Perfluorinated Amines: Accelerating Lithium Electrodeposition by Tailoring Interfacial Structure and Modulated Solvation for High-Performance Batteries.

Modulating interfacial electrochemistry represents a prevalent approach for mitigating lithium dendrite growth and enhancing battery performance. Nevertheless, while most additives exhibit inhibitory characteristics, the accelerating effects on interfacial electrochemistry have garnered limited attention. In this work, perfluoromorpholine (PFM) with facilitated kinetics is utilized to preferentially adsorb on the lithium metal interface. The PFM molecules disrupt the solvation structure of Li+ and enhance the migration of Li+. Combined with the benzotrifluoride, a synergistic acceleration-inhibition system is formed. The ab initio molecular dynamics (AIMD) and density functional theory (DFT) calculation of the loose outer solvation clusters and the key adsorption-deposition step supports the fast diffusion and stable interface electrochemistry with an accelerated filling mode with C─F and C─H groups. The approach induces the uniform lithium deposition. Excellent cycling performance is achieved in Li||Li symmetric cells, and even after 200 cycles in Li||NCM811 full cells, 80% of the capacity is retained. This work elucidates the accelerated electrochemical processes at the interface and expands the design strategies of acceleration fluorinated additives for lithium metal batteries.

Synergistic Effects of Doping and Strain in Bismuth Catalysts for CO2 Electroreduction.

Doping is a recognized method for enhancing catalytic performance. The introduction of strains is a common consequence of doping, although it is often overlooked. Differentiating the impact of doping and strain on catalytic performance poses a significant challenge. In this study, Cu-doped Bi catalysts with substantial tensile strain are synthesized. The synergistic effects of doping and strain in bismuth result in a remarkable CO2RR performance. Under optimized conditions, Cu1/6-Bi demonstrates exceptional formate Faradaic efficiency (>95%) and maintains over 90% across a wide potential window of 900 mV. Furthermore, it delivers an industrial-relevant partial current density of -317 mA cm-2 at -1.2 VRHE in a flow cell, while maintaining its selectivity. Additionally, it exhibits exceptional long-term stability, surpassing 120 h at -200 mA cm-2. Through experimental and theoretical mechanistic investigations, it has been determined that the introduction of tensile strain facilitates the adsorption of *CO2, thereby enhancing the reaction kinetics. Moreover, the presence of Cu dopants and tensile strain further diminishes the energy barrier for the formation of *OCHO intermediate. This study not only offers valuable insights for the development of effective catalysts for CO2RR through doping, but also establishes correlations between doping, lattice strains, and catalytic properties of bismuth catalysts.

Porphyrin-Thiophene Based Conjugated Polymer Cathode with High Capacity for Lithium-Organic Batteries.

Organic electrode materials are promising for next-generation energy storage materials due to their environmental friendliness and sustainable renewability. However, problems such as their high solubility in electrolytes and low intrinsic conductivity have always plagued their further application. Polymerization to form conjugated organic polymers can not only inhibit the dissolution of organic electrodes in the electrolyte, but also enhance the intrinsic conductivity of organic molecules. Herein, we synthesized a new conjugated organic polymer (COPs) COP500-CuT2TP (poly [5,10,15,20-tetra(2,2'-bithiophen-5-yl) porphyrinato] copper (II)) by electrochemical polymerization method. Due to the self-exfoliation behavior, the porphyrin cathode exhibited a reversible discharge capacity of 420 mAh g-1, and a high specific energy of 900 Wh Kg-1 with a first coulombic efficiency of 96 % at 100 mA g-1. Excellent cycling stability up to 8000 cycles without capacity loss was achieved even at a high current density of 5 A g-1. This highly conjugated structure promotes COP500-CuT2TP combined high energy density, high power density, and good cycling stability, which would open new opportunity for the designable and versatile organic electrodes for electrochemical energy storage.

Spontaneous Desaturation of the Solvation Sheath for High-Performance Anti-Freezing Zinc-Ion Gel-Electrolyte.

