Surface Formation Energy Research Articles

The role of crystallographic orientation on surface properties and ion transport in lithium germanate (Li2GeO3) anodes: A computational approach

The performance of lithium-ion batteries (LIBs) hinges on the surface properties of their anodes. Compared to the bulk material, the anode surface is more susceptible to environmental changes during lithium (Li) intake and release, directly impacting factors like capacity, cycling stability, and charge/discharge rates. Lithium germanate (Li2GeO3, LGO) has emerged as a promising anode material due to its fast Li-ion conduction. While numerous studies have explored performance improvements through various methods, including defect engineering. However, there is currently a lack of atomistic-level understanding of the surface structure. Consequently, despite the importance of precisely understanding the surface to manipulate its different properties, specific surface details of LGO remain unclear. This knowledge gap hinders precise manipulation of surface properties for optimal performance.This study addresses this critical need by employing theoretical calculations to predict the structural, electrochemical characteristics, and Li-ion transport behavior in LGO surfaces. Our results indicate that polar surfaces exhibit lower formation energies compared to non-polar surfaces. Further investigation revealed that Li-terminated surfaces possess the lowest surface energy among various surface terminations. Interestingly, the work function calculations displayed an opposite trend to surface formation energy, with polar surfaces exhibiting the lowest work function values.To explore Li-ion transport, we employed ab initio molecular dynamics simulations. Notably, the (003) surface displayed the highest Li-ion diffusion rate among all considered surfaces.Further analysis of the (001) surface, which exhibited similar diffusion pathways to the (003) surface, revealed a lower diffusion rate.To understand this disparity, nudged elastic band (NEB) simulations were used to estimate the energy barriers for Li-ion migration along each pathway in both structures. Despite sharing similar pathways, the energy barriers in the (003) surface were significantly lower than those in the (001) surface. This finding suggests that the intrinsic energy landscape of the surface plays a crucial role in dictating Li-ion transport behavior.

Elucidating Black α-CsPbI3 Perovskite Stabilization via PPD Bication-Conjugated Molecule Surface Passivation: Ab Initio Simulations.

The cubic α-CsPbI3 phase stands out as one of the most promising perovskite compounds for solar cell applications due to its suitable electronic band gap of 1.7 eV. However, it exhibits structural instability under operational conditions, often transforming into the hexagonal non-perovskite δ-CsPbI3 phase, which is unsuitable for solar cell applications because of the large band gap (e.g., ∼2.9 eV). Thus, there is growing interest in identifying possible mechanisms for increasing the stability of the cubic α-CsPbI3 phase. Here, we report a theoretical investigation, based on density functional theory calculations, of the surface passivation of the α-, γ-, and δ-CsPbI3(100) surfaces using the C6H4(NH3)2 [p-phenylenediamine (PPD)] and Cs species as passivation agents. Our calculations and analyses corroborate recent experimental findings, showing that PPD passivation effectively stabilizes the cubic α-CsPbI3 perovskite against the cubic-to-hexagonal phase transition. The PPD molecule exhibits covalent-dominating bonds with the substrate, which makes it more resistant to distortion than the ionic bonds dominant in perovskite bulks. By contrasting these results with the natural Cs passivation, we highlight the superior stability of the PPD passivation, as evidenced by the negative surface formation energies, unlike the positive values observed for the Cs passivation. This disparity is due to the covalent characteristics of the molecule/surface interaction of PPD, as opposed to the purely ionic interaction seen with the Cs passivation. Notably, the PPD passivation maintains the optoelectronic properties of the perovskites because the electronic states derived from the PPD molecules are localized far from the band gap region, which is crucial for optoelectronic applications.

Bivalent metal ion co-doped methylammonium lead tribromide perovskite nanocrystal scintillator for X-ray imaging

Perovskite scintillators with low cost, easy preparation, environmental stability, and high-resolution have become candidates for X-ray imaging applications. Here, based on the calculation results of surface formation energy (Ef) and vacancy defect energy (Evac), a series of co-doped perovskite nanocrystals (NCs) with photoluminescence high quantum yield (PLQY) and fast luminescence decay time had been prepared by doping several bivalent metal ions into the B-site of methylammonium lead tribromide (MAPbBr3). In addition, the scintillator with flexibility was prepared using poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) as the carrier, showing excellent stability and scintillation performance, with a light yield of 21,200 photons/MeV, imaging resolution reached 11.7 lp/mm, and low detection limits of 462 nGyair s−1. Finally, we demonstrated the scintillator characteristic with high-quality imaging results and excellent tolerance under high dose rate X-ray (25 mGy s−1). Therefore, the combination of co-doped nanocrystals with excellent optical properties and PVDF-HFP further paves the way for the development of a scintillator.

