Chemical Stability Research Articles

Conducting LixPOy Interface Generated From Insulating Residual Lithium Compounds on LiNi0.8Mn0.1Co0.1O2 Surface Improves Cycle Life and Assists in Fast Cycling.

LiNi0.8Mn0.1Co0.1O2 (NMC811) is the most promising cathode material for future Li-ion batteries (LIBs). However, the bulk and surface structural instabilities retard its commercial success. Surface chemical instability toward exposure to moisture (H2O and CO2) leads to the formation of residual lithium compounds (RLCs: Li2CO3, LiOH) on the surface. The alkaline RLCs form a resistive layer on the surface of NMC811 by undergoing parasitic side reactions with electrolytes. Herein, an "Adverse-to-Beneficial" approach is proposed to eliminate RLCs by chemically transforming them into a LixPOy (Li3PO4 and LiPO3) interface. The interface protects the NMC811 surface from moisture attack and unwanted side reactions with electrolytes. It enhances the cycle life by retaining 70% of the initial capacity after 300 cycles at a 0.5C rate and 60% after 500 cycles, even at a 5C rate in a voltage window of 3.0-4.3V versus Li+/Li. The coexistence of two Li-conducting phases lowers the voltage polarization of the kinetically sluggish H1 → M phase transition to unlock fast cycling, reduces cationic disorder, improves coulombic efficiency, enhances ion diffusion kinetics, and minimizes particle crack formation after long-term cycling. Hence, the LixPOy interface yields multifaceted benefits in the storage, processing, and electrochemistry of NMC811.

Quantification of morphine in exhaled breath condensate using a double network polymeric hybrid hydrogel functionalized with AuNPs

BackgroundMorphine serves as a foundation for creating other opioid derivatives, such as hydro/oxymorphine and heroin, which possess enhanced pain-relieving properties but are also prone to addiction and abuse. In cases of morphine overdose, it not only affects multiple immune functions but can also cause severe health complications. Given these concerns and the widespread use of morphine, it is crucial to develop efficient, uncomplicated, and precise methods for accurately detecting morphine in various biological and pharmaceutical samples.ResultsIn this investigation, a novel gold nanoparticle (AuNPs)-based double network hydrogel (DNH) nanoprobe has been fabricated for sensitive quantification of morphine in exhaled breath condensate samples. For that, gelatin/agarose DNH was fabricated through a one-step heating-cooling method in the presence of AuNPs, providing not only chemical stability but also prevent the AuNPs aggregation during synthesis process. In this method, the absorbance intensity of the nanoprobe gradually decreased with increasing morphine concentration due to the interaction morphine with AuNPs surface plasmon. The aggregation of AuNPs by addition of morphine was verified by UV-Vis spectrophotometry. The sensor displayed high sensitivity with detection limit of 0.006 µg.mL-1 in the linear range from 0.01 to 1.0 µg.mL-1. A reliable performance was attained for the spectrophotometric method for determination of morphine in the real samples.

Decarboxylative and Decarbonylative Borylation of Carboxylic Acids and Their Derivatives†

Comprehensive SummaryBoronate esters are highly valued in synthetic and pharmaceutical industries for their versatility in creating C—C and C—X bonds. They also find applications as catalysts in chemical transformations as well as stimuli‐responsive materials in materials science. Some alkyl boronates themselves also show promising applications in medicinal chemistry. In the past few decades, chemists have been devoted to developing new methods or new starting materials for synthesizing boronate esters. Carboxylic acids and their derivatives are privileged chemical entities due to their readily availability or natural abundance, structural diversity, and chemical stability. Hence, the transformation of carboxylic acid and their derivatives to alkyl/aryl boronate esters has seen its fast development in the past decade. This review summarized the state‐to‐art development of decarboxylative and decarbonylative borylation of carboxylic acids and their derivatives to aryl and alkyl boronate esters. Key ScientistsThe decarboxylative and decarbonylative borylation of carboxylic acids and their derivatives started only in the past decade. In 2016, the decarbonylative borylation of carboxylic esters and amides was reported by Zhuangzhi Shi and Magnus Reuping's groups. Then, in 2017, studies on the decarboxylative borylation of redox‐active esters such as NHPI esters started to receive increasing attention by Aggarwal, Baran, Fu, Glorius, and Li's groups. From 2018 to 2023, large numbers of studies on the decarboxylative and decarbonylative borylation of carboxylic acids and their derivatives using transition‐metal‐catalyst, organo‐catalyst, or under photochemical or electrochemical conditions emerged. Due to space limitations, only pictures of scientists who have contributed more than two works in this area are shown herein.

