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The combined influence of spin–orbit coupling and spatial inversion asymmetry leads to an enhancement of electronic properties, including Rashba spin-splittings as well as spin Hall effect. Recent research has shown the possibility to create two-dimensional Janus materials with inherent structural asymmetry. In this work, the structural stability, piezoelectricity, electronic properties, and intrinsic spin Hall conductivity of quintuple-layer atomic Janus Sb2XSX' (X, X' = S, Se, Te; X ≠ X') monolayers are investigated using first-principles calculations within the framework of density functional theory. They demonstrate relatively high in-plane piezoelectric coefficients ( d 22) and also possess out-of-plane piezoelectric coefficients ( d 31), which is due to the breaking of inversion symmetry in the crystal structure with the space group P3m1. Large Rashba parameters are obtained in Janus Sb2XSX' monolayers, especially high for Sb 2 S 2 Te (1.62 eV Å) and Sb 2 SeSTe (1.33 eV Å) due to strong spin–orbit coupling. Moreover, Rashba-like spin-splitting is also observed in the edge-states as well, which is highest for Sb 2 SeSTe with 2.17 eV Å. Furthermore, Sb 2 S 2 Te and Sb 2 SeSTe monolayers reveal a significantly high Berry curvature (65.59 and 61.05 Bohr 2), spin Berry curvature (− 118.4 and − 120.6 Bohr 2), and spin Hall conductivity (1.8 and 1.6 e 2 /h). Our results suggest that Janus Sb 2 S 2 Te and Sb 2 SeSTe monolayers could be an excellent platform for multifunctional electronic applications. [ABSTRACT FROM AUTHOR]

High-performance thermoelectric (TE) properties of pristine Sn-based colusites are investigated theoretically. A recent experimental article [Bourgès et al., J. Am. Chem. Soc. 140, 2186 (2018)] showed how structural disordering reduced the lattice thermal conductivity in Cu 26 V 2 Sn 6 S 32 and improved the TE figure of merit (ZT). In this article, it is observed that low energy soft optical phonons and the vacancy defect play a crucial role in reducing thermal conductivity. An ultra-low lattice thermal conductivity 0.35 Wm − 1 K − 1 is observed in Cu 26 V 2 Sn 6 Se 32. It is seen that mass variance perturbation and number of vacancies are important to tune the thermal and electrical properties. Though the electrical conductivity decreases with the number of vacant sites, the Seebeck coefficient enhances due to the reduction in carrier concentration. The detailed study of thermoelectric properties of Cu 26 V 2 Sn 6 Se 32 with Se vacancies points to enhanced ZT values of 0.34 at 300 K, which is ∼ 15 times greater than ZT of Cu 26 V 2 Sn 6 S 32. A maximum ZT of 1.68 at 755 K is predicted for Cu 26 V 2 Sn 6 Se 32 with Se vacancies, which is the highest to date reported for Sn-based colusites. [ABSTRACT FROM AUTHOR]

Ti2AlNb intermetallic is a potential substitute for Ni-based superalloys in next-generation aerospace materials. In the current work, the structural, mechanical, and thermodynamic properties of the Ti2AlNb in B2 phase are studied at various temperatures by implementing first principle calculations under quasi-harmonic approximations. The lattice parameter, elastic moduli, and linear coefficient of thermal expansion (CTE) are well reproduced according to the experimental reports. The intermetallic remains mechanically and dynamically stable at all temperatures. The elastic moduli and microhardness decrease slightly from 0 to 1300 K. Furthermore, the calculations reveal that Ti2AlNb remains ductile at all temperatures. Phonon calculations show that Nb atoms are dominant contributor to the vibrational modes. The temperature-dependent heat capacities, entropy, CTE, and isothermal bulk modulus are further investigated. Present calculations predict that the B2 phase Ti2AlNb is a suitable candidate for the manufacturing of high-temperature application parts such as turbine blades of aerospace engines. [ABSTRACT FROM AUTHOR]

