Hydroxide Ion Research Articles

Flavin‐N5OOH Functions as both a Powerful Nucleophile and a Base in the Superfamily of Flavoenzymes

AbstractFlavoenzymes can mediate a large variety of oxidation reactions through the activation of oxygen. However, the O2 activation chemistry of flavin enzymes is not yet fully exploited. Normally, the O2 activation occurs at the C4a site of the flavin cofactor, yielding the flavin C4a‐(hydro)hydroperoxyl species in monooxygenases or oxidases. Using extensive MD simulations, QM/MM calculations and QM calculations, our studies reveal the formation of the common nucleophilic species, Flavin‐N5OOH, in two distinct flavoenzymes (RutA and EncM). Our studies show that Flavin‐N5OOH acts as a powerful nucleophile that promotes C−N cleavage of uracil in RutA, and a powerful base in the deprotonation of substrates in EncM. We reason that Flavin‐N5OOH can be a common reactive species in the superfamily of flavoenzymes, which accomplish generally selective general base catalysis and C−X (X=N, S, Cl, O) cleavage reactions that are otherwise challenging with solvated hydroxide ion base. These results expand our understanding of the chemistry and catalysis of flavoenzymes.

Effect of Radical‐Mediated Cross‐Linking on Partially Fluorinated Aromatic Anion Exchange Membranes and their Applications in Alkaline Water Electrolysis Cells

To investigate the effect of cross‐linking on partially fluorinated anion exchange membranes tethered with trimethylpropyl side chains (QPAF‐C3), styrene‐based cross‐linker is introduced into the precursor copolymers and then cross‐linked via free radical reaction. The one‐pot cross‐linking and quaternization reactions are successful as confirmed through nuclear magnetic resonance spectra. By solution casting, the resulting polymers provide flexible membranes (xQPAF‐C3‐VB) with 9.1–36.0% degree of cross‐linking. The cross‐linking results in smaller hydrophilic/hydrophobic phase‐separated morphology as confirmed by transmission electron microscopy images. The cross‐linking effect on the membrane properties is observed in the suppressed water uptake and decreased hydroxide ion conductivity. Among the cross‐linked membranes, xQPAF‐C3‐VB membranes with 17.4% degree of cross‐linking and 1.16 meq g−1 of ion exchange capacity exhibit the highest hydroxide ion conductivity (56 mS cm−1 at 30 °C) that is comparable to that of the pristine membrane (54 mS cm−1). The cross‐linking contributes to improving the thermomechanical properties with higher glass transition temperature. The cross‐linked xQPAF‐C3‐VB is applied to alkaline water electrolyzer to achieve high efficiency (74%) and reasonable performance (1.67 V at 1.0 A cm−2).

Effect of seawater on flotation separation of sphalerite from pyrite

ABSTRACT There is divalent magnesium and calcium ions existed in seawater. Under alkaline conditions, magnesium and calcium ions would react with hydroxide ions to generate insoluble hydroxyl complexes or hydroxide precipitates. In flotation process, the hydrophilic substances and collectors compete for adsorption on the surface of minerals, thereby reducing the floatability of minerals. In this study, the effects of seawater on the flotation separation of sphalerite from pyrite were investigated. The results show that under strong alkaline conditions, seawater has significant adverse effects on the flotation separation. Flotation regulators such as ethylenediamine tetraacetic acid, sodium hexametaphosphate, and sodium silicate can eliminate the adverse effect to a certain extent. The mechanisms were revealed through micro-flotation experiments, contact angle measurements, zeta potential measurements, XPS analysis and FT-IR analysis.

