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Given its superior structure, the abundance of surface functional groups, and low cost, cotton fiber filtration paper can be used as the support for hydrogen evolution reaction (HER) and oxygen evolution reaction catalysts (OER) instead of copper foam (CF), nickel foam (NF), or carbon cloth (CC). Herein, the chemical plating method was used to create thin self-supporting electrodes based on cotton fiber filtration paper (FP). The Co-Ni-P amorphous nanospheres can be uniformly dispersed on the self-supporting FP due to its porous structure and oxygen functional groups. The Co-Ni-P/FP electrode has an overpotential as low as 125 mV for HER and 320 mV for OER at the current density of 10 mA cm−2. Additionally, according to density functional theory (DFT) calculations, the Co atom added to the Ni-P nanosphere can lead to considerably more charge accumulation around the Co and Ni active sites, which greatly encourages the HER and OER processes. The novel porous support, FP, provides a fresh way the preparation of self-supporting electrodes. [Display omitted] • Filter paper is used to prepare the self-supporting electrode as the substrate. • The preparation method is simple and the properties are stable. • Rich oxygen-containing functional groups of FP promote deposition and dispersion. • Explore the excellent electrochemical performance of amorphous Co-Ni-P/FP by DFT. [ABSTRACT FROM AUTHOR]

The influence of pressure on the optical properties of nanostructured tetragonal Cu 2 Sb has been investigated jointly by experimental Raman spectroscopy (RS) and theoretical first-principles calculation based on density functional theory (DFT) varying pressure from zero (ambient condition) to 45 GPa. The DFT determined pressure dependence of the Raman active modes and the mode-Grüneisen parameters for each Raman mode are found to be in excellent agreement with those experimentally determined. Comparison of the pressure evolution of the experimental Raman data with those of DFT has allowed us to make the proper assignment of optical phonon modes. Image 1 • The Raman modes of the Cu 2 Sb were observed under high-pressures conditions. • The high-pressure in-situ data were supported by ab initio calculations. • The compressibility parameter of the Cu2Sb were obtained. • In-situ high-pressure Raman scattering and ab-initio studies in Cu2Sb up to 45 GPa. [ABSTRACT FROM AUTHOR]

Introducing defects into Pd-based metallene has been shown to significantly enhance its electrocatalytic performance. In this study, we embedded a new type of atomic-scale cavities into the basal plane of PdMo bimetallene (c-PdMo) through precise etching. These cavities introduced tensile strain and increased the generalized coordination number (CN ̅), resulting in superior performance in formate oxidation reaction (FOR) and methanol oxidation reaction (MOR), with mass activities of 5.01 mA μ g NM − 1 and 5.38 mA μ g NM − 1 , respectively. Notably, a two-electrode system comprising commercial Pt/C and c-PdMo coated on carbon paper achieved cell voltages of only 0.517 V and 0.362 V at 10 mA cm−2 for FOR and MOR, respectively. Additionally, density functional theory calculations revealed that the deliberate lattice tensile strain and enhanced coordination numbers reduced the D-band center of defective PdMo, which improved OH adsorption and reduced CO adsorption, thus optimizing FOR and MOR catalysis on the surface of c-PdMo bimetallene. [Display omitted] • PdMo bimetallene with atomic-scale cavities (c-PdMo) was prepared via etching. • Atomic-scale cavities can regulate coordination number and strain of bimetallene. • Atomic-scale cavities can modulate the surface adsorption energies of CO and OH. • c-PdMo exhibited highly-efficient mass activity for FOR and MOR. [ABSTRACT FROM AUTHOR]

Electroactive FeS 2 -modified MoS 2 (FeS 2 /MoS 2) nanosheet grown on Mo foil is designed as supercapacitor electrode material. FeS 2 /MoS 2 nanosheet is crosslinked to form nanoporous microstructure. Density functional theory calculation reveals FeS 2 /MoS 2 exhibits much narrowed bandgap and high density of states at the Fermi level, suggesting highly improved conductivity. The charge transfers resistance decreases from 1.375 Ω of MoS 2 to 0.4167 Ω of FeS 2 /MoS 2. FeS 2 /MoS 2 exhibits higher specific capacity (495 and 394 mF cm−2) than MoS 2 (132 and 218.1 mF cm−2) and FeS 2 (315 and 286.5 mF cm−2) at 1.0 mA cm−2 in 3.0 M KOH and 0.5 M Na 2 SO 4. The rate capacity retention is enhanced from 57.8% of MoS 2 and 73.3% of FeS 2 to 76.14% of FeS 2 /MoS 2 in 0.5 M Na 2 SO 4 when current density increases from 1 to 10 mA cm−2, indicating its improved rate capability. The cycling capacity retention keeps 100.2% of MoS 2 and 100.7% of FeS 2 /MoS 2 for 5000 cycles at 5 mA cm−2 in 0.5 M Na 2 SO 4 , indicating the similar cycling stability. An asymmetric solid-state supercapacitor using FeS 2 /MoS 2 anode, exfoliated graphite carbon paper cathode and NaMoO 4 –Na 2 SO 4 -PVA gel electrolyte achieves specific capacity of 1.88 F cm−3 (112.8 mF cm−2) at 1.0 mA cm−2, energy density of 0.936 mWh cm−3 (56.56 mWh cm−2), capacity retention of 97.8% after 5000 cycles at 5.0 mA cm−2 and 1.9 V output voltage. • Conductive FeS 2 and stable MoS 2 are integrated to form electroactive FeS 2 /MoS 2 nanosheet. • Density functional theory calculation proves highly improved conductivity of FeS 2 /MoS 2. • FeS 2 /MoS 2 shows superior capacitance of 495 mF cm−2 at 1.0 mA cm−2 in 3.0 M KOH. • FeS 2 /MoS 2 keeps 95% capacity retention at 5 mA cm−2 for 5000 cycles in 3.0 M KOH. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) with excellent soft magnetic properties are gradually emerging as a new generation of electromagnetic wave (EMW) absorption materials. Existing HEAs still cannot efficiently absorb EMW due to inadequate magnetic properties. This paper aims to modulate the ferromagnetic properties of Fe 1.1 Co 1.1 (CrAl x) 1.8 Gd 0.1 (x=1, 1.2, 1.4, 1.6) to enhance the permeability and achieve efficient absorption of EMW. The experimental results show that when the ratio of Al to Cr is 1.6:1, the saturation magnetization and permeability reach their highest values. First-principles calculation confirms from an atomic perspective that when the ratio of Al to Cr is 1.4:1, Gd begins to undergo a ferromagnetic transformation. Its magnetic moment increases from −1.2 μ Β to 1.4 μ Β , and the degree of electron localization also increases. The Fe 1.1 Co 1.1 Cr 0.75 Al 1.05 Gd 0.1 achieves an effective absorption of −51 dB at a thin thickness of 2 mm and an effective absorption bandwidth of 6.2 GHz of 1.4 mm. The cocktail effect also depends on having good corrosion and oxidation resistance. This paper provides theoretical guidance for the design of high-performance soft magnetic EMW absorption materials. [Display omitted] • High-efficiency electromagnetic wave absorption materials are prepared by mechanical alloying combined with heat treatment. • Fe 1.1 Co 1.1 (CrAl x) 1.8 Gd 0.1 exhibit a significant transformation in ferromagnetic properties. • High-entropy alloys can optimize their magnetic loss by regulating their magnetic properties. • High-entropy alloys have excellent resistance to harsh environments. [ABSTRACT FROM AUTHOR]

Abstract In this paper, the topological phase of LuX (X = Sb, Bi) compounds under hydrostatic and biaxial pressures is investigated based on first principles of density functional theory by WIEN2k package. To find out the Z 2 topological invariants of centrosymmetric compounds with the time reversal symmetry, the Bloch functions parity analysis can be used via electronic band structure calculations. So in this paper the Z 2 topological invariants of the LuX (X = Sb, Bi) compounds with the time reversal and inversion symmetries are calculated using this approach. The results show that the d-p band inversion can be occurred in these compounds due to spin orbit interaction and appropriate pressure. These compounds have the strong electronic interaction due to their large d -electronic orbitals near the Fermi energy. The dynamic stability of these compounds is verified by phonon modes analysis. The surface states topological phase of these compounds are investigated based on the band structure calculations. Highlights • The LuX (X = Sb, Bi) compounds have normal band order at zero pressure. • The pressures effects on LuX compounds band order are studied. • The LuX nano-layers have topologically trivial surface states. • The d-p band inversion occurs in LuX compounds under pressure. • The phonon dispersions of LuX (X = Sb, Bi) compounds are studied. [ABSTRACT FROM AUTHOR]

