Partial Density Of States Analysis Research Articles

Discovery of eight-coordinated layered phase of SbBr3 under high pressure

Layered trihalides have attracted significant interest due to their potential applications in optical and spintronic devices. Herein, we report a combined experimental and theoretical investigation of antimony tribromide (SbBr3) under high pressure (up to 30 GPa) using synchrotron x-ray diffraction, Raman spectroscopy, alternating current (AC) impedance measurements, and first-principles calculations. The results indicate that SbBr3 transforms from a molecular phase (space group Pbnm) to an eight-coordinated layered phase (space group P21/a) at 7.6 GPa. A partial density of states analysis reveals that the eight-coordinated layered geometry of SbBr3 is rooted in the electron transfer from the Sb p orbital to the Br p orbital. Furthermore, based on AC impedance measurements, the resistance decreases with increasing pressure due to the gradual narrowing of the bandgap of SbBr3 in the Pbnm phase. The positive resistance–pressure relationship in the P21/a phase is attributed to the low carrier mobility caused by lattice distortion. Our current findings not only provide information on the phase diagram and electronic transport of SbBr3 but also expand the realm of layered functional materials in molecular trihalides.

Metal-Free Activation of Molecular Oxygen by Quaternary Ammonium-Based Ionic Liquid: A Detail Mechanistic Study.

Most oxidation processes in common organic synthesis and chemical biology require transition metal catalysts or metalloenzymes. Herein, we report a detailed mechanistic study of a metal-free oxygen (O2) activation protocol on benzylamine/alcohols using simple quaternary alkylammonium-based ionic liquids to produce products such as amide, aldehyde, imine, and in some cases, even aromatized products. NMR and various control experiments established the product formation and reaction mechanism, which involved the conversion of molecular oxygen into a hydroperoxyl radical via a proton-coupled electron transfer process. Detection of hydrogen peroxide in the reaction medium using colorimetric analysis supported the proposed mechanism of oxygen activation. Furthermore, first-principles calculations using density functional theory (DFT) revealed that reaction coordinates and transition state spin densities have a unique spin conversion of triplet oxygen leading to formation of singlet products via a minimum energy crossing point. In addition to DFT, domain-based local pair natural orbital coupled cluster, (DLPNO-CCSD(T)), and complete active space self-consistent field, CASSCF(20,14) methods complemented the above findings. Partial density of states analysis showed stabilization of π* orbital of oxygen in the presence of ionic liquid, making it susceptible to hydrogen abstraction in a mild, metal-free condition. Inductively coupled plasma atomic emission spectroscopic (ICP-AES) analysis of reactant and ionic liquids clearly showed the absence of any significant transition metal contamination. The current results described the origin of O2 activation within the context of molecular orbital (MO) theory and opened up a new avenue for the use of ionic liquids as inexpensive, multifunctional and high-performance alternative to metal-based catalysts for O2 activation.

Defects mediated weak ferromagnetism in Zn1−yCyO (0.00 ≤ y ≤ 0.10) nanorods semiconductors for spintronics applications

A series of carbon-doped ZnO [Zn1−yCyO (0.00 ≤ y ≤ 0.10)] nanorods were synthesized using a cost-effective low-temperature (85 °C) dip coating technique. X-ray diffractometer scans of the samples revealed the hexagonal structure of the C-doped ZnO samples, except for y = 0.10. XRD analysis confirmed a decrease in the unit cell volume after doping C into the ZnO matrix, likely due to the incorporation of carbon at oxygen sites (CO defects) resulting from ionic size differences. The morphological analysis confirmed the presence of hexagonal-shaped nanorods. X-ray photoelectron spectroscopy identified C–Zn–C bonding, i.e., CO defects, Zn–O–C bond formation, O–C–O bonding, oxygen vacancies, and sp2-bonded carbon in the C-doped ZnO structure with different compositions. We analyzed the deconvoluted PL visible broadband emission through fitted Gaussian peaks to estimate various defects for electron transition within the bandgap. Raman spectroscopy confirmed the vibrational modes of each constituent. We observed a stronger room-temperature ferromagnetic nature in the y = 0.02 composition with a magnetization of 0.0018 emu/cc, corresponding to the highest CO defects concentration and the lowest measured bandgap (3.00 eV) compared to other samples. Partial density of states analysis demonstrated that magnetism from carbon is dominant due to its p-orbitals. We anticipate that if carbon substitutes oxygen sites in the ZnO structure, the C-2p orbitals become localized and create two holes at each site, leading to enhanced p–p type interactions and strong spin interactions between carbon atoms and carriers. This phenomenon can stabilize the long-range order of room-temperature ferromagnetism properties for spintronic applications.

