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Abstract: We have synthesized undoped and Ti-doped SnO2 spheres with a facile yet efficient hydrothermal approach and investigated their microstructures and gas sensing response to carbon monoxide, focusing especially on the impact of Ti doping. We find that gas response of SnO2 is enhanced significantly by doping, the origin of which is clarified in light of a proposed adsorption model. Through a combination of systematic measurements with density-functional-theory calculations, we discuss the enhancement mechanism of the gas-sensing function arising from the doping. [Copyright &y& Elsevier]

Based on the first-principles method of density functional theory (DFT), the adsorption properties, bond strength and electronic structure of two sulfur-containing compounds (H 2 S and CH 3 SH) in oil and natural gas were analyzed by means of adsorption energy, partial density of states (PDOS) and charge difference density. The adsorption energy of H 2 S and CH 3 SH molecules on the LB site of Fe (110) surface is the lowest. Their adsorption energies are −2.88 eV and −3.13 eV, respectively. When the H 2 S symmetry axis is perpendicular to the surface, the S–H bond is easy to break. The generated S atom is firmly adsorbed on the hollow site. The results of partial density of states show that the hybrid conjugation peaks of the three adsorbed species appear on the substrate surface, and new bonds are formed between the surface molecules and the iron substrate. The charge around the three adsorbates is redistributed, and the order of interaction size between these molecules and the Fe (110) surface is S > CH 3 SH > H 2 S. This also shows that in oil and gas, H 2 S, CH 3 SH and S atoms generated after dissociation are very easy to adsorb on the surface of iron pipes, which directly affects the accuracy of the determination of sulfide gas in oil and natural gas. • The adsorption of H 2 S and CH 3 SH on four highly symmetric sites of Fe (110) surface is calculated. • The adsorption configurations of hydrogen sulfide and methyl mercaptan on Fe (110) surface were constructed. • The adsorption structure, adsorption energy, bonding and the change of electronic structure were discussed in detail. • The H 2 S molecules adsorbed horizontally are easy to dissociate. [ABSTRACT FROM AUTHOR]

In this work, we used first-principles calculations based on density functional theory to discuss the changes in the adsorption structure, adsorption energy, bonding and electronic structure of typical sulphide gas molecules on the perfect γ-Fe(1 1 1) surface and its vacancy and doping sites, and did a comparative study. We constructed their adsorption model and determined the best adsorption site, explaining the adsorption mechanism and dissociation mode. [Display omitted] • DFT is used to calculate the adsorption of typical sulphide gas molecules on the surface of γ-Fe(1 1 1). • The adsorption configurations of typical sulphide gas molecules on γ-Fe(1 1 1) surface were constructed respectively. • The adsorption structure, adsorption energy, bonding and the change of electronic structure were discussed in detail. • The generation of vacancy defects will promote the dissociation and adsorption of sulfide gas molecules. In this work, based on the first-principles method of density functional theory (DFT), the adsorption and dissociation paths of sulphide gas molecules on pure, vacancy-defective, Ni-doped and Cr-doped γ-Fe(1 1 1) surfaces have been studied systematically. The results show that H 2 S, COS, CH 3 SH can be spontaneously adsorbed on these four surfaces. Significant adsorption properties, changes in molecular structure and charge transfer indicate that chemical adsorption has taken place. The calculation results of the density of states show that the electronic orbitals between the sulphide molecules and the substrate surface are hybridized, indicating the formation of new chemical structures between them. Meanwhile, the chemical bonds of the three sulphide molecules are easy to break during the adsorption process, and the products are adsorbed on the surface in a more stable form. This work can provide theoretical guidance for anticorrosion and material selection of natural gas pipeline. [ABSTRACT FROM AUTHOR]