Short-wave infrared (SWIR) light in the 1000–1700 nm range has high penetration capability through biological tissues and is non-destructive, making it widely used in biomedical applications and near-infrared imaging. Currently, the development of SWIR light sources is urgently needed. This paper discusses the luminescent properties of the near-infrared emitting transition metal ions Cr3+ and Ni2+. By using the traditional high-temperature solid-state method, we successfully synthesized YAGG:3.5 %Cr3+-0.5 %Ni2+ (YAGG:Cr-Ni) garnet-based phosphor ceramic in one step. The phosphor ceramic emits ultra-broadband NIR-I (600–900 nm, FWHM=131 nm) and SWIR (1100–1700 nm, FWHM=377 nm) light when excited by a 450 nm commercial blue LED. Position analysis combined with density functional theory (DFT) simulation confirmed the effective substitution of luminescent center ions for the [Al/GaO 6 ] sites. Spectral and lifetime analyses further verified the energy transfer process between Cr3+ and Ni2+ is dipole-quadrupole interaction. Additionally, this phosphor ceramic has a high thermal conductivity of 8.018 W·m⁻¹·K⁻¹ at room temperature. Finally, SWIR pc-LED devices were fabricated by packaging the phosphor ceramic with a 450 nm commercial blue LED, achieving skeletal and venous imaging of biological tissues up to 20 mm thick, providing a new approach for the development of SWIR devices. ● Y 3 Al 2 Ga 3 O 12 :Cr3+-Ni2+ phosphor ceramics achieved ultra-broadband near-infrared emission at 600–900 nm (FWHM=131 nm) and 1100–1700 nm (FWHM=377 nm) under 450 nm commercial blue light excitation. ● Position analysis combined with density functional theory (DFT) simulation confirmed the effective substitution of luminescent center ions for the [Al/GaO 6 ] sites. ● SWIR pc-LED devices achieved skeletal and venous imaging of biological tissues up to 20 mm thick. [ABSTRACT FROM AUTHOR]

Transition metal-based alloy nanostructures have emerged as promising catalysts for electrochemical water splitting, offering a potential solution to the growing demand for clean and renewable energy. Also, research on encapsulation engineering of alloy nanostructures using carbon matrices has recently advanced, presenting a new approach that combines the conductive properties of carbon matrices with an alloy structure to enhance electrochemical performance in water splitting. However, the specific roles of the alloy core, carbon shell, and their synergistic effect in improving electrochemical performance are still not well understood. In this paper, we report on the encapsulation of a ternary Co–Fe–Al alloy nanostructure using a carbon matrix and investigate its electrochemical oxygen evolution reaction (OER). The optimized carbon matrix-encapsulated Co 0.3 Fe 0.2 Al 0.5 alloy catalyst demonstrated superior electrocatalytic activity for OER (achieving 250 mV at 10 mA cm−2) and long-term stability. Through density functional theory calculations, we also elucidate the crucial role of Al in enhancing the OER catalytic performance of the proposed carbon-encapsulated Co–Fe alloy catalyst. By comparing the free electron concentration and required applied potentials to trigger OER, we provide insights into the beneficial effects of incorporating Al into the Co–Fe alloy catalyst. [Display omitted] • CoFeAl alloy nanostructures within conductive carbon matrices, enhancing both stability and electrochemical performance for the oxygen evolution reaction. [ABSTRACT FROM AUTHOR]

Efficient detection and timely resolution of internal faults within synthetic ester oil transformers are imperative for ensuring the stability of power systems. This paper proposes the utilization of MoSTe monolayer modified with Cu n and Pd n (n=1–3) clusters for detecting internal fault gases (C 2 H 2 , C 2 H 4 , and CH 4) in transformers. The adsorption mechanism and electronic properties of target gases on the modified substrate surface are systematically studied through density functional theory analysis of adsorption energy, density of states, and deformation charge density. The results indicate that TM n clusters possess the capability to enhance the reactivity of the MoSTe surface, leading to varying degrees of improvement in conductivity and adsorption capacity. Different target gases exhibit distinct adsorption characteristics, with the modified monolayer showing strong adsorption capabilities for C 2 H 2 and C 2 H 4. The calculation of work function and recovery time further reveal the promising potential of Pd n -MoSTe monolayer as resistive gas sensing materials for detecting C 2 H 2 and C 2 H 4 , while Cu n -MoSTe monolayer are also identified as high-quality candidates for C 2 H 4 sensing materials. This study is expected to facilitate the practical application of MoSTe monolayer in the field of transformer operational state monitoring, providing new insights for exploring novel gas sensing materials. • The conductivity of the TM n clusters modified MoSTe monolayers is consequently improved to different extents compared with the initial MoSTe substrate. • Combined adsorption parameters, DOS and DCD analysis reveal that the adsorption of C 2 H 2 and C 2 H 4 on TM n -MoSTe monolayers is chemisorption, while the adsorption of CH 4 is weak physisorption. The adsorption capability ranking is: C 2 H 2 > C 2 H 4 > CH 4. • The variation of work function and band gap demonstrate that the adsorption of target gases can improve the surface properties of substrate. This effect is particularly pronounced in the TMn-MoSTe/C 2 H 2 and TM n -MoSTe/C 2 H 4 systems. • The recovery time reveals the promising potential of Pd n -MoSTe monolayer as sensing materials for detecting C 2 H 2 and C 2 H 4 , while Cu n -MoSTe monolayer is suitable for rapid recovery of C 2 H 4 under ambient conditions. [ABSTRACT FROM AUTHOR]

Synergistic effects of mixed oxides have the potential to improve sensing performances of environmental, domestic and industrial monitoring devices. However, mixed oxides often come in the form of separate particles and are thus addressed separately by the environment, instead of capitalizing on the interface between the metal oxides. This paper describes a new core@shell gas sensing material of tetrapodal zinc oxide with a surface coating of crystalline copper oxide(t-ZnO@CuO). The special surface conversion strategy yields a unique, self-assembled and pinhole-free coating of CuO nanoplatelets. The morphologies, structural, chemical and gas sensing properties of the heterostructure were investigated. To evaluate the sensing properties of the heterostructure, t-ZnO@CuO was fabricated as nanosensors, consisting of one core-shell rod of CuO-coated crystalline ZnO. The single core@shell rod showed high selectivity towards hydrogen already at comparatively low operation temperatures of 150 °C. Computational calculations based on the density functional theory (DFT) have been carried out to understand the interaction of the H 2 gas molecule with the surface of the CuO nanostructures. The surface conversion was done wet chemically and is a novel method for generating heterostructures that can be potentially transferred to heterojunctions with unique properties for chemosensors. [Display omitted] • A perfect coating of amorphized nanoplatelets of CuO with t-ZnO rods were obtained. • Absolute selectivity for H 2 was obtained from single microrod t-ZnO@CuO sensors. • The selectivity for H 2 over VOCs is due to complete coverage of CuO on t-ZnO arm. • Hetero2 structure (two substitutional Cu atoms) exhibits stronger interaction of H 2. • Bader charge analysis confirms Hetero2 structure as a favourable interaction site. [ABSTRACT FROM AUTHOR]

Fluoride pollution is a problem of increasing concern to global public health, and it is important to reduce the concentration of fluoride ions in water. In this paper, the composite adsorbent (Al 2 O 3 -COF) of Al 2 O 3 and melamine polymer network (MPN) was prepared by the solvothermal method, and the physicochemical properties of the material were characterized. The characterizations showed that Al 2 O 3 -COF had a porous and loosely packed morphology, and the adsorption behavior conformed to the pseudo-first-order kinetic and the Langmuir isotherm model. This study showed that Al 2 O 3 -COF exerted the synergistic effect of Al 2 O 3 and COFs to adsorb fluoride, with an adsorption capacity superior to that of a single alumina at 66.2 mg/g. The adsorption performance test showed that the interfering anions (PO 4 3-, Cl-, Br-, NO 3 -, SO 4 2-) had little effect on the adsorption performance of Al 2 O 3 -COF while maintaining a fluoride removal rate of over 83 %. After 5 cycles of recycling, more than 75 % of fluoride ions could also be removed. In addition, insights into the adsorption mechanism of Al 2 O 3 -COF, mainly through ion exchange and chemisorption, were calculated by density functional theory. This experiment is to apply COFs in the field of F- adsorption, which can provide ideas and guidance for future research. [Display omitted] • Al 2 O 3 -COF adsorbent in the form of yellowish powder was prepared by solvothermal method. • For the first time, COF materials were applied to the field of adsorption and fluorine removal. • The maximum adsorption capacity of the Al2O3-COF adsorbent was 66.2 mg/g. • Al 2 O 3 -COF possesses excellent adsorption regeneration capacity and has good economic benefits. • The adsorption mechanism was found to be mainly chemisorption and ion exchange after DFT calculations. [ABSTRACT FROM AUTHOR]

