Binding Energies Of Ions Research Articles

Polyzwitterionic hydrogel using waste biomass as solar absorbent for efficient evaporation in high salinity brine

Solar-driven interfacial vapor generation (SVG) is a promising strategy for brine purification. However, the effective combination of functional evaporator backbones and solar absorbers for SVG enhancement remains challenging in high-salinity brines (≥10 wt%). Herein, a biomass-based polyzwitterionic hydrogel (PZH) was developed to improve the SVG performances in 10 wt% brine. Zwitterions with specific anti-polyelectrolyte effects served as backbones for accelerating H2O transportation, with fewer salt deposits and macropore channels. The biomass of straw prepared at a pyrolysis temperature at 600 ℃ was the most effective solar absorber. The synthesis of So600-PZH-8mm yielded the optimal solar evaporator with a low evaporation enthalpy of 877.79 J·g−1, a remarkable solar-to-vapor energy efficiency of 87.1 %, and a high evaporation rate of 3.57 kg·m−2·h−1 under 1 sun irradiation and a relative humidity of 30 %. Multi-cycle evaporation tests further verified the high quality of the steam water, high salt resistance, reliability, and durability of So600-PZH-8mm in practical applications. Furthermore, density functional theory calculations of the binding energies of charged groups and ions verified the anti-polyelectrolyte effect and swelling behavior of the PZHs. Overall, this study demonstrated the effectiveness of waste biomass as solar absorber for high-efficiency solar adsorption and water activation, which opens a new perspective to inspire the up-conversion of waste biomass in more valuable and meaningful ways.

On the Strong Binding Affinity of Gold-Graphene Heterostructures with Heavy Metal Ions in Water: A Theoretical and Experimental Investigation.

Minimum energy configurations in 2D material-based heterostructures can enable interactions with external chemical species that are not observable for their monolithic counterparts. Density functional theory (DFT) calculations reveal that the binding energy of divalent toxic metal ions of Cd, Pb, and Hg on graphene-gold heterointerfaces is negative, in contrast to the positive value associated with free-standing graphene. The theoretical predictions are confirmed experimentally by Surface Plasmon Resonance (SPR) spectroscopy, where a strong binding affinity is measured for all the heavy metal ions in water. The results indicate the formation of a film of heavy metal ions on the graphene-gold (Gr/Au) heterointerfaces, where the adsorption of the ions follows a Langmuir isotherm model. The highest thermodynamic affinity constant K = 3.1 × 107 L mol-1 is observed for Hg2+@Gr/Au heterostructures, compared to 1.1 × 107 L mol-1 and 8.5 × 106 L mol-1 for Pb2+@Gr/Au and Cd2+@Gr/Au, respectively. In the case of Hg2+ ions, it was observed a sensitivity of about 0.01°/ppb and a detection limit of 0.7 ppb (∼3 nmol L-1). The combined X-ray photoelectron spectroscopy (XPS) and SPR analysis suggests a permanent interaction of all of the HMIs with the Gr/Au heterointerfaces. The correlation between the theoretical and experimental results indicates that the electron transfer from the graphene-gold heterostructures to the heavy metal ions is the key for correct interpretation of the enhanced sensitivity of the SPR sensors in water.

Large scale atomistic and quantum mechanical study of Na+ ion transport in liquid electrolytes for batteries

Lithium–ion batteries (LIBs) have long dominated energy storage markets due to their high energy density and reliability. However, concerns over lithium scarcity and geographic distribution necessitate alternatives. Sodium-ion batteries (SIBs) offer a promising solution due to sodium's abundance, cost-effectiveness, and favorable electrochemical properties. This study investigates Na+ ion transport, aggregation, and performance in various organic electrolytes using molecular dynamics (MD) simulations and density functional theory (DFT) calculations. The electrolytes studied include ethylene carbonate (EC), propylene carbonate (PC), dimethoxyethane (DME), and dimethyl carbonate (DMC) at 320 K. We focused on conductivity, diffusivity, and survival probability of Na+ ions at different salt concentrations. Furthermore, the solvation structure and the binding energy of ions in the electrolytes are thoroughly analyzed. Key findings reveal that at 2 M salt concentration, Na+ ion diffusivity and ionic conductivity follow the order EC>PC>DME>DMC. Increasing salt concentration decreases self–diffusion coefficients of Na+ and PF6− ions across all electrolytes, affecting conductivity. EC shows the highest ionic conductivity at both 1 M and 2 M salt concentrations. These insights suggest that a 2 M NaPF6 concentration in EC optimizes ionic conductivity, making it ideal for high–performance SIBs. This study provides crucial understanding for optimizing electrolytes in SIBs, advancing their development for scalable energy storage solutions.