SF 6 is widely used in insulation and arc extinguishing due to its excellent insulation performance. The detection of its decomposed gases can help us to effectively identify the types of internal malfunctions in gas-insulated switchgear (GIS). Based on the Density functional theory (DFT), the adsorption performance of intrinsic MoTe 2 and Sc-doped MoTe 2 (Sc-MoTe 2) on four gases (SO 2 , H 2 S, SO 2 F 2 , SOF 2) from SF 6 decomposition were studied in this paper. The calculation results indicate that the intrinsic MoTe 2 monolayers have weak adsorption capacity and low adsorption energy (E ad) for SF 6 decomposition gas products, which are all physical adsorption and with small transfer charge. However, the adsorption ability of MoTe 2 monolayer film to SF 6 decomposition gas products is significantly enhanced after doping the Sc atom. The adsorption energy is changed into chemical adsorption, and the amount of transferred charge in the adsorption process is significantly increased. Therefore, the adsorption performance of Sc-MoTe 2 for four gas products (SO 2 , H 2 S, SO 2 F 2 , SOF 2) from SF 6 decomposition are obviously superior to intrinsic MoTe 2. The results are helpful to further explain the sensing mechanism of gases in MoTe 2 , and establish a foundation for the sensor based on MoTe 2 to detect SF 6 decomposition gases. [Display omitted] • The effect of Sc dopant on structural and electronic properties of MoTe 2 monolayer were discussed. • The adsorption performances of intrinsic MoTe 2 monolayer to SF 6 decompositions SO 2 , H 2 S, SO 2 F 2 , SOF 2 are discussed. • The excellent adsorption performances of Sc-doped MoTe 2 monolayer to SO 2 , H 2 S, SO 2 F 2 , SOF 2 are discussed in detail. [ABSTRACT FROM AUTHOR]

The influence of Ni atoms doping on the structure parameters and electronic properties of MoTe 2 monolayer was studied based on DFT calculations. We found Ni doped MoTe 2 monolayer exhibits excellent adsorption capacity to SF 6 decomposition gases in GIS cell and the processes of absorption both are chemical. [Display omitted] • The effect of Ni dopant on structural and electronic properties of MoTe 2 monolayer was discussed in detail. • The adsorption performances of MoTe 2 monolayer to SF 6 decomposition gases in GIS gas cell such as H 2 S, SO 2 , SOF 2 , SO 2 F 2 were discussed in detail. • The excellent adsorption performances of Ni doped MoTe 2 monolayer to SF 6 decomposition gases in GIS gas cell such as H 2 S, SO 2 , SOF 2 , SO 2 F 2 were discussed in detail. It is significant to probe SF 6 decomposition gas product to determine the type of faults in Gas-insulated substations (GIS). In the text, the adsorption features of intrinsic and Ni doped MoTe 2 (Ni-MoTe 2) on SF 6 decomposition gas products H 2 S, SO 2 , SOF 2 and SO 2 F 2 in GIS gas cell were investigated according to density functional theory (DFT). The adsorption parameters, energy band structure (BS) and density of states (DOS) of the adsorption structures were obtained as well as analyzed. The findings show that the Ni-MoTe 2 monolayer has better adsorption performance than intrinsic MoTe 2 for SF 6 decomposition gases (H 2 S, SO 2 , SOF 2 and SO 2 F 2). The larger adsorption energy and more charge transfer amount were noticed by the comparative analysis, demonstrating that the chemisorption between these four gas molecules and Ni-MoTe 2 produced strong interactions that could enhance the adsorption performance of gas detection. As a result, Ni-MoTe 2 monolayer gas sensor may be recommended for SF 6 decomposition gas detection in GIS gas cell. [ABSTRACT FROM AUTHOR]

In this paper, the adsorption performances for HCN upon pure and metal (Fe, Ag, Au, As and Mo) doped WSe 2 monolayers are analyzed on the ground of the density functional theory (DFT) and the best sites of doping are assumed. The adsorption performance of intrinsic WSe 2 , Fe-WSe 2 , Ag-WSe 2 , Au-WSe 2 and Mo-WSe 2 to HCN molecule were simulated according to the charge transfer, DOS and molecular orbital. The results manifest that all metal (Fe, Ag, Au, As and Mo) doped WSe 2 monolayers have better adsorption properties for HCN. Nevertheless, occurrence of chemisorption only exists in HCN/Mo-WSe 2 system, indicating this system might be candidate materials for the adsorption of HCN. Besides, after adsorption, the conductivity of all systems changes a lot, meaning that monitoring conductivity change of all systems above could be a method to sensing HCN. Thus, all metal (Fe, Ag, Au, As and Mo) doped WSe 2 could be favorable materials for HCN detection. [Display omitted] • The structural and electronic properties of Ag, As, Au, Fe and Mo doped WSe 2 monolayer were discussed in detail. • The adsorption properties of HCN on intrinsic and doped WSe2 monolayers were explored. [ABSTRACT FROM AUTHOR]

