Adsorption Of HF Research Articles

High-Efficiency Adsorption of HF and HCN Gases by Transition Metal X (X=Pd, Mo, Ni) Doped WS2 :A first-principles study

Abstract This article studies the adsorption effect of pristine WS2 and Pd, Mo, Ni-doped WS2 on HF and HCN gases based on density functional theory. The energy band structure, density of states (DOS), charge differential density (CDD), adsorption energy, charge transfer, and molecular orbitals of the materials are calculated. The results show that Pd, Mo, Ni-doped WS2 significantly improve the adsorption energy of HF and HCN gases. Moreover, the Mo_WS2/HF system exhibits a charge transfer of 0.48 e, significantly higher than other systems. Mo_WS2 and Ni_WS2 systems exhibit an increase in transferred charges compared to pristine WS2 as adsorbing HCN, which are easy to adsorb HCN. Using recovery time as an indicator, Mo_WS2 is the most suitable for adsorbing HF between 300 K and 400 K, while Ni_WS2 is the most suitable for adsorbing HCN. Analyzed the application of materials in adsorbing harmful gases HF and HCN.

Pseudo-Wet Plasma Mechanism Enabling High-Throughput Dry Etching of SiO2 by Cryogenic-Assisted Surface Reactions.

Manufacturing semiconductor devices requires advanced patterning technologies, including reactive ion etching (RIE) based on the synergistic interactions between ions and etch gas. However, these interactions weaken as devices continuously scale down to sub-nanoscale, primarily attributed to the diminished transport of radicals and ions into the small features. This leads to a significant decrease in etch rate (ER). Here, a novel synergistic interaction involving ions, surface-adsorbed chemistries, and materials at cryogenic temperatures is found to exhibit a significant increase in the ER of SiO2 using CF4/H2 plasmas. The ER increases twofold when plasma with H2/(CF4 + H2) = 33% is used and the substrate temperature is lowered from 20 to -60°C. The adsorption of HF and H2O on the SiO2 surface at cryogenic temperatures is confirmed using in situ Fourier transform infrared spectroscopy. The synergistic interactions of the surface-adsorbed HF/H2O as etching catalysts and plasma species result in the ER enhancement. Therefore, a mechanism called "pseudo-wet plasma etching" is proposed to explain the cryogenic etching process. This synergy demonstrates that the enhanced etch process is determined by the surface interactions between ions, surface-adsorbed chemistry, and the material being etched, rather than interactions between ion and gas phase, as observed in the conventional RIE.

The design of CN/C3N2 heterostructures and the potential as gas sensor and scavenger for SF6 decomposed gases

The design, electronic and gas-sensing properties of the CN/C3N2 heterostructures with and without the adsorption of H2S, SO2, HF, SOF2, and SO2F2 were systematically investigated by using DFT calculations. All SF6 decomposition gases can physically adsorb on both sides of the CN/C3N2 heterostructure with significant adsorption strength and charge transfer. Although the adsorption of these gases, in general, hardly affects the electronic properties, but can remarkably tune the work function (Φ) of the heterostructure. The CN/C3N2 heterostructure as Φ-type gas sensors has an ultra-high sensitivity for SF6 decomposed gases (at least over 71.2 %), especially for the C3N2 side (at least over 568.7 %), and has relatively low recovery times for HF, H2S, SOF2, and SO2F2 gases at 300 K, indicating the reusability of the heterostructure at room temperature, but much more favorable at 350∼400 K for SO2 gas. Further, the heterostructure as adsorbents for the capture and scavenging of SF6 decomposition gases has high adsorption capacity and strength. Therefore, our findings reveal that the CN/C3N2 heterostructure is a promising candidate as Φ-type gas sensors with high sensitivity and reusability for the detection of SF6 decomposition gases, while as an optimal scavenger for removing these toxic gases.

