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This contribution demonstrates density functional theory calculations on the optoelectronic properties of monoclinic CuO under high pressures up to 15 GPa. In this account, the experimentally measured indirect band gap energy value of 1.41 eV has theoretically been predicted by tuning the Hubbard parameter (U) values for the partial electronic states. The values of the Hubbard parameter correspond to UCu-3d = 8 eV and UO-2p = 4.5 eV. The electronic and optical characteristics were examined under applied pressure and the results reveal development in the band gap values with increasing pressure from 1.41 to 2.01 eV. Total and projected density of states for the adopted pressures have been provided and displayed that the major contribution in the valance and conduction bands comes from O-2p and Cu-3d electronic states, respectively. The plotted reflectivity data suggest high optical reflectivity magnitudes relatively in the ultraviolet area. The investigated systems under variant pressures manifest rather an excellent absorption coefficient in the ultraviolet area, pushing them to be employed in solar cell technologies. Our analyzed results of the wavelength-dependent electrical conductivity of the investigated materials confirm the absorptivity behavior in the ultraviolet and small part of visible region of electromagnetic waves (EMW). Finally and most importantly, our obtained results of loss functions for the entire surveyed systems reveal a slight energy loss in a range of EMW, including ultraviolet and visible regions. [ABSTRACT FROM AUTHOR]

Owing to their remarkable characteristics, refractory molybdenum nitride (MoNx)-based compounds have been deployed in a wide range of strategic industrial applications. This review reports the electronic and structural properties that render MoNx materials as potent catalytic surfaces for numerous chemical reactions and surveys the syntheses, procedures, and catalytic applications in pertinent industries such as the petroleum industry. In particular, hydrogenation, hydrodesulfurization, and hydrodeoxygenation are essential processes in the refinement of oil segments and their conversions into commodity fuels and platform chemicals. N-vacant sites over a catalyst's surface are a significant driver of diverse chemical phenomena. Studies on various reaction routes have emphasized that the transfer of adsorbed hydrogen atoms from the N-vacant sites reduces the activation barriers for bond breaking at key structural linkages. Density functional theory has recently provided an atomic-level understanding of Mo–N systems as active ingredients in hydrotreating processes. These Mo–N systems are potentially extendible to the hydrogenation of more complex molecules, most notably, oxygenated aromatic compounds. [ABSTRACT FROM AUTHOR]

Porous carbon derived from grape marc (GM) was synthesized via carbonization and chemical activation processes. Extrinsic nitrogen (N)-dopant in GM, activated by KOH, could render its potential use in supercapacitors effective. The effects of chemical activators such as potassium hydroxide (KOH) and zinc chloride (ZnCl2) were studied to compare their activating power toward the development of pore-forming mechanisms in a carbon electrode, making them beneficial for energy storage. GM carbon impregnated with KOH for activation (KAC), along with urea as the N-dopant (KACurea), exhibited better morphology, hierarchical pore structure, and larger surface area (1356 m2 g−1) than the GM carbon activated by ZnCl2 (ZnAC). Moreover, density functional theory (DFT) investigations showed that the presence of N-dopant on a graphite surface enhances the chemisorption of O adsorbates due to the enhanced charge-transfer mechanism. KACurea was tested in three aqueous electrolytes with different ions (LiOH, NaOH, and NaClO4), which delivered higher specific capacitance, with the NaOH electrolyte exhibiting 139 F g−1 at a 2 mA current rate. The NaOH with the alkaline cation Na+ offered the best capacitance among the electrolytes studied. A multilayer perceptron (MLP) model was employed to describe the effects of synthesis conditions and physicochemical and electrochemical parameters to predict the capacitance and power outputs. The proposed MLP showed higher accuracy, with an R2 of 0.98 for capacitance prediction. [ABSTRACT FROM AUTHOR]