Sulphide gas is an impurity that affects the quality of natural gas, which needs reasonable storage and transportation. In this work, we investigated the adsorption structure and electronic behavior of hydrogen sulfide (H2S), carbonyl sulfur (COS), and methyl mercaptan (CH3SH) on sulphide gas molecules on pure and vacant α-Fe2O3(001) surfaces by density functional theory with geometrical relaxations. The results show that H2S and CH3SH are mainly adsorbed in the form of molecules on the pure Fe2O3(001) surface. On the vacant α-Fe2O3(001) surface, they can be adsorbed on Fe atoms in molecular form and by dissociation. The absolute value of the adsorption energy of H2S and CH3SH on the vacancy defect α-Fe2O3 surface is larger, and the density of states show that the electron orbital hybridization is more significant, and the adsorption is stronger. The charge differential density and Mulliken charge population analysis show that the charge is rearranged and chemical bonds are formed. The affinity of H2S to the vacancy α-Fe2O3(001) surface is slightly higher than that of CH3SH, while COS molecules basically do not adsorb on the α-Fe2O3(001) surface, which may be related to the stable chemical properties of the molecules themselves. [ABSTRACT FROM AUTHOR]

In this paper, the adsportion properties of three typical industrial toxic gases (Cl 2 , NO 2 and NH 3) on intrinsic WSe 2 monolayer and Ag 3 -WSe 2 monolayer were investigated on the basis of the density functionmal calculations (DFT). By analyzing the adsorption energy, charge transfer, density of states, deformation charge density and molecular orbit, we discovered that the Ag-cluster-doped could cause a distinct promotion to the adsorption behavior of intrinsic WSe 2 monolayer to these gases. Thus Ag 3 -WSe 2 monolayer can be applied to a promising sensing candidate for the detection of Cl 2 , NO 2 and NH 3. [Display omitted] • The influence of the doping cluster formed by three Ag atoms on WSe 2 monolayer was delved. • The adsorption properties of intrinsic WSe 2 and Ag 3 -WSe 2 monolayers towards three Cl 2 , NH 3 , NO 2 were discussed and analyzed attentively. • The interaction mechanism between Ag 3 -WSe 2 monolayer and Cl 2 , NH 3 , NO 2 was studied theoretically by calculation. In this study, we explored the adsorption of three industrial toxic gases (Cl 2 , NO 2 , and NH 3) on Ag 3 -WSe 2 monolayers using density functional theory calculations. The possible application of Ag 3 -WSe 2 as an industrial toxic gas sensor and adsorbent is discussed through our analyses of the density of states, adsorption energy, band structures, and charge transfer of the three gas molecules absorbed on the Ag 3 -WSe 2 and WSe 2 monolayers. The results show that the Ag 3 -WSe 2 monolayer exhibits better adsorption for these gas molecules than the WSe 2 monolayer. Thus, Ag 3 -WSe 2 might be a candidate material for the detection of industrial toxic gases. In addition, it provides guidance for the further investigation of transition metal cluster-doped WSe 2 monolayers for gas detection. [ABSTRACT FROM AUTHOR]

The online detection and control of concentration for agricultural greenhouse gas SO 2 is an important technology to ensure normal agricultural production. This paper reports on a facile hydrothermal method to synthesis Pd-decorated and Pt-decorated MoSe 2 nanomaterials, i.e. multistage flower-like structures with attached nanometallic particles and nanosheets hierarchical structures. The Pd/MoSe 2 and Pt/MoSe 2 hierarchical materials were characterized for the nanostructure, microscopic morphology and elemental compositions. The gas-sensing properties results show that the Pd/MoSe 2 and Pt/MoSe 2 nanofilm sensors have good sensitivity, stability and response rate to SO 2 gas. The response values for the metal Pd and Pt decorated samples to 20 ppm SO 2 were 2.04 and 3.42 times higher than those for the intrinsic MoSe 2 samples at room temperature. The hierarchical flower-like structure proved to be beneficial in providing more adsorption drop points. In addition, based on the first-principles, the geometrical parameters and electronic properties of the metal-decorated modified structures were calculated to comparatively investigate the enhanced sensing mechanism of SO 2 by nanoflower materials. The Pt-MoSe 2 nanofilm sensor achieves a high sensitivity detection with a response value of 2.89 for low concentration (1 ppm) of SO 2 , which is confirming the promotion of charge transfer by metal decorating. This study suggests that Pd-MoSe 2 and Pt-MoSe 2 hierarchical structures may be recommended for the detection of the agricultural greenhouse gas SO 2. • On the optimal structures of SO 2 /Pd-MoSe 2 and SO 2 /Pt-MoSe 2 monolayers, the changes in conductivity, Density of States and Frontier molecular orbital before and after gas adsorption were analyzed, and the effect of metal decorating on the electron distribution of the systems was investigated from an atomic point of view. • Preparation of MoSe 2 , Pd-MoSe 2 and Pt-MoSe 2 nanoflower-like structure materials by hydrothermal method, characterization of their material properties, and preparation of planar-type sensors. • Test the gas-sensitive performance of the three materials to the harmful gas SO 2 in agricultural greenhouse, including sensitivity characteristics, temperature characteristics, concentration characteristics, response recovery time, etc. • The Pd-doped and Pt-doped MoSe 2 exhibited good adsorption performance for the agricultural greenhouse gas SO 2 , which provides some guidance for the practical application in the detection field. [ABSTRACT FROM AUTHOR]