In recent years, gel-electrolyte becomes pivotal in preventing hydrogen evolution, reducing dendrite growth, and protecting the zinc metal anode for zinc-ion batteries. Herein, a polyvinyl alcohol-based water-organic hybrid gel electrolyte with Agar and dimethyl sulfoxide is designed to construct the spontaneous desaturation of the solvation sheath for reducing hydrogen evolution and dendrite growth at room temperature and even low temperature. According to experimental characterization and theoretical calculations, the well binding between multihydroxy polymer and H2 O is achieved in the hybrid desaturated gel-electrolyte to regulate the inner and outer sheath. The ionic conductivity of hybrid gel-electrolyte reaches 7.4 mS cm-1 even at -20 °C with only 0.5 m zinc trifluoromethanesulfonate (Zn(OTf)2 ). The Zn symmetric cells cycle over 1200 h under 26 and -20 °C with improved mechanical properties and electrochemical performance. The asymmetric Zn || Cu cell with hybrid gel electrolyte reaches ≈99.02% efficiency after 250 cycles. The capacity of full cell is maintained at around 74 mAh g-1 with almost unchanged retention rate from 50 to 300 cycles at -20 °C. This work provides an effective strategy for desaturated solvation to reach anti-freezing and high-density Zn energy storage devices.

Multiple Heteroatom-Hydrogen Bonds Bridging Electron Transport in Covalent Organic Framework-Based Supramolecular System for Photoreduction of CO2.

Supramolecular systems consisting of covalent organic frameworks (COFs) and Ni complex are designed for robust photocatalytic reduction of CO2 . Multiple heteroatom-hydrogen bonding between the COF and Ni complex is identified to play a decisive role in the photoexcited electron transfer across the liquid-solid interface. The diminution of steric groups on COF or metal complex can optimize catalytic performance, which is more attributable to the enhanced hydrogen-bond interaction rather than their intrinsic activity. The photosystem with relatively strong strength of hydrogen bonds exhibits remarkable photocatalytic CO2 -to-CO conversion, far superior to photosystems with supported atomic Ni or metal complex alone in the absence of hydrogen-bond effect. Such heteroatom-hydrogen bonds bridging electron transport pathway confers supramolecular system with high photocatalytic performance, providing an avenue to rationally design efficient and steadily available photosystems.

In situself-assembly fabrication of ultrathin sheet-like CuS modified g-C3N4heterojunction and its enhanced visible-light photocatalytic performance.

Photocatalysts with heterojunction structure have been widely used for organic degradation. In this study, CuS/g-C3N4heterojunction was formed byin situself-assembly via a simply hydrothermal method. A series of characterizations were applied to analyzing the morphology, structure, optical properties and photo-induced electron transfer of the samples. The effect of CuS mass ratio in the CuS/g-C3N4composite on methyl blue (10 mg l-1) degradation under visible-light illumination was discussed. When CuS mass ratio was 60%, CuS/g-C3N4behaved the highest photocatalytic efficiency which is 17 times higher than that of pure g-C3N4, and the optimal heterojunction exhibited promising photocatalytic stability as well. The synthesized CuS/g-C3N4with intimate contact and promising photocatalytic performance provides important implications on analogous researches on g-C3N4-based heterojunctions for photocatalytic applications.

Donor-Acceptor Pairs in Covalent Organic Frameworks Promoting Electron Transfer for Metal-Free Photocatalytic Organic Synthesis.

The donor-acceptor-type covalent organic frameworks (COFs) have recently gained increasing interest in photocatalysis, but the photoinduced electron-transfer regimes in the COFs are underexplored. Herein, we demonstrate a designed porphyrinic COF possessing a donor-acceptor structure together with its photocatalytic performance in aerobic coupling of primary amines. The COF could be photoexcited by the full range of visible light to generate electron-hole pairs that could be separated by donor-acceptor pairs. Electron transfer as the mechanism of the reaction from anthracene unit to porphyrin unit was revealed by natural transition orbitals analyses. The electrons migrate to the adsorbed O2 to generate reactive oxidative species. The COF displays remarkable photocatalytic activities in the coupling of amines to imines, which can be explained mainly by the sufficient charge separation and mobility, benefiting from the donor-acceptor pairs in the COF and their interactions to the reactants and intermediates.