Co-doped NiFe-LDH nanosheets arrays supported on nickel foam as an efficient oxygen evolution electrocatalysis

In the field of water electrolysis for hydrogen production, NiFe-layered double hydroxides (NiFe-LDH) is currently one of the most excellent oxygen evolution electrocatalyst. However, its application in this field is limited due to its low durability, low conductivity and few active sites. In this work, we present a Co-introduced fine-modulated NiFe-LDH performance strategy to construct Co-doped NiFe-LDH nanosheets arrays supported on nickel foam (Co-NiFe-LDH/NF). The optimized Co-NiFe-LDH/NF showed ultralow overpotentials at 211, 237, 261 and 281 mV at 50, 100, 200 and 300 mA cm−2 current densities, separately, with an extremely low Tafel slope (40 mV dec−1). The Co-NiFe-LDH/NF was highly stable during the constant current test, and the potential increased by only 10 and 13 mV after 100 h stability test at 200 and 300 mA cm−2. Notably, it also works stably at the 500 and 1000 mA cm−2 very high current densities, representing high potential of commercial application. The theoretical calculation showed that: (1) Introducing Co into NiFe-LDH can reduce the energy barrier of OH* conversion to O* and increase the activity of OER; (2) Considering the formation energy, Co is more likely to replace Fe site in NiFe-LDH than Ni site; (3) The energy barrier, differential charge and partial density of states analysis show that the best OER performance is obtained when the Fe-to-Co ratio of 2:1, and the theoretical calculation is consistent with the experimental verification. This work provides a simple and effective method for the design and construction of doping elements into NiFe-LDH electrocatalysts for efficient water oxidation, and promoted NiFe-LDH material application in commercial alkaline water electrolysis cell.

Highly efficient H2S capture using pentagonal B2C monolayer: A periodic DFT study

AbstractThe adsorption and storage properties of the chalcogenide H2S gas by pentagonal B2C nanosheet (penta‐B2C) have been explored utilizing periodic density functional theory. The present results disclose that pristine penta‐B2C nanosheet can take up eight H2S molecules with an H2S capture capacity of 50.28 wt%. Average adsorption energy values for the 1H2S/penta‐B2C, 2H2S/penta‐B2C, 3H2S/penta‐B2C, 4H2S/penta‐B2C, and 8H2S/penta‐B2C complexes are −0.876, −0.808, −0.725, −0.721, and −0.535 eV, respectively. The band structure and the total and partial density of states analyses displayed the reduction in the band gap of the penta‐B2C nanosheet after H2S adsorption of about 13%–25%. Hirshfeld charge analysis reports the charge transfer from the H2S molecules toward the penta‐B2C sheet. As the number of the adsorbed H2S molecules increases, the amount of charge transferred increases. The molecular dynamics (MD) calculations results for the pristine penta‐B2C nanosheet and ultimate 8H2S/penta‐B2C complex confirm their thermal stability at 300 K. Based on the reported analysis, penta‐B2C nanosheet can be introduced as an investible substrate for efficient H2S capture and storage.

Chiral Recognition of Amino Acids Using CC2 Porous Organic Cages.