It is highly important to develop low-cost hydrogen evolution cathode materials. In this paper, Ni(OH) 2 /NF electrode was prepared by a hydrothermal method using nickel foam (NF) as a substrate, and NiTe-Ni(OH) 2 /NF cathode with high efficiency and low cost was prepared by secondary hydrothermal method. The material was characterized by physical characterization and electrochemical performance tests. Ni(OH) 2 /NF electrode materials prepared by a one-step hydrothermal method had a three-dimensional petal-like pore space structure. This special structure provided abundant active points for the two-step hydrothermal preparation of NiTe-Ni(OH) 2 /NF, which helps to improve the efficiency of HER. Compared with NF and Ni(OH) 2 /NF, NiTe-Ni(OH) 2 /NF cathode exhibited better HER catalytic performance. The results shown that NiTe-Ni(OH) 2 /NF is possesed excellent hydrogen evolution performance, and density functional theory can confirm this. At a current density of 10 mV∙cm−2, the NiTe-Ni(OH) 2 /NF electrode has an overpotential of only 129 mV, long-term stability, and an electrochemically active specific surface area (ECSA) of 91.75 cm−2. The Tafel slope was 31.5 mV∙dec−1, and the charge transfer resistance obtained by electrochemical impedance analysis was 9.81 Ω. This article provided valuable insights into the rational regulation of crystal phases on nickel telluride to improve HER properties. • The synergistic effect of porous petal-like Ni(OH) 2 /NF and uniform nanorod-like NiTe effectively maintained the stable structure of NiTe-Ni(OH) 2 /NF. • NiTe-Ni(OH) 2 /NF nanobars could provide excellent conductive networks and abundant H+ transfer active sites. • The NiTe-Ni(OH) 2 /NF composite had a low overpotential, abundant electrocatalytically active sites, and ultralong stability. • Density functional theory confirmed that NiTe-Ni(OH) 2 /NF had a low hydrogen adsorption energy and excellent kinetic properties. [ABSTRACT FROM AUTHOR]

In this paper, the molecular adsorption behavior and photoelectric properties of tungsten trioxide monohydrate (WO 3 ·H 2 O) (002) crystal plane into tungsten trioxide (WO 3) (002) crystal plane were studied by Density Functional Theory (DFT) and Electrochemical Impedance Spectrum (EIS). DFT simulation shows that the adsorption active sites change from two to one after the transformation of WO 3 ·H 2 O (002) crystal plane to WO 3 (002) crystal plane, which further affects the molecular adsorption behavior of the crystal plane. The crystal plane conversion leads to the decrease of the adsorption energy of water (H 2 O) molecules and the increase of the adsorption energy of oxygen (O 2) molecules, which reduces the adverse effect of water molecules on the gas sensing performance of the material and enhances the adsorption of O 2 molecules. Like O 2 molecules and H 2 O molecules, the adsorption of four kinds of organic molecules on two crystal planes will lead to an increase in the conductivity of the crystal plane. The competitive adsorption of organic molecules with O 2 molecules leads to the decrease of the conductivity of both crystal planes. However, acetone (C 2 H 6 CO) molecules are combined in the form of hydrogen bond on the WO 3 ·H 2 O (002) crystal plane, and the contribution to the increase of the conductivity of the crystal plane is significantly higher than that of O 2 molecules. After the conversion to the WO 3 (002) crystal plane, this hydrogen bond disappears. These results were confirmed by EIS test experiments. The UV-Vis diffuse reflectance absorption spectra and photocurrent spectra show that the band gap increases after the WO 3 ·H 2 O (002) crystal plane is converted into the WO 3 (002) crystal plane. Understanding the influence of crystal plane transformation on molecular adsorption behavior and photoelectric properties is of great significance for optimizing the gas sensing properties and regulating the photoelectric properties of materials. • Crystal transformation affects the surface adsorption and photoelectric properties. • Density functional theory is used to simulate the crystal plane molecular adsorption. • The change of the active sites affects the molecular adsorption behavior. • Different molecules have competitive adsorption at the same adsorption active site. • The adsorption of molecules will change the crystal surface conductivity. [ABSTRACT FROM AUTHOR]

In this paper, a new type of Ba 2 La 8 (SiO 4) 6 O 2 : Sm3+ phosphor was synthesized by solid-phase reaction, and the hydrophobic agent was used to restrain the hydrolysis of silicate phosphor. The microstructure, optical properties and electroluminescence properties of the samples were systematically analyzed. The results show that the Ba 2 La 8 (SiO 4) 6 O 2 : x Sm3+ phosphors have a strong orange-red emission at 600 nm, which corresponds to the 6G 5/2 →6H 7/2 energy level transition of Sm3+ ions. The optimal luminescence intensity was achieved at the dopant concentration of 10 mol%. The prepared phosphor has good thermal stability, the luminescence intensity at 423 K is still 85% of that at 298 K, and the internal quantum efficiency (IQE) is 22.59%. The ultraviolet-visible-near-infrared (UV–VIS–NIR) spectrum and the density functional theory reveal that the Ba 2 La 8 (SiO 4) 6 O 2 host can provide an excellent band-gap environment for the luminescent center. In addition, the modified Ba 2 La 8 (SiO 4) 6 O 2 : 0.10Sm3+ phosphor showed excellent hydrophobicity and luminescent properties, with a contact angle of 140.315°, and the luminescent intensity remained 75% of the pre-modified level. The Ba 2 La 8 (SiO 4) 6 O 2 : Sm3+ phosphor has good dispersion in PVA solution and emits bright red light. The above properties indicate that Ba 2 La 8 (SiO 4) 6 O 2 : Sm3+ phosphor has excellent luminescence properties and has broad application prospects. [ABSTRACT FROM AUTHOR]

The paper presents the systematic approach to calculating the structure parameters and stability of intermediate (Cr, Fe) 7 C 3 carbides in hexagonal and orthorhombic phases as well as in the liquid state within the framework of density functional theory. For chromium carbide, the hexagonal structure appears to be more stable than orthorhombic; for iron concentrations above 40 at.%, the situation is the opposite. This stability change is attributed to the attractive interaction of iron atoms in the system, both in solid and liquid state. It is shown, that for low iron concentrations, the formation energy of the system changes nonmonotonically with iron concentration, if substitution positions are chosen non-randomly. • Structure and stability of pure and intermediate (Cr, Fe) 7 C 3 carbides were calculated. • Hexagonal structure is more stable for Cr 7 C 3 ; Fe 7 C 3 is more stable in orthorhombic structure. • The structure of intermediate 7:3 carbides may change upon addition of iron. • Bonds between carbon and iron are shorter than between carbon and chromium in solid and liquid state. [ABSTRACT FROM AUTHOR]

The toxic gas trimethylamine (TMA) with fishy odor can not only be used as an indicator for evaluating seafood spoilage, but also as a biomarker for trimethylaminuria and kidney disease. This paper constructs a ppb-level trimethylamine gas sensor that operates at room temperature based on MoO 3 /V 2 O 5 nanocomposites, which were fabricated by hydrothermal synthesis process. The adsorption energy of TMA on sensitive materials was calculated through the density functional theory, and the sensing mechanism was explored by simulating the adsorption process of TMA on the sensitive materials. The response (11.37%) of MoO 3 /V 2 O 5 composites to ultra-low concentration (20 ppb) TMA was better than that of pure MoO 3 nanorods (5.49%) and V 2 O 5 nanospheres (6.36%) at room temperature. Compared with pure MoO 3 sensors, an n-n heterojunction is formed between MoO 3 and V 2 O 5 , which enhances the sensing performance of pure sensing material for TMA. In addition, the detection of exhaled gas in simulated kidney disease patients indicates that this sensor has great potential as an effective TMA detection tool in the field of non-invasive disease diagnosis. • MoO 3 /V 2 O 5 hierarchical heterostructures were prepared by hydrothermal method. • MoO 3 /V 2 O 5 sensor exhibits high sensitivity to 20 ppb TMA at room temperature. • The effects of MoO 3 /V 2 O 5 heterojunction were analyzed by first-principles calculations. [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]