Zinc Manganate: Synthesis, Characterization, and Electrochemical Application toward Flufenamic Acid Detection.

The construction of novel electrocatalysts for efficient and economic electrochemical sensors is continuously a significant conceptual barrier for the point-of-care technology. Binary metal oxides with heterostructures have gained plenty of attention due to their promising physicochemical properties. Herein, we develop a rapid and sensitive electrochemical probe for the detection of flufenamic acid (FFA) by using a zinc manganate (ZnMnO)-modified electrode. The formation of ZnMnO was confirmed by various analytical techniques, such as X-ray diffraction, Raman spectroscopy, Fourier transform infrared spectroscopy, transmission electron microscopy, and field-emission scanning electron microscopy with energy dispersive X-ray spectroscopy and elemental mapping. The ZnMnO-based electrocatalyst, which was used for the electrochemical detection of FFA, shows better performance than the previously reported electrode materials. The ZnMnO assay shows a linear quantitative range from 0.05 to 116 µM with a limit of detection of 0.003 µM and sensitivity of 0.385 µA µM-1 cm-2. Its good electrochemical performance can be ascribed to the large surface area, rapid charge mass transfer, copious active sites, and high carrier mobility. The electrochemical study displays that the fabricated ZnMnO-based sensor has the potential to be applied in the clinical analysis. This work constructs an advanced functional electrode material with a microscale architecture for the point-of-care technology.

Mechanism of Pd-catalysed C(sp3)-H arylation of thioethers with Ag(I) additives.

Mechanistic studies reveal that Pd-catalyzed C(sp3)-H arylation of thioethers with silver(i) additives takes place via C(sp3)-H activation, oxidative addition and reductive elimination, wherein all steps proceed via the heterodimeric Pd-Ag pathway. Besides, the active heterodimeric Pd-Ag species are detected by mass spectrometry via control experiments.

Mechanistic studies of Cp*Ir(III)/Cp*Rh(III)-catalyzed branch-selective allylic C-H amidation: why is Cp*Ir(III) superior to Cp*Rh(III)?

Density functional theory calculations have revealed the mechanism and origins of the reactivity and regioselectivity of the Cp*Ir(iii)/Cp*Rh(iii)-catalyzed allylic C-H amidation of alkenes and dioxazolones. Generally, the catalytic cycle consists of alkene coordination, C(sp3)-H activation, dioxazolone oxidative addition, reductive elimination and proto-demetallation to give the final amidation product. The C-H activation is found to be the rate-determining step, and it controls the reactivity of the reaction. For the Cp*Ir(iii)-catalyzed system, the C-H activation undergoes an Ir(iii)-assisted proton transfer process with a low energy barrier, elucidating its high reactivity. In contrast, the C-H activation step is more like a direct deprotonation in the Cp*Rh(iii)-catalyzed system, which is responsible for its higher barrier and lower reactivity. The branched-selectivity arises from the electronic effect of the alkyl group on the charge distribution over the allylic moiety. Herein, iridium(v) polarizes the allylic group greater than that of the rhodium(v) system, which accounts for its good regioselectivity. The mechanistic insights will be useful for the further development of transition metal-catalyzed selective C-H amination reactions.

Cocrystal Engineering: Toward Solution-Processed Near-Infrared 2D Organic Cocrystals for Broadband Photodetection.

Large-area 2D cocrystals with strong near-infrared (NIR) absorption have been designed and prepared. Driven by the intermolecular charge-transfer (CT) interactions, zinc tetraphenylporphyrin (donor) and C60 (acceptor) self-assemble into a NIR cocrystal with absorption wavelength up to 1080 nm. By tailoring the growth solvents and processes, the cocrystal morphologies can be tuned from 1D nanowires, 2D nanosheets to large-area 2D cocrystal films with length reaching several millimeters. Owing to the highly ordered donor-acceptor arrangement, the CT absorption in the 2D cocrystals is enhanced and is comparable to singlet absorption. The uniform 2D cocrystals, with enhanced CT absorption in the NIR region, displays a high responsivity of 2424 mA W-1 to NIR light and a fast response time of 0.6 s. The excellent device performance is attributed to the generation of long-lived free charge carriers as revealed by transient absorption spectroscopy and optimization of device configuration.

