Nowadays, the extensive emission of toxic gases is a common problem in most countries. Resistive sensors are used for sensing of gases, however, generally they have weak selectivity and their performance is significantly degraded by the presence of water molecules in humid air. To overcome these shortages, the use of noble metals with high catalytic activity is helpful. Among various noble metals, rhodium (Rh) has high catalytic activity towards some gases. Hence, Rh or its oxidized form (Rh2O3) are used for the boosting of the sensing properties of resistive sensors. Nevertheless, less attention has been focused on this noble metal compared to other common noble metals mainly due to its rare nature and high cost. Herein, we are dealing with Rh and Rh2O3-decorated or doped resistive gas sensors. We have presented a detailed discussion of these sensors with emphasis on the gas detection mechanism.

This study explores a two-dimensional material based on iron phthalocyanine, termed as FePc sheet. The structural, electronic, mechanical, and optical characteristics of this sheet are explored using density functional theory. The results confirm that the FePc sheets are energetically highly favorable and mechanically stable. Its mechanical behavior and anisotropic properties are shown by calculating Young's modulus as well as Poisson's ratio. Findings suggest that the FePc sheet could be a promising candidate for use in nanoscale devices or systems that require a delicate or less rigid material. The electronic analysis indicates the metallic and magnetic nature for this sheet. Additionally, the optical parameters including the dielectric function, optical conductivity, refractive index, absorption coefficient, reflection, and transmission coefficients over a range of photon energies are studied. The results point to the potential use of this sheet in optoelectronic devices as well as energy harvesting systems.

Chalcogenides have gained prominence in recent years with a focus in optoelectronics due to their tunable bandgaps, phase-change abilities, and infrared applications. However, bulk chalcogenides are not as efficient as nanostructured materials that tailor the material’s morphology, structure, and interfacial dynamics. This paper reviews recent advancements in chalcogenide nanostructures based on dimensionality (0D, 1D/3D, 2D) and analyzes how different synthesis and characterization techniques are used to describe the optoelectronic enhancements such as photoluminescence efficiency, bandgap changes, carrier charge mobility, stability, among many others. This paper provides a framework for future designs of optoelectronic devices using scientific advancement in future systems.

Perovskite inorganic materials for solar cell applications have been widely investigated, with the highest power conversion efficiency approaching 30.9%. Furthermore, widely investigated materials such as lead-halide and tin-halide along with other mixed halide perovskites introduce challenges associated with stability, toxicity, and scalability. To address these issues, a comprehensive investigation is conducted to explore the layered perovskite-like structure CsMnF4 using density functional theory (DFT) computations to evaluate its suitability for solar cell and optoelectronic applications. Mechanical stability is demonstrated through examination of its elastic characteristics. In terms of electronic properties, CsMnF4 exhibits an indirect fundamental bandgap of ~1 eV, with a direct transition at ~1.1 eV. The values of dielectric constant, optical conductivity, susceptibility, and polarizability exhibit their maxima within the energy range 1.0–3.0 eV. These findings suggest that CsMnF4 holds significant promise for use in solar cells, optoelectronic systems, and various flexible electronic devices due to its superior mechanical, electrical, optical, and structural characteristics.

The electronic and optical characteristics of single and multilayer phagraphene are investigated using first-principles calculations. Energy calculations confirm that these sheets are energetically favorable, with layers assembled together through weak van der Waals forces. The electronic behavior of phagraphene is found to be sensitive to the number of layers: mono- and tri-layer phagraphene exhibit semimetallic behavior, whereas bi- and tetra-layer phagraphene display semiconducting properties. The observed optical response of the structures is highly anisotropic under both in-plane and out-of-plane both polarizations. The phagraphene sheets possess high dielectric constants, indicating strong energy storage abilities. The sheets show efficient light transmission, high optical absorption, and strong conductivity across an extensive range of the electromagnetic spectrum. Our findings offer promising prospects for the advancement and application of phagraphene in optoelectronic devices.

