Large Adsorption Energy Research Articles

2D Si3N as a Promising Anode Material for Li/Na-Ion Batteries from First-Principles Study

The development of high-efficiency anode materials with large capacity, high stability and fast diffusion rates is a key requirement for rechargeable Li-ion and Na-ion batteries (LIBs/NIBs). In this work, the adsorption and diffusion of Li and Na atoms on two-dimensional (2D) Si3N materials is studied using first-principles calculations. The Si3N monolayers have large adsorption energies (2.74 eV for Li and 2.17 eV for Na) and a high theoretical capacity (1772.0 mAh/g for Li and 859.6 mAh/g for Na). Moreover, the low diffusion barriers (0.45 and 0.24 eV) for Li and Na atoms indicate that Si3N has an excellent high charge/discharge capability. In addition, molecular dynamics simulations showed that the structure of the 2D Si3N monolayer with adsorption of 32 Li/Na atoms has a very small change at 400 K due to the large adsorption energies for Li/Na. Owing to its good features, the Si3N monolayer is a highly promising anode material for energy storage devices.

Functionalisation of hexagonal boron phosphide (h-BP) monolayer via atomic adsorption

ABSTRACTIn this study, we investigate the adsorption properties of Fe, Co, Ni, Cu, Zn, In, Tl, Ar atoms on hexagonal boron phosphide monolayer (h-BP) using density functional theory within both GGA and LDA functionals. Bare h-BP is a direct gap semiconductor with planar structure. The adsorption of the atoms on h-BP exhibits a large variety of electronic properties like semiconducting, metallic, and half-metallic states. Fe- and Ni-adsorbed h-BPs show semiconducting character with decreased band gaps. Ni atom is strongly adsorbed on the surface giving largest adsorption energy observed in this work. Fe-adsorbed system is a semiconducting ferromagnet with 1.95 magnetic moment. Co adsorption results in a half-metallic behaviour with 1.00 net magnetic moment and a perfect spin polarisation at Fermi level. Cu, In, and Tl adsorbed h-BP systems show metallic character. The results obtained show that h-BP surface can be functionalised via adsorption of related single atoms and can be suitable for various applications in optoelectronics and spintronics.

RETRACTED: Adsorption of gas molecules on the defective stanene nanosheets with single vacancy: A DFT study

Abstract Using the first-principles calculations, we have systematically examined the adsorption of gas molecules on the pristine and vacancy defective stanene monolayers. The adsorption of gas molecules on the defective monolayers is much stronger than that on the perfect ones, indicating the suitability of defective stanene nanosheets for adsorption processes. The large adsorption energies for SO2 and SO3 adsorbed complexes indicate the strong reactivity of stanene systems with adsorbed gas molecules, leading to the formation of multiple contacting points at the interface. The formation energies for the defective stanene systems were calculated. Our results indicated that the single vacancy defective stanene monolayers are thermodynamically stable, and can be used as effective gas sensors. The charge density difference calculations indicate that the electronic densities were largely accumulated between the atoms interacting with each other. This strong chemical interaction was also evidenced by the large overlaps of the density of states between the interacting atoms. The band structure calculations reveal the semiconductor features for defective stanene monolayers with adsorbed gas molecules. Our obtained results would be useful to search for promising gas sensor devices based on vacancy defective stanene monolayers.

First-Principles Insight Into Au-Doped MoS2 for Sensing C2H6 and C2H4

C2H6 and C2H4 gases are two typical decompositions produced by partial discharge of transformer oil. To fully evaluate the feasibility of MoS2-based materials for the detection of C2H6 and C2H4 gases, the adsorption of C2H6 and C2H4 molecules on intrinsic and Au-doped MoS2 monolayer have been studied in this paper by the First-principle of Density Functional Theory (DFT). The adsorption mechanism of MoS2-based monolayer were investigated carefully in terms of adsorption energy, adsorption distance, bandgap structure, charge transfer and density of states (DOS). The calculated results show that the adsorption structures of the C2H6 and C2H4 molecules on Au-doped MoS2 monolayer with larger adsorption energies were stable, and have shorter adsorption distance, higher charge transfer and stronger orbital hybridization compared with the corresponding MoS2 monolayer adsorption structures. It is concluded that the doped-Au atom affects the electronic structure of MoS2 monolayer to enhance the adsorption capacity. From this aspect, the present research offers a theoretical guidance to the application of Au-doped MoS2 materials as the sensing material for C2H6 and C2H4 gases.

