Sodium‐ion batteries capable of operating at rate and temperature extremes are highly desirable, but elusive due to the dynamics and thermodynamics limitations. Herein, a strategy of ...electrode–electrolyte interfacial chemistry modulation is proposed. The commercial hard carbon demonstrates superior rate performance with 212 mAh g−1 at an ultra‐high current density of 5 A g−1 in the electrolyte with weak ion solvation/desolvation, which is much higher than those in common electrolytes (nearly no capacity in carbonate‐based electrolytes). Even at −20 °C, a high capacity of 175 mAh g−1 (74 % of its room‐temperature capacity) can be maintained at 2 A g−1. Such an electrode retains 90 % of its initial capacity after 1000 cycles. As proven, weak ion solvation/desolvation of tetrahydrofuran greatly facilitates fast‐ion diffusion at the SEI/electrolyte interface and homogeneous SEI with well‐distributed NaF and organic components ensures fast Na+ diffusion through the SEI layer and a stable interface.
In a THF‐based electrolyte with a weak solvation structure, Na+ desolvation is fast and a uniform solid electrolyte interphase (SEI) with abundant NaF and organic compounds is generated on the commercial hard carbon anode. This greatly enhances the interface stability and enables the rapid migration of Na+ in the SEI, thus realizing the high rate capability, long‐term stability and good low‐temperature performance for the hard carbon anode.
Regioselective transformation is among the long‐standing challenges in organic synthesis. In this communication, a copper‐catalyzed selectivity controlled regiodivergent borocarbonylation of imines ...with alkyl iodides has been developed. Various α‐amino ketones and α‐boryl amides were produced in moderate to good yields from the same substrates. The choice of the ligand is key for the regioselectivity control: α‐amino ketones were produced selectively in good yields with (p‐CF3C6H4)3P as the ligand, whereas the corresponding α‐boryl amides were obtained with high regioselectivities when using MeIMes as the ligand.
A novel ligand‐controlled copper‐catalyzed borocarbonylation for the selective synthesis of α‐amino ketones and α‐boryl amides from imines and alkyl iodides has been developed. In this catalyst system, the choice of the ligand is key for the regioselectivity control: α‐amino ketones were produced selectively in good yields with (p‐CF3C6H4)3P as the ligand, whereas the corresponding α‐boryl amides were obtained with high regioselectivities when using MeIMes as the ligand.
The rapid progress of proton exchange membrane fuel cells (PEMFCs) and alkaline exchange membrane fuel cells (AMFCs) has boosted the hydrogen economy concept via diverse energy applications in the ...past decades. For a holistic understanding of the development status of PEMFCs and AMFCs, recent advancements in electrocatalyst design and catalyst layer optimization, along with cell performance in terms of activity and durability in PEMFCs and AMFCs, are summarized here. The activity, stability, and fuel cell performance of different types of electrocatalysts for both oxygen reduction reaction and hydrogen oxidation reaction are discussed and compared. Research directions on the further development of active, stable, and low‐cost electrocatalysts to meet the ultimate commercialization of PEMFCs and AMFCs are also discussed.
The development of fuel cells is of great significance for achieving a sustainable society. Recent progress in cathodic electrocatalysts for proton exchange membrane fuel cells and anodic and cathodic electrocatalysts for alkaline exchange membrane fuel cells is summarized. The rational design strategies, structure evolution, activities, fuel cell performance, and durability of noble‐metal‐ and non‐noble‐metal‐based electrocatalysts are discussed.
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Constant-rate inflation, including ultra-slow-roll inflation as a special case, has been widely applied to the formation of primordial black holes with a significant deviation from the ...standard slow-roll conditions at both the growing and decaying phases of the power spectrum. We derive analytic solutions for the curvature perturbations with respect to the late-time scaling dimensions (conformal weights) constrained by the dilatation symmetry of the de Sitter background and show that the continuity of conformal weights across different rolling phases is protected by the adiabatic condition of the inflaton perturbation. The temporal excitation of subleading states (with the next-to-lowest conformal weights), recorded as the “steepest growth” of the power spectrum, is triggered by the entropy production in the transition from the slow-roll to the constant-rate phases.
A long-standing challenge in nanozyme catalysis is low activity at physiological pH, especially for oxidase- and peroxidase-mimicking nanozymes. We herein communicate that Mn(II) can promote ...catalysis at neutral pH for carbon dots (C-dots) as a photo-oxidase nanozyme. The C-dots produce singlet oxygen upon light irradiation to oxidize Mn(II) to Mn(III), which is confirmed by a suite of spectroscopic evidence. The in situ produced Mn(III) acts as a mediator, analogous to mediators in electrochemistry to enhance electron transfer. None of the other divalent metal ions show such an effect, allowing the selective detection of Mn(II) down to 5 nM. EDTA further enhances the activity by stabilizing the highly active Mn(III), producing an intense blue color by oxidizing 3,3′,5,5′-tetramethylbenzidine (TMB) in just 10 s. Finally, this reaction was used to evaluate antioxidants. With this method, more analytical and biomedical applications of nanozymes can be exploited at neutral pH, and it may inspire other strategies to overcome the pH limitation in nanozyme catalysis.