Dodecagonal GaN Microrods: Chemical Stability of a‐, m‐, and c‐Plane Walls and Their Application to Water‐Splitting

AbstractPhotoelectrolysis of water is a sustainable option for the production of hydrogen fuel. GaN nano‐ or microstructures are considered for water‐splitting due to their general high chemical stability and high surface‐to‐volume ratio enhancing the process effectiveness. In this study GaN structures with dodecagonal microrods are used as a working electrode for the water‐splitting process. Microrods are grown using a plasma‐assisted molecular beam epitaxy process allowing tailoring of microrod height and density. Their unique property is the of presence twelve sidewalls with alternating a‐ and m‐plane orientations. This enables a simultaneous study of the chemical stability of c‐, a‐, and m‐plane walls of GaN. The water‐splitting process is performed using a 1 mol l−1 NaOH electrolyte solution. Non‐zero current measured at zero bias under illumination indicates that the process takes place. A degradation of the GaN structure is observed after a prolonged process time. In short‐term exposures, etching of microrod sidewalls is observed. Roughening of the a‐plane walls studied by transmission electron microscopy indicates that this orientation is etched with a fastest rate. The internal crystalline structure is not influenced by the etching and remains stable as shown by the X‐ray absorption spectroscopy study.

Chemical Synergic Stabilization of High Br-Content Mixed-Halide Wide-Bandgap Perovskites for Durable Multi-Terminal Tandem Solar Cells with Minimized Pb Leakage.

High Br-content mixed-halide perovskites with wide-bandgap (WBG) of 1.6-2.0 eV have showcased vast potential to be used in tandem solar cells. However, they often suffer from severe halide segregation, phase separation and ion migration issues, which would accelerate the decomposition of perovskites films,deteriorate the photovoltaic performance and even aggravate the lead leakage from damaged devices. Here, we report a novel chemical synergic interaction strategy to mitigate the abovementioned issues. A small amount of cationic β-cyclodextrin, composed of multiple ammonium cations, chlorine ions and abundant hydroxyl functional groups, was introduced into WBG perovskites, which effectively stabilized the halide ions and homogenized the phase distribution, comprehensively passivated the defects,and efficiently immobilized the Pb2+ ions. Encouragingly, the cationic β-cyclodextrin was universal and useful for different WBG perovskites, which favorably boosted the efficiencies by 10%-36% and extended the device operational stability to 2680 h. The integrated four-terminal orsix-terminal all-perovskite tandem solar cells exhibited efficiencies up to 24.39% and 22.42%, respectively. We demonstrated the cationic β-cyclodextrin-assisted internal chemical encapsulation effectively prevented the Pb leakage from severely damaged devices with only 5.63 ppb Pb leaching out. The target tandem solar cells with cationic β-cyclodextrin modification also realized a Pb sequestration efficiency of 93.4%.

Operando X-ray and Mass Spectroscopy of Reduced Graphene Oxide ( rGO )-Mediated Cobalt Catalysts for Boosting the Hydrogen Evolution Reaction