Removal of lead ions onto potassium-type fine-grained zeolite prepared from dry or wet milling treatment

Potassium-type zeolite (KZ) was prepared from coal fly ash by hydrothermal activation treatment using potassium hydroxide solution and potassium-type fine-grained zeolite was prepared by dry milling (KZ-D) or wet milling (KZ-W). The effects of the different treatments on the Pb2+ adsorption performance were assessed. KZ-W resulted in a much smaller particle diameter (0.61 ± 0.12 µm) than KZ-D (1.4 ± 0.48 µm) and KZ (6.5 ± 0.49 µm). KZ-W also realized a higher pore volume, mean pore diameter, and specific surface area, than KZ-D and KZ. Additionally, KZ-W realized a greater Pb2+ adsorption capacity (242.6 mg/g) than KZ (195.3 mg/g) or KZ-D (188.9 mg/g). The adsorption phenomena were fitted to the Freundlich and Langmuir models to clarify the Pb2+ adsorption mechanism, and then both models showed a good fit to the experimental data (the correlation coefficients of 0.914–0.996 for Freundlich model and 0.897–0.981 for Langmuir model). Additionally, the ion exchange capability, elemental distribution, and binding energy before and after adsorption were analyzed. The results indicated that the physicochemical characteristics of the tested adsorbent surface affected the Pb2+ adsorption capacity in the aqueous phase. According to kinetics, the pseudo-second-order model matched the experimental data (the correlation coefficients of 0.996–0.999). The samples also demonstrated selective adsorption of Pb2+ in a binary solution. The results demonstrated that KZ-W can effectively remove Pb2+ from the aqueous phase and that it may be a useful tool for preventing contamination of water bodies.

Modeling the Zigzag Curves of Transition Metal Ions' Charge Transition Levels in Crystals.

Predicting the defect levels of transition metal (TM) dopants in the band gap of crystals is critical in determining the charge states of TM dopants and explaining their electronic and optical properties. By analyzing the calculated charge transition levels and the crystal-field strengths of all the 3d-TM ions in several insulators, we demonstrate that the variation trend of the 3d-TM dopants in a crystal is a scaling of the variation of 3d-electron binding energies (ionization potential) of the free TM ions corrected by adding the contribution of the 3d-orbital's crystal-field splitting. We therefore develop a model to predict the relative location of TM ions' defect levels in the band gap from the defect level and crystal-field splitting of a reference TM ion in the host of concern. The model is applied to predict the defect levels of the series of TM ions in β-Ga2O3 and ZnO, which have moderate to small band gaps, making some of the levels fall into the conduction or valence bands. These results show that the model may serve as a quick reference for related material design and optimization.

Discovering Molecular Coordination Environment Trends for Selective Ion Binding to Molecular Complexes Using Machine Learning.

The design of ion-selective materials with improved separation efficacy and efficiency is paramount, as current technologies fail to meet real-world deployment challenges. Selectivity in these materials can be informed by local ion binding in confined membrane ion channels. In this study, we utilize a data-driven approach to investigate design features in small molecular complexes coordinating ions as simplified models of ion channels. We curate a data set of 563 alkali metal coordinating molecular complexes (i.e., with Li+, Na+, or K+) from the Cambridge Structural Database and calculate differential ion binding energies using density functional theory. Using this information, we probe when and why structures favor exchange with alternate ions. Our analysis reveals that energetic preferences are related to ion size but are largely due to chemical interactions rather than structural reorganization. We identify unique trends in the selectivity for Li+ over other alkali ions, including the presence of N coordination atoms, planar coordination geometry, and small coordinating ring sizes. We use machine learning models to identify the key contributions of both geometric and electronic features in predicting selective ion binding. These physical insights offer preliminary guidance into the design of optimal membranes for ion selectivity.