We theoretically investigate the optical response of monolayer boron antimonide (BSb) under uniaxial tensile as well as compressive strains applied along the armchair and zigzag directions. Employing a fifth nearest-neighbor tight-binding model, we reveal significant strain-induced modifications in the density of states (DOS), including band gap modulation and anisotropic splitting of Van Hove singularity (VHS) peaks. The optical dipole matrix element for y polarization direction Dy is non-zero only at Dirac K point, while x polarization direction Dx is nonzero across the Brillouin zone except near the Gamma point. The linear optical spectra and quadratic electronic optical response (DC Kerr effect) exhibit pronounced strain-induced anisotropy, including red/blue shifts, peak splittings, and intensity modulations, particularly near the first two optical transitions (E11 and E22). In addition to the general red/blue shifts of optical peaks under uniaxial strain, we identify a distinct strain-induced splitting of the second optical transition (E22) for x-polarized light, while y-polarized spectra exhibit only peak shifts without splitting. This polarization-dependent behavior highlights a pronounced optical anisotropy unique to uniaxial strain in BSb. This splitting is attributed to strain-induced symmetry breaking among the M and M ' points in the Brillouin zone, which lifts the degeneracy and generates two distinct optical transitions with different energies and dipole strengths. The extent of peak shifts, splitting, and intensity variations depends linearly on the magnitude, type, and sign of the applied strain. Comparative analysis with monolayer BAs highlights the stronger strain sensitivity of BSb and its potential in tunable optical applications. These findings provide precious insights into strain-engineered optical phenomena in group III-V, paving the way for advanced optoelectronic and photonic devices.

Half-metallic materials are a class of materials that change their characteristics between semiconducting and metallic upon changing the spin state. The impact of transition metal doping of MoSeS dichalcogenide nanostructure on its half metallic transformation is examined in this work. Doping of MoSeS alters its selective gas adsorption for selected gases. Therefore, the effect of doping of MoSeS on its adsorption for greenhouse and climate change-related gases (NO, NO2, NH3, CO, CO2, O-2, H-2, H2O, and H2S) is explored. The gas adsorption length (d) and energy (E-ad), the density of states (DOS) in addition to the projected density of states (PDOS), and charge exchange among gas and structure (Delta Q) were evaluated upon gas adsorption on undoped and Co doped MoSeS structure by means of first principles computation associated with density functional theory (DFT). The outcomes demonstrate that Co doping of MoSeS monolayer introduces significant modification in the energy gap such that it is transformed from a typical semiconductor into a low energy gap semiconductor. NO exhibits the best adsorption on the doped monolayer followed by O-2 and then NO2. Doping of MoSeS with Co induces its selective gas adsorption as a result of variation in adsorption energies which can be utilized to fabricate selective gas detectors. Additionally, this doping enables access to energy gap adjustment through a selection of spin states.

In the present study, new two-dimensional materials, denoted as BeN4C8 and MgN4C8 sheets, are predicted by density functional theory. This research focuses on the structural stability of these sheets by examining cohesive energy and phonon dispersion. The findings indicate that both BeN4C8 and MgN4C8 sheets demonstrate structural stability, evidenced by their negative cohesive energies and no imaginary frequencies in their phonon spectra. Herein, the thermal stability of these sheets is confirmed at temperatures beyond room temperature. We have also investigated the mechanical characteristics, calculating Young's modulus along with Poisson's ratio to understand their anisotropic behavior. The results reveal that BeN4C8 and MgN4C8 sheets can be the suitable candidates for applications in nanomechanics, especially when softer materials than graphene are required. The electronic properties of both materials are examined, highlighting their metallic characteristics. The study also delves into the optical properties of BeN4C8 and MgN4C8, studying their dielectric function, absorption coefficient, optical conductivity, and reflection coefficient across a range of photon energies. The results highlight significant enhancement in the optical response of the electromagnetic spectrum, suggesting that these materials have promising potential for applications in optoelectronic devices and energy harvesting technologies.

