Enhanced Microbial Ferrihydrite Reduction by Pyrogenic Carbon: Impact of Graphitic Structures

Electron-shuttling agents such as pyrogenic carbon (PC) can mediate long-distance electron transfer and play numerous key roles in aquatic and soil biogeochemical processes. The electron-shuttling capacity of PC relies on both the surface oxygen-containing functional groups and bulk graphitic structures. Although the impacts of oxygen-containing functional groups on the electron-shuttling performance of PC are well studied, there remains insufficient understanding on the function of graphitic structures. Here, we studied the functions of PC in mediating microbial (Shewanella oneidensis MR-1) reduction of ferrihydrite, a classic and geochemically important soil redox process. The results show that PC enhanced microbial ferrihydrite reduction by 20–115% and the reduction rates increased with PC pyrolysis temperature increasing from 500 to 900 °C. For PC prepared at low temperature (500–600 °C), the electron-shuttling capacity of PC is mainly attributed to its oxygen-containing functional groups, as indicated by a 50–60% decline in the ferrihydrite reduction rate when PC was reduced under a H2 atmosphere to remove surface oxygen-containing functional groups. In stark contrast, for PC prepared at higher temperature (700–900 °C), the formation of PC graphitic structures was enhanced, as suggested by the higher electrical conductivity; accordingly, the graphitic structure exhibits greater importance in shuttling electrons, as demonstrated by a minor decline (10–18%) in the ferrihydrite reduction rate after H2 treatment of PC. This study provides new insights into the nonlinear and combined role of graphitic structures and oxygen-containing functional groups of PC in mediating electron transfer, where the pyrolysis temperature of PC acts as a key factor in determining the electron-shuttling pathways

Dearomatization of Pyridines: Stereoselective Synthesis of Functionalized [1,2,4]Triazolo[4,3‑<i>a</i>]pyridines

The stereoselective preparation of functionalized [1,2,4]triazolo[4,3-a]pyridines from N-tosylhydrazones and pyridines was developed through the dearomatization of pyridines. The current transformation features good step- and atom-economy, high diastereoselectivity, and the efficient formation of four new carbon–heteroatom bonds in the corresponding product tetrahydro pyridines

Dearomatization of Pyridines: Stereoselective Synthesis of Functionalized [1,2,4]Triazolo[4,3‑<i>a</i>]pyridines

The stereoselective preparation of functionalized [1,2,4]triazolo[4,3-a]pyridines from N-tosylhydrazones and pyridines was developed through the dearomatization of pyridines. The current transformation features good step- and atom-economy, high diastereoselectivity, and the efficient formation of four new carbon–heteroatom bonds in the corresponding product tetrahydro pyridines

Reacquainting the Sudden-Death and Reaction Routes of Li–O₂ Batteries by Ex Situ Observation of Li₂O₂ Distribution Inside a Highly Ordered Air Electrode

The unclear Li2O2 distribution inside an air electrode stems from the difficulty of conducting observation techniques inside a porous electrode. In this work, an integrated air electrode is prepared with highly ordered channels. The morphological composition and distribution of Li2O2 inside the real air electrode are clearly observed for the first time. The results show that the toroidal Li2O2 is constrained by the channel size and exhibits a larger diameter on the separator side at high currents. In contrast to the reported single-factor experiments, the coupling effects of charge transfer impedance and concentration polarization on sudden death are analyzed in-depth at low and high currents. The growth model suggests that toroidal Li2O2 exhibits a high dependence on the electrode surface structure. A new route is proposed in which the Li2O2/electrode interface of a toroid is controlled partially by the second single-electron reduction

Tailoring the Electrochemical Deposition of Zn by Tuning the Viscosity of the Liquid Electrolyte