Direct Enamido C(sp2 )-H Diphosphorylation Enabled by a PCET-Triggered Double Radical Relay: Access to gem-Bisphosphonates.

Herein we report a novel and straightforward protocol for the construction of valuable gem-BPs by means of proton-coupled electron-transfer (PCET)-triggered enamido C(sp2 )-H diphosphorylation. This reaction represents a rare example of realizing the challenging double C-P bond formation at a single carbon atom, thus providing facile access to a broad variety of structurally diverse bisphosphonates from simple enamides under silver-mediated conditions. Initial mechanistic studies demonstrated that the diphosphorylation involves two rounds of PCET-initiated radical relay process.

Ultratrace Naked-Eye Colorimetric Ratio Assay of Chromium(III) Ion in Aqueous Solution via Stimuli-Responsive Morphological Transformation of Silver Nanoflakes.

In this work, we discover an effective domino-effect-based detection mechanism for the rapid, high-selectivity, and ultrasensitive naked-eye colorimetric ratio assay of chromium(III) ion (Cr3+) in aqueous solutions. This naked-eye colorimetric ratio assay to Cr3+ relies on changes in absorbance properties that are due to the stimuli response of Cr3+ for the morphological transformation of silver nanoflakes. In the presence of Cr3+, large silver nanoflakes can be stimulated to transform to small nanoparticles (NPs), which promoted a color change in solution from bright yellow to wine red that was detected by the naked eye and spectroscopic absorption methods. The proposed naked-eye sensing strategy was coupled with an ultraviolet (UV)-spectroscopic chemosensor for the detection of trace Cr3+. The detection method showed an ultralow detection limit of 1.4 nM (nanomole) for Cr3+ in ultrapure water and 11.5 nM in human serum sample, respectively. On the basis of colorimetry, the lowest concentration of ∼50 nM for Cr3+ in ultrapure water and human serum can be detected by the naked eye. This naked-eye-based colorimetric ratio assay for accurate and selective identification and high sensitivity of Cr3+ is expected to have large potential and wide applications such as pharmaceutical analysis, clinical diagnosis, and environmental monitoring.

A Unified Mechanism to Account for Manganese- or Ruthenium-Catalyzed Nitrile α-Olefinations by Primary or Secondary Alcohols: A DFT Mechanistic Study.

Acceptorless dehydrogenative coupling (ADC) reactions generally involve a nucleophile (e.g., amine) as a coupling partner. Intriguingly, it has been reported that nitriles could also act as nucleophiles in ADC reactions, achieving the α-olefination of nitriles with primary or secondary alcohols by employing a manganese or ruthenium pincer complex as the catalyst, respectively. Although different mechanisms have been postulated for the two catalytic systems, the results of our DFT mechanistic study, reported herein, have allowed us to propose a unified mechanism to account for both nitrile α-olefinations. The reactions take place in four stages, namely alcohol dehydrogenation, nitrile activation to generate a nucleophilic metal species, coupling of an aldehyde or ketone with the metal species to form a C-C bond and to transfer a nitrile (Cα -)H atom to the carbonyl group, and dehydration by transferring the protonic (N-)H to the hydroxy group. A notable feature of the coupling stage is the activation of water or alcohol to give an intermediate featuring an OH- - or OR- -like group that activates a nitrile Cα -H bond. Moreover, the mechanism can even be applied to the base (KOtBu, modeled by the (KOtBu)4 cluster)-catalyzed Knoevenagel condensation of nitriles with ketones, which further indicates the generality of the mechanism and the resemblance of the metal pincer complexes to the (KOtBu)4 base. We expect these in-depth mechanistic insights and the finding of the resemblance of the metal pincer complexes to the (KOtBu)4 cluster could assist the development of new ADC reactions.

