Electron Affinity Research Articles

DFT study on the electronic and structural properties of M-Salen and M-Salphen electrocatalysts towards effective HER

We report on the electrochemical properties of Salen (N, N’- bis salicylaldehyde ehtylenediamine) and Salphen (N, N’- bis salicylaldehyde phenylenediamine) ligands using density functional approach. The structural and electronic properties, and the reduction potentials of metalated M-Salen and M-Salphen ligands (where M = Sb & Mo) that involve in hydrogen evolution reaction were explored. Optimized geometries of the chosen metalated complexes were obtained at B3LYP/6-31+G(d, p) & LANL2DZ level of theory. The effects solvation on the electrochemical properties of M-Salen and M-Salphen systems were considered in the presence of solvent acetonitrile using conductor-like polarisable continuum model (CPCM) at the same level of theory. Upon reduction process, the charge distribution around the metal centers Mo and Sb, and C, N and O atoms that lie in the coordination sphere is found to change considerably. As the first unoccupied orbital LUMO is directly connected to the electron affinity, the greater negative values of LUMO observed in Mo substituted Salen and Salphen ligands indicate their ability to exhibit better reduction process. Calculated reduction potential values of M-Salen systems were found to vary from −2.23V to −0.62V and hence the catalytic activity of M-Salen ligands follows the order of Mo-Salen > Sb-Salen > Salen and the same trend has been observed in M-Salphen systems with enhanced reduction potential of −0.54V recorded for Mo-Salphen system.

Heterostructure WSe2/copper hexadecafluorophthalocyanine (F16CuPc) field-effect transistors for efficient suppression of electron transport

The use of the organic semiconductor copper hexadecafluorophthalocyanine (F16CuPc) in WSe2 based heterostructure field-effect transistors (FETs) is shown to result in a large reduction in electron current while not significantly impacting the hole current. This approach is promising for use in p-channel FETs in which electron transport is undesirable and increases leakage currents and power dissipation in the off-state. The reduction in on-state electron currents, by up to three orders of magnitude, is due to the transfer of electrons to the low-mobility states in F16CuPc due to the greater electron affinity of the organic semiconductor compared to WSe2. The off-state currents under a drain bias are reduced by more than four orders of magnitude due to the effective suppression of electron currents. This is a result of the formation of type II heterostructure between F16CuPc and WSe2. Electrons in this heterostructure FET will preferentially transfer to F16CuPc, while holes will tend to remain in the high mobility WSe2 layer. This effect is more marked in monolayer WSe2 based FETs compared to multilayer WSe2 FETs due to a larger difference in electron affinities with respect to F16CuPc. Also, the magnitude of electron current suppression was further enhanced when F16CuPc is deposited only on a part of the channel near the source of WSe2 +F16CuPc FETs.

A novel method to evaluate insulation performance of SF6 alternative gases based on modified GIPF-Local properties model

Abstract The development of structure-activity relationships (SAR) emerges as a crucial strategy to establish the correlations between molecular micro-parameters and the macroscopic dielectric strength, thus markedly improving the gases screening efficiency. However, conventional prediction approaches have failed to characterize the molecule electronegativity accurately, resulting in inadequate prediction precision within extensive gas databases. To address this limitation, we have devised an insulation prediction method that incorporates corrections based on molecular local properties, including local ionization energy and local electron affinity. They enable us to determine both the electron acceptance and donation capacity of the whole molecular orbital electron cloud: a more accuracy assessment of electronegativity. Compared with previous method, our enhanced approach combined local properties with structural and GIPF parameters. It has yielded substantial improvements based on an extensive database comprising 91 gases, as evidenced by an increase in the correlation coefficient from 0.848 to 0.969. Utilizing the modified GIPF-Local properties model, over ten potential gases were found and categorized according to their application. This innovative screening strategy provides crucial insights for exploration and design of new eco-friendly gases as substitute for SF6 used in high-voltage power equipment.