Potential‐Induced Electrochemical Corrosion in Crystalline Silicon Solar Cells

In this article, the electrochemical corrosion of full‐area aluminum back‐surface field (Al–BSF) and bifacial passivated emitter and rear cell (PERC) crystalline silicon (c‐Si) solar cells subjected to different potential in sodium chloride (NaCl) solution is systematically investigated. Based on different potential‐induced corrosion, the electrochemical corrosion mechanism of c‐Si solar cells is revealed for the first time. Under zero potential, an important finding is that the silicon beneath silver electrode is corroded and perforated for Al–BSF cells. This phenomenon is attributed to the interaction between hydroxide ions from galvanic corrosion and electrons from silicon corrosion. For bifacial PERC cells, the pyramidal structure of silicon surface beneath the aluminum finger is observed at zero potential, which is similar to the silicon texturing etched in alkaline environment. Additionally, it is found that silicon corrosion is inhibited when positive or negative potential is applied to the back of Al–BSF and bifacial PERC cells. Moreover, it is observed the aluminum suffers from more serious corrosion at positive potential than that at zero or negative potential, which is attributed to synthetical results of galvanic corrosion and electrolytic corrosion. In this work, a new insight on the potential‐induced electrochemical corrosion for c‐Si solar cells is provided.

The mutual neutralization of hydronium and hydroxide.

Mutual neutralization of hydronium (H3O+) and hydroxide (OH-) ions is a very fundamental chemical reaction. Yet, there is only limited experimental evidence about the underlying reaction mechanisms. Here, we report three-dimensional imaging of coincident neutral products of mutual-neutralization reactions at low collision energies of cold and isolated ions in the cryogenic double electrostatic ion-beam storage ring (DESIREE). We identified predominant H2O + OH + H and 2OH + H2 product channels and attributed them to an electron-transfer mechanism, whereas a minor contribution of H2O + H2O with high internal excitation was attributed to proton transfer. The reported mechanism-resolved internal product excitation, as well as collision-energy and initial ion-temperature dependence, provide a benchmark for modeling charge-transfer mechanisms.

Effect of seawater on flotation separation of galena from sphalerite

Magnesium and calcium ions in seawater react with hydroxide ions to generate insoluble hydroxyl complexes or hydroxide precipitates, which affects the floatability of sulfide minerals and causes uncertain effects on flotation separation. In order to ascertain the mechanism of the effects, the flotation separation of lead and zinc in seawater was investigated in this study. Compared with that in DI water, Pb grade in lead concentrate decreased from 59.30% to 53.00%, and galena recovery decreased from 63.47% to 47.79%. The SI decreased from 2.051 to 1.451. The results show that under strong alkaline conditions, seawater has significant adverse effects on the flotation separation. When EDTA, SHMP and SS were added, the SI altered from 1.451 to 1.435, 2.271 and 2.137, respectively. This demonstrates that regulators can eliminate the adverse effect to a certain extent. The mechanisms were revealed through micro-flotation tests, contact angle measurements, bubble-particle attachment tests, zeta potential measurements, XPS analysis and FT-IR analysis.

Chemiluminescence initiated by nebulization of oxidant- and catalyst-free aqueous luminol solutions

Chemiluminescence (CL), i.e., the emission of light during chemical reactions without external optical excitation, is widely used in clinical medicine, bioassays, reporter gene assays, and bioimaging. Given the complexity of traditional CL systems, which typically contain catalysts and oxidants, one-component (i.e., luminophore-only) alternatives are urgently required. Herein, to demonstrate the feasibility of such simple systems, we realize CL by nebulizing oxidant- and catalyst-free aqueous luminol solutions and demonstrate that it originates from the oxidation of luminol by the •OH radicals spontaneously formed on the microdroplet surface. The higher intensity of this CL system compared to that observed for a reference bulk-phase CL system containing H2O2 as an oxidant and FeSO4 as a catalyst is ascribed to the high specific surface area and luminol adsorption capacity of the microdroplets, and excess hydroxide ions on their surface. Thus, this work demonstrates that microdroplets provide a favorable environment for CL reactions and paves the way for the establishment of one-component CL systems.