2D MXene‐based catalysts, such as Ti3C2Tx have unique, excellent properties and show extraordinary advantages in many catalytic reactions. However, as cocatalysts for photocatalytic hydrogen evolution reaction (HER), MXene has insufficient catalytic activity because the active metal sites of H+ binding are hidden by passivation −F/−O termination, which hinders postreaction desorption of H2. A simple ultrasonic treatment method is used to expose more active sites and adjust the surface work function of Ti3C2Tx, and additionally inactive −F/−O terminal groups are replaced with diaminoethanethiol, denoted as Ti3C2‐Ax, as the surface terminal group through covalent bonds (Ti−S). The optimized photocatalyst (Cd0.4Zn0.6S/Ti3C2‐A40) demonstrates excellent catalytic activity (HER: 13.44 mmol h−1 g−1), which is about 5.8 and 1.9 times higher than that of pristine Cd0.4Zn0.6S and Cd0.4Zn0.6S/Ti3C2 with stability (24 h of cycle experiments), outperforming most of the reported MXene‐based photocatalysts. The results of relevant experiments and density functional theory calculations reveal that the excellent conductivity of Ti3C2‐A40, well‐structured Cd0.4Zn0.6S/Ti3C2‐A40 Schottky junction, and the efficient interfacial charge transfer are major factors that contribute to the improved photocatalytic mechanism. This promotes application of surface‐modified MXene as an efficient cocatalyst and provides a new idea for design and synthesis of heterojunction materials. [ABSTRACT FROM AUTHOR]

The efficient separation and utilization of intrinsic carriers in photocatalyst, as well as the adsorption and elimination of target pollutants, are two critical challenges in the development of photocatalytic oxidation technology. Herein, the different crystal facet of Cu (111), Cu (100), Cu (111 +100) were engineered and coupled with Poly (heptazine imide) (PHI) as an emerging photocatalyst for CH 3 SH elimination under simulated solar light (SSL). Cu (111)/PHI exhibited 87.8% elimination efficiency after 30 min of illumination, significantly higher than that of pure PHI (60.4%), Cu (100)/PHI (71.5%), and Cu (111 +100)/PHI (70.4%). Besides, the photocatalytic performance was maintained at 83.3% after a prolonged reaction time of up to 450 min, indicating that Cu (111)/PHI has good stability and reusability. A comprehensive characterizations study confirmed that Cu (111) exhibited the enhanced surface electron pump effect compared to Cu (100) and Cu (111 +100), facilitating the accelerated extraction and transfer of photogenerated charge carriers. Density functional theory (DFT) calculations revealed that Cu (111) surface active sites can effectively adsorb H 2 O, O 2 , and CH 3 SH due to unsaturated pairing of d-orbital electrons, thus prompting the activation of H 2 O, O 2 into reactive oxygen species (•OH/•O 2 −/1O 2) for the eliminating of adjacent CH 3 SH. This study presents a new facet engineering approach for the rational design of highly efficient photocatalysts for the elimination of S-VOCs. [Display omitted] • Novel Cu (111)/PHI catalysts has efficiently photocatalytic elimination of CH 3 SH. • Cu (111) NCs with enhanced electron pump effect accelerates the transfer of photogenerated electrons. • Cu (111)/PHI has good adsorption and activation capacity for H 2 O and O 2. • Unsaturated electron filling of the antibonding energy levels enhances the catalytic activity. [ABSTRACT FROM AUTHOR]

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Abstract: Iron‐immobilized nanoporous carbon is a well‐known adsorbent used in treating arsenic‐contaminated waters. In this contribution, we present findings on the adsorptive interactions and dynamics of arsenate–goethite cluster ([FeO(OH)]6) with carbon nanotubes (CNTs) using hybridized quantum mechanics/molecular mechanics (QMMM) calculations. The CNTs adsorption mechanism is of interest since a better understanding of the fundamental interactions between arsenate, goethite, and carbon surfaces would translate to advances in CNT‐based adsorbent production and utilization. Novel applications of general amber force field (GAFF) and isobaric‐isothermal Gibbs ensemble Monte Carlo (NpT‐GEMC) methods are described. By the abovementioned methods, we postulate that the [FeO(OH)]6/CNT‐2.3 (diameter 2.3 nm ‐ mesoporous) system enhances the qualitative (i.e., improved chemisorption) rather than the quantitative adsorptive aspect (i.e., total HAsO 4 2 − ions adsorbed) in comparison to the [FeO(OH)]6/CNT‐1.6 (diameter 1.6 nm ‐ microporous) system. [ABSTRACT FROM AUTHOR]