Inserting underlying reduced graphene oxide (rGO) into Co aims to regulate the chemical integrity and catalytic ability of the Co upper layer for hydrogen evolution reaction (HER) as a green-hydrogen goal. Principally, an mass spectrometer indicates 3.8 times more considerable hydrogen generation in Co/rGO than in Co. The spectroscopical approaches, combining soft and hard X-ray probing, illustrate the chemical oxidation evolution of electronic Co-3 and Co-4 states differently regarding the underlying rGO contribution. A unique examination is regarded as the phase transition from the initial middle to high oxidation and to deoxidation, related to the intermediate Co0 existence and H2 generation. The chemical adsorption of Co–O(H), Co–Hads, and H2 molecules desorption have been assigned their spectral significances. The rGO mediation indicates two significant metal Co and Co–O(H) blocks in the two-dimensional - domain. Density-functional-theory (DFT) calculation provides the regeneration, sustained stability, and decreasing energy barrier of Co–Hads catalysts due to the rGO incorporation, thereby augmenting the HER enhancement through the alternative Volmer-Heyrovsky process. The experiment, including mass spectrometer, soft, and hard X-ray, provides evidence regarding the catalyst’s HER enhancement. This study offers insights into the chemical composition, electronic structure, and active role of Co bonded with or without the extinct OH and H bonds, advancing our comprehension of electrocatalytic reactions, thus taking our knowledge of composite materials to stepwise electrocatalytic reactions forward. This cutting-edge experiment under environment and DFT studies gives critical information regarding the catalytic mechanism and chemical stability of the Co and rGO materials. Published by the American Physical Society 2024

In-situ construction of novel Sb2(S,Se)3/CdSe S-scheme heterojunction with enhanced photoelectrochemical performance

Abstract Antimony selenosulfide (Sb2(S,Se)3) was considered to have great potential for photoelectrochemical (PEC) water splitting applications due to its excellent chemical stability, good light absorption, abundant reserves and non-toxicity. However, Sb2(S,Se)3 faces some limitations in the field of PEC, such as the serious recombination problem of photogenerated carriers. Therefore effectively restraining its deep-level defects is the crucial for enhancing its photoelectrochemical properties. In this paper, We successfully fabricated Sb2(S,Se)3/CdSe S-scheme heterojunction via one-step hydrothermal method, which improves its solar absorption capacity, facilitates efficient carrier separation. And, Sb2(S,Se)3/CdSe S-scheme heterojunction can suppress the adverse effects of deep-level defects on the PEC performance of Sb2(S,Se)3. Under simulated solar irradiation, the light current density can reach 4.02 mA cm2 (33.5 times that of monomeric Sb2(S,Se)3) at 1.23 VRHE, accompanied by low initial voltage and extremely high surface charge injection efficiency. This study is of great significance for the application of Sb2(S,Se)3 in the PEC field.

Toward an Ideal Light Source for Indoor Photosynthesis: Broadband Red Emission in Zero-Dimensional Hafnium-Based Metal Halide (TPP)2HfCl6·4C2H3N:Sb3.

With suitable electron-phonon coupling strength, a near-unity broadband photoluminescence quantum yield (PLQY) can be achieved in organic-inorganic hybrid metal halides (OIHMHs) via self-trapped exciton (STE) emission. However, it is still challenging to obtain high-quality red emission from OIHMHs with a desirable emission wavelength and high chemical stability, which hinders their practical application in high-performance displays, plant-growth lighting, and biomedical imaging. Herein, a series of hafnium-based zero-dimensional (TPP)2HfCl6·4C2H3N (TPP: tetraphenylphosphonium) single crystals with different Sb3+ doping levels are synthesized. The Sb3+-doped (TPP)2HfCl6·4C2H3N shows dual-band red emission with a full width at half-maximum of 178 nm and a high PLQY of 91.09%. This broad dual-band emission originates from dopant-induced extrinsic free excitons and STEs. Furthermore, (TPP)2HfCl6·4C2H3N:Sb3+ was employed as a luminescence converter in a light-emitting diode (LED) for plant growth regulation. A correlated color temperature of 4055 K and a color rendering index of 82.13 were achieved upon excitation of the LED at 365 nm. These results provide fundamental perspectives on the emission behavior of Sb3+-doped OIHMHs and illustrate their promise for use in plant-growth lighting.