Impedance Response Analysis of Anion Exchange Membrane Electrolyzers for Determination of the Electrochemically Active Catalyst Surface Area

AbstractPolymer membrane electrolyzers benefit from high‐pressure operation conditions and low gas cross‐over and can either conduct protons (H+) or hydroxide ions (OH−). Both types of electrolyzers have a similar design, but differ in power density and the choice of catalysts. Despite the significant endeavor of their optimization, to date, there is no well‐established impedance model for detailed analysis for either type of these devices. This complicates the in‐situ characterization of electrolyzers, hindering the investigation of degradation mechanisms and electrocatalytic processes as a function of applied current density or time. Nevertheless, a detailed understanding of such individual processes and distinguishing the performance‐limiting factors are the keystones for sophisticated device optimization. In this work, an impedance model based on electrode processes has been developed for an anion exchange membrane electrolyzer utilizing iridium oxide anode and platinum cathode electrocatalysts. This model allows to deconvolute the measured impedances into constituents related to the individual electrode processes and to estimate actual physico‐chemical quantities such as the reaction kinetic parameters and double‐layer capacitances. We discuss the meaning of the fitting parameters and show that this model enables, for the first time, the estimation of the electrochemically active surface area of the anode electrocatalysts under reaction conditions.

Ratiometric fiber optic fluorescent pH sensor for hydroxide diffusion measurements in concrete

This article delineates the development of an advanced ratiometric pH optode designed for protracted monitoring of pH dynamics in cementitious materials—a crucial aspect of structural management. The optode features a dual-layer Hydromed™ D4 polymer pellet incorporating a pH-sensitive Naphth-AlkyneOMe fluorescent probe (pKa ≈ 12) and CdSe quantum dots as an internal reference. The polymer matrix, optimized with diamond powder and carbon black, enhances the signal while minimizing light artifacts. Demonstrating a robust response to pH fluctuations, the optode, utilizing ratiometric measurements, enables steadfast monitoring for up to 75 days.The experimental setup includes a Delrin® sample compartment housing a glass slide with the optode connected to an optical fiber via an SMA connector. HydroMed™ D4 films, forming the pH-sensitive layer, are deposited on the glass slide and secured. The optode configuration is fine-tuned to optimize signal intensity by reducing its length. For optode-detector coupling, a 1000 µm core diameter optical fiber links the optode, and a 405 nm LED illuminates the sensing film. The emission signal is collected through the optical fiber, and signals are processed using computer-controlled lock-in amplifiers.In the investigation of hydroxide ion diffusion through a concrete sample, the optode's efficacy was validated, aligning with pH electrode measurements. Addressing long-term stability, a degradation model uncovered leisurely kinetics with commendable stability. Slow degradation kinetics, with a reaction rate coefficient of 1.6 × 10⁻⁷ s⁻¹ and a half-life of 1180 h, exceeded expectations.This pH optode, showcasing an accurate and resilient response to pH variations within the 10 to 12.5 range, stands as a promising tool for monitoring pH dynamics in low-pH cementitious materials. The incorporation of a degradation model underscores fidelity over prolonged durations and offers a blueprint for enduring surveillance of concrete structures.

Fabrication of Dual-Functional Bacterial-Cellulose-Based Composite Anion Exchange Membranes with High Dimensional Stability and Ionic Conductivity.