Enantiomers have the same physical properties but different chemical properties due to the difference in the orientation of groups in space and thus Chiral discrimination is quite necessary, as an enantiomer of drug can have lethal effects. In this study, we used the CC2 cage for chiral discrimination of amino acids using density functional theory. The results indicated the physisorption of amino acids in the central cavity of the cage. Among the four selected amino acids, proline showed maximum interactions with the cage and maximum chiral discrimination energy is also observed in the case of proline that is 2.78 kcal/mol. Quantum theory of atoms in molecules and noncovalent interaction index analyses showed that the S enantiomer in each case has maximum interactions. The charge transfer between the analyte and surface is further studied through natural bond orbital analysis. It showed sensitivity of cage for both enantiomers, but a more pronounced effect is seen for S enantiomers. In frontier molecular orbital analysis, the least EH-L gap is observed in the case of R proline with a maximum charge transfer of -0.24 e-. Electron density difference analysis is carried out to analyze the pattern of the charge distribution. The partial density of state analysis is computed to understand the contribution of each enantiomer in overall density of the complexes. Our results show that S-CC2 porous organic cages have a good ability to differentiate between two enantiomers. S-CC2 porous organic cages efficiently differentiated the S enantiomer from the R enantiomers of selected amino acids.

Anthracene-bridged sensitizers for environmentally compatible dye-sensitized solar cells: In silico modelling and prediction

Advancement in solar cells has gained the attention of researchers due to increasing demand and renewable energy sources. Modeling of electron absorbers and donors has been performed extensively for the development of efficient solar cells. In this regard, efforts are being made for designing effective units for the active layer of solar cells. In this study, CXC22 was utilized as a reference in which acetylenic anthracene acted as a π bridge and infrastructure was D-π-A. We theoretically designed four novel dye-sensitized solar cells JU1-JU4 by utilizing reference molecules to improve the photovoltaic and optoelectronic properties. All designed molecules differ from R by donor moiety modifications. Different approaches were done to R and all molecules to explore different analyses like binding energies, excitation energies, dipole moment, TDM (transition density matrix), PDOS (partial density of states), absorption maxima, and charge transfer analysis. For the evaluation of results, we used the DFT technique and the findings demonstrated that the JU3 molecule showed a better redshift absorption value (761 nm) as compared to all other molecules due to the presence of anthracene in the donor moiety which lengthens the conjugation. JU3 was proven to be the best candidate among all due to improved excitation energy (1.69), low energy band gap (1.93), higher λmax value, and improved electron and hole energy values leading toward higher power conversion efficiency. All the other theoretically formed molecules exhibited comparable outcomes as compared to a reference. As a result, this work revealed the potential of organic dyes with anthracene bridges for indoor optoelectronic applications. These unique systems are effective contributors to the development of high-performance solar cells. Thus, we provided efficient systems to the experimentalists for the future development of solar cells.

Newly designed triazatruxene-based dye-sensitized solar cells containing different benzothiazine π-linkers: Geometric, optoelectronic, charge transfer properties, and cyanoacrylic acid versus benzoic acid

In this work, six new organic (D–π–A) dyes based on triazatruxene have been designed by modifying the π- linkers groups and the anchor unit of the reference dye R. Their structural, electronic, frontier molecular orbital, chemical reactivity, and photovoltaic have been studied using DFT (density functional theory) at B3LYP/6-31G (d,p). Furthermore, the TD-DFT (time-dependent DFT) at TD-BHandH/6-31G (d,p) level method was chosen to calculate the optical characteristics of the investigated dyes in the solvent CH2Cl2. Molecular properties such as geometric parameters, optoelectronic properties, frontier molecular orbitals, natural bonding orbitals, the partial density of states analysis, electrostatic surface potential, absorption spectra, and electron accepting and donating parameters were assessed to predict proper candidates for the DSSC device. The studied dyes not only show significant λmax in the range of 500–650 nm, with a band gap in the range of 1.64–1.98 eV, lower λtot, but also high light capture efficiency and significant intramolecular charge transfer properties compared to the reference dye (R). Notably, dyes with C(CH3)2 and Si(CH3)2 exhibit the best performance among the designed dyes.