Accommodating a hexagonal [formula omitted]- phase Mn2N film on a cubic MgO (001) substrate

The thin films of c-plane dominated hexagonal ζ- phase Mn2N were successfully grown on a cubic MgO (001) substrate directly using plasma-assisted molecular beam epitaxy. The surface was comprehensively studied through experimental and theoretical approaches. Reflection high energy electron diffraction revealed two pseudo-cubic domains along [100]MgO and [110]MgO, and one hexagonal domain, which is 30° apart from the [100]MgO direction. Scanning tunneling microscopy was used to image and resolve the high quality surface, revealing a distorted hexagonal surface structure. Furthermore, atomic resolution of the hexagonal domain with a 2 × 2 reconstructed surface is presented. For the c-plane surface, theoretical investigations were carried out using first-principle studies to determine the surface formation energy for various reconstructed surfaces. The theoretical study shows that the nitrogen terminated 2 × 2 structure with a manganese adatom on the surface is the most stable reconstruction that reproduces the experimental results. A corresponding simulated scanning tunneling microscopy model is also presented, providing strong support for the experimentally observed in-plane lattice structures. The manganese:nitrogen stoichiometry within the bulk and surface is in good agreement with the expected ratio of 2:1.

Large magnetic entropy change in Ni–Mn–In–Sb alloys via directional solidification and calculated by first-principles calculations

In this work, the magnetocaloric effect in Ni50Mn36In5Sb9 alloy was increased by more than 50% through directional solidification, and the magnetic entropy change increased to 36.2 J kg−1 K−1 under the field of 5 T. The calculated results of differential scanning calorimetry curves confirmed the enhanced entropy change, which also increased from 29.7 to 40.7 J kg−1 K−1. Moreover, first-principles calculations show that the surface formation energy along the L21 (220) plane is the lowest at room temperature, and it is easy to form and undergo martensitic transformation from the (220) crystal plane. Directional solidification causes the alloy to grow basically toward the (220) crystal plane, improve atomic ordering, reduce grain boundaries, and increase grain size. Thereby, the magnetic entropy change is enhanced.

Estimation of the Thermophysical Properties of Pentaalkylguanidinium-Based Magnetic Ionic Liquids with Unusual Thermal Expansion Coefficient.

The thermal expansion coefficient (αexp. ), the molecular volume (Vm ), the entropy of surface formation (Sa ), and the Gibbs energy of surface formation (Ea ) of four pentaalkylguanidinium-based MILs [Cn TMG][FeCl3 Br] (n=2, 4, 6, 8) were calculated based on the density and surface tension data determined from 278.15 to 323.15 K. In terms of classical semiempirical methods, the standard molar entropy (S0 ), the lattice energy (UPOT ), the molar enthalpy of evaporation ( , (298 K)), and the thermal expansion coefficient (αest. ) of the MILs were further estimated. The estimation results indicate that the classical semiempirical methods are suitable for estimating the thermophysical properties of the MILs, except the unusual αexp. , which were extremely larger than those of representative non-magnetic ionic liquids (ILs). We further optimized the estimation methods and discussed the potential reasons for the unusual thermal expansion coefficient of the MILs.

Surface reconstruction and cleavage of phyllosilicate clay edge by density functional theory

Phyllosilicate materials (e.g., smectite) have been proposed to act as a waste barrier within long-term deep geological repositories. Aside from longevity, these clay materials must also limit the mobility of radionuclides, which is achieved through intermolecular interaction involving clay basal planes and edge surfaces. We aim to contribute to the fundamental knowledge of clay edges by investigating surface reconstruction in a dehydrated context. Using density functional theory, surface reconstruction, charge redistribution, and formation energies have been explored for pyrophyllite edges resulting from thirteen terminations. Three primary reconstruction mechanisms were identified: (1) the displacement of Al into the tetrahedral layer, (2) proton shift, and (3) sub-surface reconstruction involving sub-surface -OH or apical O and surface Si. Reduction in overall relative bond deficiency and charge redistribution to becoming more bulk-like were found to be the main driving force for reconstruction. Formation energies were also determined with dispersion correction for dehydrated and hydrated surfaces. The presence of water terminating agents reduced energetic costs by approximately one order of magnitude and the inclusion of dispersion correction resulted in indistinguishable formation energies between different hydrated surfaces. Linear regression models were also explored to predict surface formation energies based on relative bond deficiency and charge. These models were able to identify the key contributions to the surface energy; however, due to the small dataset they were not found to be predictive.