Density Functional Theory Mechanistic Insight into the Base-Free Nickel-Catalyzed Suzuki-Miyaura Cross-Coupling of Acid Fluoride: Concerted versus Stepwise Transmetalation.

Density functional theory mechanistic study has been carried out to account for the base-free nickel-catalyzed Suzuki-Miyaura coupling of acid fluorides (ArC(O)F) with boronic acids (Ar'B(OH)2). After oxidative addition to break the C-F bond of acid fluoride, the resultant ArC(O)[Ni]F species undergoes transmetalation with Ar'B(OH)2 to give ArC(O)[Ni]Ar'. Subsequently, ArC(O)[Ni]Ar' can either undergo decarbonylation, finally leading to the coupling product (ArAr'), or reductive elimination to give ketone byproduct ArC(O)Ar'. The kinetic competition between the two pathways controls the chemoselectivity of the reaction, and transmetalation is the rate-determining step of the coupling. Importantly, it was found that transmetalation prefers a stepwise mechanism over a conventional concerted one. Detailed analyses indicate that the strong fluorophilicity of boron facilitates the base-free transmetalation and the coordination interaction between an oxygen atom of boronic acid and nickel gears the base-free transmetalation to undergo the stepwise pathway. The stepwise transmetalation mechanism also involves the nickel-catalyzed Suzuki-Miyaura coupling of aldehydes with ketone (PhC(O)CF3) as the transmetalation promoter.

Strong Preference of the Redox-Neutral Mechanism over the Redox Mechanism for the TiIV Catalysis Involved in the Carboamination of Alkyne with Alkene and Diazene.

Titanium catalysis generally prefers redox-neutral mechanisms. Yet it has been reported that titanium could promote bond formations in a way similar to reductive elimination. Accordingly, redox catalytic cycles involving TiIV /TiII cycling have been considered. By studying, as an example, the carboamination of alkynes with alkenes and azobenzene catalyzed by the [TiIV ]=NPh imido complex, we performed DFT computations to gain an understanding of how the "abnormal" catalysis takes place, thereby allowing us to clarify whether the catalysis really follows TiIV /TiII redox mechanisms. The reaction first forms an azatitanacyclohexene by alkyne addition to the [TiIV ]=NPh bond, followed by alkene insertion. The azatitanacyclohexene can either undergo Cα -Cγ coupling, to afford bicyclo[3.1.0]imine, or ß-H elimination, to yield a [TiIV ]-H hydride, which then undergoes Cα =Cß or Cγ =Cδ insertion to give an α,ß- or ß,γ-unsaturated imine, respectively. Both the geometric and electronic structures indicate that the catalytic cycles proceed through redox-neutral mechanisms. The alternative redox mechanisms (e.g., by N-H or C-H reductive elimination) are substantially less favorable. We concluded that electronically, the TiIV catalysis intrinsically favors the redox-neutral mechanism, because a redox pathway would involve TiII structures either in the triplet ground state or in the high-lying open-shell singlet state, but the involvement of triplet TiII structures is spin-forbidden and that of singlet TiII structures is energetically disadvantageous.

Experimental Study on the Flexural Performance of Steel-Polyvinyl Alcohol Hybrid Fiber-Reinforced Concrete.

This paper explores the impact of steel-PVA hybrid fibers (S-PVA HF) on the flexural performance of panel concrete via three-point bending tests. Crack development in the concrete is analyzed through Digital Image Correlation (DIC) and Scanning Electron Microscope (SEM) experiments, unveiling the underlying mechanisms. The evolution of cracks in concrete is quantitatively analyzed based on fractal theory, and a predictive model for flexural strength (PMFS) is established. The results show that the S-PVA HF exhibits a synergistic effect in enhancing and toughening the concrete at multi-scale. The crack area of steel-PVA hybrid fiber concrete (S-PVA HFRC) is linearly correlated with deflection (δ), and it further reduces the crack development rate and crack area compared to steel fiber-reinforced concrete (SFRC). The S-PVA HF improves the proportional ultimate strength (fL) and residual flexural strength (fR,j) of concrete, and the optimal flexural performance of concrete is achieved when the steel fiber dosage is 1.0% and the PVA fiber dosage is 0.2%. The established PMFS of hybrid fiber-reinforced concrete (HFRC) can effectively predict the flexural strength of concrete.