Metal and nitrogen co‐doped carbon dots in the sensitized solar cells

Doped carbon dots are used to upgrade the efficiency of the porphyrin‐sensitized solar cells (PSSCs). Nitrogen‐doped carbon dots (NCDs) and metal and nitrogen co‐doped carbon dots ([M]NCDs; M: manganese, iron, cobalt, nickel, copper, and zinc) are applied in the PSSCs structure to improve the performance. Study on the substituted porphyrins is showing the effect of the substitutions of the porphyrins on the performance of PSSCs in the presence of NCDs as co‐sensitizer. The ZnTCPP/NCDs has made the biggest impact on the performance of the solar cell relative to other porphyrins; increase from 0.76% to 1.84% in PCE (power conversion efficiency) relative to ZnTPP/NCDs can be seen. The results that are related to the use of NCDs and (M)NCDs as co‐sensitizer are showing the impact of impurity doping in CDs on the PSSCs' efficiency. In the case of doped CDs in the presence of ZnTCPP, the performance of PSSCs using (Ni)NCDs and (Zn)NCDs is showing more increase relative to the use of other prepared carbon dots as co‐sensitizer. PCE of the solar cells sensitized by ZnTCPP/(Ni)NCDs and ZnTCPP/(Zn)NCDs was increased from 1.10% to 2.75% and 3.09%, respectively, in comparison with only ZnTCPP. Based on computational results, the Zn2+ and Ni2+ are playing a direct role on the highest occupied molecular orbital (HOMO) and (lowest unoccupied molecular orbital) LUMO of (Zn)NCDs and (Ni)NCDs, respectively. Also, based on the partial density of states analysis, the metal ions such as Zn2+ and Ni2+ in the (Zn)NCDs and (Ni)NCDs, respectively, are playing an important role in HOMO and LUMO of investigated systems, and these two metals have high amount of contributions in the mentioned levels.

Two-Dimensional α-SiX (X = N, P) Monolayers as Efficient Anode Material for Li-Ion Batteries: A First-Principles Study

Density functional theory simulations were performed to investigate the structural, electronic, and electrochemical properties of the two-dimensional α-SiX (X = N, P) monolayers as anode material in Li-ion batteries (LIBs). Our result indicates that α-SiX monolayers have excellent mechanical, dynamical, and thermal stability. The obtained adsorption energy values suggest that the Li atom adsorption over α-SiX is a favorable process. According to the Löwdin charge transfer and partial density of states analysis, charge transfer takes place from Li atom to α-SiX monolayers. From the band structure plots, we observed that after the adsorption of a single Li atom, the α-SiX monolayers are converted into a metallic state from the semiconductor state and remain in the metallic state for the different adsorption concentrations of Li atoms, which is essential to facilitate the diffusion of stored electrons. The calculated specific storage capacity is 956.16 and 733.66 mA h g–1 for α-SiN and α-SiP monolayers, respectively, which is remarkably higher than that of the conventional anode materials (such as graphite and TiO2). Ab initio molecular dynamics simulations confirm the room-temperature stability of the α-SiX monolayers at the maximum loading of Li atoms. The lower diffusion energy barriers of 0.30 eV (for α-SiN monolayers) and 0.16 eV (for α-SiP monolayers) ensure good diffusivity of ions over monolayers. The calculated open-circuit voltage is also favorable for battery applications. The aforementioned findings suggest that the α-SiX monolayers could be beneficial and compelling host anode material for high-performance LIBs.

