Search

A forward‐bias bipolar membrane (BPM) provides an alkaline cathode condition, which can be beneficial to some electrochemical reactions, such as the CO2 reduction reaction (CO2RR), but the water association (WA) in forward‐bias BPM is not well understood at all. In this study, BPMs are designed with different interfacial polymeric catalysts to investigate the WA reaction under forward‐bias for electrochemical applications. An enhanced current density is observed with added polymeric catalysts (−OH, −O−, −N−, and graphene oxide) compared to the blank control. Temperature‐dependent measurements indicated that the WA in BPM is not kinetically controlled. The in‐plane and through‐plane ions diffusion is investigated, which showed that the WA in BPM is limited mostly by the transport of OH− and, to a lesser degree, H+ at the interface. Molecular dynamic studies presented that the migration rate of OH− at the interface is approximately one order of magnitude lower than that of H+, indicating that the WA is mainly governed by the transport of OH−. Finally, a forward‐bias CO2RR electrolyzer is demonstrated with an Faradaic effeiciency CO (FECO) of 92.2 ± 2.7%. This work provides important fundamental insights into the WA reaction that would enable the use of forward‐bias BPM electrolyzers in future electrochemical applications. [ABSTRACT FROM AUTHOR]

A Cu(I)‐catalyzed [4+2] oxidative annulation of α,β‐unsaturated ketoxime acetates with cyclopropanols has been developed for the synthesis of 2,4,5‐trisubstituted pyridines in 28–76% yields. This method employs cyclopropanols as C2 synthons and features various functional group compatibility and gram‐scale synthesis. In addition, a plausible reaction pathway was proposed based on the mechanism studies. [ABSTRACT FROM AUTHOR]

Due to scale effects, directly enlarging the size of the micromixer is an easy way to reduce the efficiency of mass and heat transfer in the continuous flow chemical process. It is urgently needed to solve the problem of mass and heat transfer efficiency of the scale‐up mixer. A scale‐up microfluidic mixer with a porous structure was designed to improve the mass and heat transfer efficiency using computational fluid dynamics (CFD) simulations. The effects of rotation angle, porosity, and baffle spacing were studied to optimize the mixer structure. Compared with the 1 mm mixer without structure, the scale‐up mixer has a higher mixing efficiency and an 80% reduction in energy consumption at Re ≥ 700. A Nusselt number was used to evaluate the heat transfer efficiency of the mixer during fluid heating. The results show that the porous baffle promotes the generation of secondary flow and enhances the heat transfer effect, making its Nu increase by three times compared with the unstructured mixer. The scale‐up microfluidic mixer with a porous structure can effectively improve the mass and heat transfer performance. This study can provide a reference for the design or development of a novel scale‐up mixer. [ABSTRACT FROM AUTHOR]

This article demonstrates spatial mapping of the local and nanoscale structure of thin film objects using spatially resolved pair distribution function (PDF) analysis of synchrotron X‐ray diffraction data. This is exemplified in a lab‐on‐chip combinatorial array of sample spots containing catalytically interesting nanoparticles deposited from liquid precursors using an ink‐jet liquid‐handling system. A software implementation is presented of the whole protocol, including an approach for automated data acquisition and analysis using the atomic PDF method. The protocol software can handle semi‐automated data reduction, normalization and modeling, with user‐defined recipes generating a comprehensive collection of metadata and analysis results. By slicing the collection using included functions, it is possible to build images of different contrast features chosen by the user, giving insights into different aspects of the local structure. [ABSTRACT FROM AUTHOR]

The two‐electron pathway to form hydrogen peroxide (H2O2) is undesirable for the oxygen reduction reaction (ORR) in iron and nitrogen doped carbon (Fe–N–C) material as it not only lowers the catalytic efficiency but also impairs the catalyst durability. In this study, a relay catalysis pathway is designed to minimize the two‐electron selectivity of Fe–N–C catalyst. Such a design is achieved by introducing two other sites, that is, MnN4 site and α‐Fe(110) face. A combination of transmission electron microscopy image and X‐ray absorption spectra verify the three site formation. Electrochemical test coupled with post‐treatment confirm the improvement of MnN4 site and α‐Fe(110) face on catalyst performance. Theoretical calculation proposes a relay catalysis pathway of three sites, that is, H2O2 released from the FeN4 site migrates to the MnN4 site or α‐Fe(110) face, on which the captive H2O2 is further reduced to H2O. The relay catalysis pathway positioned the as‐prepared catalyst among the best ORR catalysts in both aqueous electrode and alkaline direct methanol fuel cell test. This study examples an interesting relay catalysis pathway of multi‐sites for the ORR, which offers insights into the design of efficient electrocatalysts for fuel cells or beyond. [ABSTRACT FROM AUTHOR]

Per‐ and polyfluroalkyl substances (PFAS) are drawing increasing attention in the research community due to their wide spread applications and their toxicity to animals and humans. Effective early detection method of PFAS chemicals in aqueous environment is important to reduce exposure and mitigate the potential toxic effects. This study focuses on the electrochemical detection of per‐fluoro octane sulfonate (PFOS) with differential pulse voltammetry and electrochemical impedance spectroscopy on a bare platinum electrode. We observe three distinct regions of adsorption behaviors with respect to PFOS concentration from 0–1000 nM, reflecting changes in the modes of adsorption due to different adsorbate‐adsorbate interactions on a bare electrode. The adsorption isotherm constant for PFOS adsorption on a Pt electrode is calculated to be 1.6×1012 cm3 mol−1 from fitting the electrochemical data with a modified Langmuir isotherm model. [ABSTRACT FROM AUTHOR]