Charge transfer complex induced confinement effect between organic semiconductor and polymer chains for enhancing high-temperature capacitive energy storage

High-temperature polymer dielectrics, renowned for their ultrahigh power densities, robust voltage endurance, and remarkable reliability, present significant potential in optimizing the functionality of microelectronics and electrical power systems. Herein, to elucidate a notable correlation between the confinement effect induced by charge transfer complexes (CTCs) and the discharged energy density (Ue), a series of PI-based composites were synthesized, integrating organic semiconductors with diverse electron affinities. The density functional theory (DFT) simulations revealed that escaping from the CTCs required higher activation energy, besides, a more pronounced electron localization function was observed in the interfacial region between PI chain and F6TCNNQ in comparison to pristine PI, PI/F2TCNQ, and PI/F4TCNQ. Consequently, the CTCs present in PI/F6TCNNQ exhibit the greatest electron localization, significantly impeding electron transport within the composite. Furthermore, at 200 °C, the Ue for the PI/F6TCNNQ composite remains notably high at 5.06 J cm−3 with an efficiency above 90 %, representing a 2.45-fold increase compared to that of pristine PI (2.03 J cm−3). The findings provide evidence for a positive correlation between the confinement effect induced by CTCs and the discharged energy density (Ue) of the composite materials at elevated temperatures, thus offering valuable insights for future investigations focused on all-organic dielectric composite materials.

Determination of Cytotoxic and Apoptotic Properties of Lobaric Acid, a Secondary Metabolite of Lichen and Investigation of Its Theoretical Potential

In this study, we aimed to elucidate some of the mechanisms of cell death induced by lobaric acid in A549 (human lung cancer) cells. For this purpose, the effects of cytotoxic concentrations on p53 and caspase-3 gene expressions were investigated. A549 cells were treated with varying concentrations of lobaric acid (12.5, 25, 50, and 100 µg/ml) for 48 hours and then their viability was evaluated and p53 and caspase-3 mRNA expressions were determined at statistically cytotoxic concentrations of 12.5, 50, and 100 µg/ml. According to beta-actin, it was determined that the increase in lobaric acid concentration revealed an upward trend in p53 and caspase-3 mRNA expressions. Furthermore, quantum chemical parameters such as frontier molecular orbitals, band gap energy and ionization potential, electronic affinity, chemical softness, chemical potential, electrophilicity index and chemical hardness were analyzed. Furthermore, molecular docking was performed to identify the binding sites and the binding behavior of lobaric acid to some target proteins (P53, Caspase-3 and Bcl-2).

Tunable Properties of New Cyano‐Substituent Heptahelicenes for Optoelectronic Devices: A Combined Experimental and DFT Computational Study

AbstractHere, we describe a set of coupled experimental and theoretical analyses. The introduction of one and two additional cyano groups in the carboheptahelicene backbone enhance its electron‐accepting properties. New carboheptahelicene derivatives are synthesized, and relevant characterizations of structural features, photophysical and electrochemical properties, and structure‐property relationships are described. This present work concerns the use of the density functional theory (DFT) to highlight the structural and the optoelectronic properties of carboheptahelicene derivatives and comparing the obtained findings with the experimental ones. The experimental and theoretical spectra (UV‐Vis absorption and photoluminescence) provide excellent concurrence. Afterward, molecular structures, structural parameters, molecular electrostatic potential (MEP), highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies of frontier molecular orbitals (FMOs) are constructed. Some other optoelectronic parameter including electron affinity (EA), ionization potential (IP), and some reactive descriptor such as chemical potential (μ), global hardness (η), electronegativity (χ) and the overall electrophilicity index (ω) are determined and indicating its potential uses as an active layer in optoelectronic efficient devices. The topological methods such as electron localization function (ELF), localization orbital locator (LOL) and the reduced density gradient method (RDG) were also conducted to clarify the strengths and kinds of interactions.

Porphyrin photosensitizer molecules as effective medicine candidates for photodynamic therapy: electronic structure information aided design.

Traditional photosensitizers (PS) in photodynamic therapy (PDT) have restricted tissue penetrability of light and a lack of selectivity for tumor cells, which diminishes the efficiency of PDT. Our aim is to effectively screen porphyrin-based PS medication through computational simulations of large-scale design and screening of PDT candidates via a precise description of the state of the light-stimulated PS molecule. Perylene-diimide (PDI) shows an absorption band in the near-infrared region (NIR) and a great photostability. Meanwhile, the insertion of metal can enhance tumor targeting. Therefore, on the basis of the original porphyrin PS segments, a series of metalloporphyrin combined with PDI and additional allosteric Zn-porphyrin-PDI systems were designed and investigated. Geometrical structures, frontier molecular orbitals, ultraviolet-visible (UV-vis) absorption spectra, adiabatic electron affinities (AEA), especially the triplet excited states and spin-orbit coupling matrix elements (SOCME) of these expanded D-A porphyrin were studied in detail using the density functional theory (DFT) and time-dependent density functional theory (TDDFT) methods. PS candidates, conforming type I or II mechanism for PDT, have been researched carefully by molecular docking which targeted Factor-related apoptosis (Fas)/Fas ligand (Fasl) mediated signaling pathway. It was found that porphyrin-PDI, Fe2-porphyrin-PDI, Zn-porphyrin-PDI, Mg-porphyrin-PDI, Zn-porphyrin combined with PDI through single bond (compound 1), and two acetylenic bonds (compound 2) in this work would be proposed as potential PS candidates for PDT process. This study was expected to provide PS candidates for the development of novel medicines in PDT.