The issues during Zn deposition in rechargeable Zn-based batteries greatly hinder cycling stability. In this work, a simple and inexpensive approach to tailor the Zn electrodeposition is proposed by tuning the viscosity of the liquid electrolyte (LE). First, the growth mechanisms of Zn deposition under different electrolyte properties are investigated by numerical simulation, from which the bottom deposition tends to fuse with each other when there are more deposition sites, and the mass-transfer coefficient is lower, thus achieving uniform deposition. Besides, the whole process of Zn deposition in charging–discharging cycling is in situ observed by an optical microscope. It is found that the cause of the poor stability in the LE is due to the uneven Zn deposition, resulting in weak bonding between the deposition and the electrode surface, which is also the reason for the formation of dead Zn. In contrast, when an appropriate amount of the polymer is added to the LE to increase the viscosity, an appropriate overpotential can be created, generating more deposition sites. In addition, the viscosity reduces the mass-transfer coefficient, making the distance from the ion to the deposition sites the main controlling factor. The Zn ions are more inclined to move in the direction of electric field lines, which results in a uniform and dense deposition layer. Furthermore, the effectiveness of this method is demonstrated in a Zn–LiFePO4 battery, from which the battery with the modified electrolyte condition still works properly even in the Zn utilization of 100% and shows a capacity retention rate (35%) of nearly twice that in the original LE condition (18%) after 10 cycles. This work provides a theoretical basis for Zn deposition and provides ideas for the future development of high-performance Zn-based batteries

Tailoring the Electrochemical Deposition of Zn by Tuning the Viscosity of the Liquid Electrolyte

The issues during Zn deposition in rechargeable Zn-based batteries greatly hinder cycling stability. In this work, a simple and inexpensive approach to tailor the Zn electrodeposition is proposed by tuning the viscosity of the liquid electrolyte (LE). First, the growth mechanisms of Zn deposition under different electrolyte properties are investigated by numerical simulation, from which the bottom deposition tends to fuse with each other when there are more deposition sites, and the mass-transfer coefficient is lower, thus achieving uniform deposition. Besides, the whole process of Zn deposition in charging–discharging cycling is in situ observed by an optical microscope. It is found that the cause of the poor stability in the LE is due to the uneven Zn deposition, resulting in weak bonding between the deposition and the electrode surface, which is also the reason for the formation of dead Zn. In contrast, when an appropriate amount of the polymer is added to the LE to increase the viscosity, an appropriate overpotential can be created, generating more deposition sites. In addition, the viscosity reduces the mass-transfer coefficient, making the distance from the ion to the deposition sites the main controlling factor. The Zn ions are more inclined to move in the direction of electric field lines, which results in a uniform and dense deposition layer. Furthermore, the effectiveness of this method is demonstrated in a Zn–LiFePO4 battery, from which the battery with the modified electrolyte condition still works properly even in the Zn utilization of 100% and shows a capacity retention rate (35%) of nearly twice that in the original LE condition (18%) after 10 cycles. This work provides a theoretical basis for Zn deposition and provides ideas for the future development of high-performance Zn-based batteries

Selective Separation Catalysis Membrane for Highly Efficient Water and Soil Decontamination via a Persulfate-Based Advanced Oxidation Process

The application of sulfate radical advanced oxidation for organic pollutant removal has been hindered by some shortages such as the recycling difficulty of a powered catalyst, the low utilization efficiency of oxidants, and the secondary pollution (including soil acidification) after reaction. Herein, we fabricate a selective separation catalysis membrane (SSCM) for a highly efficient and environment-friendly persulfate-based advanced oxidation process. The SSCM comprises a top polydimethylsiloxane layer which is selectively penetrable to hydrophobic organic pollutants, followed by a catalyst layer with a magnetic nitrogen-doped porous carbon material, targeting the advanced oxidation of the selected pollutants. Compared with the catalyst in powder form, such SSCM devices significantly reduced the dosage of peroxymonosulfate by more than 40% and the catalyst dosage by 97.8% to achieve 80% removal of phenol with the coexistence of 20 mg L–1 humic acid (HA). The SSCM can extract target pollutants while rejecting HA more than 91.43% for 100 h. The pH value in the receiving solution demonstrated a significant reduction from 7.01 to 3.00. In comparison, the pH value in the feed solution varied from 6.05 to a steady 4.59. The results can be ascribed to the specific functionality for the catalyst anchored, natural organic matter isolation, and reaction compartmentation provided by SSCMs. The developed SSCM technology is beneficial for catalysts reused in remediation practices, saving oxidant dosage, and avoiding acidification of soil and water, thus having tremendous application potential