We theoretically investigate the thermoelectric properties of sintered SiGe alloys, compare them with new and previous experimental measurements, and evaluate their potential for further improvement. The theoretical approach is validated by extensive comparison of predicted bulk mobility, thermopower, and thermal conductivity, for varying Ge and doping concentrations, in the 300-1000K temperature range. The effect of grain boundaries is then included for Si0.8Ge0.2 sintered nanopowders and used to predict optimized values of the thermoelectric figure of merit at different grain sizes. Our calculations suggest that further optimization of current state of the art n-type (p-type) material would be feasible, possibly leading to ∼5% (4%) ZT enhancement at 1000 K and 16% (6%) at room temperature. Even larger enhancements should be possible if the phonon scattering probability of the grain boundaries could be increased beyond its present value. [ABSTRACT FROM AUTHOR]

Perovskite oxide surfaces and their interfaces host two-dimensional electron gas (2DEG) and many other emergent properties. Polar-polar perovskite oxide heterostructure LaVO 3 /KTaO 3 with the n-type interface is studied using comprehensive first principle calculations. Our calculations involve crystal orientation-dependent investigation of 2DEG for two types of terminations of KTO surface slab namely asymmetric and symmetric terminations in [001] and [111] orientations. Electronic structure calculations show n-type conducting interface and the Rashba spin splitting in the bands with α R in the range 0. 37 − 0. 9 eV Å and E R in the range of 0. 6 − 4. 5 eV owing to the high spin–orbit coupling of Ta and symmetry breaking electric field present in the heterostructure. The occupation of heavy bands d y z / d x z and the additional occupation of d z 2 bands in [111] orientation give rise to orbital-dependent Rashba splitting. The charge density difference plots corroborate the transfer of charge from the surface to the interfacial region. Constant energy contour plots of spin texture confirm the 2D Rashba spin splitting of 2DEG in [001] orientation, while a complex spin structure is observed in [111] orientation. Thus, our findings extend the scope of perovskite-based heterostructures for future spintronic applications maneuvering the Rashba effect with a fascinating spin structure. • The heterostructure has an n-type conducting interface and a 2DEG with parabolic bands. • The Rashba spin splitting with Rashba coefficient α R in the range 0. 3 − 0. 9 eV Å is calculated. • Orbital-dependent Rashba splitting is seen due to the orbital occupation or hybridization. • The charge transfer occurs from the surface layers to the interfacial region. • 2D Rashba splitting and complex spin structure is noticed in [001] and [111] orientations, respectively. [ABSTRACT FROM AUTHOR]

Recent experiments show that strontium titanate (STO) can be a very good thermoelectric photodetector and has very high photoconductivity under the illumination of UV light. By using a simple theoretical model based on the Boltzmann transport equation (BTE) photothermoelectric properties of STO are investigated in this article employing the photocarriers concentration same as doping effect. An enhancement in electrical conductivity from 0.350 S/m to 222 S/m is obtained at 300 K with ∼ 70% agreement with the experiment. In power factor, about 182 times (0.43 μ Wm − 1 K − 2 to 78.3 μ Wm − 1 K − 2 ) enhancement is observed after UV illumination. A strong role of Ti atoms is observed in electron–phonon scattering and different scattering mechanisms have dominance at different carrier concentrations. This mechanistic understanding will be helpful for designing photodetectors based on photothermoelectric (PTE) effect. [ABSTRACT FROM AUTHOR]