P507-modified magnetic porous carbon derived from metal-organic frameworks for efficient separation of zirconium(IV) and hafnium(IV)

Extractant-based solid phase extraction exhibit practical application potential for efficient separation of Zr(IV) and Hf(IV), where the key is to regulate the host–guest interaction between the guest extraction agents and the host matrices to obtain high performance. However, the current research on the host matrices of extraction agents is insufficient. Leveraging the tunability of metal–organic frameworks (MOFs), we successfully prepared a magnetic MOF-derived porous carbon (C(Zn/Co-ZIF)) with a high specific surface area and Co-Nx active sites as an excellent matrix. This was achieved by deliberately controlling the pore volume and microenvironment through a mixed precursor strategy and high-temperature pyrolysis method. Furthermore, as an excellent extractant for the separation of Zr(IV) and Hf(IV) in solvent extraction, 2-ethylhexyl phosphonic acid mono-(2-ethylhexyl) ester (P507) was carefully selected to modify C(Zn/Co-ZIF) to obtain C(Zn/Co-ZIF)@P507 by impregnation. Impressively, the maximum adsorption capacities of C(Zn/Co-ZIF)@P507 for Zr(IV) and Hf(IV) were up to be 0.58 and 0.39 mmol/g, respectively, while exhibiting excellent separation coefficient. Further mechanism studies indicated that the combination of high specific surface area and abundant Co-Nx active sites of C(Zn/Co-ZIF) leaded to strong interaction with P507, resulting in the excellent adsorption and separation performance of Zr(IV) and Hf(IV) based on the coordination between phosphinic groups of P507 and Zr(IV)/Hf(IV).

Investigations of the reaction mechanism of sodium with hydrogen fluoride to form sodium fluoride and the adsorption of hydrogen fluoride on sodium fluoride monomer and tetramer.

The reaction between Na and HF is a typical harpooning reaction which is of great interest due to its significance in understanding the elementary chemical reaction kinetics. This work aims to investigate the detailed reaction mechanisms of sodium with hydrogen fluoride and the adsorption of HF on the resultant NaF as well as the (NaF)4 tetramer. The results suggest that the reaction between Na and HF leads to the formation of sodium fluoride salt NaF and hydrogen gas. Na interacts with HF to form a complex HF···Na, and then the approaching of F atom of HF to Na results in a transition state H···F···Na. Accompanied by the broken of H-F bond, the bond forms between F and Na atoms as NaF, then the product NaF is yielded due to the removal of H atom. The resultant NaF can further form (NaF)4 tetramer. The interaction of NaF with HF leads to the complex NaF···HF; the form I as well as II of (NaF)4 can interact with HF to produce two complexes (i.e., (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF), but the form III of (NaF)4 can interact with HF to produce only one complex (NaF)4(III)···HF. These complexes were explored in terms of noncovalent interaction (NCI) and quantum theory of atoms in molecules (QTAIM) analyses. NCI analyses confirm the existences of attractive interactions in the complexes HF···Na, NaF···HF, (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF, and (NaF)4(III)···HF. QTAIM analyses suggest that the F···Na interaction forms in the HF···Na complex while the F···H hydrogen bonds form in NaF···HF, (NaF)4(I-1)···HF, (NaF)4(I-2)···HF, (NaF)4(II-1)···HF and (NaF)4(II-2)···HF, and (NaF)4(III)···HF complexes. Natural bond orbital (NBO) analyses were also applied to analyze the intermolecular donor-acceptor orbital interactions in these complexes. These results would provide valuable insight into the chemical reaction of Na and HF and the adsorption interaction between sodium fluoride salt and HF. The calculations were carried out at the M06-L/6-311++G(2d,2p) level of theory which were performed using the Gaussian16 program. Intrinsic reaction coordinate (IRC) calculations were carried out at the same level of theory to confirm that the obtained transition state was true. The molecular surface electrostatic potential (MSEP) was employed to understand how the complex forms. Quantum theory of atoms in molecules (QTAIM) and noncovalent interaction (NCI) analysis was used to know the topology parameters at bond critical points (BCPs) and intermolecular interactions in the complex and intermediate. The topology parameters and the BCP plots were obtained by the Multiwfn software.

Highly sensitive sensing of CO and HF gases by monolayer CuCl.