Design of Thick Electrodes with Vertical Channels for Aqueous Batteries: Experimental and Numerical Analysis

Developing thick electrodes with high-area loadings is a direct method for boosting the energy density. However, this approach also leads to a proportional increase in the resistance to charge transport. Optimizing the microstructure of the electrode can effectively enhance the charge transport kinetics in thick electrodes. Herein, a low-tortuosity nickel electrode with vertical channels (VC-Ni) is fabricated using a phase inversion method. A high-loading VC-Ni electrode (26.7 mg cm–2) delivers a superior specific capacity of 134.0 mAh g–1 at a 5 C rate, significantly outperforming the conventional nickel electrode (Con-Ni). Numerical simulations reveal the fast transport kinetics within the vertical channel electrodes. For the thick electrode, the VC-Ni electrode shows a substantially lower concentration gradient of OH– and H+ compared to the Con-Ni electrode. Notably, beyond a critical loading of 26.5 mg cm–2, the specific capacity initially increases with volume fraction, peaking at 50%, and then diminishes. The specific capacity increases as the channel size decreases, but the tendency to increase gradually decreases. The highest specific capacity is achieved with an inverted trapezoidal channel shape, characterized by larger pores near the separator and smaller pores near the current collector. This work is of guidance for the design of thick electrodes for high-performance aqueous batteries

Deep Learning Enables Rapid Whole-Organ Histological Imaging with Ultraviolet-Excited Sectioning Tomography

Three-dimensional (3D) histopathology involves the microscopic examination of a specimen, which plays a vital role in studying tissue’s 3D structures and the signs of diseases. However, acquiring high-quality histological images of a whole organ is extremely time-consuming (e.g., several weeks) and laborious, as the organ has to be sectioned into hundreds or thousands of slices for imaging. Besides, the acquired images are required to undergo a complicated image registration process for 3D reconstruction. Here, by incorporating a recently developed vibratome-assisted block-face imaging technique with deep learning, we developed a pipeline termed HistoTRUST that can rapidly and automatically generate subcellular whole organ’s virtual hematoxylin and eosin (H&E) stained histological images, which can be reconstructed into 3D by simple image stacking (i.e., without registration). The performance and robustness of HistoTRUST have been successfully validated by imaging all six organs (e.g., brain, heart, liver, lung, kidney, and spleen). The imaging process for a whole organ takes hours to days, depending on the volume of imaged samples. The generated 3D dataset has the same color tune as the traditional H&E stained histological images. Therefore, the virtual H&E stained images can be directly analyzed by pathologists. HistoTRUST has a high potential to serve as a new standard in providing 3D histology for research or clinical applications

Copper-Catalyzed Aerobic Oxidative [3+2] Annulation for the Synthesis of 5‑Amino/Imino-Substituted 1,2,4-Thiadiazoles through C–N/N–S Bond Formation

A copper-catalyzed aerobic oxidative annulation reaction of 2-aminopyridine/amidine with isothiocyanate has been reported. This strategy involving C–N/N–S bond formations provides various 5-amino/imino-substituted 1,2,4-thiadiazole derivatives under a Cu/O₂ catalytic system. This method has demonstrated high reactivity, mild reaction conditions, and a broad substrate scope. Furthermore, the synthetic utilities of the approach are demonstrated by further modifications