A theoretical study is performed on narrow bandgap Janus monolayer MoWCO2 using the density functional theory and the Boltzmann transport equation. The scattering rate is calculated for electron–phonon, phonon–phonon, phonon-boundary, and electron-boundary scattering. It has a power factor (6.5 × 103 μ W/mK2) for p-type and (1.5 × 103 μ W/mK2) for n-type at T = 700 K. A strong effect of surface scattering is observed in phonon transport, and lattice thermal conductivity is reduced to 65 W/m K from 308 W/m K at T = 300K for 1 μ m width (L) of ribbon. In contrast, there is no change observed in electrical conductivity. This reduction in thermal conductivity improves the thermoelectric figure of merit to 0.33 (p-type) and 0.08 (n-type) at T = 700 K for L = 10 nm from 0.04 (p-type) and 0.01 (n-type). The obtained Young's modulus and Poisson's ratio are 244 N/m and 0.55, respectively, indicating that the material can be deformed under small strain. The obtained in-plane piezoelectric coefficients are e11 = 268 pC/m and d11 = 1.6 pm/V. This indicates the material will be suitable for wearable thermoelectric devices and sensor applications. [ABSTRACT FROM AUTHOR]

Although a large number of Zintl compounds have shown high thermoelectric efficiency, a very few n-type compounds are reported. Here, we use theoretical models based on Boltzmann transport formalism to determine the electrical and phonon transport properties of Potassium Antimonide (KSb) and Potassium Bismutide (KBi). Electron–phonon scattering rate is calculated based on simple model of Deformation potential and compared with the mode-dependent scattering rates by using Born approximation. The results of the two models are in good agreement. The lattice thermal conductivity is found as 0.83 W m − 1 K − 1 for KSb and 0.52 W m − 1 K − 1 for KBi at room temperature. The obtained maximum value of thermoelectric figure of merit (ZT) is 0.96 for KSb and 0.78 for KBi at 600 K by tuning the carrier concentration and temperature reveal these two n-type materials can be used as efficient thermoelectric materials. [ABSTRACT FROM AUTHOR]

Twisted bilayer graphene (tBLG) is an intriguing low-dimensional material due to the possible modulation of electronic and thermal properties and a subject of intense research, both for its fundamental physics as well as for its potential in technological applications. Here, the thermoelectric properties of bilayer graphene are investigated for twist angles of 0 ° and 20 °. The thermoelectric properties are calculated using density functional theory, molecular dynamics, and Boltzmann transport theory. An increase in the power factor is observed for 20 ° tBLG due to an increase in the Seebeck coefficient by 2.2 times at 700 K. The thermal conductivity for 20 ° tBLG is reduced by 20% and 22% for 325 and 700 K, respectively, as compared to BLG. Consequently, an overall ∼ 3 times enhancement of a thermoelectric figure of merit (ZT) for 20 ° tBLG compared to BLG at 700 K is obtained. A strong effect of boundary scattering on thermal transport is observed. However, for electron transport, it is negligible for 20 ° tBLG. Due to this combined effect, an increase of 194 times in ZT is obtained at a ribbon width of L = 10 nm and T = 700 K for 20 ° tBLG. This indicates that 20 ° twisted bilayer graphene could be an efficient thermoelectric power generator and can be a suitable material for carbon-based technology and devices. [ABSTRACT FROM AUTHOR]

Thermal conductivity of Si nanowire is calculated by applying Monte Carlo (MC) simulation of 110 nm, 37 nm, and 22 nm wire diameter. To study the thermal conductivity of both thick and thin nanowires different phonon group velocity is used in the simulation. This change in the phonon velocity for small diameter nanowire is due to the phonon confinement effect, which decreases the slope of phonon acoustic modes. Very good agreement with previously reported experimental value is obtained for all nanowire diameters. Another investigation by using average relaxation time approximation is also discussed along with the Monte Carlo simulation. [ABSTRACT FROM AUTHOR]

Oxygen and hydrogen evolutions are the two fundamental processes involved in electrocatalytic water splitting. Two dimensional (2D) transition metal dichalcogenides (TMDCs) and graphene-based materials are regarded as the emergent catalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Herein, doped graphene and molybdenum dichalcogenide heterostructures are evaluated for their catalytic activity using density functional theory (DFT). The Janus MoSSe and P-doped graphene heterostructure is found to have the best electrocatalytic activities with smaller overpotential values (ηOER = 1.67 V and ηHER = 0.10 V) as compared to those of the parent monolayers graphene (ηOER = 1.85 V and ηHER = 1.80 V) and MoS2 (ηOER = 2.99 V and ηHER = 1.72 V). [ABSTRACT FROM AUTHOR]

