized carbon catalyst, B-C catalyst presents enhanced activity (saving more than 210 mV overpotential) under industrial-relevant currents (up to 300 mA cm
−2
) while maintaining high H
2
O
2
selectivity (85–90%). Density-functional theory calculations reveal that the boron dopant site is responsible for high H
2
O
2
activity and selectivity due to low thermodynamic and kinetic barriers. Employed in our porous solid electrolyte reactor, the B-C catalyst demonstrates a direct and continuous generation of pure H
2
O
2
solutions with high selectivity (up to 95%) and high H
2
O
2
partial currents (up to ~400 mA cm
−2
), illustrating the catalyst’s great potential for practical applications in the future.
During eukaryote cell division, molecular motors are crucial regulators of microtubule organization, spindle assembly, chromosome segregation and intracellular transport. The kinesin-14 motors are ...evolutionarily conserved minus-end-directed kinesin motors that occur in diverse organisms from simple yeasts to higher eukaryotes. Members of the kinesin-14 motor family can bind to, crosslink or slide microtubules and, thus, regulate microtubule organization and spindle assembly. In this Commentary, we present the common subthemes that have emerged from studies of the molecular kinetics and mechanics of kinesin-14 motors, particularly with regard to their non-processive movement, their ability to crosslink microtubules and interact with the minus- and plus-ends of microtubules, and with microtubule-organizing center proteins. In particular, counteracting forces between minus-end-directed kinesin-14 and plus-end-directed kinesin-5 motors have recently been implicated in the regulation of microtubule nucleation. We also discuss recent progress in our current understanding of the multiple and fundamental functions that kinesin-14 motors family members have in important aspects of cell division, including the spindle pole, spindle organization and chromosome segregation.
Although multifunctional, flexible, and wearable textiles with integrated smart electronics have attracted tremendous attention in recent years, it is still an issue to balance new functionalities ...with the inherent performances of the textile substrates. 2D early transition metal carbides/nitrides (MXenes) are considered as ideal nanosheets for fabricating multifunctional and flexible textiles on the basis of their superb intrinsic electrical conductivity, tunable surface chemistry, and layered structure. Herein, highly conductive and hydrophobic textiles with exceptional electromagnetic interference (EMI) shielding efficiency and excellent Joule heating performance are fabricated by depositing in situ polymerized polypyrrole (PPy) modified MXene sheets onto poly(ethylene terephthalate) textiles followed by a silicone coating. The resultant multifunctional textile exhibits high electrical conductivity of ≈1000 S m−1 in conjunction with an exceptional EMI shielding efficiency of ≈90 dB at a thickness of 1.3 mm. The thin silicone coating renders the hydrophilic PPy/MXene‐decorated textile hydrophobic, leading to an excellent water‐resistant feature while retaining a satisfactory air permeability of the textile. Interestingly, the multifunctional textile also exhibits an excellent moderate voltage‐driven Joule heating performance. Thus, the deposition of PPy‐modified MXene followed by silicone coating creates a multifunctional textile that holds great promise for wearable intelligent garments, EMI shielding, and personal heating applications.
An efficient and scalable dip‐coating approach for the fabrication of flexible multifunctional transition metal carbides/nitrides (MXenes)‐derived textiles by decorating polypyrrole‐modified MXene sheets onto polyethylene terephthalate textiles followed by silicone coating is reported. The highly conductive and hydrophobic textiles show exceptional electromagnetic interference shielding efficiency, outstanding water‐resistant feature, and excellent Joule heating performances.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Although personal thermal management (PTM) materials for daily routine environments are widely investigated, the exploration of multifunctional PTM materials with excellent feasibility in complex and ...outdoor scenarios is still in its infancy. Herein, inspired by the temperature regulation effect of the atmosphere, a novel design for fabricating solar‐thermal gradient reduced graphene oxide (RGO) aerogel‐based bilayer phase change composite (GRGC) featuring “energy regulation” and “energy inverse compensation” is proposed for self‐adaptive PTM applications. By integrating the solar‐thermal energy conversion ability of RGO, the heat regulation of the aerogel/octadecane bilayer structure with the unique gradient RGO framework inside, and the latent‐heat compensation of octadecane, the bilayer GRGC can serve as an efficient PTM device to mitigate drastic temperature changes of human skin in harsh environments. This multifunctional PTM device can not only keep a warm skin surface microclimate in a frigid environment of −5 °C via the synergistic effect of the solar‐thermal conversion, the aerogel thermal insulation, and the phase‐change latent heat release, but also provide efficient thermal buffering to prevent hyperthermia in hot environments through its phase‐change behavior and its thermal insulation. This gradient and bilayer design opens a new avenue for fabricating self‐adaptive PTM devices for applications in harsh environments.