Ge-Doped Boron Nitride Nanoclusters Functionalized with Amino Acids for Enhanced Binding of Bisphenols A and Z: A Density Functional Theory Study.

This study uses density functional theory to investigate boron nitride nanoclusters functionalized with amino acids for enhanced binding of bisphenols A (BPA) and Z (BPZ) to mimic the estrogen-related receptor gamma. Three categories of nanoclusters were examined: pristine B12N12, and those which were germanium-doped for boron or nitrogen. The study reveals that hydrogen bonding patterns and molecular stability are significantly influenced by the type of functional group and the specific amino acids involved. Ge-doping generally enhances the binding stability and spontaneity of the nanocluster-amino acid-bisphenol complexes, with Glu 275 emerging as the most stable binding site. The analysis of electronic properties such as energy gap, ionization potential, electron affinity, and chemical hardness before and after bisphenol binding indicates a general trend of increased reactivity, particularly in Ge-doped nanoclusters. The findings highlight the potential of these nanocluster composites in applications requiring high reactivity and electron mobility, such as pollutant removal and drug delivery.

Synthesis, characterization, DFT and molecular docking study of an antiviral drug, the crystallized 6-methoxylated derivative of favipiravir, in the presence of an iron (III) Lewis acid.

Few years ago, the COVID-19 infection, caused by SARS-CoV-2 virus, presented a worldwide health pandemic that taken the life of millions of people. In this concern, Favipiravir (FAV) has attracted considerable attention as an effective antiviral drug against this disease. In this study, the favipiravir's derivative (3‑hydroxy-6-methoxypyrazine-2-carboxamide) was synthetized, in presence of iron (III), and fully characterized through various analytical techniques including single-XRay, IR, UV and 1H/13C NMR. The refinement show the exclusive existence of enol form in the solid state. In solution, UV and NMR data were used to highlight the tautomeric equilibrium of this molecule. Additionally, the density functional theory (DFT) calculations were achieved to estimate the chemical parameters, electronic affinity and molecular electrostatic potential of the compound. Mulliken atomic charges as well as the chemical reactivity descriptors were investigated. Finally, the two tautomer forms of synthetized derivative were docked on SARS-CoV-2 main protease (PDB: 6LU7) and spike receptor-binding domain (PDB: 7BZ5) to evaluate their binding affinity. The docking simulation studies was predicted that the two forms had high binding affinity the critical amino acids residues of the receptor. This affinity was attributed to the presence of several hydrogen bonds for both tautomer along with five different hydrophobic interactions with the enol form. These results conduct to conclude that the synthetized product could be an interest potential drug for that type of diseases.

Computational, molecular docking and spectroscopic insights of drug–drug interaction between Ibuprofen and Paracetamol

The combination of existing drugs or drug–drug interaction enthralls researcher because of their potential applications in multiple diseases and better efficacy. The present work is undertaken to study the interaction between two drugs, Ibuprofen and Paracetamol, using Density Functional Theory and spectroscopic techniques (Infrared and Raman spectroscopy). The molecular modeling of the two drugs indicates their interaction through intermolecular hydrogen bonds (O34-H53-O2 and (O1-H33-O34), which is observed in Natural Bond Orbital and atoms in molecules analysis of the compound (Ibuprofen + Paracetamol). The experimental Raman, Surface Enhanced Raman Spectroscopy and Infrared spectra of the physical mixture (Ibuprofen + Paracetamol) are found close to their computed wavenumbers. The interacting state, that is, Ibuprofen + Paracetamol is optimized using B3LYP/6-31G ++ (d, p) model under density functional theory framework and different computed quantum chemical parameters such as, dipole moment, ionization energy, electron affinity, electrophilicity index, chemical potential, hardness and the Highest Occupied and Lowest Unoccupied Molecular Orbital energies and energy gaps are calculated and compared to the monomer state of the drugs. The lowering of energy gap and increased in dipole moment of combined drug molecules show potency as an effective hybrid drug. The molecular docking study of the combined drug molecule against the 4PH9 receptor shows a better binding affinity with its residues through hydrogen bonding and hydrophobic interaction.