Anion exchange membranes (AEMs) are increasingly becoming a popular research area due to their ability to function with nonprecious metals in electrochemical devices. Nevertheless, there is a challenge to simultaneously optimize the dimensional stability and ionic conductivity of AEMs due to the "trade-off" effect. Herein, we adopted a novel strategy of combining filling and cross-linking using functionalized bacterial cellulose (PBC) as a dual-functional porous support and brominated poly(phenylene oxide) (Br-PPO) as the cross-linking agent and filler. The PBC nanofiber framework together with cross-linking can provide a reliable mechanical support for the subsequent filled polymer, thus improving the mechanical properties and effectively limiting the size change of the final quaternized-PPO (QPPO)-filled PBC composite membrane. The composite membrane showed a very low swelling ratio of only 10.35%, even at a high water uptake (81.83% at 20 °C). Moreover, the existence of multiple -NR3+ groups in the cross-link bonds between BC and Br-PPO can provide extra OH- ion transport sites, contributing to the increase in ionic conductivity. The final membrane demonstrated a hydroxide ion conductivity of 62.58 mS cm-1, which was remarkably higher than that of the pure QPPO membrane by up to 235.93% (80 °C). The successful preparation of the PBC3/QPPO membrane provides an effective avenue to tackle the trade-off effect through a dual-functional strategy.

Maintaining the concentration equilibrium of proton and hydroxide ions by construction of bis(2-aminoethyl)amine-based inner helmholtz plane toward long-life zinc metal anodes

Despite the merits of high safety and low cost, the development of rechargeable aqueous Zn metal batteries is oppressed by the short cycling life of Zn metal anodes, due to the hydrogen evolution reaction (HER) and the formation of irreversible Zn4SO4(OH)6·nH2O that are caused by the decomposition of H2O molecules adsorbed in the inner Helmholtz plane (IHP) of Zn metal anodes. To solve this issue, we herein use bis(2-aminoethyl)amine (B2AA) organic molecules as additives to suppress Zn corrosion and HER via reconstructing the IHP and maintaining the concentration equilibrium of protons and hydroxide ions, thus achieving long-term and highly reversible Zn metal batteries. Density functional theory calculations and molecule dynamics simulations reveal that B2AA are preferentially adsorbed on the interface of Zn anode owing to the high adsorption energy, forming a water-deficient IHP via repelling ≈19% of H2O molecules. Additionally, the −NH2/−NH− groups of B2AA can reversibly capture H+ derived from the decomposition of H2O and dynamically neutralize OH−, thus suppressing the corrosion reaction. Using an aqueous electrolyte involving B2AA, symmetric Zn//Zn cells exhibit a long cycling life of 2400 h at 10 mA cm−2. Matched with a NH4V4O10 (NVO) cathode, the Zn//NVO full cell delivers a high initial capacity of 147.24 mAh/g at 10 A/g, and maintains a high capacity retention of 66% after 3000 cycles.

Hydroxide Modified Synthesis of Atomically‐Doped Photoluminescent WS2 Monolayers

AbstractAtomically doping in thin film poses a significant challenge due to the potential for dopant precipitation caused by self‐purification effects. This challenge is particularly pronounced in the case of doping monolayers of photoluminescent transition metal dichalcogenides, where high energy barriers are also required to break the in‐plane bonds between the transition metal (TM) and chalcogen atoms. To address this issue, this study introduces hydroxide ions to adsorb onto the surface of WS2 monolayers. This results in a significant reduction in the formation energy of the TM─S bonds, enabling them to substitute for W sites and overcoming the self‐purification effect of WS2 monolayers. The in‐plane doping of TMs including Cr, Mn, Fe, Co, and Ni atoms is confirmed through precise atomic‐scale chemical imaging using scanning transmission electron microscopy with electron energy loss spectroscopy mapping. Photoluminescence measurements reveal that the band structure of WS2 monolayers can be systematically modulated by different doping metals, owing to their distinct atomic sizes. In addition, the atomically‐doped WS2 monolayers exhibit room‐temperature ferromagnetism, which has never been seen in pristine WS2 monolayers. The modulation of the band structure and the emergence of magnetism in TMs‐doped WS2 monolayers hold significant promise for optoelectronic and magnetoelectric applications.