This work presents a comprehensive theoretical investigation of the electronic and optical responses of mono-layer honeycomb boron antimony (h-BSb) and hexagonal boron phosphide (h-BP) under various biaxial strain conditions, employing a tight-binding approach validated through DFT calculations. Our findings reveal that monolayer h-BSb possesses a direct band gap that can be effectively modulated through mechanical strain: tensile strain raises the band gap, whereas compressive strain decreases it. This strain-induced tunability manifests directly in the optical spectra, where prominent optical peaks exhibit significant redshifts under compressive strain and blueshifts under tensile conditions. The refractive index n(omega) demonstrates clear strain-dependent modulations, with the zero-frequency value increasing under compressive strain and decreasing under tensile deformation. Additionally, the DC Kerr effect displays a distinctive double-peak structure that shows high sensitivity to mechanical strain. Comparative analysis demonstrates that monolayer h-BSb exhibits lower-energy optical transitions and enhanced sensitivity to strain-induced peak displacement compared to h-BP. This superior performance stems from h-BSb's small band gap and narrow interband separations at the points of high-symmetry in the Brillouin zone. These characteristics position h-BSb as a highly promising material for strain-engineered optoelectronic applications, particularly in infrared photodetectors and sensors.

In this research, electro-optical characteristics of a covalent organic framework named COF-LZU1 are examined by density functional theory. The results demonstrate that COF-LZU1 sheet is structurally stable, as indicated by its negative cohesive energy and ab initio molecular dynamics simulations. The electronic property analysis reveals the semiconducting behavior of COF-LZU1. The study further explores the optical characteristics of COFLZU1, including the dielectric function, optical conductivity, absorption coefficient, reflection, and transmission coefficients across a broad range of photon energies. Owing to its atomic structure, COF-LZU1 displays pronounced in-plane and out-of-plane optical anisotropy. The findings indicate that the dielectric constant of COFLZU1 is comparable to that of other highly porous sheets, such as graphdiyne. The incident light is effectively absorbed in the visible and ultraviolet regions. The material is transparent due to its low reflection coefficient and high transmission coefficient. Collectively, these optical properties suggest that COF-LZU1 has promising potential for use in optoelectronic devices, operating in the visible and ultraviolet regimes.

The half metallic transformation of MoSeS dichalcogenide structure upon doping with a transition metal is explored in this work. Additionally, the effect of doping on its adsorption capacity for CO, CO2, NO, and NO2, H2, H2O, H2S, and NH3 gases is investigated. Those gases are considered due to their impact on the greenhouse effect as well as climate change. Density functional theory (DFT) and first principles computation are utilized to evaluate the effect of Fe doping of MoSeS structure on the adsorption energy (Ea) and length d), charge relocated between gas molecules and the structure (triangle q), along with the density of states (DOS). The results reveal that Fe doping of MoSeS structure generates significant adjustments of the band gap so that the structure could be transformed from semiconductor into metallic or semimetallic. NO, NO2, and O2 gases exhibit favorable adsorption on doped structure with a maximum adsorption capacity for NO. Additionally, the doped structure exhibits selective adsorption for the gases with different adsorption energies. The doping of MoSeS dichalcogenide with Fe transition metal is a decent pathway to adjust its band gap along with its selectivity for gas adsorption.

Even though resistive gas sensors are popular devices for gas detection, weak selectivity is still one of their shortages, limiting their usage in places with need for highly selective detection of a particular gas. Noble metals are characterized by their high catalytic activity and different work function than semiconducting materials, making them good choices for the enhancement of selective response to a particular gas. Among noble metals, ruthenium (Ru) is a rare noble metal belonging to the platinum group with high catalytic activity. It is mainly used as a dopant and decoration in combination with resistive gas sensing materials such as metal oxides. However, compared to other noble metals (Ag, Au, Pd, and Pt) less attention has been devoted to Ru for gas sensing applications. Herein, we have discussed the role of Ru for gas sensing detection. Also, sensing mechanisms and selectivity associated with the use of Ru have been discussed.