The thermodynamic equilibrium potential of urea electrolysis (0.37 V) is lower than that of conventional water electrolysis (1.23 V). In this paper, the urea oxidation reaction performance of Ni-Co 2 P was regulated and enhanced by doping with different quantity of Mo. The growth characteristics of Mo doping Ni-Co 2 P were characterized and analyzed to reveal the electrochemical properties of the target catalysts, and finally the electrochemical performance tests were carried out. The experimental results show that MoNi-Co 2 P-0.12 electrode exhibits superior catalytic activity and durability at an iR compensation of 90. What is noteworthy is that at a current density of 10 mA cm−2, the MoNi-Co 2 P-0.12 catalyst showed an ultra-low voltage of 1.244 V with a small Tafel slope (79.52 mV dec−1) and stable catalysis for over 12 h, which is one of the best catalytic activities reported to date. Experimental results show that the increased activity of the MoNi-Co 2 P-0.12 catalyst is attributable to synergic catalytic effect of Mo and Co, electron regulation and exposure of more active sites. Density functional theory (DFT) calculations demonstrate the doping of Mo can increase the urea adsorption energy of the MoNi-Co 2 P material compared with the Ni-Co 2 P material, and is also conducive to the improvement of the conductivity of the MoNi-Co 2 P material. This work provides new research into the use of cheap transition metal catalysts as an alternative to precious metal catalysts for urea electrolysis. [Display omitted] • Mo and Ni codoped Co 2 P electrodes was synthesized for the first time through hydrothermal processes. • The potential of MoNi-Co 2 P-0.12 electrode is only 1.244 V at 10 mA cm−2 for UOR. • The electrolytic performance of MoNi-Co 2 P-0.12 in seawater, simulated seawater, water, and urea gradually improved. [ABSTRACT FROM AUTHOR]

Bi 3 O 4 Br with different facet has different activity. In this paper, the noble metal Ag was designed to dope on the (002) facet (surface) or (020) facet (edge) of Bi 3 O 4 Br by simple solvothermal methods. The morphology, band structure and crystal form of the prepared composites were systematically studied and discussed. The photocatalytic efficiencies of the materials were tested through bisphenol A degradation under irradiation of simulated sunlight. Comparatively, the rate constant of Ag/Bi 3 O 4 Br (002) is 1.81 and 2.84 times higher than that of Ag/Bi 3 O 4 Br (020) and Bi 3 O 4 Br, respectively, indicating that: (1) the (002) facet of Bi 3 O 4 Br has the distinct activity; (2) the construction of metal particle doping in the (002) crystal plane can effectively improve the carrier transport rate. In order to further explore the photocatalytic pathways of bisphenol A, the intermediates and the free radicals were determined, which was also verified by the density functional theory calculation. The degradation mechanism was put forward to explain the separation and migration behavior of photogenerated charge pairs and the distinguished performance of Ag/Bi 3 O 4 Br (002). [Display omitted] • The Ag doped on (002)/(020) facet of Bi 3 O 4 Br were prepared by hydrothermal method. • The photocatalytic efficiency of bisphenol A reaches 94.9 % after 90 min irradiation. • The catalytic mechanism was explored by DFT calculation and energy band structure. • The ·O2- and h+ are the main active species on bisphenol A degradation. • Carrier directed migration and Ag plasmon resonance effect promote photocatalysis. [ABSTRACT FROM AUTHOR]

Abstract To replace the costly, noble platinum electrocatalyst, the inexpensive, earth abundant and highly efficient electrocatalysts of layered transition metal dichalcogenides (TMDs) are explored for the hydrogen evolution reaction (HER). This paper describes cost-effective synthesis of 1T-MoS 2 on 3D-graphene/Ni foam (NF) via a facile solution bath approach as an electrocatalyst for HER. The improved HER performances were observed due to the 3D-structure of MoS 2 /graphene. HER performance of MoS 2 /graphene/NF electrocatalyst exposed a superior catalytic performance with the low overpotential (−89 mV vs RHE) to drive the 10 mA cm−2, steep Tafel slope (45 mV dec−1), large exchange current density (4.16 × 10−1 mA cm−2), and robust stability over 18 h. Density functional theory (DFT) calculations also confirmed the reduced Gibbs free energy for H-adsorption (ΔG H) for MoS 2 /graphene compared to MoS 2. The observed results suggest that the 1T-MoS 2 /graphene/NF is an interesting alternative to platinum-based catalyst for boosting HER efficiency. Graphical abstract Image 1 Highlights • Active electrocatalyst of MoS 2 decorated on graphene/NF by chemical route. • Raman and XRD results confirmed the observation of 1T-MoS 2. • The robust stability over 18 h with over potential of 89 mV vs RHE was observed. • DFT calculations explained in terms of density of states for high HER performance. [ABSTRACT FROM AUTHOR]

Abstract Salicylhydroxamic acid (SHA) is a typical chelate collector. This study elucidated the effect of steric hindrance on SHA adsorption on the MgTi 2 O 5 surface using density functional theory. The geometry optimisation and electronic structures of SHA ion and the MgTi 2 O 5 (110) surface were calculated. Subsequently, six adsorption configurations of SHA ion on the MgTi 2 O 5 (110) surface were calculated and compared by analysing geometric configuration, bond length, adsorption energy, density of states (DOS), and Mulliken population. The results show that both the oxygen molecules of C ╱ ╲ = O and N ╱ ╲ O − in SHA ion can coordinate to the metal ion. Steric hindrance affects the formation of a five-membered ring structure. The four adsorption configurations of the newly established structure can effectively avoid steric hindrance, and stable chelate rings are formed. The adsorption energies of the four new configurations range from −300 kJ/mol to −400 kJ/mol, and the bond lengths are about 2 Å. DOS and Mulliken population results indicate that O atoms bond to Ti and Mg atoms. Traditional chelate collector adsorption theory ignores the presence of steric hindrance. At the same time, the species distribution of SHA solution, zeta potential and flotation have also been studied in this paper, and there is a consistency between the calculation and experiment results. This study provides insights into the adsorption mechanism of a chelate collector on a mineral surface. Highlights • Steric hindrance affects the formation of a five-membered ring structure. • The limitation of the traditional chelate collector adsorption theory was discussed. • New adsorption configurations of SHA ion on the MgTi 2 O 5 (110) surface were established. • Experiments were conducted to validate adsorption mechanism of DFT calculations. [ABSTRACT FROM AUTHOR]

In this paper, experiments combined with density functional theory (DFT) are used to investigate the toughness enhancement mechanism of Ni-doped Cr 2 N coatings. The deposited Cr 2- x Ni x N (x = 0–4.5 at%) coating exhibits a single trigonal structure identified as a Cr 2 N-Ni solid solution. The columnar structure of the Cr 2 N coating, with a width of approximately 80 nm, does not change with the doping of Ni. With 2.0 at% Ni alloyed, the hardness increases from 27 GPa for Cr 2 N to the maximum of 34 GPa. which is mainly due to an increase in residual compressive stress and dislocation density resulting from Ni doping. Interestingly, the elastic modulus shows a linearly decreasing trend as the Ni doping content increases, which indicates that Ni alloying improves the ductility of the Cr 2 N coating. The sand erosion test shows that the erosion rate of the Cr 2 N coating is significantly reduced when the Ni doping content is 2.0 at%, decreasing from 0.42 µm·min−1 to 0.15 µm·min−1. DFT results reveal that the metallic d - d state density increases with increased d -electron concentration contributed by Ni atoms, enhancing metallic interaction along the Ni-Cr stacking plane under shear loading, which leads to the improved ductility of the Cr 2- x Ni x N coating. ● Cr 2- x Ni x N (x = 0–4.5 at%) is prepared by magnetic filtered cathodic vacuum arc. ● Hardness increases and elastic modulus decreases with increasing Ni content in Cr 2 N. ● Cr 2 N erosion rate decreases from 0.42 to 0.15 µm·min−1 with 2.0 at% Ni doping. ● Higher d- electron concentration in Ni leads to an increased d-d density of states. ● Enhanced Ni-Cr interaction in the stack plane increases Cr 2- x Ni x N ductility. [ABSTRACT FROM AUTHOR]

The main goal of this paper is to investigate the structural and electronic properties of small tin-oxide clusters, Sn x O y (x = 2–6), before and after methane (CH 4 ) physisorption. To this end, we employ the dispersion-corrected density functional theory (DFT-D2). At first, we demonstrate the relative binding stability of Sn x O y clusters with a fixed number of tin atoms via analysis of their binding energy per atom and second-order energy differences. Our results show that the highest relative stability occurs at y = 2, y = 3, y = 4, y = 6 and y = 8 for Sn 2 O y , Sn 3 O y , Sn 4 O y , Sn 5 O y and Sn 6 O y clusters, respectively. Furthermore, with the cluster size increasing, the ring-shape to cube-like structural crossover is occurred. The higher average coordination and total number of bonds in cube-like clusters make their interatomic bonds weaker and longer. On the other hand, the cube-like clusters, in comparison with ring-shape ones, possess higher chemical potential and lower chemical hardness that lead to their more chemical reactivity. We then proceed to study the CH 4 adsorption properties of the resulted most stable clusters. The lowest-energy structures of CH 4 -adsorbed clusters have been found by comparing the adsorption energy of different configurations. It is found that Van der Waals interactions lead to exothermic physisorption of CH 4 on each tin-oxide cluster with the adsorption energy ranging from −101 to −191 meV. In addition, upon CH 4 adsorption on Sn x O y clusters, the energy gap is decreased which shows an enhancement in the conductivity of the clusters. As a result, the CH 4 physisorption ability of these small studied tin-oxide clusters provides their application feasibility as the low-temperature CH 4 gas sensors. [ABSTRACT FROM AUTHOR]