A smart platform for monitoring the whole life-course of self-healing coatings with the cooperation of self-reporting microcapsules and coating matrix

Constructing a smart system with the capability to self-report the whole life-course of self-healing coatings, containing damage, self-healing, and restoration of protection capability after maintenance of large-scale damages, is a formidable challenge. In this study, we propose a facile strategy to address this issue by developing an intelligent platform using acrylic coating containing pH-responsive microcapsules loaded with phenolphthalein indicator. Upon damage, the color probes are released from the microcapsules and turn pink to locate cracks due to increased pH in the cathode region. The smart platform enables the sequencing of anticorrosion dynamics for various self-healing coatings as the slender pink color resulting from the low hydroxide ion generation rate signals the high anticorrosion efficiency. The highest-performance coating containing smart microspheres loaded with cerium acetate as corrosion inhibitors was easily screened, which was validated using electrochemical impedance spectroscopy (EIS). Furthermore, the hydroxide ions generated during electrogalvanic reactions could be consumed by coating matrix of acrylic resin through ester hydrolysis after repairing cracks. Hence, smart platform can be employed to evaluate the restoration of coating protection by monitoring the disappearance of the pink color. This facile yet effective strategy exhibits tremendous potential for real-time monitoring of the entire life-cycle and rapid screening of excellent self-healing coating formulations.

Colloidal pathways of amorphous calcium carbonate formation lead to distinct water environments and conductivity.

CaCO3 is the most abundant biomineral and a major constituent of incrustations arising from water hardness. Polycarboxylates play key roles in controlling mineralization. Herein, we present an analytical and spectroscopic study of polycarboxylate-stabilized amorphous CaCO3 (ACC) and its formation via a dense liquid precursor phase (DLP). Polycarboxylates facilitate pronounced, kinetic bicarbonate entrapment in the DLP. Since bicarbonate is destabilized in the solid state, DLP dehydration towards solid ACC necessitates the formation of locally calcium deficient sites, thereby inhibiting nucleation. Magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy of poly-aspartate-stabilized ACC reveals the presence of two distinct environments. The first contains immobile calcium and carbonate ions and structural water molecules, undergoing restricted, anisotropic motion. In the second environment, water molecules undergo slow, but isotropic motion. Indeed, conductive atomic force microscopy (C-AFM) reveals that ACC conducts electrical current, strongly suggesting that the mobile environment pervades the bulk of ACC, with dissolved hydroxide ions constituting the charge carriers. We propose that the distinct environments arise from colloidally stabilized interfaces of DLP nanodroplets, consistent with the pre-nucleation cluster (PNC) pathway.

Design enhancement in hydroxide ion conductivity of viologen-bakelite organic frameworks for a flexible rechargeable zinc-air battery.

Quasi-solid-state rechargeable zinc-air batteries (ZABs) are suitable for the generation of portable clean energy due to their high energy and power density, safety, and cost-effectiveness. Compared to the typical alkaline aqueous electrolyte in a ZAB, polymer or gel-based electrolytes can suppress the dissolution of zinc, preventing the precipitation of undesirable irreversible zinc compounds. Their low electronic conductivity minimizes zinc dendrite formation. However, gel electrolytes suffer from capacity fade due to the loss of the volatile solvent, failing to deliver high-energy and high-power ZABs. Consequently, developing polymers with high hydroxide ion conductivity and chemical durability is paramount. We report cationic C-C bonded robust polymers with stoichiometrically controlled mobile hydroxide ions as solid-state hydroxide ion transporters. To boot, we increased the viologen-hydroxide-ion concentration through "by-design" monomers. The polymers constructed with these designer monomers exhibit a commensurate increase in their ionic conductivity. The polymer prepared with 4 OH- ion-containing monomer was superior to the one with 3 OH-. The conductivity increases from 7.30 × 10-4 S cm-1 (30 °C) to 2.96 × 10-3 S cm-1 (30 °C) at 95% RH for IISERP-POF12_OH (2_OH) and IISERP-POF13_OH (3_OH), respectively. A rechargeable ZAB (RZAB) constructed using 3_OH@PVA (polyvinyl alcohol) as the electrolyte membrane and Pt/C + RuO2 catalyst delivers a power density of 158 mW cm-2. In comparison, RZABs with a PVA interlayer provided only 72 mW cm-2. Notably, the device suffered an initial charge-discharge voltage gap of merely 0.55 V at 10 mA cm-2, which increased by only 2 mV after 50 hours of running. The battery operated at 10 mA cm-2 and worked steadily for 67 hours. We accomplished a flexible and rechargeable zinc-air battery (F-RZAB) exhibiting a maximum power density of 79 mW cm-2. This demonstration of a cationic viologen-bakelite polymer-based flexible secondary ZAB with versatile stochiometric hydroxide-ion tunability marks an important achievement in hydroxide-ion conducting solid-state electrolyte development.