In intelligent agriculture, the development of gas sensing technology has practical significance. In a bid to achieve fast, accurate and effective detection of noxious gases NH 3 , H 2 S and CO 2 from breeding farms, Ti 3 C 2 O 2 , an excellent gas sensing material in the MXene family, was investigated by means of density functional theory (DFT) calculations. The optimal configuration of Pt atomic catalyst doped Ti 3 C 2 O 2 sheet was obtained via the analysis of binding energy (−1.796 eV) and charge transfer (0.373 e). The adsorption energy, charge transfer, deformation charge density (DCD), density of states (DOS), average electrostatic potential, and work function of NH 3 , H 2 S and CO 2 adsorbed on Ti 3 C 2 O 2 and Pt-Ti 3 C 2 O 2 sheet were further scrutinized. From comparative analysis against Ti 3 C 2 O 2 , Pt-Ti 3 C 2 O 2 possesses excellent adsorption capacity, electron density rearrangement and electrostatic binding ability for the adsorption of NH 3 , H 2 S and CO 2 , among which the adsorption energy for NH 3 is the largest (−2.593 eV). The results verify that Pt-Ti 3 C 2 O 2 is a potential material for gas sensors, providing guidance for expanding the gas sensing application of MXene materials. [Display omitted] • The most stable structure of the Pt doped Ti 3 C 2 O 2 sheet was firstly constructed via DFT. • The Ti 3 C 2 O 2 sheet is not suitable for the NH 3 , H 2 S and CO 2 gas sensor material. • The Pt-Ti 3 C 2 O 2 sheet can be exploited as a potential NH 3 H 2 S and CO 2 gas sensing material. [ABSTRACT FROM AUTHOR]

Four MoO 3 samples with the Zn element doped mole ratio of 0%, 3%, 6% and 9% were prepared by applying a convenient one-step hydrothermal synthesis method, and the samples presented three-dimensional microflower-like structures assembled by nanosheets. The systematic analysis results indicate that the 6 mol% Zn-doped sample had the most amazing detection characteristics for 50 ppm CO, with a response of 31.23 (4 times of the pure MoO 3) at a lower temperature (240 °C). The large specific surface area, big pore size and tiny particle size were proved to be beneficial to the gas sensitivity, which promotes gases transfer and provides more gases landing points during the gas-sensitive reaction. Besides, based on the density functional theory (DFT), the facilitation effect of doped Zn on the adsorption ability of MoO 3 to CO molecule was verified from the perspective of electronic properties. The excellent gas-sensing performances indicate that the 6 mol% Zn-doped MoO 3 has potential to be applied as a reliable CO sensor. [ABSTRACT FROM AUTHOR]

The intrinsic and Pt-doped MoSe 2 gas sensing materials with hierarchical flower structure were prepared by hydrothermal routes, and its crystal morphology and chemical element composition were studied by microscopic characterization. The response properties of the MoSe 2 -based sensors to NO 2 were tested by the gas sensing test platform. The test results confirmed that the Pt-doped sample exhibited excellent detection properties for 20 ppm NO 2 , with a response of 7.29 (3.14 times of the intrinsic MoSe 2) at room temperature. The introduction of Pt caused the beneficial specific surface area of MoSe 2 , and offered more reaction sites for gas-sensitive reactions. In addition, the promotion impact of doped Pt on the adsorption capability of MoSe 2 to NO 2 was confirmed from the aspects of electronic properties and adsorption behavior based on the density functional theory (DFT). The combination of experimental consequence and theoretical analysis indicates the promising application prospects of the Pt-doped MoSe 2 nanoflower for low-concentration NO 2 detection at room temperature. [Display omitted] • The Pt-MoSe 2 sensors based on hierarchical flower structures were fabricated by hydrothermal and drip-coating technology. • The effects of Pt as dopant on the morphology structures and gas sensitivity of the prepared MoSe 2 sample were explored. • The gas sensing mechanism of the MoSe 2 based materials to NO 2 was discussed by electronic property and adsorption behavior. [ABSTRACT FROM AUTHOR]