Comparative Study on Sodium Storage Properties of Two CNTs and a Novel CNT Design

Density functional theory (DFT) is employed to research three carbon tubes (CNTs), SWCNT, N-NiCNT, and N-CoCNT. The first two structures synthesized by other groups and N-NiCNT has better sodium storage properties as sodium-ion battery (SIB) anode than SWCNT, the last one is a designed structure. Here, the intrinsic cause why N-NiCNT has better performance than SWCNT has been located at molecular and atomic levels, meanwhile the potential of N-CoCNT as anode candidate is predicted. The researched properties that determine the electrochemical performances involve in structure stability, frontier molecular orbital, partial density of state analysis, and sodiation barrier comparison. The results indicate that the lower sodiation barrier, expanding transfer space, more stable structure stability of N-NiCNT should be responsible for its better sodium storage performance, which consists with the experimental results. In addition, the designed N-CoCNT anode is a promising candidate as SIB anode owing to better stability, lower barrier, and strong N-Co interaction than N-NiCNT

First-principles study of oxygen evolution on Co3O4 with short-range ordered Ir doping

The large overpotential of oxygen evolution reaction (OER) in water-splitting process prevented its application in energy field, researchers attempted to find efficient catalysts. Here, we used short-range ordered Ir-doped Co3O4 (100) model to study the OER performance under various coordination conditions through first-principles calculations. This doping pattern enabled the model to display three types of active sites, included single Ir/Co site and double Ir sites, which were different in terms of propensity to adsorb reaction intermediates. The OER performance of three types of active sites with the same O and OH coverage was evaluated, we found that O covered surface increased OER catalytic activity for single Ir/Co site. While for double Ir sites, it exhibited the lowest overpotential among the above three types, and O/OH coverage had a little influence on its activity. Furthermore, Bader charge and partial density of states analyses showed that, for single Ir/Co site, the overpotential on covered surface was reduced due to the valence electrons decrease at the metal site. While for double Ir sites, the overpotential reduction was due to the unique adsorption patterns. Additionally, the solvation effect was considered. It was found that the solvation had a key effect on the adsorption energy depending on the binding site of the intermediate. But the overpotential trend in solvent was similar with that in vacuum on the same active site.

First-principles study on the hydrogen storage properties of MgH2(1 0 1) surface by CuNi co-doping

Exploring the hydrogen storage properties on the surface of transition metal-modified MgH2 systems is beneficial to develop new hydrogen storage regions. The first-principles approach was used to study the hydrogen storage mechanism on the CuNi co-doped MgH2(101) surface. The most stable energy adsorption site for hydrogen on the surface of CuNi co-doped MgH2(101) is above the Ni atom, and the corresponding chemisorption energy is −0.51 eV. The distribution of charge densities indicates substantial charge exchange occurs between the hydrogen molecule and Ni atom, while partial density of state analysis reveals orbital hybridization between the H-s (H2) and Ni-d orbits. Furthermore, molecular dynamics simulations indicate that the temperature range (473 to 573 K) of hydrogen desorption on the surface is similar to previous experimental results. Therefore, the (101) surface of CuNi co-doped MgH2 can be well matched with itself to obtain the additional hydrogen storage region.

Possible half-metallicity and suppressed double-exchange interaction in spinel Mn2.4Ni0.6O4: A Ni-substitution effect

In this work, we present detailed structural, magnetic, dielectric, and transport properties as well as electronic structure studies of a Mn2.4Ni0.6O4 system. The Mn2.4Ni0.6O4 system acquires cubic Fd3̅m crystal structure at room temperature and exhibits a ferrimagnetic transition around 108 K. The pristine Mn3O4 acquires a tetragonal I41/amd structure at room temperature and exhibits ferrimagnetic transition and magneto-dielectric coupling at around 43 K. The magneto-dielectric coupling is found to be absent in cubic Mn2.4Ni0.6O4, but still shows interesting transport behavior. The resistivity results show semiconducting behavior of the system, but interestingly, this semiconducting behavior weakens at low temperatures. This is evident from the decreased rate of change of resistivity with decreasing temperature. X-ray absorption spectra results have confirmed that to compensate for the charge imbalance caused by Ni2+ cations at the octahedral-site, a few Mn3+ cations transform into Mn4+. The density of state calculations reveal that at Fermi-level, Mn2.4Ni0.6O4 exhibits small but finite bands in the majority channel while a band gap of 1.5 eV exists in the minority channel. The ground state electronic structure of Mn2.4Ni0.6O4 predicts a half-metallic character for the system. The partial density of states analysis of Mn2.4Ni0.6O4 suggests that the bands near the Fermi-level are predominantly contributions of Mn3+, Mn4+ and O2-. We further discuss the origin of the weak semiconducting behavior of Mn2.4Ni0.6O4 at low temperatures.