Effect of Inorganic Anions on the Structure of Alkali-Activated Blast Furnace Slag

Analyzing the effect of anions on the structure of geopolymers is crucial because anions can significantly influence the material’s chemical stability, mechanical properties, and long-term durability. Understanding these effects helps optimize geopolymer compositions for various applications, such as construction materials and waste encapsulation. This research report describes the effects of nitrate, sulfate, and phosphate anions on alkali-activated blast furnace slag’s structural integrity and properties. Advanced techniques like XRD, FT-IR, Raman spectroscopy, and XPS have been employed to analyze structural modifications caused by anions, providing insights into their interactions and effects. These anions generally decrease compressive strength by disrupting geopolymerization and altering microstructure. For example, sulfate ions lead to the formation of ettringite, while phosphate ions bind calcium into separate phases. We can also observe microstructural changes, such as increased porosity with phosphate, which significantly reduces strength. Nitrate’s effect is less detrimental but still influences the overall structural dynamics.

Reliability of two-dimensional steady magnetized Jeffery fluid over shrinking sheet with chemical effect

Abstract A numerical framework is established for a two-dimensional steady flow of the magnetized Jeffery fluid model over elongated/shrinking sheets, with potential applications such as coating sheets, food products, fiber optics, drilling fluids, and the manufacturing processes of thermoplastic polymers. The model also demonstrates the influence of chemical reaction, magnetic field, and stability analysis which provide a novel contribution to this study. To ensure the ease and effectiveness of this analysis, we transform the set of difference equations governing the system into ordinary equations using the similarity transformation. The reliability of the solution is examined by using stability analysis. The Navier–Stokes equations have been transformed into self-similar equations by adopting appropriate similarity transformations and subsequently solved numerically using the bvp4c (three-stage Labatto-three-A formula) approach. The comparison between the derived asymptotic solutions and previously documented numerical results is quite remarkable. The self-similar equations display a duality of solutions within a limited range of the shrinking parameter, as observed from the data. For each stretching scenario, there is a unique solution. Hence, an examination of temporal stability has been conducted through linear analysis to establish the most fundamentally viable solution. The determination of stability in the analysis is based on the sign of the smallest eigenvalue, which indicates whether a solution is unstable or stable. The analysis of stability reveals that the first solution, which describes the primary flow, remains stable. Through the utilization of graphs, we thoroughly examine and discuss the influence of emerging factors. The numerical results obtained from this analysis demonstrate multiple solutions within a certain range of M 1 ≥ M ci {M}_{1}\ge {M}_{{ci}} , i = 1 , 2 , 3 i=1,2,3 , and no solution in the range M 1 < M ci {M}_{1}\lt {M}_{{ci}} . M ci {M}_{{ci}} denotes the critical values, which increase as the quantities of Sc {\rm{Sc}} increase from 0.3 to 0.9. Similarly, multiple solutions exist for λ ≥ λ ci \lambda \ge {\lambda }_{{ci}} , i = 1 , 2 , 3 i=1,2,3 , and no solution in the range λ < λ ci \lambda \lt {\lambda }_{{ci}} is observed.

Synergistic charge-transfer dynamics of novel D-D-A-π-A framework containing indoline-benzo[d][1,2,3]thiadiazole based push-pull sensitizers: from structural engineering to performance metrics in photovoltaic solar cells.