Impact of mechanical activation on bioleaching of pyrite: A DFT study

The impact of mechanical activation on the bioleaching of pyrite was studied, and the mechanisms were elucidated by DFT (density functional theory). The characterization result of the pyrite that were mechanically activated showed that the average diameter of the pyrite particles decreased sharply when the activation time was up to 80 min and remained constant from 80 min to 120 min due to the sample agglomeration effect. The change in the specific surface area exhibited the opposite trend, and the contact angles of the pyrite particles decreased gradually as the grinding time increased from 0 to 120 min, which implied that the hydrophilic property of the pyrite increased. The pyrite lattices increased after mechanical activation, indicating the presence of S defect sites on the pyrite surface. Notably, all these changes favored the increase in the bioleaching rate of pyrite. The result showed that the leaching rate of pyrite increased noticeably after mechanical activation by Sulfobacillus thermosulfidooxidans (S.t), and the cell exhibited enhanced adsorption on the activated pyrite surface. The DFT result proved that the activated pyrite could be easily adsorbed by H2O and cells, with relatively large adsorption energies, strong bonds, and an increased number of electron transfers.

Two-dimensional graphitic carbon nitride (g-C4N3) for superior selectivity of multiple toxic gases (CO, NO2, and NH3)

Using first principles calculations, we investigated the possibility of selecting multiple toxic gases using one substrate material. Here, we explored the transport property of H2, N2, O2, CO, CO2, NO2, and NH3 gas molecules on two-dimensional graphitic carbon nitride (2D g-C4N3). The homonuclear molecule such as H2, N2, and O2 has very weak adsorption energy (equal to or less than 0.1 eV) and also CO2 has an adsorption energy of 0.23 eV. In the typical toxic gas molecule adsorption systems, we found an appreciable charge transfer. In CO and NH3 adsorption systems, the charge transfer of 0.397 and 0.418 electrons from the molecule to the substrate was found, while the NO2 molecule gained 0.124 electrons from the substrate. Due to this large amount of charge transfer, we obtained large adsorption energies of 4.57, 1.29, and 1.93 eV in CO, NO2, and NH3 systems. Moreover, through the I–V curve calculations, we found large difference in the current. The calculated current was 21, 13.11, and 16.16 μA for CO, NO2, and NH3 systems at the bias voltage of 0.5 V. Our results imply that the 2D g-C4N3 can be a superior substrate material for sensing of multiple toxic gases.

Morphology Modulation‐Engineered Flowerlike In2S3 via Ionothermal Method for Efficient CO2 Electroreduction

AbstractElectroreduction of carbon dioxide (CO2) to chemicals is a promising route to convert and utilize CO2 under atmospheric conditions. However, the relative poor reaction efficiency seriously hinders the practical applications of this route. In this work, flowerlike In2S3 assembled by nanoflakes was synthesized via ionothermal method and exhibited a high Faradaic efficiency (FE) of 86 % with excellent formate formation rate of 478 μmol h−1 cm−2 in ionic liquid (IL) electrolyte. Flowerlike structure can provide large electrochemically active surface area and enhance mass transfer rate. Additionally, density functional theory (DFT) calculations reveal that the origin of the improved performance can be attributed to the large adsorption energy of CO2* and OCHO* intermediate on the (440) facet which is the main exposed crystal facet of flowerlike In2S3.[f1]

First-Principles Modeling of Oxygen Adsorption on Ag-Doped LaMnO3 (001) Surface

The density functional theory (DFT) method has been used to calculate oxygen adsorption on the Ag-doped MnO2- and LaO-terminated (001) LaMnO3 surfaces. The catalytic effect of Ag doping is revealed by comparison of the adsorption energies, electron charge redistribution, and interatomic distances for the doped and undoped surfaces. Adsorption of Ag on the MnO2-terminated surface increases the adsorption energy for both atomic and molecular oxygen. This increases the oxygen surface concentrations and could improve the cathode efficiency of fuel cells. The opposite effect takes place at the LaO-terminated surface. Due to the large adsorption energies, adsorbed oxygen atoms are immobile and the oxygen reduction reaction rate is controlled by the concentration and mobility of oxygen vacancies.