Numerical investigation and design optimization for enhanced efficiency of Cs2AgBiBr6 perovskite solar cell

Nowadays, environmental concerns are becoming increasingly important. As a result of the imperative to protect society, lead-free perovskites are becoming increasingly important. The lead-free compound cesium silver bismuth bromide (Cs2AgBiBr6) was numerically investigated as a potential candidate for double perovskite solar cells application. In the proposed architecture, we combine FTO/ETL-SnO2/Cs2AgBiBr6/HTL-CuI/Au, all optimized for performance. To optimize the solar cell’s performance, the device configuration was modelled using SCAPS-1D. An evaluation of the impact of various factors, including absorber thickness, defect density, electron affinity, electron and hole transport layer optimization, band diagram analysis, working temperature and quantum efficiency, was conducted. The proposed device configuration exhibited excellent photovoltaic performance, achieving a PCE of 8.15%, a Voc of 1.041 V, a Jsc of 11.79 mA cm−2, an FF of 66.41%, and a quantum efficiency of 99.19% within the visible range. This research highlights the potential of Cs2AgBiBr6 as a promising perovskite material for use in lead-free photovoltaic technology.

Hydrogen adsorption on fcc metal surfaces towards the rational design of electrode materials

The successful large-scale implementation of hydrogen as an energy vector requires high performance electrodes and catalysts made of abundant materials. Rational materials design strategies are the most efficient means of reaching this goal. Here we present a study on the adsorption of H-atoms onto fcc transition metal surfaces and propose descriptors for the rational design of electrodes and catalysts by means of correlations between fundamental properties of the materials and among other properties, their experimentally measured performance as hydrogen evolution electrodes (HEE). A large set of quantum mechanical modelling data at the DFT level was produced, covering the adsorption of H-atoms onto the most stable surfaces (100), (110) and (111) of: Ag, Au, Co, Cu, Ir, Ni, Pd, Pt and Rh. For each material and surface, a coverage dependent set of minimum energy structures was produced and chemical potentials for adsorption of H-atoms were obtained. Averaging procedures are here proposed to approach modelling to the experiments. Several correlations between the computed data and experimentally measured quantities are done to validate our methodology: surface plane dependent adsorption energies, chemical potentials and experimentally determined surface energies and work functions. We search for descriptors of catalytic activity by testing correlations between the DFT data obtained from our averaging procedures and experimental data on HEE performance. Our methodology allows us to obtain linear correlations between the adsorption energy of H-atoms and the exchange current density (i0) in a HEE, avoiding the volcano-like plots. We show that the chemical potential has limitations as a descriptor of i0 because it reaches an early plateau in terms of i0. Simple quantities obtained from database data such as the first stage electronegativity (χ) as devised by Mulliken has a strong linear correlation i0. With a quantity we denominate modified second-stage electronegativity (χ2m) we can reproduce the typical volcano plot in a correlation with i0. A theoretical and conceptual framework is presented. It shows that both χ and χ2m, that depend on the first ionization potential, second ionization potential and electron affinity of the elements can be used as descriptors in rational design of electrodes or of catalysts for hydrogen systems.

Effect of Oriented External Electric Fields on the Electronic Properties of Linear Acenes: A Thermally Assisted Occupation DFT Study.

Recently, oriented external electric fields (OEEFs) have earned much attention due to the possibility of tuning the properties of electronic systems. From a theoretical perspective, one can resort to electronic structure calculations to understand how the direction and strength of OEEFs affect the properties of electronic systems. However, for multi-reference (MR) systems, calculations employing the popular Kohn-Sham density functional theory with the traditional semilocal and hybrid exchange-correlation energy functionals can yield erroneous results. Owing to its decent compromise between accuracy and efficiency for MR systems at the nanoscale (i.e., MR nanosystems), in this study, thermally assisted occupation density functional theory (TAO-DFT) is adopted to explore the electronic properties of n-acenes (n = 2-10), containing n linearly fused benzene rings, in OEEFs, where the OEEFs of various electric field strengths are applied along the long axes of n-acenes. According to our TAO-DFT calculations, the ground states of n-acenes in OEEFs are singlets for all the cases examined. The effect of OEEFs is shown to be significant on the vertical ionization potentials and vertical electron affinities of ground-state n-acenes with odd-number fused benzene rings. Moreover, the MR character of ground-state n-acenes in OEEFs increases with the increase in the acene length and/or the electric field strength.