Dye-sensitized solar cells (DSSCs) present a convincing substitute for conventional silicon-based solar cells because of their possible lower manufacturing costs and versatile uses. Electron injection and dye regeneration processes are important in meeting the need for photosensitizers with improved efficiency and stability. Aimed at enhancing the performance and efficiency of DSSCs, this study focuses on the structural engineering to performance metrics of novel indoline-benzo[d][1,2,3]thiadiazole based push-pull sensitizers (LHZ1 to LHZ9) with D-D-A-π-A framework. The current study provides insights into the photovoltaic and optoelectronic properties of the investigated dyes, which are significantly influenced by the modification of auxiliary donors (D), internal acceptors with thiophene as a spacer, and cyanoacrylic acid (A) as the terminal acceptor. These modifications enhance rapid charge transfer among the dyes, highlighting the critical role of dye-semiconductor interactions. The suitability of developed sensitizers for DSSCs applications is confirmed by executing quantum methods like NBO, TDM, FMO, DOS, Eb, ΔGreg, ΔGinject, VRP, and ICT parameters qCT (e-), DCT ( ), H index ( ), ∆( ), t index ( ), and μCT (D). All of the investigated dyes have HOMO levels lower than the electrode I-/I3-'s redox potential (-4.8 eV) and LUMO values that are appropriately higher than the conduction band of TiO2 (-4.0 eV). The novel dyes showed a closing of the energy gap (2.38-1.84 eV). The LHZ7 and LHZ8 molecules with the lowest Eg (1.97 eV and 1.84 eV) demonstrated the highest absorption (up to 746 nm > 402 nm for LHZ), which was caused by the insertion effect of varied donors and internal acceptors. Almost all photosensitizers appeared with remarkable properties, i.e., red-shifted absorption maxima (746 nm), lowest Ex (1.66 eV), Eb (0.02 eV), and highest values of LHE (0.958). The TDM analysis revealed high charge density on HOMO of donor and LUMO of acceptors in designed dyes. DOS analysis revealed that the donor parts of the molecules delocalized the highest occupied molecular orbitals of dye particles. The electronic properties predicted by the NBO analysis showed that donor groups donate high and faster transfer of charge, and internal acceptor groups rapidly accept them. The electron injection (ΔGinject) and dye regeneration (ΔGreg) analysis of photosensitizers attached with TiO2 proved efficient charge transfer properties from the donor of newly designed dyes onto the conduction band of TiO2. This study, also supported by the thermodynamic stability of dyes with negative values of Gibbs free energy, revealed that the performance of the designed dyes is augmented by modifying the donor and internal acceptors of the reference photosensitizer for effective application in the experimental community. All of the dyes are suitable for DSSCs based on the calculated parameters. Still, the LHZ9 dye proved proficient in applying dye-sensitized solar cells due to its remarkable properties, i.e., lowest gap and red-shifted absorption maxima.

Radiocatalytic Synthesis of Acetic Acid from CH4 and CO2

AbstractThe C−C coupling of methane (CH4) and carbon dioxide (CO2) to generate acetic acid (CH3COOH) represents a highly atom‐efficient chemical conversion, fostering the comprehensive utilization of greenhouse gases. However, the inherent thermodynamic stability and kinetic inertness of CH4 and CO2 present obstacles to achieving efficient and selective conversion at room temperature. Our study reveals that hydroxyl radicals (⋅OH) and hydrated electrons (eaq−) produced by water radiolysis can effectively activate CH4 and CO2, yielding methyl radicals (⋅CH3) and carbon dioxide radical anions(⋅CO2−) that facilitate the production of CH3COOH at ambient temperature. The introduction of radiation‐synthesized CuO‐anchored TiO2 bifunctional catalyst could further enhance reaction efficiency and selectivity remarkably by boosting radiation absorption and radical stability, resulting in a concentration of 7.1 mmol ⋅ L−1 of CH3COOH with near‐unity selectivity (>95 %). These findings offer valuable insights for catalyst design and implementation in radiation‐induced chemical conversion.

Fermi level limitation in Na1/2Bi1/2TiO3–BaTiO3 piezoceramics by electrochemical reduction of Bi

The (electro)chemical stability of undoped and Zn-doped 0.94Na1/2Bi1/2TiO3–0.06BaTiO3 lead-free piezoceramics (NBT–6BT) was studied. For this purpose, the Fermi level at the interface between NBT–6BT and Sn-doped In2O3 (ITO) electrode is varied by gradually reducing the ITO film either by annealing in vacuum or by applying a voltage across a Pt/NBT–6BT/ITO. The chemical and electronic changes are monitored in situ by x-ray photoelectron spectroscopy. The experiments reveal the formation of metallic Bi when the Fermi level is reaching a value of 2.23 ± 0.10 eV above the valence band maximum, while no reduction of Ti is observed. The electrochemical reduction of Bi constitutes an upper limit of the Fermi level at ≈1 eV below the conduction band minimum. High electron concentrations in the conduction band and a contribution of free electrons to the electrical conductivity of NBT–6BT can, therefore, be excluded. The reduction occurs for an ITO work function of 4.2–4.3 eV. As typical electrode materials such as Ag, Cu, Ni, or Pt have higher work functions, an electrochemical instability of the electrode interfaces in ceramic capacitors is not expected. Under the given experimental conditions (350 °C, electric fields <40 V/mm), no degradation of resistance and no enrichment of Na at the interface are observed.