This study introduces a new class of carbon nanotubes derived from net-C and net-W sheets. By rolling these sheets into cylinders, we obtained net-C and net-W nanotubes with two configurations named (n,0) and (0,n). First-principles calculations are employed to explore the structural, electronic, and optical properties of these nanotubes. Our results demonstrate that net nanotubes exhibit excellent structural and thermal stability at room temperature. All examined nanotubes show metallic behavior, regardless of their size and chirality. The high dielectric constants of these nanotubes, which increase with tube diameter, suggest potential for enhanced energy storage applications. Moreover, net nanotubes exhibit strong light absorption across a wide spectral range, from infrared to ultraviolet, and they show high transparency. The metallic conductivity, tunable dielectric constant, and broadband light absorption of net nanotubes make them particularly attractive candidates for future technological advancements.

Molecular bridges are opening up exciting new applications in diverse fields, improving the efficiency of conductive inks, enhancing the performance of devices such as organic light-emitting diodes and low-cost solar cells, and advancing the development of highly sensitive sensors, chemical reactions, drug delivery systems, and more. In this paper, we study the electron transport properties of a C80H20 fulleryne (dodecahedryne) connected to two cumulene electrodes. Using density functional theory (DFT), we determine the optimal molecular bridge structure. Based on the IR vibration spectra, different stable phases of the molecular bridge are obtained. The corresponding tight-binding (TB) parameters of the cage are obtained by assigning appropriate values of the length and type of bonds for the fulleryne cage through matching the HOMO-LUMO gap between the DFT calculations and the TB parameters. The electron transport for the desired structures is investigated using the obtained tight-binding parameters and the non-equilibrium Green's function (NEGF) method. Finally, it is concluded that among the five possible configurations for the cumulene-dodecahedryne -cumulene molecular bridge, only one specific configuration—where the electrodes are one edge apart—exhibits metallic behavior, while other positions act as insulators. In addition, the system exhibits quantum phase transitions from metal to semiconductor and from insulator to metal in the presence of critical electric fields. The ability to control quantum phase transitions in these molecular systems can be leveraged to develop qubits for quantum computing. The unique properties can be utilized to design advanced molecular electronic devices.

In this study, we investigate the electrical and thermodynamic properties of trilayer boron nitride (BN) nanoribbons with varying stacking orders (AAA, ABA) using the tight-binding approach. Our findings demonstrate that the large bandgap of the pristine BN structure is strongly dependent on the stacking order and can be effectively modulated through the substitution of the middle layer with graphene (BNC structure) and the application of a perpendicular bias voltage and magnetic field. These modifications also shift the peaks of the density of states (DOS) toward the Fermi level, leading to notable enhancements in electrical conductivity and heat capacity. Thermodynamic analysis reveals that the negligible thermal properties of pristine BN structures below 2000 K, are enhanced significantly with the incorporation of a graphene layer and application of a bias voltage and magnetic field. Comparisons between the different structures show that, under similar conditions, the ABA stacking order offers better thermodynamic performance compared with AAA stacking. Investigation of the Lorenz function shows that the BNC structure exhibits a main peak at lower temperatures with reduced magnitude compared with pristine BN and this peak shifts towards lower temperatures with variations in system parameters. These results indicate that bias voltage can serve as a highly effective control parameter for enhancing the electrical conductivity of BN nanoribbons to levels comparable with graphene nanoribbons. The theoretical findings of this research can be used in the design and fabrication of nanodevices based on BNC nanoribbons for electronic and thermal applications with tunable high efficiency.