Exploring the interfacial structure and crystallinity for direct growth of Mn3Sn(0001) on sapphire (0001) by molecular beam epitaxy

The Kagome antiferromagnet Mn3Sn has garnered a lot of attention due to the presence of interesting properties such as anomalous Hall effects and Nernst effects. Until now, few papers have been reported to grow using molecular beam epitaxy with a buffer layer or on other substrates. In this paper, we discuss the synthesis of crystalline Mn3Sn layers, prepared on Al2O3 (0001) without a buffer layer using molecular beam epitaxy. The growth is monitored in-situ using reflection high energy electron diffraction and measured ex-situ using X-ray diffraction, Rutherford back-scattering, and cross-sectional scanning transmission electron microscopy. The samples were deposited at 524 ± 5 °C, with an Mn: Sn atomic flux ratio of 3.2:1 for 90 min. Orientation relationships between the Mn3Sn films and the sapphire substrates are determined from in-plane and out-of-plane measurements. Our analysis indicates that the resulting film is predominantly c−plane oriented. Lastly, the samples prepared in this way were found to be discontiguous, showing a 3-dimensional morphology. According to first-principles calculations, the Mn3Sn exhibits a displaced Kagome structure in the very first stages of growth, for 2 ML and 4 ML growth on Al2O3 (0001). This result is corroborated by calculating the surface formation energies and explains the observed RHEED patterns.

Crystal Facet Structure Dependence and Promising Pd-Pt Catalytic Materials for Perhydroacenaphthene Dehydrogenation.

Designing an effective Pd-Pt catalytic material with excellent catalytic performance for perhydroacenaphthene (PHAN) dehydrogenation is a great challenge. In this work, in order to explore the crystal facet structure over the bimetallic Pd-Pt catalyst on the dehydrogenation performance of PHAN, the surface compositions of two kinds of Pd (Pt) atoms with different coverage on Pd modulated Pt (PdPt) and Pt modulated Pd (PtPd) catalysts were designed and studied by means of density functional theory (DFT). Through the investigation of the reaction path of PHAN dehydrogenation on PdMLPt(111) and PtMLPd(111) surfaces, it was found that PdMLPt(111) was advantageous to PHAN dehydrogenation (Ea = 2.317 eV). This was attributed to a lower energy barrier, more stable dehydrogenation products, and the fact that Pd doping brought Pt(111) close to the Fermi level. Apparently, Pd modulated Pt catalyst has a broad application prospect in the dehydrogenation of PHAN. In the process of optimizing the PdPt morphology, a method for selecting the minimum active unit of PdPt catalysts with different ratios was proposed, that is, the most stable active unit: rhombus structure was determined according to the surface formation energy. Moreover, we correlated the relationship among the number of H atoms removed, adsorption energy, surface charge, activation energy, reaction energy, and surface coverage, and obtained the important parameters to predict the performance of PdPt catalyst in PHAN dehydrogenation system: surface charge and d-band center. Finally, the essential correlativity among Pd-Pt surface characteristics, catalytic PHAN activity, and adsorption energy was constructed; that is, the relationship model among d-band center, H atom, and product C12H8 adsorption energy was established. This work opens a new simultaneous path to improve the catalytic performance of Pd-Pt-based catalytic materials for PHAN dehydrogenation, which can be achieved by regulating the rhombic active units of Pt modulated by Pd.

Evolution hydrothermal aging mechanism for Ag/CeO2 catalysts in regeneration of catalytic diesel particulate filter with DFT calculation.