Colloidal Quasi-2D Methylammonium Lead Bromide Perovskite Nanostructures with Tunable Shape and High Chemical Stability.

Control over the lateral dimensions of colloidal nanostructures is a complex task which requires a deep understanding of the formation mechanism and reactivity in the corresponding systems. As a result, it provides a well-founded insight to the physical and chemical properties of these materials. In this work, the preparation of quasi-2D methylammonium lead bromide nanostripes and discuss the influence of some specific parameters on the morphology and stability of this material is demonstrated. The variation in the amount of the main ligand dodecylamine gives a large range of structures beginning with 3D brick-like particles at low concentrations, nanostripes at elevated and ultimately nanosheets at large concentrations. The amount of the co-ligand trioctylphosphine can alter the width of the nanostripe shape to a certain degree. The thickness can be adjusted by the amount of the second precursor methylammonium bromide. Additionally, insights are given for the suggested formation mechanism of these anisotropic structures as well as for stability against moisture at ambient conditions in comparison with differently synthesized nanosheet samples.

Organic device fabrication and characterizations: DFT support

In this study, the effects of introducing a zinc cation into a zinc-phthalocyanine (ZnPc) cluster are examined in relation to organic phthalocyanine material. The Au/ZnPc/Si-based organic diode is made using the thermal evaporation method. The optical properties of the filter are checked and a selected wavelength of 360[Formula: see text]nm is recorded. Au/ZnPc/Si/Al exhibits high rectifying performance, and the organic device’s primary conduction mechanism is Space Charge Limited Current. ZnPc film’s superior transparency is shown in the visible spectrum, and its optical bandgap of 3.32[Formula: see text]eV is found. According to this result, ZnPc is a semiconductor. ZnPc has a weak exciton binding energy (600[Formula: see text]meV), a high chemical stability, and non-zero value of second hyperpolarizability (4.73[Formula: see text]10[Formula: see text][Formula: see text]esu). These features can offer our ZnPc-based organic device a wide range of applications, including microelectronics, solar cells, and nonlinear optical devices.

High Transition Temperature Driven by Type-II Dirac Fermions in Topological Superconductor B7Be2B7 Nanosheet.

Topological superconductors (TSCs) offer a promising avenue for delving into exotic states of matter and fundamental physics. We propose a strategy for realizing high transition temperatures (high-Tc) in TSCs by leveraging nontrivial topology alongside a high carrier density near the Fermi level in metal-doped borophenes. We identified 39 candidates with exceptional thermodynamic stability from thousands of Be-intercalated borophenes (Be1-xBx) via extensive structural searches. Seven candidates exhibit high carrier densities, with B7Be2B7 emerging as a particularly promising candidate. This nanosheet displays both type-I and type-II Dirac fermions, indicative of topological metals, thereby positioning it as an ideal platform for high-Tc TSCs. The high-density π electrons of B7Be2B7 originating from type-II Dirac fermions, coupled with the out-of-plane vibrations of B and Be atoms, significantly enhance the electron-phonon coupling (λ = 1.42), resulting in a substantially high-Tc of 31.5 K. These findings underscore the potential of metal-doped borophenes as a cutting-edge material platform for achieving high-Tc TSCs.

Durable one-component polyurea icephobic coatings with energy-saving performance in electrical heating de-icing

Ice formation and accumulation on the surfaces of aircraft, wind turbines, and boat hulls might result in serious economic losses and catastrophic accidents. The development of a new generation of icephobic surfaces has emerged in recent years for anti-icing. However, insufficient durability of the existing icephobic surfaces remains a significant challenge to their applications. In this study, durable one-component polyurea icephobic coatings (OPICs) with a low ice adhesion strength (∼25.3 kPa) were prepared via a solvent-free method by combining the NCO-terminated prepolymer, latent curing agent, and silicone oil. The chemical structure, surface morphology, wettability, mechanical properties, icephobicity, and durability of the OPICs were studied. The optimized design of OPICs with synergistic icephobic mechanisms endowed them with excellent icephobicity and durability. The superior mechanical durability and chemical stability were revealed by the maintaining icephobicity of OPICs even after 3000 continuous Taber abrasion cycles, as well as 50 icing/de-icing cycles, 72 h of NaOH immersion, and 240 h of neutral salt spray test. The effect of OPICs on minimizing the electric power consumption was further investigated by icing wind tunnel. In comparison to the epoxy primer coated and Al alloy coated airfoil surface, airfoil surface coated by OPIC-30 was found to achieve about 43.7 % and 43.9 % energy savings in the keeping entire airfoil surface ice-free, respectively. The one-component polyurea icephobic coatings have great prospects for practical applications that require long-term anti-icing properties.