First-Principles Study of Gas Molecule Adsorption on C-doped Zigzag Phosphorene Nanoribbons

Phosphorene, due to its large surface-to-volume ratio and high chemical activity, shows potential application for gas sensing. In order to explore its sensing performance, we have performed the first-principles calculations based on density functional theory (DFT) to investigate the perfect and C-doped zigzag phosphorene nanoribbons (C-ZPNRs) with a series of small gas molecules (NH3, NO, NO2, H2, O2, CO, and CO2) adsorbed. The calculated results show that NH3, CO2, O2 gas molecules have relatively larger adsorption energies than other gas molecules, indicating that phosphorene is more sensitive to these gas molecules. For C-ZPNRs configuration, the adsorption energy of NO and NO2 increase and that of other gas molecules decrease. Interestingly, the adsorption energy of hydrogen is −0.229 eV, which may be suitable for hydrogen storage. It is hoped that ZPNRs may be a good sensor for (NH3, CO2 and O2) and C-ZPNRs may be useful for H2 storage.

Transition metal doped arsenene: Promising materials for gas sensing, catalysis and spintronics

Based on first-principles calculations, we systematically investigated the stability, electronic and magnetic properties of transition metal (TM)-doped arsenene (TM = Cr, Mn, Fe, Co, Ni, and Cu) with O2 adsorbed, and further explored the catalytic performance of TM-doped arsenene for CO oxidation. The substitutions of TM atoms induce the magnetic ground states of arsenene exception for Cu, which arises from the strong hybridizations of 3d orbitals of TM atoms and 4p orbitals of surrounding As atoms. Mn-, Co- and Ni-doped arsenenes are half metals showing potential applications in spintronics. O2 molecule prefers to chemisorb at the TM-doped arsenene systems with larger adsorption energies than those for perfect arsenene, indicating TM-doped arsenene can be used as O2 sensor with promoted sensitivity. It is worthy to notice that Cr-doped arsenene transforms from a diluted magnetic semiconductor to a magnetic metal owing to the adsorption of O2. The partially occupied O 2p and Cr 3d orbitals suggest that O2 molecule is highly activated, which is consistent with the largest elongation of OO bond length. The barrier of CO oxidation on Cr-doped arsenene through Langmuir-Hinshelwood (LH) mechanism is 0.72 eV, which implies that TM-doped arsenene may be promising single atom catalysts for the oxidation of CO.

A DFT study on Pt doped (4,0) SWCNT: CO adsorption and sensing

In this study, Density Functional Theory calculations have been utilized for the platinum doped (4,0) single walled carbon nanotube (SWCNT) in order to investigate the use of the CO gas sensor at room temperature. Hybrid B3LYP method with 6-31G (d,p) basis set for C, O and H atoms and LanL2DZ basis set for Pt atom have been used in calculations. The structural and electronic properties have been detailed. The charge distributions obtained for structures showed that charge transfer was occurred from the adsorbed CO molecule to carbon nanotube structure as an electron acceptor. The HOMO–LUMO gap of the Pt doped SWCNT decreased with adsorbing of CO molecule. The results obtained in this study stated that the CO molecule can be adsorbed on Pt site of SWCNT in order to form the PtC bond with large adsorption energy and significant charge transfer. There is a consistency between the results of previous experimental study and the data of our study. As a conclusion, the electrical conductivity of Pt doped (4,0) SWCNT cluster increased after a CO molecule adsorption. Accordingly, Pt doped (4,0) SWCNT have potential for sensing of carbon monoxide at room temperature.

Multidimensional Integrated Chalcogenides Nanoarchitecture Achieves Highly Stable and Ultrafast Potassium-Ion Storage.

Potassium-ion batteries (KIBs) have come into the spotlight in large-scale energy storage systems because of cost-effective and abundant potassium resources. However, the poor rate performance and problematic cycle life of existing electrode materials are the main bottlenecks to future potential applications. Here, the first example of preparing 3D hierarchical nanoboxes multidimensionally assembled from interlayer-expanded nano-2D MoS2 @dot-like Co9 S8 embedded into a nitrogen and sulfur codoped porous carbon matrix (Co9 S8 /NSC@MoS2 @NSC) for greatly boosting the electrochemical properties of KIBs in terms of reversible capacity, rate capability, and cycling lifespan, is reported. Benefiting from the synergistic effects, Co9 S8 /NSC@MoS2 @NSC manifest a very high reversible capacity of 403 mAh g-1 at 100 mA g-1 after 100 cycles, an unprecedented rate capability of 141 mAh g-1 at 3000 mA g-1 over 800 cycles, and a negligible capacity decay of 0.02% cycle-1 , boosting promising applications in high-performance KIBs. Density functional theory calculations demonstrate that Co9 S8 /NSC@MoS2 @NSC nanoboxes have large adsorption energy and low diffusion barriers during K-ion storage reactions, implying fast K-ion diffusion capability. This work may enlighten the design and construction of advanced electrode materials combined with strong chemical bonding and integrated functional advantages for future large-scale stationary energy storage.