The development of efficient oxygen electrocatalysts and understanding their underlying catalytic mechanism are of significant importance for the high‐performance energy conversion and storage ...technologies. Herein, we report novel CoCu‐based bimetallic metal–organic framework nanoboxes (CoCu‐MOF NBs) as promising catalysts toward efficient electrochemical oxygen evolution reaction (OER), fabricated via a successive cation and ligand exchange strategy. With the highly exposed bimetal centers and the well‐designed architecture, the CoCu‐MOF NBs show excellent OER activity and stability, with a small overpotential of 271 mV at 10 mA cm−2 and a high turnover frequency value of 0.326 s−1 at an overpotential of 300 mV. In combination of quasi in situ X‐ray absorption fine structure spectroscopy and density‐functional theory calculations, the post‐formed CoCu‐based oxyhydroxide analogue during OER is believed to account for the high OER activity of CoCu‐MOF NBs, where the electronic synergy between Co and neighbouring Cu atoms promotes the O−O bond coupling toward fast OER kinetics.
Cobalt‐copper‐based conductive bimetal–organic framework nanoboxes (CoCu‐MOF NBs) have been synthesized as a promising oxygen electrocatalyst, through a successive cation and ligand exchange strategy. With the bimetallic synergetic effect and the well‐designed hollow architecture, the CoCu‐MOF NBs show excellent electrocatalytic activity and robust long‐term stability toward efficient oxygen evolution electrocatalysis.
3-D printing, which is an automated production process with layer-by-layer control, has been gaining rapid development in recent years. The technology has been adopted in the manufacturing industry ...for decades and has recently been introduced in the construction industry to print houses and villas. The technology can bring significant benefits to the construction industry in terms of increased customization, reduced construction time, reduced manpower, and construction cost. A few isolated products and projects have been preliminarily tested using the 3-D printing technology. However, it should be noted that such tests and developments on the use of 3-D printing in the construction industry are very fragmented at the time of the study. It is therefore necessary for the building and construction industry to understand the technology, its historical applications and challenges for better utilization in the future. A systematic review shows that 3-D printing technology, after years of evolution, can be used to print large-scale architectural models and buildings. However, the potential of the technology is limited by the lack of large-scale implementation, the development of building information modeling, the requirements of mass customization, and the life cycle cost of the printed projects. It is therefore expected that future studies should be conducted on these areas to consolidate the stability and expand the applicability of 3-D printing in the construction industry.
Hybrid materials, integrating the merits of individual components, are ideal structures for efficient oxygen evolution reaction (OER). However, the rational construction of hybrid structures with ...decent physical/electrochemical properties is yet challenging. Herein, a promising OER electrocatalyst composed of trimetallic metal‐organic frameworks supported over S/N‐doped carbon macroporous fibers (S/N‐CMF@FexCoyNi1‐x‐y‐MOF) via a cation‐exchange strategy is delicately fabricated. Benefiting from the trimetallic composition with improved intrinsic activity, hollow S/N‐CMF matrix facilitating exposure of active sites, as well as their robust integration, the resultant S/N‐CMF@FexCoyNi1‐x‐y‐MOF electrocatalyst delivers outstanding activity and stability for alkaline OER. Specifically, it needs an overpotential of 296 mV to reach the benchmark current density of 10 mA cm−2 with a small Tafel slope of 53.5 mV dec−1. In combination with X‐ray absorption fine structure spectroscopy and density functional theory calculations, the post‐formed Fe/Co‐doped γ‐NiOOH during the OER operation is revealed to account for the high OER performance of S/N‐CMF@FexCoyNi1‐x‐y‐MOF.
Trimetallic metal‐organic frameworks supported over the hollow S/N‐doped carbon macroporous fibers (S/N‐CMF@FexCoyNi1‐x‐y‐MOF) are prepared as a promising electrocatalyst for the oxygen evolution reaction (OER). Benefiting from the trimetallic composition with improved intrinsic activity, hollow S/N‐CMF matrix facilitating active sites exposure, as well as their robust integration, the resultant S/N‐CMF@FexCoyNi1‐x‐y‐MOF electrocatalyst delivers excellent OER performance with an overpotential of 296 mV at 10 mA cm−2, a Tafel slope of 53.5 mV dec−1, and outstanding durability.
An unprecedented and challenging defluorinative carbonylation was achieved. Enabled by a Pd/Cu cooperative catalyst system, the first example of defluorinative carbonylative coupling has been ...established. With gem‐difluoroalkenes and aryl iodides as the substrates, this methodology offers flexible and facile access to privileged α‐fluorochalcones under mild reaction conditions in moderate‐to‐excellent yields. Mechanistic studies indicated transmetalation between palladium and copper intermediates as a crucial step of the catalytic cycle.
Enabled by a Pd/Cu cooperative catalyst system, the first example of defluorinative carbonylative coupling has been established. With gem‐difluoroalkenes and aryl iodides as the substrates, this methodology offers flexible and facile access to privileged α‐fluorochalcones under mild reaction conditions in moderate‐to‐excellent yields.
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