Electronic and transport properties of Bi2S3 with various dopants are studied using density functional theory and experimental characterizations. First, principle calculations of thermoelectric properties are used to evaluate the thermoelectric potential of the orthorhombic Bi2S3 structure. The computational screening of extrinsic defects is used to select the most favorable n-type dopants. Among all the dopants considered, hafnium and chlorine are identified as prospective dopants, whereas, e.g., germanium is found to be unfavorable. This is confirmed by experiment. Seebeck coefficient (S) and electrical conductivity (σ) measurements are performed at room temperature on pellets obtained by spark plasma sintering. An increase of power factors (S2·σ) from around 50 up to 500 μW K-2m-1 is observed for differently doped compounds. In several series of samples, we observed an optimum of power factor above 500 μW K-2m-1 at room temperature for a chlorine equivalence of 0.25 mol. % BiCl3. The obtained results are plotted on a semilogarithmic log (r) versus S graph to demonstrate that a very strong linear trend that limits the power factor around 500 μW K-2m-1 exists. Further improvement of Bi2S3 as thermoelectric material will require finding new doping modes that will break through the observed trend. The results of stability tests demonstrate that properties of optimally doped Bi2S3 are stable. [ABSTRACT FROM AUTHOR]

An energetic and dynamical stability analysis of five candidate structures—hexagonal, buckled hexagonal, litharge, inverted litharge, and distorted-NaCl—of the SnS monolayer is performed using density functional theory. The most stable is found to be a highly distorted-NaCl-type structure. The thermoelectric properties of this monolayer are then calculated using the density functional theory and the Boltzmann transport equation. In terms of phonon scattering, there is a sharp contrast between this monolayer and bulk materials, where normal processes are more important. The calculations reveal that the SnS monolayer has enhanced electrical performance as compared to the bulk phase. As a consequence, high figures of merit Z T ∼ 5 and Z T ∼ 1.36 are predicted at 600 and 300 K, respectively, for the monolayer, ∼ 33 times higher than the Z T of its bulk analog. Therefore, this structure is an interesting candidate for room-temperature thermoelectric applications. A comparison between the fully ab initio results and simpler models based on relaxation times for electrons and phonons highlights the efficiency of computationally inexpensive models. However, ab initio calculations are found to be very important for the prediction of thermal transport properties. [ABSTRACT FROM AUTHOR]

Herein, the formation of the NiWO 4 -NiO interface has been designed and synthesized via a three-step method. This strategy enhances the chance of the formation of abundant heterointerfaces due to the fine distribution of NiWO 4 nanoparticles over Ni(OH) 2 sheets. NiWO 4 -NiO has superior HER activity in an alkaline (1M KOH) electrolyte with modest overpotentials of 68 mV at 10 mA cm−2 current density. The catalyst is highly stable in an alkaline medium and negligible change was observed in the current density even after 100 h. This study explores a unique method for high-performance hydrogen generation by constructing transition metal-oxides heterojunction. The XPS studies reveal an electronic redistribution driven by charge transfer through the NiWO 4 -NiO interface. The density functional theory (DFT) calculations show that the NiWO 4 -NiO exhibits a Pt-like activity with the hydrogen Gibbs free energy (ΔG H *) value of 0.06 eV compared to the Pt(ΔG H *=-0.02eV) [Display omitted] The activity-enhancement of a new-generation catalyst focuses on the collegial approach among specific solids which exploit the mutual coactions of these materials for HER applications. Strategic manipulation of these solid interfaces typically reveals unique electronic states different from their pure phases, thus, providing a potential passage to create catalysts with excellent activity and stability. Herein, the formation of the NiWO 4 -NiO interface has been designed and synthesized via a three-step method. This strategy enhances the chance of the formation of abundant heterointerfaces due to the fine distribution of NiWO 4 nanoparticles over Ni(OH) 2 sheets. NiWO 4 -NiO has superior HER activity in an alkaline (1 M KOH) electrolyte with modest overpotentials of 68 mV at 10 mA cm−2 current density. The catalyst is highly stable in an alkaline medium and negligible change was observed in the current density even after 100 h of continuous operation. This study explores a unique method for high-performance hydrogen generation by constructing transition metal-oxides heterojunction. The XPS studies reveal an electronic redistribution driven by charge transfer through the NiWO 4 -NiO interface. The density functional theory (DFT) calculations show that the NiWO 4 -NiO exhibits a Pt-like activity with the hydrogen Gibbs free energy (ΔG H *) value of 0.06 eV compared to the Pt(ΔG H * = −0.02 eV). [ABSTRACT FROM AUTHOR]