Assessing toxicity mechanism of silver nanoparticles by using brine shrimp (Artemia salina) as model

The acute toxicity of silver nanoparticles (AgNPs) in Artemia salina is primarily attributed to the interaction between silver ions (Ag+) and chitin, which constitutes the main structural component of the organism's cuticle. To investigate this interaction and gain a deeper understanding of its nature, geometric optimization calculations and symmetry-adapted perturbation theory (SAPT0) analysis were performed. These calculations aimed to determine the most favorable conformation based on the binding energies of silver ions with chitin and to elucidate the underlying mechanisms of their interaction. The results indicate an ionic effect dependent on the ion state, with simulations revealing that Ag3+ ions have the potential to cause significant deformation of the chitin structure. Furthermore, this study evaluated the behavior of AgNPs using nauplii of A. salina instar I, assessing both mortality rates and cell damage. Toxicity of AgNPs was observed in A. salina at concentrations of 50 and 100 ppm within a timeframe of 24–48 h. The toxicity of AgNPs can be attributed to their interaction with the cuticle and subsequent modification of the chitin structure through the binding of ionic silver. Light microscopy (LM) analysis confirmed the presence of AgNPs in the cuticle, while confocal laser scanning microscopy (CLSM) revealed cellular damage. In addition, this research offers new perspectives on the toxicity mechanism of AgNPs by introducing a novel model that explores the interaction of silver ions with the cuticle of A. salina. These insights are derived from a combination of atomistic models and ecotoxicology assays.

Mapping the Identity of Transition Metal Doping and Surface Passivation in Indium Phosphide with Theoretical Calculation.

Understanding the electronic structure of doped InP quantum dots (QDs) is essential to optimize the material for specific optoelectronic applications. However, current synthesis approaches are often tedious and unfavorable for rational tunning. Herein, a combination of experimental and computational studies was conducted to address the doping mechanism and surface passivation of InP QDs. The successful dopant introduction requires low Cu doping concentration and heavy Mn doping, while the Ag doping amount is relatively moderate. This may correspond to the theoretical doping formation energy presented as Cu (-2.52 eV) < Ag (-1.76 eV) < Mn (-0.38 eV). As for surface passivation, inorganic ions and shell-like ZnS are unraveled through simulational investigation. Chloride ion promotes oriented growth toward tetrahedron morphology while nitrate-passivated InP QDs exhibit blurry transmission electron microscope (TEM) morphology. Correspondingly, the binding energy of chloride ion with (111) facet is -2.13 eV significantly lower than those of (110) and (100) facets. Further, the additional Zn 3d bands are more involved in the formation of conduction band, which optimized the Mn-doped InP with a 0.32 eV bandgap. These experimental and model results provide more microscopic details of doped InP, which can motivate theoretically exact control of guest ion stoichiometry with optimized characteristics for electrical devices.

Experimental Study on the Curing Mechanism of Red Mud-Based Stabilized Soil Co-Modified by Nano-SiO2 and Gypsum.

In order to effectively utilize red mud and reduce its occupation of land resources, as well as its impact on the environment, experiments were conducted to develop stabilized soil materials using nano-SiO2 synergistically modified red mud and to investigate the curing mechanism of stabilized soil. The unconfined compressive strength, microscopic morphology, and curing mechanism of the red mud-based stabilized soil materials with different amounts of modified materials were investigated. The test results show that after 7 days of curing, the unconfined compressive strength of red mud-based stabilized soil meets the compressive strength requirement of road base material when nano-SiO2, gypsum, and cement are synergistically modified. In such cases, the soil structure has the lowest fracture rate and the best structural compactness when the amount of nano-SiO2 is 1%. It is found that the needle-like and columnar calcium alumina in the modified red mud-based stabilized soil increases, and the binding energy of hydration product ions in the modified material is improved. The chemical curing mechanism of modified red mud-based stabilized soil includes hydration reaction, pozzolanic reaction, promotion effect of nano-SiO2, and enhancement effect of gypsum. On this base, a model of the early start hydration process of red mud-based stabilized soil promoted by nano-SiO2 is established.

Stabilizing Zn Metal Anode Through Regulation of Zn Ion Transfer and Interfacial Behavior with a Fast Ion Conductor Protective Layer.