Using a first-principles approach, the adsorption characteristics of CO and HF on a CuCl monolayer (ML) are studied with Grimme-scheme DFT-D2 for accurate description of the long-range (van der Waals) interactions. According to our study, CO gas molecules undergo chemisorption and HF gas molecules show a physisorption phenomenon on the CuCl monolayer. The adsorption energy for CO is -1.80 eV, which is quite a large negative value compared to that on other previously studied substrates, like InN (-0.223 eV), phosphorene (0.325 eV), Janus Te2Se (-0.171 eV), graphene (P-graphene, -0.12 eV, B-graphene, -0.14 eV, N-graphene, -0.1 eV) and monolayer ZnS (-0.96 eV), as well as pristine hBN (0.21 eV) and Ti-doped hBN (1.66 eV). Meanwhile, for HF, the adsorption energy value is -0.31 eV (greater than that of Ti-doped hBN, 0.27 eV). For CO, the large value of the diffusion energy barrier (DEB = 1.26 eV) during its movement between two optimal sites indicates that clustering can be prevented if many molecules of CO are adsorbed on the CuCl ML. For HF, the value of the DEB (0.082 eV) implies that the adsorption phenomenon may happen quite easily upon the CuCl ML. The transfer of charge according to Bader charge analysis and the variation in the work function depend only on the properties of the elements involved, i.e., their nature, rather than the local binding environment. The work function and band-gap energy variation of the CuCl ML (before and after adsorption) show high sensitivity and selectivity of CO and HF binding with the CuCl monolayer. HF molecules give a more rapid recovery time of 1.09 × 10-7 s compared to that of CO molecules at a room temperature (RT) of 300 K, which indicates that the necessary adsorption and reusability of the CuCl ML for HF can be accomplished effectively at RT. Significant changes in the conductivity are observed due to the CO adsorption at various temperatures, as compared to adsorption of HF, which suggests the possibility of a modification in the conductivity of the CuCl ML.

The Adsorption Mechanisms of SF6-Decomposed Species on Tc- and Ru-Embedded Phthalocyanine Surfaces: A Density Functional Theory Study.

Designing high-performance materials for the detection or removal of toxic decomposition gases of sulfur hexafluoride is crucial for both environmental monitoring and human health preservation. Based on first-principles calculations, the adsorption performance and gas-sensing properties of unsubstituted phthalocyanine (H2Pc) and H2Pc doped with 4d transition metal atoms (TM = Tc and Ru) towards five characteristic decomposition components (HF, H2S, SO2, SOF2, and SO2F2) were simulated. The findings indicate that both the TcPc and RuPc monolayers are thermodynamically and dynamically stable. The analysis of the adsorption energy indicates that H2S, SO2, SOF2, and SO2F2 underwent chemisorption on the TcPc monolayer. Conversely, the HF molecules were physisorbed through interactions with H atoms. The chemical adsorption of H2S, SO2, and SOF2 occurred on the RuPc monolayer, while the physical adsorption of HF and SO2F2 molecules was observed. Moreover, the microcosmic mechanism of the gas-adsorbent interaction was elucidated by analyzing the charge density differences, electron density distributions, Hirshfeld charges, and density of states. The TcPc and RuPc monolayers exhibited excellent sensitivity towards H2S, SO2, and SOF2, as evidenced by the substantial alterations in the band gaps and work functions of the TcPc and RuPc nanosheets. Our calculations hold significant value for exploring the potential chemical sensing applications of TcPc and RuPc monolayers in gas sensing, with a specific focus on detecting sulfur hexafluoride.

Chemical bonding of HF, HCl, and H O onto YF surfaces: Quantification by first principles.

The surfaces of waimirite β- have been studied for their fluorine and chlorine versus water affinity. Bonding patterns of HF, HCl, and chemically adsorbed onto surfaces of (010), (100), (011), and (101) have been quantified by density functional theory applying energy decomposition analysis. We found that the adsorption of is dominated by about 65% of electrostatics, which causes a low surface sensitivity and weak interactions. On the contrary, the adsorptions of HF and HCl are driven by strong hydrogen bonds resulting in a highly surface-dependent ratio of 30-60% electrostatic versus orbital contribution. Among the stoichiometric surfaces, the shortest and strongest hydrogen bonds and consequently most covalent bonding patterns are found within HCl. However, when including the preparation energy, each surface favors the adsorption of HF over HCl, which reproduces the higher affinity of yttrium towards fluoride over chloride, previously known for solutions, also for the solid state.

Adsorption of HF and H2S on α-Al2O3 (0001) Surfaces: A DFT Study

Ex-service SF6 adsorbents in SF6 gas-insulated electric equipment contain many toxic substances. Inside, HF and H2S are two typical toxic gases. Based on the first principle, the interaction process between HF/H2S and α-Al2O3 (0001) surfaces was calculated using the density functional theory (DFT). The results showed that the adsorption of HF on α-Al2O3 (0001) is stronger than that of H2S. Under the five adsorption sites, the adsorption effect of HF-H and HF-F was similar. At O-2 site, the adsorption energy of H2S-H adsorption configuration is significantly higher than that of the other four sites. The density of states (DOS) indicated that new peaks appeared after adsorption. The DOS and partial density of states (PDOS) indicated that the adsorption of HF and H2S occurs via chemical adsorption. The DOS and PDOS shifted to the right when the S atom was approaching, proving that the system shifts to instability. Compared with the energy gap of α-Al2O3 (0001), HF and H2S adsorption systems decreased significantly. The energy gap of the HF adsorption system was 1.173 eV larger than that of the H2S system and the geometry was relatively stable, which is consistent with the DOS and PDOS adsorption calculation results. Thus, the adsorption of HF and H2S on α-Al2O3 (0001) surfaces was clearly different. The findings of this study may provide theoretical guidance for the adsorption of other gases or developing a new adsorbent.