Structures and stabilities Ru-doped Agn (n = 1–13) clusters: Ag10Ru a 18-ve cluster superatom

The geometrical and stability properties of Ru-doped silver clusters (AgnRu with n = 1–13) are investigated by density functional theory (DFT) calculations. The results show that the Ru dopant adopts central positions in the lowest-energy structures of AgnRu clusters. The most stable structures found are planar and curved for n = 3–6, while for n = 6 onward the structures follow a pentagonal growth pattern. Interestingly for n = 10, we found a cage structure with fulfills the 18 electron rule. The relative stability of the clusters is further evaluated through energetic parameters such as ionization energy, electron affinity, second order energy difference and HOMO–LUMO gap. The results show that the most stable structures in this series are Ag3Ru, Ag6Ru and Ag10Ru, as supported by electronic structure analyses. The plausible formation of the Ag10Ru cluster as a superatomic species is rationalized with 1.64 eV of HOMO–LUMO gap and 6.23 eV of adiabatic ionization energy.

Recent Progress on Cross-Linkable Fullerene-Based Electron Transport Materials for Perovskite Solar Cells.

Fullerene-based derivatives are frequently used as electron transport materials (ETMs) and interface buffers for perovskite solar cells (PSCs) due to their excellent properties, including high electron affinity and mobility, low recombination energy, tunable energy levels, and solution processability. However, significant challenges arise because fullerene derivatives tend to aggregate and dimerize, which reduces exciton dissociation and charge transport capacity. Additionally, their chemical compatibility with perovskite absorbers facilitates halide diffusion and degradation of PSCs. This overlap causes delamination and dissolution during device fabrication, hindering the performance enhancement of fullerene-based PSCs. To address these issues, researchers have developed cross-linkable fullerene materials. These materials have been shown to not only significantly improve the power conversion efficiency (PCE) of PSCs but also effectively enhance the device stability. In this review, we summarized recent research progress on cross-linkable fullerene derivatives as ETMs for PSCs. We systematically analyze the impact of these cross-linked ETMs on device performance and long-term stability, focusing on their molecular structures and working mechanisms. Finally, we discuss the future challenges that need to be overcome to advance the application of cross-linkable fullerene materials in PSCs.

Polarizable Continuum Models and Green's Function GW Formalism: On the Dynamics of the Solvent Electrons.

The many-body GW formalism, for the calculation of ionization potentials or electronic affinities, relies on the frequency-dependent dielectric function built from the electronic degrees of freedom. Considering the case of water as a solvent treated within the polarizable continuum model, we explore the impact of restricting the full frequency-dependence of the solvent electronic dielectric response to a frequency-independent (ϵ∞) optical dielectric constant. For solutes presenting small to large highest-occupied to lowest-unoccupied molecular orbital energy gaps, we show that such a restriction induces errors no larger than a few percent on the energy level shifts from the gas to the solvated phase. We further introduce a remarkably accurate single-pole model for mimicking the effect of the full frequency dependence of the water dielectric function in the visible-UV range. This allows a fully dynamical embedded GW calculation with the only knowledge of the cavity reaction field calculated for the ϵ∞ optical dielectric constant.

A Dibenzo[g,p]chrysene‐Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation

AbstractExciton binding energy (Eb) is understood as the energy required to dissociate an exciton in free‐charge carriers, and is known to be an important parameter in determining the performance of organic opto‐electronic devices. However, the development of a molecular design to achieve a small level of Eb in the solid state continues to lag behind. Here, to investigate the relationship between aggregation and Eb, star‐shaped π‐conjugated compounds DBC‐RD and TPE‐RD were developed using dibenzo[g,p]chrysene (DBC) and tetraphenylethylene (TPE). Theoretical calculations and physical measurements in solution showed no apparent differences between DBC‐RD and TPE‐RD, indicating that these molecules possess similar properties on a single‐molecule level. By contrast, pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC‐RD had a smaller Eb value of 0.24 eV compared with that of TPE‐RD (0.42 eV). However, these molecules showed similar Eb values under dispersed conditions, which suggested that the decreased Eb of DBC‐RD in pristine film is induced by molecular aggregation. By comparison with TPE‐RD, DBC‐RD showed superior performances in single‐component organic solar cells and organic photocatalysts. These results indicate that a molecular design suitable for aggregation is important to decrease the Eb in films.