Tin-based chalcogenides have a lot of potential as thermoelectric materials due to their ultralow thermal conductivity. Therefore, most reports on doped SnS focus on its power factor as the other condition for a high thermoelectric figure of merit (ZT). Here, we use the Boltzmann transport formalism to calculate both the power factor and the thermal conductivity for SnS, SnSe, and SnS x Se 1 − x and compare it with experimental measurements. Our theoretical model, based on a relaxation-time formalism, is in very good agreement with the reported values. We conclude that, while impurity scattering plays a major role in electron transport and, therefore, largely determines the power factor, alloy scattering is crucial for phonon transport. Specifically, alloying reduces the thermal conductivity of SnSe 0.70 S 0.30 by a factor of ∼ 1.3 compared to SnSe and by a factor of ∼ 2 compared to SnS. This leads to ∼ 65 % and ∼ 33 % enhancements of ZT for p-type and n-type doping, respectively, at 800 K with respect to SnSe. [ABSTRACT FROM AUTHOR]

Perovskite oxides are well-known for exhibiting semiconducting properties and widely used for electronic applications. The combination of two different perovskite oxides form heterojunction interface that tailors the charge transfer mechanism. Here, the thermoelectric (TE) electrical transport properties are investigated of perovskite oxide heterostructure (HS) L a V O 3 / K T a O 3 (L V O / K T O) using Boltzmann transport equation (BTE) for symmetric and asymmetric termination in [001] orientation. The electron–phonon scattering and defect scattering due to oxygen vacancies are incorporated with BTE. A strong electron–phonon scattering is observed. The effect of oxygen defect concentration on electrical transport is also studied. The HS exhibits high electrical conductivity 2. 9 × 1 0 4 S/m at room temperature due to n-type conducting interface and highly dispersive degenerate conduction bands. Besides moderate Seebeck coefficient, a relatively high thermoelectric power factor of 222 μ V m − 1 K − 2 for symmetric termination HS is obtained at 300 K as compared to bulk K T a O 3 and S r T i O 3 . The high power factor and low electronic thermal conductivity (0.19 Wm − 1 K − 1 ) designate L V O / K T O HS as an efficient material for photothermoelectric-based detectors and photovoltaic applications. • Electrical transport is predicted using Boltzmann transport theory. • Defect scattering due to oxygen vacancies is implemented. • Electron phonon scattering dominant at all temperatures. • High electrical conductivity of 2.9 x 10 4 S/m is obtained at 300 K. • Enhancement in power factor compared to bulk KTO and STO. [ABSTRACT FROM AUTHOR]

A model of the lattice thermal conductivity, based on the quasi-harmonic approximation, is validated on a dataset of 42 rock-salt and zinc-blende compounds. The model reliably reproduces experimental thermal conductivities ranging over several orders of magnitude. The good performance of the model is related to the definition of the mode-averaged Grüneisen parameter. The model is applied to the silicon-based clathrates and found to correctly reproduce the two orders of magnitude reduction of the lattice thermal conductivity compared to Silicon in the diamond structure. It is shown how the introduction of the clathrate structure and the guest atoms lead to a reduction of approximately one order of magnitude each. The clathrate structure is found to both increase the anharmonicity and decrease the average phonon velocity, whereas the reduction due to the guest atom is almost purely due to increased anharmonicity. [ABSTRACT FROM AUTHOR]