Gradient RGO aerogel‐based bilayer phase change composite featuring “energy regulation” and “energy inverse compensation” is designed for self‐adaptive personal thermal management. Thanks to the synergy of efficient solar‐thermal energy conversion, afferent heat regulation, and latent‐heat compensation, the bilayer phase change composite can alleviate acute temperature changes and maintain moderate body microenvironments in harsh scenarios, delivering extraordinary personal thermal management performances.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
Electrochemical water oxidation reaction (WOR) to hydrogen peroxide (H
2
O
2
) via a 2e
−
pathway provides a sustainable H
2
O
2
synthetic route, but is challenged by the traditional 4e
−
...counterpart of oxygen evolution. Here we report a CO
2
/carbonate mediation approach to steering the WOR pathway from 4e
−
to 2e
−
. Using fluorine-doped tin oxide electrode in carbonate solutions, we achieved high H
2
O
2
selectivity of up to 87%, and delivered unprecedented H
2
O
2
partial currents of up to 1.3 A cm
−2
, which represents orders of magnitude improvement compared to literature. Molecular dynamics simulations, coupled with electron paramagnetic resonance and isotope labeling experiments, suggested that carbonate mediates the WOR pathway to H
2
O
2
through the formation of carbonate radical and percarbonate intermediates. The high selectivity, industrial-relevant activity, and good durability open up practical opportunities for delocalized H
2
O
2
production.
Asian ginseng (Panax ginseng C.A. Meyer), American ginseng (Panax quinquefolius) and notoginseng (Panax notoginseng) are the three most commonly used ginseng botanicals in the world. With the ...increasing interests on antimicrobial properties of plants, the antimicrobial activities of ginseng species have been investigated by a number of researchers worldwide. This overview interprets our present knowledge of the antimicrobial activities of the three ginseng species and some of their bioactive components against pathogenic bacteria (Pseudomonas aeruginosa, Helicobacter pylori, Staphylococcus aureus, Escherichia coli, Propionibacterium acnes, et al.) and fungi (Candida albicans, Fusarium oxysporum, et al). Ginsenosides, polysaccharides, essential oil, proteins, and panaxytriol are all might responsible for the antimicrobial activities of ginseng. The antimicrobial mechanisms of ginseng components could be summarized to the following points: (a) inhibit the microbial motility and quorum‐sensing ability; (b) affect the formation of biofilms and destroy the mature biofilms, which can weaken the infection ability of the microbes; (c) perturb membrane lipid bilayers, thus causing the formation of pores, leakages of cell constituents and eventually cell death; (d) stimulate of the immune system and attenuate microbes induced apoptosis, inflammation, and DNA damages, which can protect or help the host fight against microbial infections; and (e) inhibit the efflux of antibiotics that can descend the drug resistance of the microbial. The collected information might facilitate and guide further studies needed to optimize the use of ginseng and their components to improve microbial food safety and prevent or treat animal and human infections.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
MicroRNAs (miRNAs) are small non-coding RNAs (typically consisting of 18–25 nucleotides) that negatively control expression of target genes at the post-transcriptional level. Owing to the ...biological significance of miRNAs, miRTarBase was developed to provide comprehensive information on experimentally validated miRNA–target interactions (MTIs). To date, the database has accumulated >13,404 validated MTIs from 11,021 articles from manual curations. In this update, a text-mining system was incorporated to enhance the recognition of MTI-related articles by adopting a scoring system. In addition, a variety of biological databases were integrated to provide information on the regulatory network of miRNAs and its expression in blood. Not only targets of miRNAs but also regulators of miRNAs are provided to users for investigating the up- and downstream regulations of miRNAs. Moreover, the number of MTIs with high-throughput experimental evidence increased remarkably (validated by CLIP-seq technology). In conclusion, these improvements promote the miRTarBase as one of the most comprehensively annotated and experimentally validated miRNA–target interaction databases. The updated version of miRTarBase is now available at http://miRTarBase.cuhk.edu.cn/.
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