The influence of Pt 3 cluster doping on the structure parameters and electronic properties of SnS 2 monolayer was studied based on DFT calculations. We found Pt 3 cluster doped SnS 2 monolayer exhibits excellent adsorption capacity to SF 6 decomposition gases and the processes of absorption both are chemical. [Display omitted] • The effect of Pt cluster dopant on structural and electronic properties of SnS 2 monolayer were discussed in detail. • The adsorption performances of SnS 2 monolayer to SF 6 decomposition gases such as SO 2 , SOF 2 , SO 2 F 2 , and H 2 S were discussed in detail. • The excellent adsorption performances of Pt cluster doped SnS 2 monolayer to SF 6 decomposition gases such as SO 2 , SOF 2 , SO 2 F 2 , and H 2 S were discussed in detail. In this study, Pt 3 -cluster-doped SnS 2 was first proposed as the adsorption and sensing materials of typical SF 6 decomposed gases (SO 2 , SOF 2 , SO 2 F 2 and H 2 S). Based the density functional theory, the possible application of Pt 3 -SnS 2 as gas sensor or absorbents for the SF 6 decomposed gas is discussed through the analysis of the density of states, adsorption energy, charge transfer and the frontier molecular orbital. These results illustrate that the doping of Pt metal clusters can greatly improve the response of pure SnS2 monolayer to the characteristic decomposition gas of sulfur hexafluoride (SF 6). The excessive high adsorption energy indicates a strong chemical interaction of the Pt 3 -SnS 2 monolayer with SO 2 (−2.800 eV) and H 2 S (−3.346 eV) molecules, which suggests that Pt 3 -SnS 2 is a potential ideal candidate for gas adsorbent. Moreover, the large variation of band gap and appropriate adsorption energy show that Pt 3 -SnS 2 has the promising to be a candidate gas sensor material for the SOF 2 (−1.060 eV), and SO 2 F 2 (−0.904 eV). This study also provides guidance for further study of the SnS 2 monolayer doped by transition metal clusters. [ABSTRACT FROM AUTHOR]

Oxidation resistance of Mg alloys with different amounts of Ca were examined. The oxidation resistance of Mg at 515 °C was significantly improved by alloying with Ca, and Mg alloyed with 1.0 wt% Ca demonstrated the best oxidation resistance. Based on these observations, combined with Gibbs free energy and density functional theory calculations, α-Mg and Mg 2 Ca oxidation models describing the oxidation process are proposed. Oxide films formed on α-Mg are effective at improving the oxidation resistance, whereas those formed on Mg 2 Ca are unstable, and tend to peel off from the substrate, resulting in further oxidation. • The oxidation process was calculated and simulated. • The oxidation on α-Mg and Mg 2 Ca was observed and analysed. • The oxidation models on α-Mg and Mg 2 Ca were proposed. • The oxidation effect of α-Mg and Mg 2 Ca was analysed. [ABSTRACT FROM AUTHOR]

The adsorption performances of Cr atoms doped InN and GaN monolayers to SF 6 decomposed species were investigated based on density functional theory (DFT). We found that Cr-InN and Cr-GaN monolayers have excellent adsorption performance for SO 2 and SO 2 F 2 gas. Besides, for SOF 2 gas, the adsorption capacity of Cr-GaN monolayer is significantly stronger than Cr-InN. [Display omitted] • The effect of Cr dopant on structural and electronic properties of InN and GaN monolayer were discussed in detail. • The adsorption performances of the monolayers to three SF6 decomposition gases were discussed and compared in detail. • The changes in conductivity of Cr doped InN and GaN monolayers after adsorption were discussed in detail. In this paper, the adsorption properties of Cr modified InN (Cr-InN) and GaN (Cr-GaN) monolayers to SF 6 decomposed components were investigated based on the density functional theory (DFT). Results reveal that these two graphene-like materials exhibit strong adsorption capacity for the three decomposed species SO 2 , SOF 2 and SO 2 F 2. Remarkable adsorption energy, significant charge transfer and molecular deformation indicate the occurrence of chemisorption. The hybridization of atomic electron orbitals in the density of states calculation verifies the strong chemical interaction between the gases and two monolayers. According to this strong adsorption capacity, Cr-InN and Cr-GaN monolayers demonstrate their potential as gas Scavenger for removing SF 6 decomposition products in the insulation equipment. Besides, the significant change in conductivity of the monolayer caused by gas adsorption makes it possible to explore gas sensors based on Cr-InN and Cr-GaN monolayer. This paper indicates that Cr-doped InN and GaN monolayers can be used as adsorbents and sensors to guard the operation status of SF 6 insulation devices by detecting and scavenging SF 6 decomposed components. [ABSTRACT FROM AUTHOR]