Human breathing is analyzed via detecting NO x and Humidity on Co cluster decorated N-Gr matrix because of different adsorption energies enabling a reliable respiratory diagnostic sustainable self-power platform. [Display omitted] • Developed a Triboelectric self-power sensing platform for respiratory diagnosis. • Cobalt anchored n-doped carbon matrix has been taken for active material. • Improve reliability via sensing Humidity and NO x in same platform. • Low cost device with potential application in wearable electronics. Self-powered ultrafast sensors have received much attention for sustainable operation without any external power source in the Internet of Things (IoT) platform. This paper proposes faster responsive, highly sensitive triboelectric nanogenerator (TENG) sensors based on few layered nitrogen-doped graphene anchored with cobalt nanocluster (Co-N-Gr) to detect the relative concentration of target species, their proximity analysis, and monitor malfunction of human respiration in real-time. Herein, to understand the sensing mechanism, P-type behaviour of this active material is verified under the FET platform by reducing the leakage current density via the implementation of dual dielectric gate (NiO (200 nm)-SiO 2 (10 nm)) oxides leading to better control over channel mobility. The device exhibits maximum sensitivity of around 4722 % at zero bias conditions with excellent response and recovery time of 1.16 s and 1.39 s, respectively which falls within the range of standard human breathing frequency. The triboelectric nature of the sensor device at 1 V bias under natural breathing exhibits a high sensitivity (39.56 %) towards relative humidity of 10–90 % with excellent stability over 13 h. In addition, our TENG sensor is highly sensitive towards NO x content upto ppb level which can improve reliability towards asthma detection as NO x content is relatively higher in asthma patients. This approach provides an integrated platform not only towards selective detection of NO x content as well as to identify the individual breathing strength. Furthermore, as-fabricated self-powered device demonstrates its potential in differentiating various respiratory status and has the capability to detect acute exacerbation of chronic obstructive pulmonary disease (AECOPD) via a distinct pattern recognition. Therefore, the work paves the way to design a low-cost flexible device fabrication on Kapton substrate integrable with wearable appliances for commercialization. [ABSTRACT FROM AUTHOR]

Electrocatalytic water splitting is one of the key technologies for future energy systems envisioned for the storage of energy obtained from variable renewables and green fuels. The development of efficient, durable, Earth-abundant and cheap electrocatalysts for the oxygen evolution reaction is a scorching area of research. The oxygen evolution reaction has huge potential for fuel cell and metal–air battery applications. Herein, we reported interfacially interacted and uniformly decorated Co3O4–NiO hybrid nanostructures formed by a metal–organic framework (Co2–BDC(OH)2) using BDC as a linker to the metal center. The fine nanosheets of Co2–BDC(OH)2 were first uniformly grown over the honeycomb-like structure of nickel foam (NF). After controlled calcination of these nanosheets/NF composites, a uniformly decorated, binder-free Co3O4–NiO/NF electrocatalyst was synthesized. The transformation of Co2-BDC(OH)2/NF into Co3O4–NiO/NF was characterized by several techniques such as powder X-ray diffraction (PXRD), X-ray photoelectron spectroscopy, transmission electron microscopy, etc. The catalyst exhibits a low overpotential of 311 mV vs. RHE at 10 mA cm−2 current density. The catalyst also shows long-term stability (24 h) with a Tafel slope value of 90 mV dec−1. The obtained experimental results are also in-line with the theoretical data acquired from model systems. [ABSTRACT FROM AUTHOR]