Experimental Research on Crack Resistance of Steel-Polyvinyl Alcohol Hybrid Fiber-Reinforced Concrete.

This paper investigates the effects of steel fiber and PVA fiber hybrid blending on the compressive strength (fcc), splitting tensile strength (fts), compression energy (W1.0), and shrinkage properties of concrete. It also establishes a multi-factor crack resistance index evaluation model based on the Analytic Hierarchy Process (AHP) to comprehensively evaluate the crack resistance of concrete. The results show that the steel-PVA hybrid fiber (S-PVA HF) further enhances fcc, fts, the compression energy, and the shrinkage suppression properties of the concrete. The crack resistance of the steel-PVA hybrid fiber concrete (S-PVA HFRC) is the best when the proportion of steel fiber is 1.0% and that of the PVA fiber is 0.2%, and it increases up to 143% compared to the baseline concrete. The established concrete crack resistance evaluation model has a certain reliability.

Esculin suppresses the PERK-eIF2α-CHOP pathway by enhancing SIRT1 expression in oxidative stress-induced rat chondrocytes, mitigating osteoarthritis progression in a rat model.

OBJECTIVE: Osteoarthritis (OA) is a degenerative disease characterized by the gradual degeneration of chondrocytes, involving endoplasmic reticulum (ER) stress. Esculin is a natural compound with antioxidant, anti-inflammatory and anti-tumor properties. However, its impact on ER stress in OA therapy has not been thoroughly investigated. We aim to determine the efficiency of Esculin in OA treatment and its underlying mechanism. METHODS: We utilized the tert-butyl hydroperoxide (TBHP) to establish OA model in chondrocytes. The expression of SIRT1, PERK/eIF2α pathway-related proteins, apoptosis-associated proteins and ER stress-related proteins were detected by Western blot and Real-time PCR. The apoptosis was evaluated by flow cytometry and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining. X-ray imaging, Hematoxylin & Eosin staining, Safranin O staining and immunohistochemistry were used to assess the pharmacological effects of Esculin in the anterior cruciate ligament transection (ACLT) rat OA model. RESULTS: Esculin downregulated the expression of PERK/eIF2α pathway-related proteins, apoptosis-associated proteins and ER stress-related proteins, while upregulated the expression of SIRT1 and Bcl2 in the TBHP-induced OA model in vitro. It was coincident with the results of TUNEL staining and flow cytometry. We further confirmed the protective effect of Esculin in the rat ACLT-related model. CONCLUSION: Our results suggest the potential therapeutic value of Esculin on osteoarthritis. It probably inhibits the PERK-eIF2α-ATF4-CHOP pathway by upregulating SIRT1, thereby mitigating endoplasmic reticulum stress and protecting chondrocytes from apoptosis.

Regulating Grind-Induced Lattice Distortion for Nickel-Rich Cathodes by Annealing.

The commercialization of high-performance nickel-rich cathodes always awaits a cost-effective, environmentally friendly, and large-scale preparation method. Despite a grinding process normally adopted in the synthesis of the nickel-rich cathodes, lattice distortion, rough surface, and sharp edge transformation inevitably occurr in the resultant samples. In this work, an additional annealing process is proposed that aims at regulating lattice distortion as well as achieving round and smoother morphologies without any structural or elemental modifications. Such a structural enhancement is favored for improved lithium diffusion and electrochemical stability during cycling. Consequently, the annealed cathodes demonstrate a considerable enhancement in capacity retention, escalating from 68.7% to 91.9% after 100 cycles at 1 C. Additionally, the specific capacity is significantly increased from 64 to 142 mAh g-1 at 5 C when compared to the unannealed cathodes. This work offers a straightforward and effective approach for reinforcing the electrochemical properties of nickel-rich cathodes.