A comprehensive DFT study of CO2 methanation on the Ru-doped Ni(111) surface

Ru−Ni bimetallic catalysts show excellent performance for CO2 methanation, but the underlying mechanism remains unclear. In this study, the mechanism of CH4 synthesis on Ru-doped Ni(111) is investigated with the density functional theory methods. Through the discussion of the adsorption of all possible species, the relatively weak O* adsorption indicates that the introduction of Ru into the Ni catalyst can effectively protect the Ni active sites from being oxidized. Meanwhile, the partial density of states analyses reveals that CO2* is well activated on the catalyst. In addition, the optimal route for CO2 hydrogenation into CH4 is obtained, with an activation barrier of 1.13 eV for the rate-determining step. It shows that Ru-doped Ni(111) possesses superior catalytic activity for CO2 hydrogenation to CH4. Additionally, the activation barriers of all the surface C* formation reactions significantly increase, manifesting that the resistance to carbon deposition of Ru-doped Ni(111) is improved.

First‐principles calculation of mechanical properties and electronic structures of W 4 Co 4− n X n B 4 (X = V, Mn, Fe, Ni; n = 0,1)

The first-principles calculation is performed to explore the mechanical properties and electronic structures of transition elements X (X = V, Mn, Fe, Ni) doped WCoB (tungsten cobalt boron), which has shown high oxidation resistance and melting point under high pressure. The energy analysis indicates that the high pressure leads to the lower lattice constants and less stable structures. The deviation of cohesive energy and formation enthalpy between doped and undoped structures indicates that W4Co3FeB4 and W4Co3NiB4 have similar stability. The high pressure contributes to the increasing of elastic, shear, and bulk moduli, which indicates the increase of covalence. The increase of Poisson's ratio, B/G ratio, and anisotropy index AU indicates the higher ductility and higher anisotropy under high pressure. Based on bulk modulus and shear modulus, the hardness of W4Co4B4, W4Co3FeB4, and W4Co3NiB4 increases under high pressure, which consists of the variation of electronic structures. The density of states (DOS) and partial DOS analysis indicate that the high pressure leads to lower density around Fermi level and higher hybridization. W4Co4B4, W4Co3FeB4, and W4Co3NiB4 show similar variation of mechanical properties, which is determined by the similar atom properties of Co, Fe, and Ni. Similarly, W4Co3VB4 and W4Co3MnB4 also imply similar variation of mechanical properties and electronic structures.

DFT Study on the Compatibility Between Bentonite Clay Mineral and Hydration Products With the Polycarboxylate Water Reducer in the Cement Hydration Process

As one of the most used grouting materials, cement has the characteristics of low price and a wide resource of raw material. With the in-depth research and application of cement admixture, the compatibility between different water-reducing agents and clay has become one of the critical factors that affects the cement hydration process. Due to the adsorption of clay on cement additives, the dispersion efficiency of the water reducer will be reduced, also the strength and impermeability of hydration products will be adversely affected. This paper studies the adsorption characteristics of different PCE superplasticizers on bentonite clay minerals and hydration products using a molecular simulation technique. Results showed that there is competitive adsorption between the clay and hydration products when the admixture participates in the hydration reaction, the additives are likely to adsorb on the CH rather than the clay minerals, while the adsorption energy of the hydration product C-S-H is the highest, thus the preferential adsorption order and compatibility between clay minerals and hydration products on admixtures could also be obtained. PDOS (partial density of states) analysis concluded that some new characteristic peaks and rearrangement of the bonding orbitals may appear after the adsorption, with the peak value of the minerals higher than that of jennite, which is also consistent with the adsorption energy. This study aims to reveal the interaction mechanism and compatibility between the hydration product and clay minerals, hoping to fully utilize the advantages of both clay minerals and admixtures in the cement hydration process.