• Intrinsic magnetization in both the bulk and monolayer of CoAsS within DFT+U study. • Antiferromagnetic to ferromagnetic transition with Hubbard parameter U. • Prediction of quantum anomalous Hall effect in ferromagnetic state of CoAsS monolayer. Quantum anomalous Hall effect with intrinsic magnetism in atomically thin 2D material has huge applications in nano-electronics and spintronics. A comprehensive comparative analysis of structural, electronic, and magnetic properties of transition metal ternary chalcogenide CoAsS has been carried out employing first principle calculations with density functional theory (DFT) and DFT+U methods. DFT+U calculation also shows intrinsic magnetization in both the bulk and monolayer of CoAsS, thus revealing rare phenomenon in van der Waals (vdW) layered material. It is observed that the most stable magnetic ordering is either antiferromagnetic (AFM) or ferromagnetic (FM) depending on the U value. At higher U, direct d-d exchange interactions dominate, leading to FM stability over the indirect superexchange interactions mediated by p orbitals of As and S responsible for AFM stability (for U < 8.2 eV). A topological state is also found by computing a non-trivial Chern number in the FM phase of CoAsS monolayer. This highlights the significance of this material for realizing topological state for its potential applications in spintronics and nano-electronics. [ABSTRACT FROM AUTHOR]

• The role of the particle–fluid interface on nanofluid thermal conductivity. • The heat transfer at the interface mainly depends on surface-solvent compatibility. • The thermophysical properties of materials are not always the deciding factor. • Conductance at the interface decides the thermal conductivity in nanofluids. Thermal properties of nanofluids are very well investigated by the global research community for their various applications. The dispersion and stability of the nanoparticles in the base fluid are the essential requirements for the efficient utilization of nanofluids in many applications. The interfacial layer plays a crucial role in the dispersion, stability, and heat transfer properties of the nanofluid. The heat transfer property of the nanofluids is mainly influenced by the heat transfer properties at the particle–fluid interface. The thickness and thermal conductivity of the interfacial layer are the crucial factors that decide the heat transfer at the interface, and the difficulties in the determination of these factors limits the progress of the research. In this review article, the experimental studies on the thickness and thermal conductivity of the interfacial layer are reviewed briefly. The effect of interfacial the layer on the nanoscale mechanisms and thermophysical properties of nanofluids are reviewed. The effect of various tunable parameters on the heat transfer properties of the interfacial layer is also reviewed. This review will be beneficial for fine-tuning nanofluid's thermal properties and their commercial applications. [ABSTRACT FROM AUTHOR]

• Design of new process of conversion of metallic waste to SnO 2 :Fe 3 O 4 nanocomposite. • Tuning of the composition of nanocomposite have been carried out. • SnO 2 :Fe 3 O 4 nanocomposite act as an efficient photocatalyst in UV and Visible range. Appropriate recycling of waste to reusable materials is much sought after in the scientific community to control the incessant rising pollution in environment due to insufficient management of waste materials. To address this issue, efforts were directed to obtain SnO 2 -Fe 3 O 4 nanocomposites from scrap tin plated steel and the use of these composites for the degradation of organic pollutant. We have demonstrated a novel, efficient and facile hydrometallurgy approach for the extraction of iron from waste tin plated steel containers found in plenty in the common waste generated in society. The extracted iron has further been utilized for the preparation of SnO 2 :Fe 3 O 4 nanocomposites with different compositions (SnO 2 :Fe 3 O 4 ratio of 93.2:6.8, 85:15, 58:42 and 40:60) using hydrothermal route. The photocatalytic activities of nanocomposite were determined spectroscopically using Rhodamine-B (RhB) as a model dye. Our results indicate that among all the composites with SnO 2 (85%):Fe 3 O 4 (15%) exhibits the best photocatalytic efficiency under UV light whereas the composition of SnO 2 (93.2%):Fe 3 O 4 (6.28%) is the most efficient in visible light. The above visible light efficiency was supported by density functional theory (DFT) studies which suggest a small amount of pure Fe is present at the Sn sites in the nanocomposite, leading to the reduction in the band gap of the nanocomposite and resulting in absorption in the visible range. Thus, in the present study, we have shown a process of conversion of waste to nanomaterials and its utilization for treatment of organic pollutants. [ABSTRACT FROM AUTHOR]