This contribution investigates structural and electronic properties as well as stability phase diagrams of surfaces of the cubic boron nitride (c-BN). Our calculated parameters for bulkc-BN agree reasonably well with both experimental and computed values available in the literature. Based on the energies of the three experimentally recognised phases of bulk boron, i.e.α-B36,β-B105andγ-B28, we estimate enthalpy of formation ofc-BN to be −2.8 eV. Thec-BN(1 0 0) surface offers separate B and N terminations (denoted asc-BN(1 0 0)_B and c-BN(1 0 0)_N), whereasc-BN(1 1 1) andc-BN(1 1 0) are truncated with combinations of boron and nitrogen atoms (denoted asc-BN(1 1 1)_BN andc-BN(1 1 0)_BN). Optimised geometries of surfaces display interlayer displacements up to the three topmost layers. Downward displacement of surface boron atoms signifies a common geometric feature of all surfaces. Bulkc-BN and its most stable surfacec-BN(1 0 0)_N possess no metallic character, with band gaps of 5.46 and 2.7 eV, respectively. We find that, onlyc-BN(1 0 0)_B configuration exhibits a metallic character.c-BN(1 1 0)_BN andc-BN(1 1 1)_BN surfaces display corresponding band gaps of 2.5 and 3.9 eV and, hence, afford no metallic property. [ABSTRACT FROM PUBLISHER]

[Display omitted] • The study addresses molecular adsorption over defected h -BN (boron nitride) monolayer. • It is found that h -BN is more reactive to CO and phenol in reference to Stone-Wales surface. • A wide array of properties was computed to comprehend the observed interactive behavior. • These results find in applications that target deployment of BN materials in optoelectronic devices. Density functional theory simulations studied molecular (Phenol, pyridine, oxygen, and carbon monoxide) interactions with defected h -BN (boron nitride) monolayer structures. The simulation comprised of a supercell modelling the monolayers which contained mono-vacancies (boron or nitrogen) and Stone-Wales defect. Predictions from this analysis indicate that h -BN with vacancies are more reactive to CO and phenol when compared with the Stone-Wales defected configurations. Reacted products entail semiconductor characteristics with a band gap residing in the range 2.6 to 3.96 eV. Outcomes herein reveal a relatively strong interaction of phenol and pyridine, in comparison with smaller diatomic O 2 and CO, with defect BN surfaces. A wide array of properties was computed to elucidate an insight into the observed interactive behaviour, including Bader charge's; local atomic spin polarisation magnetic moments in the vacancy region, and energy band gap of the reaction outcome. These results should be useful in applications that target deployment of BN-based materials in optoelectronic devices, physical–chemical sensors. [ABSTRACT FROM AUTHOR]

This contribution aims to investigate volume-dependent thermal and mechanical properties of the two most studied phases of molybdenum nitride (c-MoN and h-MoN) by means of the quasi-harmonic approximation approach (QHA) via first-principles calculations up to their melting point and a pressure of 12 GPa. Lattice constants, band gaps, and bulk modulus at 0 K match corresponding experimental measurements well. Calculated Bader's charges indicate that Mo-N bonds exhibit a more ionic nature in the cubic MoN phase. Based on estimated Gibbs free energies, the cubic phase presents thermodynamic stability higher than that detected for hexagonl, with no phase transition observed in the selected T- P conditions as detected experimentally. The elastic stiffness coefficients of MoN in hexagonal structure revealed that it is stable elastically; in contrast to the cubic structure. The temperature dependence on the bulk modulus is more profound on the dense cubic phase than on the hexagonal phase. Overall, the two considered structures of molybdenum nitride display very minimal harmonic effects, evidenced by the slight variation of thermal and mechanical properties with the increase of pressure and temperature. The optical conductivity of both phases near a zero photon energy coincides well with their metallic character inferred by their corresponding DOS curves. It is expected that the thermo-elastic properties of saturated molybdenum nitrides reported in this study will aid in the continuous pursuit to enhance their catalytic and mechanical utilizations. [ABSTRACT FROM AUTHOR]

Elemental adsorption on graphene offers an effective procedure in fine-tuning electronic and mechanical properties of graphene. The effects of dopants depend on adsorption site, the degree of coverage as well as on the configuration of the deployed supercell. In this contribution, the density functional theory (DFT) calculations were performed to investigate the electronic structures of F and Cl adsorption (double-sided, top site) on graphene in terms of adsorption orientation, atomic ratios, i.e ., from C:F/Cl = 18:2 to C:F/Cl = 2:2. Despite being members of the halogens group, F- and Cl-adsorbed on graphene show contrasting trends. F is adsorbed to graphene more strongly than Cl. F favours full and 25% adsorption coverage, while Cl favours 25% coverage. Both F and Cl cases open band gap (at Fermi energy) at certain atomic concentration coverage, but none creates magnetization. [ABSTRACT FROM AUTHOR]