Single ultrathin WO3 nanowire as a superior gas sensor for SO2 and H2S: Selective adsorption and distinct I-V response

In order to take insight into the gas sensing performance of single ultrathin WO3 nanowire, we performed first principles calculation to investigate the gas adsorption properties and used non-equilibrium Green function (NEGF) to investigate the electron transport properties of WO3 nanowires with gas adsorption. Our investigation indicated that the WO3 nanowires with/without oxygen vacancies are both sensitive to H2S due to the large adsorption energies and distinct charge transfer. Besides, we found that the WO3 nanowire with Oa type oxygen vacancies is highly selective to SO2. We supposed that the high chemical activity and the small molecular volume of H2S and SO2 are the main reasons of the selectivity. Finally, the negative differential resistance (NDR) effect of single ultrathin WO3 nanowire and the gate voltage were proposed to benefit the application of WO3 nanowires gas sensors. We also supposed two ways to take advantage of the NDR effect of single ultrathin WO3 nanowire in gas sensing applications. It should be noted that this is the first theoretical investigation of WO3 nanowires gas sensors considering the electron transport properties. Our work highlighted the possibility to use the single ultrathin WO3 nanowire as superior gas sensors for SO2 and H2S.

Gas adsorption induces the electronic and magnetic properties of metal modified divacancy graphene

In this study, based on density functional theory calculations, we investigated the stable configurations, electronic structures, and magnetic properties of metal and non-metal atom-modified graphene substrates. The single-atom metal embedded divacancy (555–777) graphene (555-777-graphene-M, M = Fe, Ni and Pd) exhibited high stability, and the 555-777-graphene-Fe system had a larger magnetic moment than the Ni-doped system. The adsorption of NO on 555-777-graphene-Fe (or -Ni) was more stable than that of the HCN, NH3 and SO2 molecules. Among the other substrates, the NO adsorbed on 555-777-graphene-Fe system had the largest magnetic moment (3.0 μB). The metal atoms anchored on 3Si doped 555–777 graphene (3Si-graphene-M) had larger adsorption energies than the corresponding cohesive energy values for the bulk metal. The gas molecules adsorbed on 3Si-graphene-M sheets were more stable than those on 555-777-graphene-M. NO can be detected easily as a specific gas molecule because it has the largest adsorption energy. The NH3 or NO adsorbed on different 3Si-graphene-M substrates could lose or gain less transferred electrons and they exhibited moderate stability, thereby indicating that they are more sensitive than other gases and can be detected easily. Moreover, the electronic structures and magnetic properties of 3NM-graphene-M sheets were regulated by selecting different gas molecules, thereby facilitating the design of novel graphene-based spintronic or gas sensor devices.

Computational study of surface orientation effect of rutile TiO2 on H2S and CO sensing mechanism

The adsorption of hazardous CO and H2S on four low-index surfaces of rutile TiO2 surfaces was investigated using first-principle calculations, in an effort to distinguish the difference of surface reactivity on these surfaces in sensing process. We predicted that rutile TiO2 possessed excellent capacity for H2S detection than CO based on adsorptive structure, density of states (DOS) analysis and charge density difference (CDD) plots. Particularly, in H2S adsorption, the dissociative adsorption process occurred on the (001) surface of TiO2 with largest adsorption energy as 1.17 eV and noticeable modification in the electronic structure, rendering high sensitivity on this surface. The decomposition of H2S yielded HS and H species, whose bonding features were also analyzed. It was suggested that 3p states of HS were able to mix with surface titanium and the 1 s states of H were considerably overlapped with 2p states of surface bridging oxygen, forming OH radicals on (001) surface. The reason for different sensing properties on these surfaces was pinpointed, and the significance of rutile (100) facet in H2S monitoring was underlined. These preliminary investigations would provide a basic understanding for CO and H2S adsorption for pursuing high-performance sensor toward targeted gas.

Adsorption and Diffusion of Lithium in Doped Molybdenum Disulfide Single-Layer with Metal Substituted Sulfur Atom

Considering the S-vacancy defect in single-layer MoS2, the metal doped including Fe-, Co-, Cu-, Zn-, doped specimens in MoS2 single-layer and their effect of the adsorption and diffusion of Li on the MoS2 single-layer were investigated by Density Functional Theory (DFT). Under Mo-rich condition, the Fe-, Co-, Cu-, Zn-doped specimens by substitution of S atom have smaller formation energy than those under S-rich condition. For doped MoS2 single-layer, lithium donates electron to doped specimens, making the band level of the doped specimens downward into the valence band and the Fermi energy level further upward. The Li ion has positive charge, the ion adsorptive property was enhanced because of strong coulomb interaction. These are confirmed by the large adsorption energies (-1.11 ~ -0.44 eV). The diffusion energy barriers except for the path closest doped specimens by substitution of S atom are ~ 0.25, which are similar to that of pristine one. Above all, the metal doped by substitution of S atom MoS2 single-layer are promising anode materials of LIBs.