In order to avoid the high cost of existing precious metal catalyst like Pt, Ag/CeO2 was the most promising catalysts for mobile source soot emission control technologies, but there was a clear trade-off between hydrothermal aging resistance and catalytic oxidation performance hindered the application of this catalyst. In order to reveal the hydrothermal aging mechanism of Ag/CeO2 catalysts, the TGA (thermogravimetric analysis) experiments were investigated to reveal the mechanism of Ag modification on catalytic activity of CeO2 catalyst between fresh and hydrothermal aging and were also characterized with the related characterization experiments to in-depth research the lattice morphology and valence changes. The degradation mechanism of Ag/CeO2 catalysts in vapor with high-temperature was also explained and demonstrated based on density functional and molecular thermodynamics theories. The experimental and simulation data showed that the catalytic activity of soot combustion within Ag/CeO2 decreased more significantly after hydrothermal aging than CeO2 due to the less agglomerated, which caused by the decreased in OII/OI and Ce3+/Ce4+ compared with CeO2. As shown in density function theory (DFT) calculation, the decreased surface energy and the increased oxygen vacancy formation energy of the low Mille index surface after Ag modification led to the instability structure and the high catalytic activity. Ag modification also increased the adsorption energy and Gibbs free energy of H2O on the low Miller index surface compared to CeO2, indicating that the desorption temperature of H2O molecules in (1 1 0) and (1 0 0) was higher than (1 1 1) in CeO2 and Ag/CeO2, which led to the migration of (1 1 1) crystal surfaces to (1 1 0) and (1 0 0) in the vapor environment. These conclusions can provide a valuable addition to the regenerative application of Ce-based catalysts in diesel exhaust aftertreatment system the aerial pollution.

Atomic reconstruction and oxygen adsorption behavior of the pyrite (100) surface: a DFT study.

The analysis of the surface chemical behavior of pyrite is highly crucial in the fields of environmental conservation, metal extraction, and flotation separation. In this paper, the mechanism of atomic reconstruction on the pyrite surface and the adsorption behavior of O2 on a reconstructed surface are calculated by density functional theory (DFT). Different reconstruction surfaces were constructed by deleting S and Fe atoms on the (100) surface of pyrite. In addition, the geometric configuration, formation energy, binding energy, cohesion energy, and surface electronic properties of the reconstruction surface were calculated. The adsorption energies and geometric configurations of O2 on different reconstructed surfaces were also determined. The results show that under Fe-poor conditions, the charge of Fe atoms increases, and S atoms form Sn on the reconstructed surface. The binding energy between the Sn and the substrate (ideal surface) is lower, which is similar to the Sn adsorption on the substrate surface with the Fe atom as the site. Sn has high cohesive energy and is resistant to being attacked by oxidants, which leads to structural collapse, and a low affinity for O2. Under S-poor conditions, the -[Fe-S]n- plane structure formed on the reconstructed surface. The -[Fe-S]n- structure stably bonds to the substrate by an Fe-S bond, and exhibits strong binding energy. However, the -[Fe-S]n- structure has low cohesive energy and exhibits thermodynamic instability. In contrast, O2 shows a strong affinity for the -[Fe-S]n- structure, indicating that the deficiency of the S atom promotes the surface oxidation reaction. The mechanism of atomic reconstruction on the surface of pyrite is of utmost importance for understanding its surface chemical behavior.

Machine learning approach for screening alloy surfaces for stability in catalytic reaction conditions

A catalytic surface should be stable under reaction conditions to be effective. However, it takes significant effort to screen many surfaces for their stability, as this requires intensive quantum chemical calculations. To more efficiently estimate stability, we provide a general and data-efficient machine learning (ML) approach to accurately and efficiently predict the surface energies of metal alloy surfaces. Our ML approach introduces an element-centered fingerprint (ECFP) which was used as a vector representation for fitting models for predicting surface formation energies. The ECFP is significantly more accurate than several existing feature sets when applied to dilute alloy surfaces and is competitive with existing feature sets when applied to bulk alloy surfaces or gas-phase molecules. Models using the ECFP as input can be quite general, as we created models with good accuracy over a broad set of bimetallic surfaces including most d-block metals, even with relatively small datasets. For example, using the ECFP, we developed a kernel ridge regression ML model which is able to predict the surface energies of alloys of diverse metal combinations with a mean absolute error of 0.017 eV atom−1. Combining this model with an existing model for predicting adsorption energies, we estimated segregation trends of 596 single-atom alloys (SAAs)with and without CO adsorbed on these surfaces. As a simple test of the approach, we identify specific cases where CO does not induce segregation in these SAAs.