Aqueous Zn-ion batteries (AZIBs) attract intensive attention owing to their environmental friendliness, cost-effectiveness, innate safety, and high specific capacity. However, the practical applications of AZIBs are hindered by several adverse phenomena, including corrosion, Zn dendrites, and hydrogen evolution. Herein, a Zn anode decorated with a 3D porous-structured Na3 V2 (PO4)3 (NVP@Zn) is obtained, where the NVP reconstruct the electrolyte/anode interface. The resulting NVP@Zn anode can provide a large quantity of fast and stable channels, facilitating enhanced Zn ion deposition kinetics and regulating the Zn ions transport process through the ion confinement effect. The NASICON-type NVP protective layer promote the desolvation process due to its nanopore structure, thus effectively avoiding side reactions. Theoretical calculations indicate that the NVP@Zn electrode has a higher Zn ion binding energy and a higher migration barrier, which demonstrates that NVP protective layer can enhance Zn ion deposition kinetics and prevent the unfettered 2D diffusion of Zn ions. Therefore, the results show that NVP@Zn/MnO2 full cell can maintain a high specific discharge capacity of 168mAhg-1 and a high-capacity retention rate of 74.6% after cycling. The extraordinary results obtained with this strategy have confirmed the promising applications of NVP in high-performance AZIBs.

A mechanochemical method for one-step leaching of metals from spent LIBs

A one-step system based on mechanochemical activation and the use of grape skins (GS) was proposed to recover metals from lithium-ion batteries (LIBs) cathode waste. The effects of the ball-milling (BM) speed, BM time, and quantity of added GS on the metal leaching rate were explored. The spent lithium cobalt oxide (LCO) and its leaching residue before and after mechanochemistry were characterized by SEM, BET, PSD, XRD, FT-IR, and XPS analysis. Our study shows that mechanochemistry promotes the leaching efficiency of metals from LIBs battery cathode waste by changing the cathode material properties (that is, reducing the LCO particle size (12.126 μm ∼ 0.0928 μm), increasing the specific surface area (0.123 m2/g ∼ 15.957 m2/g), enhancing the hydrophilicity and surface free energy (57.44 mN/m2 ∼ 66.18 mN/m2), promoting the generation of mesoporous structures, refining grains, disrupting the crystal structure, and increasing the microscopic strain, while deflecting the binding energy of the metal ions). A green, efficient and environmentally friendly process for the harmless and resource-friendly treatment of spent LIBs has been developed in this study.

Rigorous Negative Ion Binding Energies in Low-Energy Electron Elastic Collisions with Heavy Multi-Electron Atoms and Fullerene Molecules: Validation of Electron Affinities

Dramatically sharp resonances manifesting stable negative ion formation characterize Regge pole-calculated low-energy electron elastic total cross sections (TCSs) of heavy multi-electron systems. The novelty of the Regge pole analysis is in the extraction of rigorous and unambiguous negative ion binding energies (BEs), corresponding to the measured electron affinities (EAs) of the investigated multi-electron systems. The measured EAs have engendered the crucial question: is the EA of multi-electron atoms and fullerene molecules identified with the BE of the attached electron in the ground, metastable or excited state of the formed negative ion during a collision? Inconsistencies in the meaning of the measured EAs are elucidated and new EA values for Bk, Cf, Fm, and Lr are presented.

High-precision electron affinity of oxygen

Negative ions are important in many areas of science and technology, e.g., in interstellar chemistry, for accelerator-based radionuclide dating, and in anti-matter research. They are unique quantum systems where electron-correlation effects govern their properties. Atomic anions are loosely bound systems, which with very few exceptions lack optically allowed transitions. This limits prospects for high-resolution spectroscopy, and related negative-ion detection methods. Here, we present a method to measure negative ion binding energies with an order of magnitude higher precision than what has been possible before. By laser-manipulation of quantum-state populations, we are able to strongly reduce the background from photodetachment of excited states using a cryogenic electrostatic ion-beam storage ring where keV ion beams can circulate for up to hours. The method is applicable to negative ions in general and here we report an electron affinity of 1.461 112 972(87) eV for 16O.