Theoretical exploration of single-molecule magnetic and single-molecule toroic behaviors in peroxide-bridged double-triangular {MII3LnIII3} (M = Ni, Cu and Zn; Ln = Gd, Tb and Dy) complexes.

Detailed state-of-the-art ab initio and density functional theory (DFT) calculations have been undertaken to understand both Single-Molecule Magnetic (SMM) and Single-Molecule Toroic (SMT) behaviors of fascinating 3d-4f {M3Ln3} triangular complexes having the molecular formula [MII3LnIII3(O2)L3(PyCO2)3](OH)2(ClO4)2·8H2O (with M = Zn; Ln = Dy (1), Tb (2) & Gd (3) and M = Cu; Ln = Dy (4), Tb (5) & Gd (6)) and [Ni3Ln3(H2O)3(mpko)9(O2)(NO3)3](ClO4)·3CH3OH·3CH3CN (Ln = Dy (7), Tb (8), and Gd (9)) [mpkoH = 1-(pyrazin-2-yl)ethanone oxime]. All these complexes possess a peroxide ligand that bridges the {LnIII3} triangle in a μ3-η3:η3 fashion and the oxygen atoms/oxime of co-ligands that connect each MII ion to the {LnIII3} triangle. Through our computational studies, we tried to find the key role of the peroxide bridge and how it affects the SMM and SMT behavior of these complexes. Primarily, ab initio Complete Active Space Self-Consistent Field (CASSCF) SINGLE_ANISO + RASSI-SO + POLY_ANISO calculations were performed on 1, 2, 4, 5, 7, and 8 to study the anisotropic behavior of each Ln(III) ion, to derive the magnetic relaxation mechanism and to calculate the LnIII-LnIII and CuII/NiII-LnIII magnetic coupling constants. DFT calculations were also performed to validate these exchange interactions (J) by computing the GdIII-GdIII and CuII/NiII-GdIII interactions in 3, 6, and 9. Our calculations explained the experimental magnetic relaxation processes and the magnetic exchange interactions for all the complexes, which also strongly imply that the peroxide bridge plays a role in the SMM behavior observed in these systems. On the other hand, this peroxide bridge does not support the SMT behavior. To investigate the effect of bridging ions in {M3Ln3} systems, we modeled a {ZnII3DyIII3} complex (1a) with a hydroxide ion replacing the bridged peroxide ion in complex 1 and considered a hydroxide-bridged {CoIII3DyIII3} complex (10) having the formula [Co3Dy3(OH)4(OOCCMe3)6(teaH)3(H2O)3](NO3)2·H2O. We discovered that as compared to the LoProp charges of the peroxide ion, the greater negative charges on the bridging hydroxide ion reduce quantum tunneling of magnetization (QTM) effects, enabling more desirable SMM characteristics and also leading to good SMT behavior.

Novel anion-exchange membranes with accelerated hydroxide ion conduction through a quaternized covalent organic framework-doped electrospinning binary polymer

The mutual restriction between hydroxide ions' conductivity and alkaline stability is the main obstacle for the practical application of anion-exchange membranes (AEMs) in anion-exchange membrane fuel cells.