The discovery of magnetic skyrmions has attracted much in the research field due to their potential applications in the storage and logic devices. In this paper, we present a study of elastic, magnetic, transport, and electronic properties of a family of magnetic skyrmions M 2 Mo 3 N ( M  = Fe, Co, Rh) along with their isotypic Ni 2 Mo 3 N compound by using density functional theory. The elastic constants and moduli of elasticity are calculated to analyze the stability of M 2 Mo 3 N. The noncentrosymmetric M 2 Mo 3 N crystals are found to be elastically stable and ductile in nature. The Vickers hardness values indicate that Fe 2 Mo 3 N and Ni 2 Mo 3 N are relatively hard, Co 2 Mo 3 N and Rh 2 Mo 3 N are relatively soft materials. The calculated Debye temperature from elastic constants of Rh 2 Mo 3 N is reasonably close to the experimental value. The calculated magnetic moment and polarization of M 2 Mo 3 N are consistent with the experimental results. The magnetic moment and polarization of Fe 2 Mo 3 N are 15.48μ B and 62% respectively indicating that it is a potential candidate for applications in the magnetic storage, logic devices, and spintronics. The linear proportionality relation of electronic heat capacity with temperature is only held for Rh 2 Mo 3 N indicating its superconducting nature. The density of states at the Fermi energy of M 2 Mo 3 N is dominated by M-d and Mo-d orbitals. Rh 2 Mo 3 N crystal is found to be a moderately coupled superconductor. The calculated superconducting transition temperature (4.53 K) of Rh 2 Mo 3 N is very close to the experimental value (4.3 K). [ABSTRACT FROM AUTHOR]

This paper reports the intrinsic size-dependent d 0 room-temperature ferromagnetism in dopant-free ZnO nanoparticles, which were fabricated by thermal decomposition route. The size of ZnO nanoparticles can be controlled by simply tuning the amount ratio of solvent. Transmission electron microscope shows that the ZnO nanoparticles are well-dispersed without aggregation. Magnetic measurement suggests that the undoped ZnO nanoparticles show room temperature ferromagnetic characteristic, which is sensitive with the particle size. Photoluminescence spectra and X-ray photoelectron spectroscopy measurements elucidate that the relative concentration of oxygen vacancies increase as the particle sizes decrease, leading to long-range ferromagnetic ordering in the undoped ZnO nanoparticles. A correlation among the particle size, ferromagnetism and relative concentration of oxygen vacancies is established, which demonstrates that oxygen vacancies play a key role to induce ferromagnetic ordering. Furthermore, density functional theory calculation demonstrates that the oxygen vacancies in ZnO with positive charge trapping can induce polar-magnetization which is stable states. The correlation between experiments and simulations suggests that the ferromagnetic behavior in diluted magnetic semiconductors can be conveniently manipulated by tuning the surface-volume ratio of nanostructures and surface defects, which is of great significance to understand and explore novel diluted magnetic semiconductors. [ABSTRACT FROM AUTHOR]

In this paper, by the density functional theory (DFT) calculations we show that the copper nanocluster can be used as catalyst for the hydrogenation of acetylene and ethylene. Since the nature of dissociation of hydrogen molecule on the copper nanocluster is the governing step for the hydrogenation reaction, the adsorption and complete dissociation of H 2 on the Cu 11 nanocluster is investigated at PBE-G/DNP-ECP level of theory. The results show that H 2 is adsorbed dissociatively on the Cu 11 nanocluster. To examine the activity of copper nanocluster as a catalyst for the hydrogenation reaction, the hydrogenations of acetylene and ethylene are investigated on the free Cu 11 nanocluster, due to its highest adsorption energies for hydrogen, acetylene and ethylene adsorptions. In the presence of the Cu 11 nanocluster as a catalyst, acetylene and ethylene can be hydrogenated to ethylene and ethane, respectively. These reactions are exothermic with the total reaction energies of −247.61 and −174.01 kJ/mol for hydrogenation of acetylene and ethylene, respectively. One of the interesting features of this catalyst is that the energy of acetylene adsorption on Cu 11 2H complex is higher than the energy of ethylene adsorption. It seems that Cu 11 nanocluster can be used as catalyst for the selective hydrogenation of acetylene. Also, we choose graphene as a support for copper nanocluster and the hydrogenation of acetylene and ethylene on graphene-supported Cu 11 nanocluster are investigated. Based on our DFT calculations, we suggest graphene-supported Cu 11 nanoclusters as candidates with good activity and selectivity for the acetylene hydrogenation reaction. [ABSTRACT FROM AUTHOR]

In this paper, B-doped TiC particles have been successfully synthesized in an Al–5Ti–0.2C–0.27B master alloy, achieved by using Al 3 BC compound as C and B sources simultaneously. The novel master alloy performs better on grain refinement for Zr-containing 7050 Al alloy than conventional Al–5Ti–1B or Al–5Ti–0.2C. Density functional theory calculations show that Zr element has slighter tendency to segregate on the surface of B-doped TiC in comparison with pure TiC, which is suggested to be the main mechanism for the strong anti Zr-poisoning performance of the Al–5Ti–0.2C–0.27B master alloy. It is regarded that such Al–Ti–C–B master alloy may have promising applications in refining Zr-containing Al alloys. [ABSTRACT FROM AUTHOR]

The development of efficient, stable and low-cost electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is the key to promote the industrialization of electrocatalytic water splitting. In this paper, the CoFe-LDH@NiCo-LDH precursor was first synthesized and then the target catalyst named Ni-Co-Fe-Se@NiCo-LDH was finally synthesized by a selenization reaction based on this precursor. In a three-electrode system with 1.0 M KOH alkaline atmosphere, Ni-Co-Fe-Se@NiCo-LDH requires an overpotential of 286 mV to deliver a current density of 100 mA/cm2 for OER and 113 mV at a current density of 10 mA/cm2 for HER. In addition, the material shows excellent overall water splitting performance and a low cell voltage of 1.55 V at 10 mA/cm2 is expected. By comparing the test results of CoFe-LDH@NiCo-LDH and NiCo-LDH, we found that increasing the number of metal species only slightly reduces the electron transfer impedance and does not help to increase the electrochemical surface area of the material. Density functional theory calculation shows that the presence of the Co-NiSe 2 material accelerates the kinetics of hydrogen production and the Fe 7 Se 8 material enhances the conductivity of the material. Their synergistic effect makes the Ni-Co-Fe-Se@NiCo-LDH catalyst exhibit enhanced hydrogen production activity. • Ni-Co-Fe-Se@NiCo-LDH nanoarrays was synthesized through typical hydrothermal processes. • This Ni-Co-Fe-Se@NiCo-LDH exhibits enhanced water splitting activity (1.55 V @10 mA cm-2). • The Ni-Co-Fe-Se@NiCo-LDH nanoarrays maintains good stability. [ABSTRACT FROM AUTHOR]

In this paper we explore the electronic nature and thermoelectric properties of filled skutterudites AFe 4 Sb 12 (A Ca, Sr and Ba) by DFT and post-DFT techniques. The calculated results show that the filling of Ca, Sr, and Ba at the empty crystal sites enhances the thermoelectric performance of the host material. This increase is a consequence of the coupling between the guest and the host atoms, which affects the electronic density at different symmetry points that increases the density of states of the valence bands. The valence band edge is almost independent of the guest atoms, i.e., the s-bands of Ca, Sr and Ba have negligibly small contribution to the valence band edge. In these compounds, the maximum value of thermoelectric PF/τ of 42.43 × 10 14 μW/cmK 2 s and 33.57 × 10 14 μW/cmK 2 s for the n-type of SrFe 4 Sb 12 in the spin-up and down states respectively. The striking feature of these compounds is their effectiveness at the low chemical potential values for the best thermoelectric performance. [ABSTRACT FROM AUTHOR]