Herein we have studied the anisotropic thermoelectric properties of MoTe 2 monolayer using density functional and semiclassical Boltzmann transport theory. The electrical and thermal properties are evaluated by considering electron–phonon and phonon–phonon scattering mechanisms. Enhancement of figure of merit (ZT) is observed along the armchair direction for both n-type and p-type MoTe 2 monolayer. Strong anisotropic ZT is found for p-type carriers due to anisotropic nature of electrical conductivity. The calculated thermoelectric figure of merit (ZT) is 1.33 for n-type and 0.83 for p-type monolayer at 700 K along the armchair orientation. ZT of MoTe 2 monolayer is ∼ 30 times larger than the ZT value for bulk MoTe 2 (0.034 at 700 K). This high anisotropic ZT will be useful to design 2D material based transverse TE devices. [ABSTRACT FROM AUTHOR]

We have performed density functional theory (DFT) in combination with Boltzmann transport calculation to theoretically estimate the thermoelectric properties of ternary palladium pnictide chalcogenide, PdPS. A large thermopower, S, both for p-type ( [ABSTRACT FROM AUTHOR]

Light illumination is widely used to tune the electronic properties of semiconductors. We have studied the effect of temperature and wavelength of light on the photoconductivity and persistent photocurrent (PPC) on an insulating (3 unit cells (u.c.) of LaVO 3 (LVO) on SrTiO 3 (STO)) and a conducting (5 u.c. of LVO on STO) oxide interface. Photo induced insulator to metal transition has been observed for the insulating interface. For 405 nm wavelength light illumination, the conducting interface shows PPC at all temperatures, however for 532 nm wavelength light, it shows PPC state only above 220K. For insulating sample, PPC has been observed only for 405 nm light illumination above ~150K. A model band structure has been presented to understand the experimental observations. • For first time we have studied the photoconductivity at conducting and insulting interface of LaVO 3 –SrTiO 3. • A light induced insulator to metal transition is observed at 76K for insulating sample. • A crucial interplay between in-gap defect states, wavelength of light and temperature to realize PPC state is also studied. • We have proposed possible band structure diagram and the mechanism that leads to PPC for both LaVO 3 -SrTiO 3 interfaces. [ABSTRACT FROM AUTHOR]

Topologically nontrivial spin textures have attracted considerable attention not only because of rich physics related to the quantum phases, but also because of their potential for novel spintronic functions. We have successfully synthesized one of the rare triclinic phase of CuSeO 3 via modified hydrothermal process. Magnetic studies on triclinic CuSeO 3 implies helimagnetic spin structure that is well contrast with ground state ferromagnetic or antiferromagnetic states for monoclinic or orthorhombic phases of CuSeO 3. The observed two helimagnetic phases can be further transformed into paramagnetic and induced ferromagnetic phases with tuning of temperature and applied magnetic field. Along with the experimental measurements, a first-principles calculation based on density functional theory reveals that triclinic CuSeO 3 is a charge-transfer type Mott insulator with non-collinear antiferromagnetic order. A spiral magnetic spin texture has been found by the theoretical calculation. [ABSTRACT FROM AUTHOR]

Oxygen vacancies play an important role in controlling the physical properties of a perovskite oxide. We report alterations in the electronic properties of a cubic perovskite oxide, namely, KTaO3, as a function of oxygen vacancies. The conducting surface of the KTaO3 single-crystal substrate has been realized via Ar+ irradiation. The band gap changes as a function of conductivity which is controlled by irradiation time, indicating the formation of defect states. Kelvin probe force microscopy suggests a sharp increase in the work function upon Ar+ irradiation for a short period of time followed by a monotonic decrease, as we increase the irradiation time. Our experimental findings along with theoretical simulations suggest a significant surface dipole contribution and an unusual change in the electronic band line-up of KTaO3 due to oxygen vacancies. [ABSTRACT FROM AUTHOR]