• Effect of Mo target power on vacuum sputtered Mo doped Cr nitride coatings. • The crystallite size of coatings increases with Mo target power and Mo content. • Coatings are transparent in the visible region with direct optical band gap. • Computational modelling provides insight to the electronic and optical properties. • Good solar selectivity of chromium nitride with high mechanical properties. In this study, Cr−Mo−N thin films with different Mo contents were synthesised via closed field unbalanced magnetron sputtering ion plating. The effects of Mo content on the microstructure, chemical bonding state, and optical properties of the prepared films were investigated by X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy, and ultraviolet-visible spectrophotometry. XRD results determined the face centered cubic (fcc) structure of pure CrN film. The incorporation of molybdenum (Mo) in the CrN matrix was confirmed by both XRD and XPS analyses. The CrMoN coatings demonstrate various polycrystalline phases including CrN, γ -Mo 2 N, Cr with oxides layers of MoO 3 , CrO 3 , and Cr 2 O 3. Microstructural results of the Cr-Mo-N coatings show that the grain size increased with an increase in Mo content due to the formation of MoN phase, in which the Mo atoms interact with N atoms around the grain boundaries of the CrN phase. XPS investigations confirmed the presence of Cr, Mo, N, C and O elements in the studied coatings. The optical results revealed that the synthesised coatings exhibit low reflection magnitudes in the visible region of the solar spectrum indicating good antireflection surfaces. Mo doped thin coatings improve the solar absorptance by ~76% in the wavelength range of 200–800 nm with a low thermal emittance of ~ 20% in the infrared range (up to 4000 nm). Furthermore, by applying density functional theory, the computational simulation provides similar trends as the experimental finding of absorption coefficient in the wavelength range. [ABSTRACT FROM AUTHOR]

Polyvinyl chloride (PVC) plastics constitute a large fraction of buildings, packaging and electronic devices, whereas, the annual emission electric arc furnace dust (EAFD) from steel manufacturing operations has recently peaked at nearly 6 Mt. Co-pyrolysis of PVC with EAFD currently represents a focal abatement technology for both categories of pollutants. However, despite of several experimental investigations; the mechanisms underlying interaction between EAFD and PVC remain largely speculative. Herein, we examine theoretically reactions of major products from thermal degradation of PVC with nanoclusters of iron (III) oxide, α -Fe 2 O 3 (hematite) as a representative model for the various metal oxides in EAFD. The facile nature for the H-Cl bond fission over hematite is in line with experimental findings, pointing out to formation of iron chlorides from pyrolysis of Fe 2 O 3 -PVC mixtures. Interaction of selected chlorinated C 1 -C 3 cuts with the hematite structure preferentially proceeds via a dissociative adsorption pathway. Results from this study shall be instrumental to understand, on a precise molecular basis, fixation of halogens on transitional metal oxides; a viable thermal recycling approach for polymeric materials laden with halogenated constituents. [ABSTRACT FROM AUTHOR]

Sol-gel derived CuCo-oxide coatings as solar selective surfaces, synthesized onto aluminium substrates at various annealing temperatures, are analysed by correlating their structural, chemical bonding states, and surface morphological topographies. As the annealing progressed, all the coatings displayed a Cu 0.56 Co 2.44 O 4 (ICSD 78-2175) phase with preferential orientation along (400) reflection plane. Rietveld refinement of X-ray diffraction (XRD) data indicate that residual stress and microstrains developed around the coating surfaces are reduced resulting in mechanically stable thin films. Enhancement of the crystallite size and preferred orientation of the surface were confirmed via XRD, field emission scanning electron microscopy (FESEM), and atomic force microscopy (AFM) analysis. X-ray photoelectron spectroscopy (XPS) analysis shows tetrahedral, octahedral and mixed states of Cu and Co ions with a stable atomic ratio of Co/Cu, and an increase of O and C contents but no metal-carbon bonding on the surface of materials. Optical reflectance investigations indicated that solar selectivity of the coatings increased from 3.81 to 24 as the annealing temperature reached up to 500 °C. [ABSTRACT FROM AUTHOR]