Capable of achieving wide control over energy band gap and following optoelectronic properties; the highly mismatched alloys (HMAs) are considered to be promising materials for solar energy conversion devices. The dramatic restructuring of energy bands and density of states in HMAs caused by the replacement of anions with distinctly-mismatched isovalent constituents could further be an important course in improving their thermoelectric efficiency. In this paper, we attempt to explore and address the composition-induced modifications in the electronic band structure and the resultant effects on optical spectra and thermoelectric coefficients of GaN 1−x Sb x based HMAs in the framework of density functional theory. We observe, the substitution of N by Sb, considerably affects its band structure and split the conduction band minimum (CBM) into sub-bands. With increasing Sb composition, the lowest sub-band stemmed from N-s electrons has experienced drastic downward shift leading to energy gap narrowing. Interestingly, the energy gap narrowing along R- Γ is found to be faster than that of Γ- Γ point leading to an amazing direct to indirect band gap crossover. On the other hand, the composition-induced energy gap narrowing stimulates the red-shift in fundamental absorption edge in both ultraviolet and the infrared regime, making the GaNSb potentially useful material for photovoltaic applications. In addition, substantial effect on the thermoelectric coefficients of GaNSb is also observed via Sb substitution. We obtain larger Seebeck coefficient, improved power factors and figure of merit (ZT) for GaNSb at low Sb substitution and found diminishing effect with the further increase of Sb composition. With enhanced Seebeck coefficient, power factor and ZT values at modest doping levels, GaNSb alloy could be a promising candidate for near or above room temperature thermoelectric applications. [ABSTRACT FROM AUTHOR]

In the context of increasingly sophisticated chemistry, the production of hydrogen from water splitting has long been a promising process. The high purity of the product and low level of contamination make water splitting as an ideal way to produce hydrogen. In this paper, we designed a series of novel NiCoP@NiM LDH/NF catalysts (M=Cu, Fe, and Co) with a three-dimensional heterogeneous structure and outstanding hydrogen production efficiency. To better compare the hydrogen production efficiency of NiCoP@NiFe LDH/NF, we also performed the doping of other nonprecious metals Cu (NiCoP@NiCu LDH/NF) and Co (NiCoP@NiCo LDH/NF) and studied them as two extra catalysts. The NiCoP@NiFe LDH/NF electrodes display a low overpotential of only 119 mV at a current density of 10 mA·cm−2 in the alkaline environment of 1 M KOH for the hydrogen evolution reaction (HER). This superior performance of HER is related to the unique structure of NiCoP@NiFe LDH/NF. In addition, the Ni foam substrate has a three-dimensional network structure, the active site of the NiCoP@NiFe LDH/NF will be more easily exposed under the support of this unique structure. These experimental results and density functional theory (DFT) demonstrate that the NiCoP@NiFe LDH/NF electrode has the best electrochemical activity for HER. [Display omitted] • NiCoP@NiM LDH/NF (M=Cu, Fe, Co) was successfully synthesized by hydrothermal processes. • Density functional theory show that the NiCoP@NiFe LDH exhibits a smaller Gibbs free energy. • The NiCoP@NiFe LDH/NF displays a low overpotential of only 119 mV for hydrogen evolution reaction. [ABSTRACT FROM AUTHOR]

Recently, room-temperature multiferroic materials have attracted great interest as they are suitable for the design of low-power electronic and spintronic devices. In this paper, we have investigated the effect of annealing temperature on the structural, electrical and magnetic properties of CrFeO 3 multiferroic nanoparticles prepared by sol-gel auto-combustion method. The structural properties by observing X-ray diffractogram and its thorough Rietveld refinement confirmed the trigonal crystal structure with space group R 3 ̅. The crystallite size calculated from the W-H plot increases from 39.6 nm to 100.5 nm with the increase of annealing temperature. FTIR results confirmed the evolution of ilmenite type ABO 3 phase. Electron microscopy images showed increase of grain size due to agglomeration of nanoparticles at higher annealing temperature. EDXA spectra and color mapping demonstrated the elemental purity. Magnetic measurements revealed the antiferromagnetic nature of CrFeO 3 multiferroic nanoparticles. Electrical measurements showed the decrease in dielectric constant with the increase in frequency. We have validated the results by running systematically first-principle calculations (Density Functional Theory) on CrFeO 3 multiferroic nanoparticles. [Display omitted] • Effect of annealing temperature on the ilmenite CrFeO 3 multiferroic nanoparticles were investigated. • The crystallite size and electrical parameters enhances with the rise of annealing temperature. • The nanoparticles showed antiferromagnetic ordering with a high magnetization value. • The energy band-gap of CrFeO 3 multiferroics decreases with the increase of annealing temperature. • Systematically validated properties of CrFeO 3 nanoparticles Density Functional Theory. [ABSTRACT FROM AUTHOR]

In this paper, we report on a micro-sensor employing two-dimensional (2D)- zero-dimensional (0D) heterostructure based on MOSe 2 /ZnO (fabricated by a novel Complementary Metal Oxide Semiconductor (CMOS) compatible microwave-irradiation-assisted solvothermal route) as a receptor. Density Functional Theory (DFT) calculations show that the heterostructure is more favorable to the adsorption of hydrogen sulfide (H 2 S) gas than the pristine 2D nanosheets. Experimentally, the device demonstrates sensitivity in the ultra-low concentration H 2 S range (i.e. 200 ppb – 6.1 ppm), and response of as high as 9.08% (200 ppb) - 186.91% (6.1 ppm) could be obtained repeatably with decent signal-to-noise ratio and response/recovery time (~600 sec). The device stands well on various sensor parameter tests including absolute response percentage, lower limit of detection (LOD), repeatability, reproducibility, hysteresis error, etc. A sensing mechanism based on Wolkentein's model is proposed to understand the detection behavior of the device. • 2D–0DMOSe 2 /ZnO nanocomposite was synthesized by two-step top-down/bottom-up approach. • Density Functional Theory (DFT) studies suggest thin nanocomposite to be selective towards H 2 S gas. • A micro-sensor based on this nanomaterial was realized based on metal IDEs inte using CMOS fabrication technique. • The device was able to detect H 2 S gas in the range of 200 ppb – 6.1 ppm. • Response of as high as 9.08–186.91% was obtained in this concentration range of this analyte. • The response and recovery time of the device was found to be in the range of ~600 seconds. [ABSTRACT FROM AUTHOR]

We present band gap calculations of zinc-blende ternary CdS x Te 1-x semiconductors within the standard DFT and quasiparticle calculations employing pseudopotential method. The DFT, the local density approximation (LDA) and the Generalized Gradient Approximation (GGA) based calculations have given very poor results compared to experimental data. The quasiparticle calculations have been investigated via the one-shot GW approximation. The present paper discuses and confirms the effect of inclusion of the semicore states in the cadmium (Cd) pseudopotential. The obtained GW quasiparticle band gap using Cd +20 pseudopotential has been improved compared to the obtained results from the available pseudopotential without the treatment of semicore states. Our DFT and quasiparticle band gap results are discussed and compared to the available theoretical calculations and experimental data. [ABSTRACT FROM AUTHOR]

This paper presents a systematic first-principles study of phonons and Raman spectra of cubic Hg 3 Te 2 Cl 2 within a framework of DFT in the GGA/PBE approximation. The phonon dispersion, total and partial density of vibrational states for Hg 3 Te 2 Cl 2 crystals are analyzed. The identification of the vibrational modes at the Brillouin zone center is conducted and discussed in details. The first-principles calculated Raman-active phonon frequencies and simulated Raman spectra are compared with experimental data. The assignment of the phonon lines to define atomic vibrations was made on the basis of their symmetries in close comparison with results of lattice-dynamical calculations. Satisfactory agreement is obtained with experimental mode frequencies. [ABSTRACT FROM AUTHOR]

In this paper, a model based on the molecular field theory is used to fit experimental data of the magnetic hyperfine field (mhf) at nuclei of a magnetic dilute impurity in a magnetic host and determine separately the contributions of the host and the impurity to mhf, which otherwise would not be possible. The model is used to fit data on the temperature dependence of mhf at 140 Ce nuclei as an impurity replacing rare-earth (RE) ions in REAg (RE = Gd, Tb, Dy, Ho) hosts. Experimental data on GdAg and DyAg are available in the literature and data on the temperature dependence of mhf for TbAg and HoAg were measured by perturbed gamma–gamma angular correlation (PAC) spectroscopy. Due to the magnetic interplay between host and impurity magnetic ions, the behavior of the temperature dependence of mhf below respective T N of each compound shows an accentuated deviation from an expected Brillouin-like pattern for each compound. This unusual behavior is a consequence of an additional magnetic interaction which emerges from the polarization of localized moments of Ce induced by the magnetic field from RE ions. The impurity contribution calculated from the model are shown to follow the same behavior of the reduced hyperfine field determined from experimental data. The host contribution is discussed in terms of the indirect magnetic coupling between the magnetic RE ions of the host and the obtained values are supported by first-principles calculations based on the density functional theory (DFT). It is also shown that both contributions calculated by the model have values within the expected experimental systematic. Moreover, density of states (DOS) from first-principles calculations explain the mechanism responsible by the observed anomalous behavior of the temperature dependence of mhf. The model presented here can be applied to understand the complex phenomenon of interactions between the magnetic ions of a ordered host and dilute magnetic impurity atoms. The physical description of these magnetic interactions might have an important impact to new applications in spintronics and quantum computing. [ABSTRACT FROM AUTHOR]