In this paper, we explored the adsorption behavior of four kinds of characteristic gases dissolved in oil on Cr doped GaN monolayer. The results show that the Cr-GaN monolayer exhibits satisfactory adsorption performance for H 2 , CO, C 2 H 4 and C 2 H 2 molecules. The adsorption energies of H 2 (−0.326 eV), CO (−0.7 eV), C 2 H 4 (−0.893 eV) and C 2 H 2 (−0.751 eV) manifest the adsorptions can occur spontaneously. According to Hirshfeld charge analysis, Cr-GaN monolayer as an electron donor loses electrons of 0.124, 0.287, 0.243 and 0.244 e when interacting with H 2 , CO, C 2 H 4 and C 2 H 2. The dramatic changes of molecules can be observed after adsorption, indicating the strong interaction between molecules and Gr-GaN monolayer. Besides, the presence of significant overlaps between Cr atom and those molecules in the PDOS analysis verify the interaction is caused by chemisorption. The calculation of the band gap based on the frontier orbital theory shows that there is a significant difference in the conductivity of Cr-GaN before and after adsorption. Therefore, Cr-GaN based material could be used as resistance transducer to detect CO and C 2 H 2. This preliminary research provides a supplement to the study of the physicochemical properties of the transition metal modified GaN monolayer, and provides a first look of the potential application of the Cr-GaN monolayer in the field of gas sensors. [ABSTRACT FROM AUTHOR]

[Display omitted] • Effect of Cr as dopant on the electronic properties of the InP 3 monolayer was explored. • Adsorption behavior of H 2 , C 2 H 2 and CH 4 on InP 3 -based monolayers was discussed. • Gas sensing mechanism of the Cr-InP 3 material to H 2 , C 2 H 2 and CH 4 was analyzed. • Conductivity and recovery time of Cr-InP 3 adsorption systems were evaluated. Transition metal doping plays a significant role to regulate the electronic properties of the material substrates. In this paper, the effect of Cr dopant on InP 3 monolayer and its adsorption performances to H 2 , C 2 H 2 and CH 4 were studied to explore the application potential of Cr-InP 3 for three dissolved gases in transformer oil with density functional theory (DFT). The adsorption behavior of intrinsic and Cr-doped InP 3 monolayers to three gas molecules were simulated in terms of the charge transfer, density of states and molecular orbital, etc. Results illustrated that the electronic structure of InP 3 monolayer could be sharply swayed with Cr dopant, as confirmed by the obviously asymmetry of densities of states around the Fermi level and the generation of magnetic moment of whole system. Besides, the Cr doping with high activation could effectively improve the adsorption properties of InP 3 monolayer for three gas molecules. The Cr-InP 3 monolayer shows more perfect adsorption performance towards C 2 H 2 molecule in all Cr-InP 3 adsorption systems, and might be a promising sensitive material for detection of C 2 H 2 gas. The electrical conductivity and recovery time of Cr-InP 3 adsorption systems were discussed to evaluate the applicability of the proposed material in three dissolved gases. [ABSTRACT FROM AUTHOR]

Through Density functional theory and Boltzmann transport theory, the ideal strength, electronic structure, elastic constants and thermoelectric performance of cubic phase PbTe are investigated. When the compressive strain is applied, both band gap and Seebeck coefficient decrease, while the electrical conductivity, power factor, thermal conductivity and ZT increase. According to the ZT of PbTe, the thermoelectric performance of p type is superior to that of n type. The optimal ZT value of p type could reach 3.88 at 0.5% strain, while the optimal ZT value of n type could reach 3.05 at 2.0% strain. Compared to the thermoelectric performance without strain, the thermoelectric performance under strain could be significantly improved, indicating that the strain engineering could be an effective strategy to improve the thermoelectric performance of PbTe. [Display omitted] • The electronic structure of PbTe is calculated, including density of states (DOS), relaxation time, mobility of carrier and effective mass. • The thermoelectric property of p type is found to be significantly better than that of n type. • For n type, the largest ZT value of 3.05 could be obtained at 2.0% strain and 850 K. • For p type, the largest ZT value of 3.88 could be obtained at 0.5% strain and 850 K. • The strain engineering could be an effective strategy to improve the thermoelectric performance of PbTe. [ABSTRACT FROM AUTHOR]