Irradiation-driven escape of primordial planetary atmospheres

Making use of the publicly available 1D photoionization hydrodynamics code ATES we set out to investigate the combined effects of specific planetary gravitational potential energy (ϕp ≡ GMp/Rp) and stellar X-ray and extreme ultraviolet (XUV) irradiation (FXUV) on the evaporation efficiency (η) of moderately-to-highly irradiated gaseous planets, from sub-Neptunes through hot Jupiters. We show that the (known) existence of a threshold potential above which energy-limited thermal escape (i.e., η ≃ 1) is unattainable can be inferred analytically, by means of a balance between the ion binding energy and the volume-averaged mean excess energy. For log ϕp ≳ log ϕpthr ≈ [12.9 − 13.2] (in cgs units), most of the energy absorption occurs within a region where the average kinetic energy acquired by the ions through photo-electron collisions is insufficient for escape. This causes the evaporation efficiency to plummet with increasing ϕp, by up to 4 orders of magnitude below the energy-limited value. Whether or not planets with ϕp ≲ ϕpthr exhibit energy-limited outflows is primarily regulated by the stellar irradiation level. Specifically, for low-gravity planets, above FXUVthr ≃ 104–5 erg cm−2 s−1, Lyα losses overtake adiabatic and advective cooling and the evaporation efficiency of low-gravity planets drops below the energy-limited approximation, albeit remaining largely independent of ϕp. Further, we show that whereas η increases as FXUV increases for planets above ϕpthr, the opposite is true for low-gravity planets (i.e., for sub-Neptunes). This behavior can be understood by examining the relative fractional contributions of advective and radiative losses as a function of atmospheric temperature. This novel framework enables a reliable, physically motivated prediction of the expected evaporation efficiency for a given planetary system; an analytical approximation of the best-fitting η is given in the appendix.

Structural Features and Defect Equilibrium in Cubic PrBa1-xSrxFe2O6-δ.

The structure, oxygen non-stoichiometry, and defect equilibrium in perovskite-type PrBa1−xSrxFe2O6−δ (x = 0, 0.25, 0.50) synthesized at 1350 °C were studied. For all compositions, X-ray diffraction testifies to the formation of a cubic structure (S.G. ), but an electron diffraction study reveals additional diffuse satellites around each Bragg spot, indicating the primary incommensurate modulation with wave vectors about ±0.43. The results were interpreted as a sign of the short-order in both A-cation and anion sublattices in the areas of a few nanometers in size, and of an intermediate state before the formation of an ordered superstructure. An increase in oxygen deficiency was found to promote the ordering, whereas partial substitution of barium by strontium caused the opposite effect. The oxygen content in oxides as a function of oxygen partial pressure and temperature was measured by coulometric titration, and the data were used for the modeling of defect equilibrium in oxides. The simulation results implied oxygen vacancy ordering in PrBa1−xSrxFe2O6−δ that is in agreement with the electron diffraction study. Besides oxidation and charge disproportionation reactions, the reactions of oxygen vacancy distribution between non-equivalent anion positions, and their trapping in clusters with Pr3+ ions were taken into account by the model. It was demonstrated that an increase in the strontium content in Pr0.5Ba0.5−xSrxFeO3−δ suppressed ordering of oxygen vacancies, increased the binding energy of oxygen ions in the oxides, and resulted in an increase in the concentration of p-type carriers.

Quantitating the Binding Energy of Metal Ions to Langmuir-Blodgett Monolayers: The Copper(II)-Octadecylphosphonic Acid System.

We report on the formation and organization of a Cu2+-complexed octadecylphosphonic acid (ODPA) monolayer formed by Langmuir-Blodgett deposition. The formation of the Cu-complexed monolayer is seen to depend sensitively on the subphase pH and Cu2+ concentration, and it is possible to form a monolayer containing the regions of complexed and free ODPA. From the pressure-area isotherm data for these monolayers, we determine the equilibrium constant and free energy of formation for the Cu2+-ODPA complex, ΔG = -22.5 kJ/mol.

Synthesis, Characterization and Remedial Action of Biogenic Silver Nanoparticles and Chitosan-Silver Nanoparticles against Bacterial Pathogens

Custard apple is a dry land fruit. Its leaves exhibit different pharmacological activities. In the present study, both silver (Ag) nanoparticles and chitosan-coated Ag (Chi-Ag) nanoparticles were fabricated using the aqueous leaf extract of the custard apple plant. During preliminary phytochemical analysis, various types of phytocompounds were found in the aqueous leaf extract of the same plant. Next, both nanoparticles were physiochemically characterized. FTIR analysis exhibited the fingerprint vibrational peaks of active bioactive compounds in plant extract, Ag nanoparticles, and Chi-Ag nanoparticles. UV/Visible spectral analysis revealed the highest absorbance peak at 419 nm, indicating the presence of Ag nanoparticles. XRD analysis presented the face-centered cubic (FCC) structure of both prepared nanomaterials. Further, the average crystalline size of both Ag nanoparticles and Chi-Ag nanoparticles was calculated to be 23 and 74 nm, respectively. FESEM analysis showed the spherical and cubical shapes of Ag nanoparticles and Chi-Ag nanoparticles, respectively. EDS analysis indicated a peak around 3.29 keV, conforming to the binding energies of Ag ions. The biogenic nanomaterial also showed strong antibacterial activity against all tested bacterial pathogens.