Adsorption of water on C sites vacancy defected graphene/h-BN: First-principles study.

Heterostructures (HS), vacancy defects in HS, and molecular adsorption on defected HS of 2D materials are fervently inspected for a profusion of applications because of their aptness to form stacked layers that confer approach to an amalgamation of favorable electronic and magnetic properties. In this context, graphene (Gr), hexagonal boron nitride (h-BN), HS of graphene/h-BN (Gr/h-BN), and molecular adsorption on Gr/h-BN offer promising prospects for electronic, spintonic, and optoelectronic devices. In this study, we investigated the structural, electronic, and magnetic properties of C sites vacancy defects in Gr/h-BN HS and adsorption of water molecule on defected Gr/h-BN HS materials by using first-principles calculations based on spin-polarized density functional theory method within van der Waals (vdW) corrections DFT-D2 approach. We found that these considered materials are stable 2D vdW HS. Based on band structure calculations, they are semimetallic, and on density of states and partial density of states analysis, they are magnetic materials. The magnetic moment developed in these defected systems is due to the unpaired up-spin and down-spin states in the orbitals of atoms present in the materials created by the vacancy defects.

Cu n Si 12 ( n = 30, 38, and 60): A series of silicide cages with high content of TM atoms

A series of silicide cages with high content of transition metal atoms, CunSi12 (n = 30, 38, and 60) clusters, have been systematically investigated in the framework of density functional theory. Among them, Cu30Si12 with a higher Eb and a lager HOMO-LUMO gap has been discussed in detail. To be specific, the hollow cage-like structure Cu30Si12, which adopts an Ih-symmetry, can be described as the combination of 12 Cu5Si. Molecular dynamics simulations and vibrational frequency analysis have been conducted to verify its stability. Electron density analysis, natural bond orbitals analysis, and partial density of states analysis have been done to explore the binding characters of Cu30Si12. The results indicate that the σ bonds between Cu and Si atoms are of great importance for structural stability. More importantly, on one hand, CunSi12 (n = 30, 38, and 60) can encapsulate atoms or molecules to regulate their properties. On the other hand, CunSi12 (n = 30, 38, and 60) may be rather tempting for the further semiconductor devices due to the existence of silicon.

Adsorption performance and mechanism of the commonly used collectors with Oxygen-containing functional group on the ilmenite surface: A DFT study

Flotation is the main method to purify ilmenite, the success of flotation is closely related to the effective adsorption of collectors on the mineral surface. Herein, the coordination chemistry adsorption mechanism of the commonly used collectors with oxygen-containing functional groups on ilmenite surface were systematically investigated by first-principles DFT calculations. Adsorption energy results shows that the O bearing pnictogen compounds are the best for ilmenite beneficiation among all the oxygen-containing collectors. In the O-bearing pnictogen compounds, the collection performance of arsenic acid is the best, followed by phosphorous acid and phosphoric acid ester. The frontier molecular orbital analysis predicted that the collectors possessed a good chemical bonding ability with ilmenite, which is confirmed by the charge population analysis that there is significant electron transfer (bonding evidence) between collectors and ilmenite. Partialdensityofstates analysis further confirmed that the physicochemical nature of the adsorption of the collectors on the surface Ti site were ascribed to the hybridization of O 2p and Ti 3d, in which the O 2p electrons of the collectors occupied the empty orbital of Ti 3d to complete the coordination shell of surface Ti atom. This work sheds new light on the screening of solidophilic functional groups for the collector design of ilmenite beneficiation and helps to explain the adsorption mechanism of oxygen-containing collectors on the oxidized mineral surface.