A bimetallic strategy to tailoring the surface formation energy and d-band center of Ni-based catalyst for efficient and stable catalytic hydrogenation of dioctyl phthalate

Hydrogenation of dioctyl phthalate (DOP) is an effective strategy to synthesize cyclohexane-1,2-dioctyl phthalate (CDP), an environmentally friendly plasticizer. Many catalysts have already been developed to achieve the hydrogenation of DOP. However, due to the stability of their aromatic rings, the high costs of noble metal catalysts, and the harsh reaction conditions, the fabrication of non-noble metal catalysts with high activity and stability is still challenging. In this work, we report a bimetallic strategy built on the confinement effect to prepare a Ni2.5Cu0.5Al1 bimetallic catalyst using Ni-Cu hydrotalcite as the precursor. Results show that DOP conversion and selectivity of CDP could both reach 99%; also, the suggested bimetallic catalyst exhibits excellent stability under harsh reaction conditions, e.g., the catalyst can be recycled up to 9 times with no change in conversion and selectivity. Certain characterizations and theoretical calculations show that introduction of an appropriate amount of Cu can reduce the surface formation energy and d-band center, which can simultaneously improve the activity and stability of the Ni-based catalysts. Therefore, the proposed Ni-Cu bimetallic catalyst is an attractive option for the synthesis of environmentally friendly plasticizers by DOP hydrogenation.

A tungsten deep neural-network potential for simulating mechanical property degradation under fusion service environment

Tungsten is a promising candidate material in fusion energy facilities. Molecular dynamics (MD) simulations reveal the atomistic scale mechanisms, so they are crucial for the understanding of the macroscopic property deterioration of tungsten under harsh and complex service environments. The interatomic potential used in the MD simulations is required to accurately describe a wide spectrum of relevant defect properties, which is by far challenging to the existing interatomic potentials. In this paper, we propose a new three-body embedding descriptor and hybridize it into the deep-potential (DP) framework, an end-to-end deep learning interatomic potential model. The potential model for tungsten, named DP-HYB, is trained with a database constructed by the concurrent learning method. The DP-HYB model is able to accurately predict elastic constants, stacking fault energy, the formation energies of free surfaces, and point defects, which are considered in the training dataset. It also accurately evaluates the formation energies of grain boundaries and prismatic loops, the core structure of screw dislocation, the Peierls barrier, and the transition path of the screw dislocation migration, which do not explicitly present in the training dataset. The DP-HYB is a good candidate for the atomistic simulations of tungsten property deterioration, especially those involving the mechanical property degradation under the harsh fusion service environment.

First-principles study of the (001) and (110) surfaces of CrCoIrGa Heusler alloy

Exploring highly spin-polarized thin films of magnetic materials is of great importance for spin-based device applications. Herein, the structure, spin-polarization and magnetic properties of the (001) and (110) surfaces of CrCoIrGa Heusler alloy have been investigated using first-principles density functional theory (DFT) and DFT + U calculations. The results demonstrate that while bulk CrCoIrGa is highly spin-polarized (89%), the surface counterparts exhibit much lower spin-polarization (SP), being due to the emergence of surface states at Fermi level (EF). It is observed that the (001) surface geometries are kept well, whereas, the (110) surface exhibit an obvious surface reconstruction after relaxation, resulting in large surface formation energy. The electronic properties investigated at DFT level revealed that CrGa-terminated (001) surface carries 100% SP, CoIr-terminated has 63% SP, and the (110) surface retains the bulk SP. Interestingly, the SP is found to be suppressed on introducing U parameter in the calculations. All the considered surfaces display ferrimagnetic coupling, with a significant total magnetic moment. In addition, the surface layer atoms carry large SP and moments than the inner layer atoms, and thus promise a dominant role in spin-based device applications of the thin film surfaces.

First principles of Fe/Co/Ni doping and the coexistence of O vacancy in the magnetic and optical properties of rutile TiO2(110) surface

The research on the photocatalytic properties of TiO2 by doping transition metals (Fe/Co/Ni) has achieved certain progress. However, the effects of Fe/Co/Ni doping and the coexistence of O vacancies on the photocatalytic properties of TiO2 have been rarely reported. Oxygen vacancies are the most common point defects in TiO2 materials, and the precise control of O vacancies in experiments presents difficulty. To solve this problem, this study used first principles under the framework of density functional theory to investigate the effects of Fe/Co/Ni doping and the coexistence of O vacancies on the magnetic and optical properties of rutile TiO2(110) surface. The findings indicated that the formation energy of the (110) surface of rutile TiO2 doped with transition metals Fe, Co, and Ni and coexisting with O vacancies was smaller under Ti-rich conditions than under O-rich conditions. Under Ti-rich conditions, the doping system easily formed and exhibited a high stability. The findings on magnetic properties indicated that the Fe/VO-TiO2, Co/VO-TiO2, and Ni/VO-TiO2 systems all exhibited magnetism on the (110) surface. The Fe/VO-TiO2(110) surface had the largest magnetic moment and the best magnetic properties. The study of optical properties showed that the Fe/VO-TiO2(110) surface had the longest carrier lifetime, strongest surface activity, and most evident red shift in the absorption spectrum. The oxidation capability of the Fe/VO-TiO2(110) surface was relatively the best. Fe doping and the coexistence of O vacancies are the most beneficial to the photocatalysts for the production of O2 by dissociation of water on the surface of rutile TiO2(110).