In this paper, the adsorption behavior of SF 6 decomposition gases (H 2 S, SO 2 , SOF 2 and SO 2 F 2) on intrinsic MoS 2 and Sc-MoS 2 monolayers was discussed based on DFT methods. Sc-MoS 2 undergoes strong chemisorption for target gases, accompanied by drastic changes in the adsorption structure and a large amount of charge transfer. The results show that Sc-doping improves the adsorption effect of H 2 S, SO 2 , SOF 2 , SO 2 F 2 on the surface of MoS 2. [Display omitted] • The adsorption of Sc doped MoS 2 to SF 6 characteristic decomposition gases was calculated for the first time. • Sc-MoS 2 monolayer exhibits ideal adsorption and sensing properties for four target gases. • The adsorption effect of Sc-MoS 2 is in the following order: SO 2 F 2 > SOF 2 > SO 2 > H 2 S. • The research results provide guidance for the preparation of Sc-MoS 2 sensors for detecting SF 6 decomposition gases. By detecting the decomposition gases of sulfur hexafluoride (SF 6), the type of internal fault of gas insulated switchgear (GIS) can be determined. In this paper, the scandium atom doped molybdenum sulfide material (Sc-MoS 2) was proposed, and the adsorption behaviors of four typical SF 6 decomposing gases (H 2 S, SO 2 , SOF 2 , SO 2 F 2) on the surfaces of intrinsic MoS 2 and Sc-MoS 2 are studied based on density functional theory (DFT) method. The adsorption models were established to calculate the electronic properties and adsorption parameters of the adsorption systems. The results show that Sc-MoS 2 has excellent adsorption properties for SO 2 , SOF 2 and SO 2 F 2 , but weak adsorption for H 2 S. Moreover, the adsorption effect for target gases was obviously enhanced by the introduction of Sc atom as the active center of the system. The findings are beneficial to refine the gas sensing mechanism of MoS 2 materials and lay a foundation for SF 6 decomposition gases detection based on MoS 2 sensors. [ABSTRACT FROM AUTHOR]

The influence of Cr atoms doping on the structure parameters and electronic properties of SnP 3 monolayer was studied based on DFT calculations. We found Cr doped SnP 3 monolayer exhibits excellent adsorption capacity to SF 6 decomposition gases and the processes of absorption both are chemical. • The effect of Cr dopant on properties of SnP 3 monolayer were discussed in detail. • The adsorption performances of SnP 3 monolayer to SF 6 decomposition were discussed. • The adsorption performances of Cr doped SnP 3 monolayer were discussed in detail. In this paper, based on density functional theory (DFT), the possibility of intrinsic and Cr doped SnP 3 (Cr-SnP 3) monolayer as candidate materials for detecting SF 6 decomposed gases SO 2 , SOF 2 and SO 2 F 2 was discussed. The adsorption energy, adsorption distance, charge transfer and density of states of adsorption systems were calculated and analyzed. Results reveal that the Cr-SnP 3 monolayer has higher chemical affinity to SO 2 , SOF 2 and SO 2 F 2 molecules than intrinsic SnP 3. Larger adsorption energy, obvious charge transfer and significant molecular structural deformation can be observed, indicating the strong interaction between gas molecule and Cr-SnP 3 caused by chemisorption, which can effectively excite electrical signals for gas detection. Therefore, Cr-SnP 3 monolayer gas sensor may be recommended in the field of SF 6 decomposition characteristics products detection. [ABSTRACT FROM AUTHOR]