Chemical Adsorption of HF, HCl, and H2O onto YF3 and Isostructural HoF3 Surfaces by First Principles

The two elements, yttrium and holmium, form a geochemical twin pair as their cations possess equivalent ratios of charge to radius. However, despite their equal electrostatics, a subtle difference in their fluoride or chloride affinity is known within solutions. In this work, we investigated whether this affinity gap is also present within the solid phase and how it depends on the surface configuration. We modeled adsorptions onto β-YF3 (waimirite) and isostructural β-HoF3 by periodic density functional theory. To draw conclusions on the affinity toward fluoride and chloride vs. water, adsorbates of HF, HCl, or H2O onto any of the four highly abundant surfaces of (010), (100), (011), and (101) were studied. Among others, the conformational landscape was explored by 200 ps of ab initio molecular dynamics. For stoichiometric surfaces of both MF3, we indeed found stronger adsorptions for HF than HCl. All (hkl)·H2O showed slightly stronger adsorption energies for HoF3, while for HF and HCl, the metal preferences varied by the surface. While (100) showed the strongest preference for HoF3, (101) preferred YF3 by the same magnitude.

Decomposition of PVDF to delaminate cathode materials from end-of-life lithium-ion battery cathodes

The growing demand of electric vehicles and rapid consumption of rechargeable lithium-ion batteries (LIBs) require recycling of spent cathode active materials (CAMs) to reduce hazardous wastes and supply raw materials to LIB production. To separate CAMs from the cathode, direct calcination of polyvinylidene fluoride (PVDF) binder is widely applied, which leads to high energy consumption and release of toxic hydrogen fluoride. It is desirable to have an environmentally friendly and effective alternative to traditional direct calcination. In this study, five lithium salts, LiOAc (lithium acetate), LiNO3, LiCl, Li2CO3, and Li2SO4, were deployed and compared for their performance in recycling CAMs. A peel-off efficiency of up to 98.5% was achieved at a LiOAc to LiNO3 molar ratio of 3:2, salt to cathode mass ratio of 10:1, and temperature of 300 °C at a holding time of 30 min. This system avoids corrosive chemicals and minimizes particle agglomeration of recycled products. Compared with sodium salt systems (NaOAc-NaNO3) or direct calcination, the LiOAc-LiNO3 system prevented high reaction temperature or further lithium loss, and minimized crystal structure and morphological changes. A decomposition mechanism of PVDF through adsorption of HF and fluorine substitution was proposed.

First-Principles Calculations for Adsorption of HF, COF2, and CS2 on Pt-Doped Single-Walled Carbon Nanotubes.

HF, CS2, and COF2 are three important decomposition components of the SF6 gas insulation medium. In this paper, the gas sensitivity of Pt doped on (8, 0) single-walled carbon nanotube (SWCNT) to HF, CS2, and COF2 is investigated based on density functional theory. The binding energy, charge transfer, density of states, and frontier molecular orbital theory are discussed. It is found that all processes of HF, CS2, and COF2 adsorbed on Pt-SWCNT are exothermic. Pt-SWCNT donated 0.182 electrons to CS2 molecules during the interaction process but acts as an electron acceptor during adsorption of HF and COF2 on it. After comprehensive consideration of binding energy and charge transfer, the response of Pt- SWCNT to CS2 may be the best, and those to HF and COF2 are almost the same. In addition, after the adsorption of the three kinds of gases on Pt-SWCNT, the order of the conductivity of the Pt-SWCNT material is CS2 > COF2 ≈ HF via frontier molecular orbital theory analysis. The Pt-SWCNT material is probably more suitable as a gas sensor for the detection of CS2 in the application of gas-insulated equipment.