BACKGROUND: Throughput, mixing efficiency and pressure drop are three key performance indicators of a mixer or reactor. However, it is difficult to simultaneously achieve high throughput, high mixing efficiency and low pressure drop in a traditional mixer. RESULTS: A novel mixer was designed and constructed by adding an ellipsoidal baffle to a large‐scale Y‐shaped mixer (YEBM) through computational fluid dynamics. The effects of ellipsoid period length, short and long axes, rotation direction, rotation angle and entrance angle of the mixer on mixing and flow characteristics were investigated and optimized. Compared with a 1 mm mixer, the throughput of the optimized YEBM is increased 100 times, the mixing efficiency is comparable and the pressure drop is reduced by 7.4%. Additionally, the application range of the YEBM with high mixing efficiency is extended to 499.1 < Re < 999.8. CONCLUSIONS: The results showed that the novel ellipsoidal baffle mixer could effectively enhance performance and reduce the pressure drop on the premise of ensuring high throughput. All the findings reported provide useful references for enhancement of mixing efficiency and reduction of pressure drop in a large‐scale mixer. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

AZ91‐0.9Ce alloy with a thickness of 8 mm is prepared by die casting. The formation process of main compounds in the alloy, the role of main compounds in fracture process, the main crack source, and crack propagation path of the alloy are studied. Results show that AZ91‐0.9Ce alloy is mainly composed of α‐Mg matrix, Mg17Al12 compound, Al4Ce compound, and a small amount of Al–Mn–Ce ternary compound. Among them, Al4Ce is formed prior to the Mg17Al12 compound. Mg17Al12 is formed by eutectic reaction, and Al–Mn–Ce ternary compound is formed at a later stage of solidification. Mg17Al12 and Al4Ce are the main crack sources of the alloy during the fracture process. Crack locations in the alloy mainly include grain boundaries, phase boundaries, and Mg17Al12 and Al4Ce compounds. The fracture mechanism of the alloy is that with the increase of load cracks occur at Mg17Al12 and Al4Ce compounds and connect with each other through intergranular and a small amount of transgranular to form the main crack. With the load continues to increase, the main crack gradually expands until alloy fracture failure. The continuous network distribution along grain boundaries of the Mg17Al12 compound is an important reason for intergranular fracture. [ABSTRACT FROM AUTHOR]

Abstract: Solid‐state Li metal battery technology is attractive, owing to the high energy density, long lifespans, and better safety. A key obstacle in this technology is the unstable Li/solid‐state electrolyte (SSE) interface involving electrolyte reduction by Li. Herein we report a novel approach based on the use of a nanocomposite consisting of organic elastomeric salts (LiO‐(CH2O)n‐Li) and inorganic nanoparticle salts (LiF, ‐NSO2‐Li, Li2O), which serve as an interphase to protect Li10GeP2S12 (LGPS), a highly conductive but reducible SSE. The nanocomposite is formed in situ on Li via the electrochemical decomposition of a liquid electrolyte, thus having excellent chemical and electrochemical stability, affinity for Li and LGPS, and limited interfacial resistance. XPS depth profiling and SEM show that the nanocomposite effectively restrained the reduction of LGPS. Stable Li electrodeposition over 3000 h and a 200 cycle life for a full cell were achieved. [ABSTRACT FROM AUTHOR]

Abstract: It is of great interest and big challenge to control the collective behaviors of nanomotors to mimic the aggregation/separation behavior of biological systems. Here, a light‐acoustic combined method is proposed to control the aggregation/separation of artificial nanomotors. It is shown that nanomotors aggregate at the pressure node in acoustic field and afterward present a collective “firework” separation behavior induced by light irradiation. The collective behavior is found to be applicable for metallic materials and polymers even different light wavelengths are used. Physical insights on the collective firework behavior resulting from the change of acoustic streaming caused by optical force are provided. It is found that diffusion velocity and diffusion region of cluster can be controlled by adjusting light intensity and acoustic excitation voltage, and irradiation direction, respectively. This harmless, controllable, and widely applicable method provides new possibilities for groups of nanomachines, drug release, and cargo transport in nanomedicine and nanosensors. [ABSTRACT FROM AUTHOR]

An improved method for the preparation of pentafluoroethylating reagent pentafluoroethyl-substituted benziodoxole (BIX-C2F5) was described. Under mild conditions, BIX-C2F5 was able to react with β-ketoesters or aryl/heteroaryl boronic acids to generate pentafluoroethylated compounds in good yields. [ABSTRACT FROM AUTHOR]

Two new silver(I) trans-cinnamates, namely [Ag(2-cca)(H2O)]2 ( 1) and [Ag(4-cca)] n ( 2) (2-ccaH = 2-chlorocinnamic acid and 4-ccaH = 4-chlorocinnamic acid), were synthesized and structurally characterized. Single crystal X-ray studies reveal that each silver(I) atom in 1 is two-coordinate by a 2-chlorocinnamate ligand and one water molecule to afford a discrete centrosymmetric dimer with the ligand-unsupported Ag···Ag interactions (3.218(4) Å), while a pair of symmetry-related silver(I) atoms in 2 are clamped by two μ2-η1:η1 4-chlorocinnamate ligands to yield a binuclear silver(I) moiety incorporating a ligand-supported Ag···Ag interaction (2.819(5) Å). Both complexes 1 and 2 show potent urease inhibitory activities with the respective IC50 values of 0.66 and 1.10 μM. [ABSTRACT FROM AUTHOR]