In this paper, we combined experiments and first-principles calculations to investigate the physical properties especially the magnetic properties of Ga 1−x Cr x N and Si-doped Ga 1−x Cr x N thin films grown by molecular beam epitaxy. The results of experiments indicate that Si doping improved the crystallinity by improving the substitution of Ga in Si-doped Ga 1−x Cr x N. And the size and/or the number of vacancy defects are reduced in the Si-doped Ga 1−x Cr x N thin films. All the samples show room-temperature ferromagnetism, and the measured saturation magnetizations are 15 emu/cm 3 (2.26 μ B per Cr atom) and 10 emu/cm 3 (1.31 μ B per Cr atom) respectively for Ga 1−x Cr x N and Si-doped Ga 1−x Cr x N thin films. First-principles calculations based density-functional theory show that there is a strong magnetic coupling between the Ga vacancies and the impurities of Cr and Si ions. And Si doping reduced the saturation magnetization in Si-doped Ga 1−x Cr x N thin films which is in agreement with the experiment results. This intrinsic defect derived magnetic interaction plays an important role on improving the ferromagnetism in Ga 1−x Cr x N and Si-doped Ga 1−x Cr x N, and the ferromagnetism of the system is the result of long-range mediation between V Ga , Cr and Si ions. [ABSTRACT FROM AUTHOR]

In this paper, we investigated room temperature magnetic properties of Fe–N codoped, undoped, Fe doped, and N doped TiO 2 samples combing by experiments and first-principles calculations. All the samples fabricated by a two-step anodic oxidation method exhibit the crystal phase of anatase with the shape of nanotube. The calculated net moment values are in the order of Fe–N codoped TiO 2 > Fe doped TiO 2 > undoped TiO 2 > N doped TiO 2 with oxygen vacancies existing, which are in accord with the experimental results. The hybridization of Fe 3d, Ti 3d (nearest to the oxygen vacancies) and O 2p (nearest to the Fe defect) led to the spin-split of Fe 3d, Ti 3d and O 2p which devoted to the magnetism. The codoping of oxygen vacancies, N and Fe led to the complete spin-split of Fe 3d, Ti 3d and O 2p for Fe–N codoped TiO 2 samples which yield the highest saturation magnetization. [ABSTRACT FROM AUTHOR]

Plutonium (Pu) metal reacts rapidly in the presence of oxygen (O), resulting in an oxide layer that will eventually have an olive green rust appearance over time. Recent experimental work suggested that the incorporation of gallium (Ga) as an alloying impurity to stabilize the highly symmetric high temperature δ-phase lattice may also provide resistance against corrosion/oxidation of plutonium. In this paper, we modeled a 9.375 at. % Ga stabilized δ-Pu (111) surface and investigated adsorption of atomic O using all-electron density functional theory. Key findings revealed that the O bonded strongly to a Pu-rich threefold hollow fcc site with a chemisorption energy of −5.06 eV. Migration of the O atom to a Pu-rich environment was also highly sensitive to the surface chemistry of the Pu–Ga surface; when the initial on-surface O adsorption site included a bond to a nearest neighboring Ga atom, the O atom relaxed to a Ga deficient environment, thus affirming the O preference for Pu. Only one calculated final on-surface O adsorption site included a Ga–O bond, but this chemisorption energy was energetically unfavorable. Chemisorption energies for interstitial adsorption sites that included a Pu or Pu–Ga environment suggested that over-coordination of the O atom was energetically unfavorable as well. Electronic structure properties of the on-surface sites, illustrated by the partial density of states, implied that the Ga 4p states indirectly but strongly influenced the Pu 6d states to hybridize with the O 2p states. The Ga 4p states also weakly influenced the Pu 5f states to hybridize with the O 2p states, even though Ga was not participating in bonding with O. [ABSTRACT FROM AUTHOR]

In this paper, a computational study is carried out on unusual electrical conductivity of α-CuSe compound in the bulk state and its nano-layers (NLs). The property is studied by using Full-potential calculations and the Boltzmann transport equation assuming a suitable temperature-dependent relaxation time for charge carriers. The dependence of electrical conductivity per temperature changes is considered from 80 up to 330 K as well as separately in low-temperature. Our results show that CuSe has a high anisotropy electrical conductivity meaning that the in-plane conductivity is very good, with high hole transport but the z -axis transport is completely different, with two types of electron and hole carriers. By considering the curves of electrical conductivity in low-temperature and again reviewing the experimental data, we predict probability of occurrence of a superconductivity phase transition in this compound in a temperature about 3 K. This possibility has been discussed by assuming a simple model. In continuation of our previous work, we calculate the values of electrical conductivity of the most stable NLs of CuSe. Our results show that the electrical conductivity of NLs in x (or y ) direction is nearly 10 6 orders of magnitude than z direction. Therefore, the NLs have very good hole conductive in x (or y ) direction but their conductivity is ultra-low in z -axis. [ABSTRACT FROM AUTHOR]

The thermodynamic modeling of non-stoichiometric, multisublattice intermetallic phases using the Compound-Energy Formalism (CEF) involves the determination of parameters representing the Gibbs energy ( G m ) of binary compounds, the so-called “end-member compounds” (EMCs), which are often metastable or hypothetical. In current CALPHAD ( i.e ., “Calculation of Phase Diagrams”) work, these quantities are treated as free parameters to be determined by searching for the best fit to the available information in the optimization procedure. The general purpose of this paper is to propose a theoretical approach to the study of the EMCs which makes use of density-functional-theory (DFT) ab initio calculations. The present method is applied to the EMCs involved in the CEF modeling of the non-stoichiometric (hP6) Ni 2 In-structure type phase of the Ni–In and Ni–In–Sn systems using the three-sublattice models (Ni) 1 (Ni,Va) 1 (In,Ni) 1 and (Ni,Va) 1 (Ni,Va) 1 (In,Ni,Sn) 1 , respectively. By means of systematic ab initio projected augmented waves (PAW) calculations using the VASP code we study the EMCs involved in the CEF formulations of the G m for this phase in the binary and the ternary systems. Specifically, we study the twelve EMCs corresponding to the following sublattice occupations: (Ni) 1 (Ni) 1 (In) 1 , which is usually described as Ni:Ni:In ( i.e ., a compound with formula “Ni 2 In”), Ni:Ni:Ni ( i.e. , “Ni 3 ”), Ni:Ni:Sn (“Ni 2 Sn”), Ni:Va:In ( i.e. , “NiIn”), Ni:Va:Ni ( i.e. , “Ni 2 ”), Ni:Va:Sn (“NiSn”), Va:Ni:In (“NiIn”), Va:Ni:Ni (“Ni 2 ”), Va:Ni:Sn (“NiSn”), Va:Va:In (“In”), Va:Va:Ni (“Ni”), and Va:Va:Sn (“Sn”). For the listed EMCs, we report the lattice-parameters, the volume per atom, the electronic density of states and various types of cohesive properties usually taken as macroscopic manifestations of the bonding strength, viz. , the bulk modulus and its pressure derivative, the cohesive energy and the energy of formation from the elements. Trends in these quantities are established as a function of the occupation of the various sublattices by the different components and discussed in terms of the interactions between d electrons of the transition element as well as the hybridization between them and the s and p electrons of the non-transition metal. In addition to the reported thermodynamic information of direct use as input in the CALPHAD optimizations, the picture of the variations in cohesive properties emerging from the present work should be useful in systematizing the thermophysical and structural database for this class of compounds. [ABSTRACT FROM AUTHOR]

The present paper reports six distinctive doping effects of γ-Si 3 N 4 resulted with C, O and F dopants. Based on density functional calculations, 15 doped structures from different doping method are appreciated with formation and binding energies. Six of them, which are considered to be more easily to synthesize, are put into investigations of electronic and optical properties. The successively reduced energy gap, transformation of semiconductor to conductor and enhanced visible-light absorption coefficient are found. The mechanisms for six doping effects are explored with four concentrations and elucidated on the basis of the electronic structure. [ABSTRACT FROM AUTHOR]

Highlights: [•] Solute–vacancy binding is a key quantity in understanding diffusion kinetics. [•] A large database of solute–vacancy binding energies in Cu from first-principles calculations based on density functional theory was presented in the paper. [•] The trends in the binding energies in terms of super cell size, solutes size and magnetic moments were analyzed. [Copyright &y& Elsevier]