Adsorption of HF on gibbsite calcined at various temperatures: A solid-state NMR study of low-level fluorinated systems

The fluorination mechanism of low-level fluorinated materials obtained by calcination of Bayer gibbsite at different temperatures was studied by 27Al and 19F solid-state NMR spectroscopy and X-ray diffraction. Gibbsite was calcined at 400, 600, 800, and 1000 °C followed by treatment with anhydrous HF/N2 gas at 100 °C. Three types of Al–F species on the surface of fluorinated gibbsite calcined at 400, 600, and 800 °C are proposed on the basis of the 19F magic angle spinning (MAS) NMR spectra, which show peaks at about −132, −137, and −163 ppm, while the spectrum of fluorinated gibbsite calcined at 1000 °C showed five additional peaks, at about −139, −164, −176, −183, and −191 ppm. The fluorination process in aluminas is based on elementary exchange reactions in which F− replaces surface –OH groups according to their basicity. The 27Al MAS NMR and 19F-27Al cross-polarization–MAS experiments confirmed the presence of octahedral Al species.

The effect of external electric field and metal impurities on the interaction of HF and boraphene: a computational study.

Using density functional theory, the effects of P, Al, and Ga atoms doping on electronic structure of boraphene (B36) were investigated. The results show the highest change in electronic structure of doped-B36 systems belongs to Al-B36 structures wherein the gap energy of the system is decreased by 17.92%. DOS diagrams and absorption spectra of doped B36 are compared to pristine and discussed. The capability of pristine and modified B36 in the field of detection/adsorption of HF molecule has been evaluated. The calculated values of adsorption energies of 0.13, 0.63, 0.24, and 0.16eV for adsorption of HF on pristine, Al-, Ga-, and P-B36 and related DOS diagrams reveal that these systems are not superior host materials for detection/adsorption applications. It was found that the external electric field could increase the interaction between HF and B36 systems leading to suggesting Al-B36 as proper candidate for HF removal applications.

Density Functional Theory and Molecular Dynamics insights into the site-dependent adsorption of hydrogen fluoride on kaolinite

The removal of fluoride from water using adsorption on a low-cost mineral such as kaolinite is an important research topic. The present communication uses Density Functional Theory (DFT) and Molecular Dynamics (MD) based simulations to comprehensively investigate the adsorption behaviour of HF, one of the most predominant species of fluoride in the aqueous solutions, on the (0 0 1) surface of kaolinite. The optimum geometric configurations of adsorption of HF on different possible sites on the mineral surface have been established, and the corresponding adsorption energies, bond distances, Partial Density of States (PDOS), Mulliken charges and electron density difference plots have been analyzed to understand the interaction at each site. To explore the site-dependent adsorption behaviour, the interaction of HF has been investigated on different sites such as aluminium centres, surface oxygen atoms (both lying and upright) and cavity site (void space encircled by six aluminium centres). The analysis shows that the F atom has a strong tendency to form hydrogen bonds with the surface H atom on kaolinite. Among the three aforementioned types of adsorption sites considered, the “cavity” site is found to offer the greatest adsorption strength. Further, MD simulations have been undertaken to explain the effect of water on the adsorption and substantiate the bonding mechanism.

Analysis of adsorption properties of SF6 decomposed gases (SOF2, SO2F2, SF4, CF4, and HF) on Fe-doped SWCNT: A DFT study

In order to develop a potential material for monitoring of SF6 decomposed gases online in insulated equipment, the Fe-doped single-walled carbon nanotube (Fe-SWCNT) was proposed and its gas sensing properties to five SF6 decomposed gases were investigated with DFT method. The adsorption structures, charge transfers, density of states (DOS), and frontier molecular orbital theory analysis have been performed. Calculations show that the doping of Fe enhances the conductivity of SWCNT and Fe acts as the active center for adsorption. The conductivity of zigzag Fe-(8, 0) SWCNT is increased with SOF2 adsorption. While the adsorption of SF4 distinctly decreases the conductivity of the system. For SO2F2 adsorption, the difference in adsorption energy of different configurations is small, but the HOMO-LUMO energy gaps vary widely. The adsorption of SO2F2 is weaker than that of SOF2 and SF4. For adsorption of CF4 and HF, the little electron transfer and the low adsorption energy indicate the weak interaction. The negligible decreases of conductivity confirms that the Fe-(8, 0) SWCNT is insensitivity for CF4 and HF detection. After SO2F2, SF4, CF4, and HF adsorbed onto armchair Fe-(5, 5) SWCNT, the conductivity of system is also changed.