High temperature thermal-mechanical stability of tribological thin coatings is extremely important to a large number of applications in modern industries. DC magnetron sputtering of single metallic element (Cr, Si) and alloy (Ni:Cr) targets formed transition metal nitrides film coatings, CrSiN and CrNiN onto M2 steel. High temperature in-situ synchrotron X-ray diffraction, in the range 25 °C–700 °C, obtained experimental data for a range of structural and mechanical properties. Furthermore, experimental room temperature Nanoindentation measurements, made before and after the in-situ heating cycle, provided corresponding hardness and shear modulus results. The structural results identified microstructure and phase transformation changes, while the mechanical results identified microstrain, hardness, elastic modulus and deformation resistance properties of the coatings. Density functional theory (DFT) and quasi-harmonic approximation (QHA) modelled the high temperature thermal and mechanical properties such as: Young's modulus, shear modulus and thermal expansion coefficients (populated up to 1200 °C). Estimates of hardness are made by correlating the bulk phase hardness and shear modulus, of the CrN and Ni phases, as a function of temperature. Results indicate that Si doping enhances the hardness of the CrN framework, increasing from 29 to 36 GPa and improves the coatings elastic modulus, and resistance to deformation. However the addition of Ni reduced these properties. Furthermore, formation of (Cr,Si)N and Ni(Cr) solid solutions is inferred from DFT, Rietveld and lattice constant analysis.

In this work, the physicochemical properties of palm oil fuel ash (POFA) based geopolymers with the addition of graphene oxide (GO) were investigated. Geopolymer composites were prepared by mixing the treated POFA, sand, NaOH, Na 2 SiO 3 , and GO. The mixtures were then cast in mortar molds to form the geopolymer composites, with different GO proportions and curing temperatures applied to the composites. Compressive strength, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) analyses, as well as density functional theory (DFT) calculations, have been performed. The compressive test results showed that the compressive strength increased proportionally with the increase of GO content and decreased when there was an excess of GO. The excessive GO and the limited amount of NaOH activator solution inhibited the formation of reduced graphene oxide (rGO) via an in-situ reduction mechanism. The FTIR and SEM analyses revealed that the excess GO tended to promote the formation of epoxy groups on the GO, which eventually confined the formation of dense agglomeration and led to a decrease in compressive strength. The DFT calculations confirmed the significance of the epoxy group stretching. Overall, the ratio of NaOH to GO is a crucial factor in determining the mechanical properties of geopolymers-GO composites. [ABSTRACT FROM AUTHOR]

Porous carbon derived from grape marc (GM) was synthesized via carbonization and chemical activation processes. Extrinsic nitrogen (N)-dopant in GM, activated by KOH, could render its potential use in supercapacitors effective. The effects of chemical activators such as potassium hydroxide (KOH) and zinc chloride (ZnCl2) were studied to compare their activating power toward the development of pore-forming mechanisms in a carbon electrode, making them beneficial for energy storage. GM carbon impregnated with KOH for activation (KAC), along with urea as the N-dopant (KACurea), exhibited better morphology, hierarchical pore structure, and larger surface area (1356 m2 g−1) than the GM carbon activated by ZnCl2 (ZnAC). Moreover, density functional theory (DFT) investigations showed that the presence of N-dopant on a graphite surface enhances the chemisorption of O adsorbates due to the enhanced charge-transfer mechanism. KACurea was tested in three aqueous electrolytes with different ions (LiOH, NaOH, and NaClO4), which delivered higher specific capacitance, with the NaOH electrolyte exhibiting 139 F g−1 at a 2 mA current rate. The NaOH with the alkaline cation Na+ offered the best capacitance among the electrolytes studied. A multilayer perceptron (MLP) model was employed to describe the effects of synthesis conditions and physicochemical and electrochemical parameters to predict the capacitance and power outputs. The proposed MLP showed higher accuracy, with an R2 of 0.98 for capacitance prediction.