Zinc-Blende GeC Stabilized on GaN (001): An Ab Initio Study

First-principle calculations have been performed to explore the initial stages of the zinc blende-like germanium carbide epitaxial growth on the gallium nitride (001)-(2 × 2) surface. First, we studied the Ge/C monolayer adsorption and incorporation at high symmetry sites. Results show that the adsorptions at the top and hcp1 sites are the most stable structures of C and Ge, respectively. Different terminated surfaces were used on the GeC epitaxial growth. According to the surface formation energies, only the first two bilayers are stable; therefore, the GeC epitaxial growth is favorable only under N-rich conditions on a Ge-terminated surface and with Ge bilayers terminated. In addition, it is demonstrated that GeC bilayers on the C-terminated surfaces are unstable and preclude the epitaxial growth. Electronic properties have been investigated by calculating the density of states (DOS) and the projected density of states (PDOS) of the most favorable structures.

Eliminating Delocalization Error to Improve Heterogeneous Catalysis Predictions with Molecular DFT + U

Approximate semilocal density functional theory (DFT) is known to underestimate surface formation energies yet paradoxically overbind adsorbates on catalytic transition-metal oxide surfaces due to delocalization error. The low-cost DFT + U approach only improves surface formation energies for early transition-metal oxides or adsorption energies for late transition-metal oxides. In this work, we demonstrate that this inefficacy arises due to the conventional usage of metal-centered atomic orbitals as projectors within DFT + U. We analyze electron density rearrangement during surface formation and O atom adsorption on rutile transition-metal oxides to highlight that a standard DFT + U correction fails to tune properties when the corresponding density rearrangement is highly delocalized across both metal and oxygen sites. To improve both surface properties simultaneously while retaining the simplicity of a single-site DFT + U correction, we systematically construct multi-atom-centered molecular-orbital-like projectors for DFT + U. We demonstrate this molecular DFT + U approach for tuning adsorption energies and surface formation energies of minimal two-dimensional models of representative early (i.e., TiO2) and late (i.e., PtO2) transition-metal oxides. Molecular DFT + U simultaneously corrects adsorption energies and surface formation energies of multilayer models of rutile TiO2(110) and PtO2(110) to resolve the paradoxical description of surface stability and surface reactivity of semilocal DFT.

Modeling the cobalt deposit on the AlN (0001)-(2 × 2) surface: Density functional theory studies

Structural, electronic and magnetic properties of the cobalt (Co) adsorption and incorporation on the AlN (0001)-(2 × 2) surface have been investigated using spin-polarized first-principle total-energy calculations. The exchange–correlation energies are treated within the generalized gradient approximation. Provided that Co is a transition metal with highly correlated electrons, the Hubbard correction is considered with U = 1 eV. The magnetic properties have been investigated considering different magnetic configurations and different coverages. In the Co adsorption, a ferromagnetic (FM) behavior is obtained for coverages from ¼ monolayer (ML) to 1 ML. Concerning the Co incorporation, we observed: FM, antiferromagnetic (AFM) and non-magnetic (NM) behavior at low, intermediate and high coverages, respectively. In the Co substitution, the ¼ an ¾ ML of coverage are FM and the ¼ and ¾ ML of coverage are AFM. We employed the surface formation energy formalism to investigate the thermodynamic stability of the different surfaces. According to the formalism, Co deposit takes place at Co-rich and Al-poor conditions. The DOS and PDOS indicate that the 1st ML of the surfaces is metallic and the lower layers are semiconductor.

A Bimetallic Strategy to Tailoring the Surface Formation Energy and D-Band Center of Ni-Based Catalyst for Efficient and Stable Catalytic Hydrogenation of Dioctyl Phthalate

A Bimetallic Strategy to Tailoring the Surface Formation Energy and D-Band Center of Ni-Based Catalyst for Efficient and Stable Catalytic Hydrogenation of Dioctyl Phthalate