Benzvalene-like Carboranes: Genuine Rule Breakers and Good Kinetic Stability.

Substituents are widespread in chemistry, but it has remained quite difficult to reliably determine the thermodynamic and kinetic stabilities of substituted compounds, though they are key to helping establish a structural rule and synthetic viability, respectively. As an important class of valence isomers in the benzene family, benzvalene-like structures have been extensively studied in systems associated with electron-neutral (i.e., C, Si, Ge, Pb, and Sn) and electron-rich (e.g., P) skeletons. However, stable benzvalene-like examples associated with electron-deficient skeletons have been very limited, possibly due to the very complicated bonding patterns of electron-deficient elements. Here, we performed an extensive structural search at the density functional theory (DFT) and CBS-QB3 level for the well-known six-vertex dicarboranes (C2B4R6), one of the central families of boranes and carboranes chemistry. We unexpectedly found that all of the previously reported benzvalene-like structures III (C2B4R6) as the long-chased "rule breaker" examples of the Wade-Mingos rule (W-M rule) are not the lowest-lying structures. Promisingly, for the first time, we succeeded in identifying several substituted III as the genuine lowest-lying structures and thus true "rule breakers." Thus, "benzvalenes" present hitherto the fourth member of the lowest-lying structural patterns for the family of six-vertex dicarboranes. Moreover, the presently revealed good kinetic stability of III' (C2B4R2R'4) over a wide range of substituents promoted us to recommend a novel kind of synthesizable carboranes beyond the Wade-Mingos rule, i.e., "benzvalene-like carboranes" with all of the classical skeletal atoms.

Role of Te-RE alloying on the passive film and pitting corrosion behavior of 316L stainless steel

This work reports the mechanism of corrosion resistance enhancement of 316 L stainless steel after Te-RE alloying. The individual MnS inclusions are replaced by composite inclusions, resulting in a reduced risk of pitting corrosion. The decrease of inclusion amount and Volta potential difference between inclusion and matrix induced by the addition of Te/La promoted the stability of the inclusions and lessened the active sites for pitting corrosion. TeO2 formed in the passive film with Te treatment could be easily reduced by Cr and Mo, and resulting in a significant increasing of MoO2 and Cr2O3 content in the passive film. This enhanced the stability of the passive film. Te and RE exhibited a synergistic effect on the increase of Cr and Mo in the passive film, resulting in a further improvement of the passive film. However, RE could not exist in the passive film stably due to its poor thermodynamic stability of the rare earth oxides, and only acted as a bridge for the formation of Cr and Mo oxides.

Dynamically Stabilizing Oxygen Atoms in Silver Catalyst for Highly Selective and Durable CO2 Reduction Reaction.

Oxide derived catalyst displays outstanding catalytic activity and selectivity in electrochemical carbon dioxide reduction reaction (CO2RR), in which, it is found that residue oxygen atoms play a pivotal role in regulating the catalyst's electronic structure and thus the CO2RR process. Unfortunately, the intrinsic thermodynamic instability of oxygen atoms in oxide derived catalyst under cathodic CO2RR potentials makes it unstable during continuous electrolysis, greatly hindering its practical industrial applications. In this work, we develop a pulsed-bias technique that is able to dynamically stabilize the residue oxygen atoms in oxide derived catalyst during electrochemical CO2RR. As a result, the oxide derived catalyst under pulsed bias exhibits super catalytic stability in catalyzing electrochemical CO2RR, while keeping excellent catalytic activity and selectivity.