First principle study of HF molecule adsorption on TiO2 (110) surface

Titanium and its alloy components are one of the most important technological materials, which has found extensive application in various industries. However, surface defects play a key role in the mechanical properties of these components. Currently, wet chemical etching is one of the most important procedure for surface processing due to the presence of HF since it can etch metal oxide. Therefore, there still a need to investigate the etching mechanism. In this work, adsorption of HF on TiO2(110) surface has been studied using density functional theory to investigate the fundamental process of etching. HF molecule is adsorbed on the TiO2 surface by dissociation to form Ti-F and O-H species. The interaction between HF and TiO2surface become more favorable at high HF coverage. The pre-adsorbed of water molecule is favorable for HF adsorption process, which is in good agreement with experimental results. Fluorination processes show the formation and desorption of water intermediate at 0.50 ML coverage. We also investigated the relation between the work function and Mulliken charge for HF adsorption. The results indicate that the interaction of F on the surface attracts electrons due to its higher electronegativity than oxygen. Our results suggest that adsorption of HF is considered chemisorption process.

Selective recovery and separation of Zr and Hf from sulfuric acid leach solution using anion exchange resin

Apart from zircon and baddeleyite, some other minerals also contain amounts of Zr and Hf, and H2SO4 can be the best candidate leachate for their recovery. The subsequent step in the process would be the recovery and separation of Hf and Zr from the resulting leach solution together with impurities. This reported study focused on the recovery process following the leaching of Zr and Hf from a eudialyte residue after REEs extraction. The chemistry of the solution was studied to determine the feasibility of different methods, and based on the results, an anion exchange resin was chosen to selectively recover Zr and Hf from the acidic sulfate solution. Batch and continuous ion exchange experiments using a strong anionic resin (MP600) were performed to develop the ion exchange process. The experimental results showed that Zr and Hf can be selectively recovered over other impurities. In the process of the adsorption of Zr and Hf, the bed volume reached 6 using the feed solution at a pH 0.94 at 25 °C with a contact time of 2 h. Pure Zr sulfate solution was used to scrub the load resin, after which the loaded resin was easily eluted using 10% NH4HCO3 + 1 mol/L NH4OH solution. This produced 21.23 g/L Zr, 0.03 g/L Hf, 0.01 g/L Fe, 0.01 g/L Al, 0.02 g/L Nb and < 0.001 g/L Ca in the eluate. The impurity removal from the leachate and the enrichment of Zr were achieved by the process.

Detection of HF and H2S with pristine and Ti-embedded twin graphene: A density functional theory study

Adsorption of HF and H2S on pristine and Ti-embedded twin graphene sheets is studied utilizing density functional theory (DFT) calculations to understand the capability of these materials for detecting these toxic gases. The optimal configurations, adsorption energies, and charge transfer are calculated. The small adsorption energies and large adsorption distance indicated that HF and H2S are weakly physisorbed on pristine twin graphene sheets. The adsorption strength increases after decorating twin graphene with a Ti atom. Electronic properties including band structures and density of states reveal that both pristine and Ti-embedded twin graphene sheets possess semiconducting properties. Adsorption of HF and H2S decreased the energy band gap of both pristine and Ti-embedded twin graphene sheets. It was found that embedding Ti to twin graphene increases the sensitivity of the material to HF and H2S adsorption, which is mainly due to the stronger integration between adsorbed molecules and Ti-embedded sheet. Hence, current research introduces Ti-embedded twin graphene as a high sensitive, and low cost gas sensor candidate for detecting the toxic gases.

First-Principles Study on the Adsorption and Dissociation of Impurities on Copper Current Collector in Electrolyte for Lithium-Ion Batteries

The copper current collector is an important component for lithium-ion batteries and its stability in electrolyte impacts their performance. The decomposition of LiPF6 in the electrolyte of lithium-ion batteries produces the reactive PF6, which reacts with the residual water and generates HF. In this paper, the adsorption and dissociation of H2O, HF, and PF5 on the Cu(111) surface were studied using a first-principles method based on the density functional theory. The stable configurations of HF, H2O, and PF5 adsorbed on Cu(111) and the geometric parameters of the admolecules were confirmed after structure optimization. The results showed that PF5 can promote the dissociation reaction of HF. Meanwhile, PF5 also promoted the physical adsorption of H2O on the Cu(111) surface. The CuF2 molecule was identified by determining the bond length and the bond angle of the reaction product. The energy barriers of HF dissociation on clean and O-atom-preadsorbed Cu(111) surfaces revealed that the preadsorbed O atom can promote the dissociation of HF significantly.