A Dibenzo[g,p]chrysene-Based Organic Semiconductor with Small Exciton Binding Energy via Molecular Aggregation.

Exciton binding energy (Eb) is understood as the energy required to dissociate an exciton in free-charge carriers, and is known to be an important parameter in determining the performance of organic opto-electronic devices. However, the development of a molecular design to achieve a small level of Eb in the solid state continues to lag behind. Here, to investigate the relationship between aggregation and Eb, star-shaped π-conjugated compounds DBC-RD and TPE-RD were developed using dibenzo[g,p]chrysene (DBC) and tetraphenylethylene (TPE). Theoretical calculations and physical measurements in solution showed no apparent differences between DBC-RD and TPE-RD, indicating that these molecules possess similar properties on a single-molecule level. By contrast, pristine films incorporating these molecules showed significantly different levels of electron affinity, ionization potential, and optical gap. Also, DBC-RD had a smaller Eb value of 0.24 eV compared with that of TPE-RD (0.42 eV). However, these molecules showed similar Eb values under dispersed conditions, which suggested that the decreased Eb of DBC-RD in pristine film is induced by molecular aggregation. By comparison with TPE-RD, DBC-RD showed superior performances in single-component organic solar cells and organic photocatalysts. These results indicate that a molecular design suitable for aggregation is important to decrease the Eb in films.

The Effect of Organic Semiconductor Electron Affinity on Preventing Parasitic Oxidation Reactions Limiting Performance of n-Type Organic Electrochemical Transistors.

A key challenge in the development of organic mixed ionic-electronic conducting materials (OMIEC) for high performance electrochemical transistors is their stable performance in ambient. When operating in aqueous electrolyte, potential reactions of the electrochemically injected electrons with air and water could hinder their persistence, leading to a reduction in charge transport. Here, the impact of deepening the LUMO energy level of a series of electron-transporting semiconducting polymers is evaluated, and subsequently rendering the most common oxidation processes of electron polarons thermodynamically unfavorable, on organic electrochemical transistors (OECTs) performance. Employing time resolved spectroelectrochemistry with three analogous polymers having varying electron affinities (EA), it is found that an EA below the thermodynamic threshold for oxidation of its electron polarons by oxygen significantly improves electron transport and lifetime in air. A polymer with a sufficiently large EA and subsequent thermodynamically unfavorable oxidation of electron polarons is reported, which is used as the semiconducting layer in an OECT, in its neutral and N-DMBI doped form, resulting in an excellent and air-stable OECT performance. These results show a general design methodology to avoid detrimental parasitic reactions under ambient conditions, and the benefits that arise in electrical performance.

Enhanced Electron Emission Performance and Air-Surface Stability in ScO-Terminated Diamond for Thermionic Energy Converters.

Diamond with negative electron affinity (NEA) and low work function surfaces are suggested as a suitable material for electron-generation applications in vacuum, in particular, as the emitter electrode in thermionic energy converters. Such NEA surfaces can be fabricated by evaporating and then annealing submonolayers of a suitable metal in vacuo onto bare or oxidized diamond. Among the metals studied, scandium termination of bare diamond (100) and (111) surfaces is recently reported to give the largest NEA values reported to date for a metal-diamond system, as well as being thermally stable to 900°C. It is now shown that preoxidized (100) diamond functionalized with 0.25monolayers of Sc also produces a large NEA value of -1.02eV with low work functions (<3.63eV). Moreover, this surface is thermally stable to 700°C and can withstand exposure to air for extended periods. Here, the structural and electronic properties of this Sc─O-functionalized diamond surface are characterized in detail using a variety of surface-science techniques. The results suggest that this material may be the ideal candidate for the fabrication of commercial thermionic energy conversion devices, e.g., for solar-power generation, as well as for various other electronic devices that rely upon electron emission.