Three types of VS 2 as electrode for magnesium ion batteries were been studied by first-principle calculations. The average working voltages results suggest that monolayer-VS 2 can be employed as anode materials, while double-layer-VS 2 , bulk-VS 2 can be used as cathode materials for magnesium ion batteries. • DFT for prediction of three types of VS 2 as electrode materials for MIBs. • Investigation of the adsorption, charge transfer, bond stability of Mg on the VS 2. • M-VS 2 can be employed as anode, while D-VS 2 , B-VS 2 can be used as cathode for MIBs. Herein, by means of first-principle calculations based on density functional theory (DFT), the electrochemical properties of monolayer VS 2 (M-VS 2), double-layer VS 2 (D-VS 2) and bulk VS 2 (B-VS 2) as electrode materials for Mg-ion batteries (MIBs) were comprehensively explored. The computation results reveal that Mg atom can strongly bind with the three different forms of VS 2. All of the Mg adsorbed VS 2 systems demonstrate metallic characteristics, which indicates a good electronic conductivity. In addition, crystal orbital hamiltonian population shows that the stability of V-S bond is weakened after adsorption of Mg atom. The low diffusion barriers of Mg give rise to the high rate performance of VS 2 in MIBs. More interestingly, the three types of VS 2 display same storage ability for Mg cations, which can adsorb 0.5 Mg atoms for VS 2 , producing maximum theoretical capacity 233 mA h g−1 for MIBs. The average working voltages results suggest that M-VS 2 can be employed as anode materials, while D-VS 2 , B-VS 2 can be used as cathode materials for MIBs. [ABSTRACT FROM AUTHOR]

First-principle calculations were carried out to simulate the three decomposition gases (SO2, SOF2, and SO2F2) of sulfur hexafluoride (SF6) on Ga-doped MoS2 (Ga-MoS2) monolayer. Based on density functional theory (DFT), pure MoS2 and multiple gas molecules (SF6, SO2, SOF2, and SO2F2) were built and optimized to the most stable structure. Four types of Ga-doped positions were considered and it was found that Ga dopant preferred to be adsorbed by the top of Mo atom (TMo). For the best adsorption effect, two ways of SO2, SOF2, and SO2F2 to approach the doping model were compared and the most favorable mode was selected. The adsorption parameters of Ga-MoS2 and intrinsic MoS2 were calculated to analyze adsorption properties of Ga-MoS2 towards three gases. These analyses suggested that Ga-MoS2 could be a good gas-sensing material for SO2 and SO2F2, while it was not suitable for SOF2 sensing due to its weak adsorption. This work provides a theoretical basis for the development of Ga-MoS2 materials with the hope that it can be used as a good gas-sensing material for electrical equipment. [ABSTRACT FROM AUTHOR]

In this study SO 2 adsorption on intrinsic graphene (IG), Ni-doped graphene (NiG) and Pd-doped graphene (PdG) has been analyzed and studied using density functional theory (DFT) based on first principles. • Ni doped graphene (NiG) and Pd doped graphene (PdG) are stable chemisorption for SO 2. • Double SO 2 molecules can be stably adsorbed on NiG and PdG. • PdG is more suitable for the detection of SO 2 gas molecules than NiG. In this study SO 2 adsorption on intrinsic graphene (IG), Ni-doped graphene (NiG) and Pd-doped graphene (PdG) has been analyzed and studied using density functional theory (DFT) based on first principles. By analyzing the adsorption energy, bond length, bond angle, charge transfer, DOS, PDOS and frontier molecular orbitals, it can be proved that NiG and PdG have excellent SO 2 adsorption performance than IG. PdG has better SO 2 adsorption performance than NiG thanks to the strong overlapping of peaks in PDOS and the obvious reduction of energy gap. In particular, the stable adsorption of double SO 2 on NiG and PdG means that Ni or Pd doping has practical value. Therefore, the study in this paper provides a feasible direction to the detection of SO 2. [ABSTRACT FROM AUTHOR]

In this study, the adsorption performances of graphene before and after modification to H2S and CH4 molecules were studied using first principles with the density functional theory (DFT) method. The most stable adsorption configuration, the adsorption energy, the density of states, and the charge transfer are discussed to research the adsorption properties of intrinsic graphene (IG), Ni-doped graphene (Ni–G), vacancy defect graphene (DG), and graphene oxide (G–OH) for H2S and CH4. The weak adsorption and charge transfer of IG achieved different degrees of promotion by doping the Ni atom, setting a single vacancy defect, and adding oxygen-containing functional groups. It can be found that a single vacancy defect significantly enhances the strength of interaction between graphene and adsorbed molecules. DG peculiarly shows excellent adsorption performance for H2S, which is of great significance for the study of a promising sensor for H2S gas. [ABSTRACT FROM AUTHOR]