Improvement of the arsine adsorption by doping on monolayer MoS2

The improvement of the arsine adsorption on monolayer MoS2 by doping has been investigated by first-principles calculation. The impurity atoms Si, P, and Cl, have been introduced to substitute S atoms to form an [Formula: see text]- or [Formula: see text]-type system. The electronic properties of MoS2 with dopants P and Cl are insensitive to the adsorption of AsH3. The Si-MoS2 with adsorbed AsH3 configuration has the largest adsorption energy, the lowest adsorbed height, and the most effective charge transfer. It is indicated that the properties of MoS2 can be improved by doping for detecting AsH3 molecules.

Two-dimensional Au2B: Robust non-magnetic metallicity independent of the native defects, strain and functional groups

Based on the first principle method, the structural and electronic properties for two-dimensional (2D) Au2B are studied. Our investigations indicate 2D Au2B has the similar crystal structure to 2D transition metal dichalcogenides (TMDs). Electronic structures show 2D Au2B is a typical non-magnetic metal. Native defects (Au and B vacancy), strains and functional groups (F and Cl absorbed cases) could not destroy its metallic characters. Stable metallic properties suggest 2D Au2B is an alternative and promising electrode material for 2D heterogeneous junctions based on the TMDs. For the Li absorbed case, large negative adsorption energies imply the strong interactions between Li and 2D Au2B, which means 2D Au2B, when utilized as the Li-ion batteries anodes, could prevent the formation of metallic Li and improve the Li-ion batteries' safety and reversibility.

Theoretical study of the adsorption characteristics and the environmental influence of ornidazole on the surface of photocatalyst TiO2

In this paper, density functional theory (DFT) was performed to study the adsorption properties of ornidazole on anatase TiO2(101) and (001) crystal facets under vacuum, neutral and acid-base conditions. We calculated the adsorption structure of ornidaozle on the anatase TiO2 surface, optimal adsorption sites, adsorption energy, density of states, electronic density and Milliken atomic charge under different conditions. The results show that when the N(3) atom on the imidazole ring is adsorbed on the Ti(5) atom, the largest adsorption energy and the most stable adsorption configuration could be achieved. According to the analysis of the adsorption configuration, we found that the stability of C(2)-N(3) bond showed a weakening trend. The adsorption wavelengths of the electronic transition between the valence band and conduction band of ornidazole on the TiO2 surface were in the visible light wavelengths range, showing that the TiO2 crystal plane can effectively make use of visible light under different conditions. We speculate the possibility of ornidazole degradation on the surface of TiO2 and found that the reactive site is the C-N bond on the imidazole ring. These discoveries explain the photocatalytic degradation of ornidazole by TiO2 and reveal the microscopic nature of catalytic degradation.

First-principles insight into Ni-doped InN monolayer as a noxious gases scavenger

Using first-principles theory, we theoretically investigate the most stable doping site of Ni atom on pristine InN monolayer and adsorption behavior of Ni-doped InN (Ni-InN) monolayer upon four noxious gases (NO, CO2, H2S and NH3). Electron localization function (ELF), electron deformation density (EDD) as well as density of state (DOS) are considered to further understand the adsorption behavior of Ni-InN monolayer towards gas molecules. For possible application of our proposed material, work function and band structure of the isolated and gas adsorbed Ni-InN monolayer are analyzed as well. It is found that the Ni dopant prefers to be adsorbed on the pristine InN monolayer at the TN site with the lowest biding force (Eb) of −3.02 eV. Four gases could be stably adsorbed on the Ni-InN monolayer surface wherein the chemisorption is identified due to the large adsorption energy (Ead) and charge transfer (QT). ELF, EDD and DOS analyses corroborate the strong chemical interaction between Ni dopant and activated atoms in gas molecules. The band structure analysis provides the sensing mechanism of Ni-InN based resistance-type chemical sensor for detection of such four gaseous species. Our calculations can supply some guidance to explore promising novel gas sensors using group III-V nitrides in the gas-sensing field and environmental monitoring fields.