Silver metaphosphate AgPO3 glass samples were prepared using the melt quenching route. The prepared samples were exposed to a total gamma irradiation dose of 0-100 kGy in steps of 20 kGy. The work aims to investigate the influence of gamma irradiation on the structure, morphology, and electric/dielectric properties of AgPO3 glass samples. X-ray diffraction (XRD) shows that the samples have some degree of crystallinity, and gamma irradiation has a small influence on the glass structure. Scanning electron microscope (SEM) shows that gamma irradiation has induced damage to the surface. Energy dispersive X-ray spectrometry (EDS) analyses demonstrate a nearly similar Ag and P atomic percentage in all samples, whereas the atomic percentage of oxygen is somewhat lower than its compositional percentage. Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy were used to investigate any structural changes that may occur due to gamma irradiation. Impedance measurements reveal that the DC conductivity, activation energy, hopping energy, dielectric constant, and dielectric loss all decrease with increasing gamma dose, reaching a minimum in the dose range 40-60 kGy and then increase again when the dose is further increased. The AC conductivity of all samples follows Jonscher's power law, and analysis of the temperature dependence of the exponent reveals that the conduction mechanism can be well described by the correlated barrier hopping model. Exposing the samples to gamma rays did not change the conduction mechanism. The effect of gamma irradiation on electric properties is discussed in terms of the possible creation of traps and conductive pathways.

A novel allotrope structure of carbon named twin irida graphene composed of 3-16-8 carbon rings is proposed. Its structural, mechanical, electronic, and optical characteristics are explored by density functional theory. It is shown that twin irida graphene has an energetically favorable structure. Its dynamical and thermal stabilities at room temperature are also examined and confirmed. The in-plane stiffness of twin irida graphene is less than graphene. It is a metal and maintains this property even against the external strain and applied electric field. This sheet exhibits an anisotropy response to the incident photon with different polarizations. The potential of sheet for use in energy storage and absorption systems is indicated by its high dielectric constant and optical absorption. The reflection constants as well as the transmission constants of twin irida graphene indicate its transparency, mostly in the high-energy region. Thus, twin irida graphene is a suitable material for use in optoelectronic applications due to its structural and physical characteristics. A new carbon allotrope named twin irida graphene composed of 3-16-8 carbon rings is introduced. Its structural, mechanical, electronic, and optical characteristics are studied by density functional theory. This sheet is a suitable material for use in optoelectronic applications due to its structural and physical characteristics. image

Microalgae harvesting at an industrial scale remains a techno-economic bottleneck for large-scale microalgae production that can account for up to 30% of the total cost of biomass production. A wide range of harvesting techniques have been applied commercially, among which, coagulation-flocculation techniques prove to be both convenient and cost-effective as pre-treatment techniques used in conjunction with other methods. In this study, process wastewater acquired from onshore natural gas facilities in Qatar was utilized to cultivate freshwater microalgae specie Scenedesmus sp. for simultaneous pollution abatement and biomass harvesting applications. Scenedesmus sp. was cultivated in two growth phases (fast and slow growth phases) to examine the influence of the microalgae growth phase on the flocculation process and rheological behavior. Effective flocculation was achieved using a commercial high charge density and high molecular weight cationic polyacrylamide-based flocculant. Flocculation efficiencies exceeded 97% for both fast and slow growth phase suspensions at an optimum flocculant dose of 10 mg/L. Optimum conditions were well corroborated by residual turbidity and zeta potential measurements. For fast growth phase suspensions, the optimum PAM dose coincided with a minimum residual turbidity of 2.35 NTU and a zeta potential of -0.52 mV. Similarly, the optimum PAM dose was fixed based on a minimum residual turbidity of 2.30 NTU and a zeta potential of +0.63 mV for slow growth phase suspensions. Large, easily settleable and compact flocs were obtained with average D50 values of 70.7 mu m and 142.0 mu m recorded for fast and slow growth phase suspensions, respectively, at optimum PAM dose. Moreover, based on rheological characterization studies, the flocculated suspensions demonstrated an overall nonNewtonian pseudoplastic (shear thinning) fluid behavior. Introduction of cationic PAM significantly improved the viscosity and yield stress of the flocculated suspensions around the optimum PAM dose range. At the optimum PAM dose, the initial viscosities were recorded as 10.37 and 39.19 mPa.s with yield stresses of 12.84 and 16.59 N/m2 for fast and slow growth phase suspensions, respectively. The flocculated biomass further displayed a viscoelastic solid (gel) behavior, characterized by high gel strength and resistance to shearing around optimum flocculant doses. At the optimum PAM dose, the storage moduli were recorded as 886.2 and 1068.6 mPa for fast and slow growth phase suspensions, respectively.