A theoretical library of N1s core binding energies of polynitrogen molecules and ions in the gas phase.

Polynitrogen molecules and ions are important building blocks of high energy density compounds (HEDCs). High energy bonds formed at the N sites can be effectively probed by X-ray photoelectron spectroscopy (XPS) at the N K-edge. In this work, with the density functional theory and the ΔKohn-Sham scheme, we simulated the N1s ionic potentials (IPs) of 72 common polynitrogen molecules [tetrazoles, pentazole (N5H), diazines, triazines, tetrazines, furazans, oxazoles and oxadiazoles], ions [pentazolate anion (cyclo-N5-), pentazenium cation (N5+), etc.], and molecular (NH3⋯N5H, H2O⋯N5H) and ionic (NH4+⋯N5-, H3O+⋯N5-) pairs, as well as mononitrogen relatives. These constitute a small theoretical database for absolute N1s IPs with an average accuracy of ca. 0.3 eV. To understand the structure-IP relationship within this family, effects of side substituent and bridging groups, local bonding types (amine or imine N), charge and protonation states, and vibronic coupling were analyzed based on selected systems. This study in the gas phase collects inherent chemical shifts of nitrogen in high-energy NN and NC bonds, which provides an essential reference into XPS interpretations of more complex HEDCs in the solid state. We especially highlight the evident N1s chemical shifts induced by protonation for nitrogen in the five-membered ring (N5H versus cyclo-N5-, ca. 7 eV; NH3⋯N5H versus NH4+⋯N5-, ca. 3 eV; H2O⋯N5H versus H3O+⋯N5-, ca. 2 eV), and suggest XPS as a sensitive tool in determining the hydrogen positions in pentanitrogen-based HEDCs.

Binding Energy and Free Energy of Calcium Ion to Calmodulin EF-Hands with the Drude Polarizable Force Field.

Calcium ions are important messenger molecules in cells, which bind calcium-binding proteins to trigger many biochemical processes. We constructed four model systems, each containing one EF-hand loop of calmodulin with one calcium ion bound, and investigated the binding energy and free energy of Ca2+ by the quantum mechanics symmetry-adapted perturbation theory (SAPT) method and the molecular mechanics with the additive CHARMM36m (C36m) and the polarizable Drude force fields (FFs). Our results show that the explicit introduction of polarizability in the Drude not only yields considerably improved agreement with the binding energy calculated from the SAPT method but is also able to capture each component of the binding energies including electrostatic, induction, exchange, and dispersion terms. However, binding free energies computed with the Drude and the C36m FFs both deviated significantly from the experimental measurements. Detailed analysis indicated that one of main reasons might be that the strong interactions between Ca2+ and the side chain nitrogen of Asn/Gln in the Drude FF caused the distorted coordination geometries of calcium. Our work illustrated the importance of polarization in modeling ion-protein interactions and the difficulty in generating accurate and balanced FF models to represent the polarization effects.

Visualization of Ion|Surface Binding and In Situ Evaluation of Surface Interaction Free Energies via Competitive Adsorption Isotherms.

Function and properties at biologic as well as technological interfaces are controlled by a complex and concerted competition of specific and unspecific binding with ions and water in the electrolyte. It is not possible to date to directly estimate by experiment the interfacial binding energies of involved species in a consistent approach, thus limiting our understanding of how interactions in complex (physiologic) media are moderated. Here, we employ a model system utilizing polymers with end grafted amines interacting with a negatively charged mica surface. We measure interaction forces as a function of the molecule density and ion concentration in NaCl solutions. The measured adhesion decreases by about 90%, from 0.01 to 1 M electrolyte concentration. We further demonstrate by molecular resolution imaging how ions increasingly populate the binding surface at elevated concentrations, and are effectively competing with the functional group for a binding site. We demonstrate that a competing Langmuir isotherm model can describe this concentration-dependent competition. Further, based on this model we can quantitatively estimate ion binding energies, as well as binding energy relationships at a complex solid|liquid interface. Our approach enables the extraction of thermodynamic interaction energies and kinetic parameters of ionic species during monolayer level interactions at a solid|liquid interface, which to-date is impossible with other techniques.