Accelerating acidic CO2 electroreduction: strategies beyond catalysts.

Carbon dioxide electrochemical reduction (CO2RR) into high-value-added chemicals offers an alternative pathway toward achieving carbon neutrality. However, in conventional neutral or alkaline electrolyte systems, a significant portion of CO2 is converted into (bi)carbonate due to the thermodynamically favorable acid-base neutralization reaction between CO2 and hydroxide ions. This results in the single-pass carbon efficiency (SPCE) being theoretically capped at 50%, presenting challenges for practical applications. Acidic CO2RR can completely circumvent the carbonate issue and theoretically achieve 100% SPCE, garnering substantial attention from researchers in recent years. Nevertheless, acidic CO2RR currently lags behind traditional neutral/alkaline systems in terms of product selectivity, stability, and energy efficiency, primarily because the abundance of H+ ions exacerbates the hydrogen evolution reaction (HER). Encouragingly, significant breakthroughs have been made to address these challenges, with numerous studies indicating that the regulation of the local catalytic environment may be more crucial than the catalyst itself. In this review, we will discuss the main challenges and latest strategies for acidic CO2RR, focusing on three key aspects beyond the catalyst: electrolyte regulation, local catalytic environment modification, and novel designs of gas diffusion electrodes (GDEs)/electrolyzers. We will also conclude the current advancement for acidic CO2RR and provide an outlook, with the hope that this technology will contribute to achieving carbon neutrality and advance towards practical application.

Advancing imine metal chelates for corrosion inhibition across diverse environments: A novel perspective

Using a suite of techniques, including potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and open circuit potential measurements, we investigated the corrosion resistance of transition metal chelates derived from Schiff base ligands against mild steel, copper oxide, aluminum, stainless steel, and high-carbon steel in acidic environments containing varying concentrations of hydrochloric acid, hydroxide ions, and sulfate ions at 25 °C. Spectral, quantitative, and physico-chemical analyses were employed to characterize the compounds under investigation. Our findings reveal a significant inhibition of corrosion across various steel substrates in the tested media by the studied compounds. Moreover, we observed an enhancement in corrosion inhibition efficacy with increasing concentrations of the investigated complexes. Notably, the negative values of Gibb's free adsorption energy (ΔG°ads) challenge the applicability of the Langmuir adsorption isotherm, suggesting a novel perspective on corrosion control mechanisms. Our study underscores the potential of Schiff bases and related transition metal chelates as effective corrosion inhibitors, providing insights into their utilization and factors influencing their application in corrosion mitigation strategies.

Long-range proton and hydroxide ion transfer dynamics at the water/CeO2 interface in the nanosecond regime: reactive molecular dynamics simulations and kinetic analysis.

The structural properties, dynamical behaviors, and ion transport phenomena at the interface between water and cerium oxide are investigated by reactive molecular dynamics (MD) simulations employing neural network potentials (NNPs). The NNPs are trained to reproduce density functional theory (DFT) results, and DFT-based MD (DFT-MD) simulations with enhanced sampling techniques and refinement schemes are employed to efficiently and systematically acquire training data that include diverse hydrogen-bonding configurations caused by proton hopping events. The water interfaces with two low-index surfaces of (111) and (110) are explored with these NNPs, and the structure and long-range proton and hydroxide ion transfer dynamics are examined with unprecedented system sizes and long simulation times. Various types of proton hopping events at the interface are categorized and analyzed in detail. Furthermore, in order to decipher the proton and hydroxide ion transport phenomena along the surface, a counting analysis based on the semi-Markov process is formulated and applied to the MD trajectories to obtain reaction rates by considering the transport as stochastic jump processes. Through this model, the coupling between hopping events, vibrational motions, and hydrogen bond networks at the interface are quantitatively examined, and the high activity and ion transport phenomena at the water/CeO2 interface are unequivocally revealed in the nanosecond regime.