• The ORR and OER on bimetallic alloys encapsulated in fullerenes are studied by DFT. • C 50 and C 60 are the better carbon shell to encapsulate bimetallic alloys than C 40. • Co 1 Ni 3 @C 50 possesses the best ORR activity with the overpotential of 0.35 V. • Co 2 Ni 2 @C 60 has the most excellent OER activity with the overpotential of 0.36 V. [Display omitted] Revealing the structure-activity relationship of catalysts is conducive to design high-activity catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this paper, the ORR and OER catalytic activity of bimetallic alloys encapsulated in fullerenes M1 x M2 4− x @C n (M1 x M2 4− x represents Fe x Co 4− x , Fe x Ni 4− x , Co x Ni 4− x ; x = 1, 2, 3; n = 40, 50, 60) are investigated by density functional theory methods. The calculated encapsulation energy (E enc) indicates that except for the value on Fe 1 Ni 3 @C 60 , all the E enc values are positive on the studied M1 x M2 4− x @C n , suggesting that additional externally supplied energy will be needed to encapsulate bimetallic alloys in fullerenes. As the size of the C n cage decreases, the charge transfer between the alloy core and the carbon shell becomes greater, resulting in a roughly increase in the binding strength of the reaction intermediates on M1 x M2 4− x @C n. Compared with C 40 , C 50 and C 60 fullerenes are recognized as the more suitable shell for encapsulating bimetallic alloys toward ORR and OER. Based on the current study, Co 1 Ni 3 @C 50 is screened out with the best ORR activity (η ORR = 0.35 V) and Co 2 Ni 2 @C 60 shows the most excellent OER activity (η OER = 0.36 V) among all the M1 x M2 4− x @C n. [ABSTRACT FROM AUTHOR]

Abstract: Combustion of citrate complex is a popular choice to synthesize nanocrystals of transition metal oxides in a single-step process. The amount of citric acid used for combustion is conventionally calculated based on the total valence of the oxidizing and reducing agents while keeping the equivalent ratio unity such that combustion energy is a maximum. This paper demonstrates by employing quantum chemical calculations that the amount of citric acid could be reduced to nearly two-third if prepared for appreciable amounts. Transition metal oxides belong to quaternary double perovskite has been synthesized as nanocrystals as examples to validate the calculations. [Copyright &y& Elsevier]

• Co 9 S 8 @NiCo 2 O 4 is prepared by hydrothermal and electrocatalytic deposited reaction. • Co 9 S 8 @NiCo 2 O 4 -10 cycles and Co 9 S 8 @NiCo 2 O 4 -70 cycles can serve as electrocatalytic water splitting catalysts. • Co 9 S 8 @NiCo 2 O 4 -10 cycles presents an excellent long-term electrochemical durability. Using Co 9 S 8 @NiCo 2 O 4 -10 cycles and Co 9 S 8 @NiCo 2 O 4 -70 cycles as a bifunctional water splitting catalyst, which overpotential of ~ 320 mV is obtained at a very low cell voltage of 1.55 V with a current density of 10 mA cm−2 in 1.0 M KOH. [Display omitted] The hydrogen and oxygen generation has been regarded as the most promising solution through electrochemical water splitting for the sake of alleviating the energy crisis and climate change. In this paper, we developed an in-situ deposition approach for depositing NiCo 2 O 4 on the surface of Co 9 S 8 , and then the loading amount of NiCo 2 O 4 was controlled by regulating the deposited number of cycles. In addition, the materials were used as catalysts for oxygen production and hydrogen production for the first time. When Co 9 S 8 @NiCo 2 O 4 -10 cycles, Co 9 S 8 @NiCo 2 O 4 -70 cycles and Co 9 S 8 is used as a bifunctional catalyst, Co 9 S 8 @NiCo 2 O 4 -70 cycles // Co 9 S 8 @NiCo 2 O 4 -10 cycles displays a smaller cell voltage (1.55 V@10 mA cm−2) than Co 9 S 8 (1.68 V@10 mA cm−2). Density functional theory calculation is used to calculate the water adsorption energy on the surface of the material to further reveal the reaction mechanism of water oxidation process. The work provides a new idea for the development of a relatively low toxicity and environmental friendly bifunctional electrocatalyst for industrial water electrolysis applications. [ABSTRACT FROM AUTHOR]

• A simple and scalable method was used to prepare nitrogen-sulfur co-doped graphene aerogels. • The adsorption and electronic properties of the N/S co-doping system were systematically studied. • Theoretical and experimental methods were used to verify the effect of doping graphene on the original anode materials. In order to prepare anode materials with a high specific capacity, super rate performance and relatively good stability, the N, S dual-doped porous graphene aerogels/natural graphite composites (denoted as N, S-pGA/NG) were designed via annealing incorporation with hydrothermal method in this paper. Commercial graphite anode materials were modified by adding a small amount of N/S dual-doped Porous graphene aerogels to make them have excellent electrochemical properties. At the same time, in order to further explain the internal mechanism of nitrogen and sulfur atoms doped graphene to improve the properties of natural graphite anode electrodes, we used density functional theory to calculate the adsorption energy, static charge and density of states, which proved that the this optimization's mechanism may lie in the effect of nitrogen and sulfur co-doping on the adsorption behavior of lithium atoms. Therefore, the N, S-pGA/NG exhibited high capacities (531 mAh g−1 at 0.1 C), improved rate performance (277 mAh g−1 at 2 C), and good cycling stability. [ABSTRACT FROM AUTHOR]

• Study of structural, mechanical, electronic, and magnetic properties of new series of Fe-based quaternary Heusler alloys. • Interesting properties like spin-gapless semiconducting (SGS) behavior and half-metallicity are realized. • Discrepancies observed in electronic and magnetic properties of Fe based quaternary Heusler alloys containing Yttrium is redressed. This paper presents a detailed investigation of FeCr-based quaternary Heusler alloys. By using ultrasoft pseudopotential, electronic and magnetic properties of the compounds are studied within the framework of Density Functional Theory (DFT) by using the Quantum Espresso package. The thermodynamic, mechanical, and dynamical stability of the compounds is established through the comprehensive study of different mechanical parameters and phonon dispersion curves. The meticulous study of elastic parameters such as bulk, Young's, shear moduli, etc. is done to understand different mechanical properties. The FeCr-based compounds containing also Yttrium are studied to redress the contradictory electronic and magnetic properties observed in the literature. The interesting properties like half-metallicity and spin-gapless semiconducting (SGS) behavior are realized in the compounds under study. [ABSTRACT FROM AUTHOR]

• Two dimensional Au (111) surface with Fe dopant is reported to investigate the catalytic activity in this paper. • N 2 molecule is activated by Fe-embedded monolayer Au (111) surface obviously. • The possible N 2 reduction paths are investigated, and the mixed mechanism is more conducive to the reaction. [Display omitted] Electrochemical N 2 reduction is a promising method for NH 3 production due to its environmental friendliness. By means of density functional theory, we systematically investigated the potential of Fe-embedded Au (111) monolayer as a candidate of N 2 fixation catalyst. As a thermodynamically stable surface, the Fe-embedded Au (111) shows a high catalytic activity for inert N 2 molecule. The bond N-N of N 2 molecule with an end-on configuration is activated due to the interaction among Fe- d z 2 , N- s and N- p z orbitals. Then, our calculated results also reveals that the limiting step of N 2 reduction reaction is the first hydrogenation step with the free energy barrier of 0.85 eV. This finding may open a promising method of NH 3 production and contribute to the development of the monolayer two-dimensional metals. [ABSTRACT FROM AUTHOR]

In this paper, the phase transition mechanism and device conversion performance of the Sb/GeTe superlattice-like films were studied and showed improved amorphous thermal stability and resistance drift compared to the pure Sb films. Transmission electron microscopy showed that the Sb layer plays a leading role in the crystallization process, forming a large number of Sb grains. The metallic behavior of the Sb/GeTe thin films was confirmed by density functional theory calculations. The thermal conductivity of the crystalline film was found to be higher than that of the amorphous film, and the thermal conductivity of the Sb/GeTe film was lower than that of the other monolayer films. In the Sb/GeTe film, the Sb–Sb and Ge–Te bonds were the main bond structures, and some Sb–Te bonds were formed at the layer interfaces, enhancing the stability of the film. Laser picosecond measurements showed that Sb/GeTe film had a higher crystallization rate than the GeTe film. The phase change memory devices based on the Sb/GeTe thin films were found to have lower operational power consumption and higher transition speed. These results showed that the Sb/GeTe thin film explored in this study was a promising phase change storage thin film with excellent performance. ● The coupling effect of multiple interfaces in Sb/GeTe superlattice films were investigated in detail. ● The redistribution of the atoms after crystallization was observed. ● The energy band structure of the Sb/GeTe superlattice films was obtained by density functional theory calculations. ● The interface coupling improved the phase transition behavior and the phase transition performance. [ABSTRACT FROM AUTHOR]