CrN, one of the most investigated transition metal nitrides, is noted for its wear, corrosion, and oxidation resistance. It also has many other unique chemical and mechanical properties. In the present study, we conducted a density functional theory (DFT) analysis to probe the structural, electronic, and optical properties of pristine and Mo-doped CrN structures in non-crystalline phases using different combinations in which one or two Cr and/or N atoms were substituted by Mo. This study found that the Cr 4 Mo 2 N 2 structure was chemically and energetically the most stable species among the six considered clusters (Cr 4 N 4 , Cr 3 Mo 2 N 3 , Cr 4 Mo 2 N 2 , Cr 2 Mo 2 N 4 , Cr 4 MoN 3 , and Cr 3 MoN 4). The DFT-derived electronic structure predicted that the Cr 3 Mo 2 N 3 and Cr 4 MoN 3 clusters possess magnetic susceptibility. Computed infrared (IR), Raman, and ultraviolet–visible (UV–Vis) analyses indicated that the Cr 4 N 4 and Cr 4 Mo 2 N 2 clusters were naturally stable. This should enable these clusters to serve as light-harnessing materials for strategic applications in solar selective surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] • Herein, we report hydrodesulfurization mechanism of thiophene over Mo 2 N. • Direct desulfurization of thiophene incurs very high activation barrier. • An overall barrier for thiophene hydrdesulfurisation attains a value of 24 kcal/mol. • Hydrodesulfurization of thiophene produces adsorbed C 4 H 6 and S atom. • Conversion of thiophene resides between 0.5 – 0.7 at 700 K and low values of GHSV. Catalytic removal of the S-content from thiophene is a central step in efforts aiming to reduce the environmental burdens of transportation fuels. In this contribution, we investigate the hydrodesulfurization (HDS) mechanisms of thiophene (C 4 H 4 S) over γ -Mo 2 N catalyst by means of density functional theory (DFT) calculations. The thiophene molecule preferentially adsorbs in a flat mode over 3-fold fcc nitrogen hollow sites. The HDS mechanism may potentially proceed either unimolecularly (direct desulfurization) or via H-assisted reactions (hydrogenation). Due to a sizable activation barrier required for the first C S bond scission of 54.6 kcal/mol, we predict that the direct desulfurization to contribute rather very insignificantly in the HDS mechanism. Transfer of adsorbed hydrogen atoms on the γ -Mo 2 N surface to the thiophene ring substantially reduces activation barrier required in the C S bond scission to only 24.1 kcal/mol in a process that affords an adsorbed C 4 H 6 * species and an S atom. Further hydrogenation of the unsaturated C 4 H 6 * produces 2-butene. Kinetics and thermodynamics attributes dictate the occurrence of partial rather than full hydrogenation of C 4 H 6 *. Calculated rate constants for all individual steps could be utilized to construct a robust kinetic model for the overall HDS process. Estimated conversion values of thiophene predict 50–70% consumption of thiophene at 700 K and low values of gas hourly space velocities. Reaction routes and kinetic parameters provided herein are useful to design stand-alone γ -Mo 2 N-based catalysts for applications entailing partial hydrogenation and hydrodesulfurization of severely contaminated S-fuels. [ABSTRACT FROM AUTHOR]

This contribution investigates the effect of the addition of the Hubbard U parameter on the electronic structural and mechanical properties of cubic ( C -type) lanthanide sesquioxides (Ln 2 O 3 ). Calculated Bader's charges confirm the ionic character of Ln O bonds in the C -type Ln 2 O 3 . Estimated structural parameters (i.e., lattice constants) coincide with analogous experimental values. The calculated band gaps energies at the U eff of 5 eV for these compounds exhibit a non-metallic character and U eff of 6.5 eV reproduces the analogous experimental band gap of cerium sesquioxide Ce 2 O 3 . We have thoroughly investigated the effect of the O/Ce ratios and the effect of hafnium (Hf) and zirconium (Zr) dopants on the reduction energies of CeO x configurations. Our analysis for the reduction energy of CeO 2 , over a wide range of temperatures displays that, shuffling between the two +4 and +3 oxidation states of Ce exhibit a temperature-independent behaviour. Higher O/Ce ratios necessitate lower reduction energies. Our results on Ce Hf Zr O alloys are in reasonable agreements with analogous fitted values pertinent to lowering reduction energies and shrinkage in lattice parameters when contrasted with pure CeO 2 . Structural analysis reveals that Hf and Zr atoms in the solid solution are shifted towards the nearest vacancies upon reduction. It is hoped that values provided herein to shed an atomic-base insight into the reduction/oxidation thermodynamics of increasingly deployed catalysts for environmental applications. [ABSTRACT FROM AUTHOR]

This study develops a systematic density functional theory alongside on-site Coulomb interaction correction (DFT + U) and ab initio atomistic thermodynamics approachs for ternary (or mixed transitional metal oxides), expressed in three reservoirs. As a case study, among notable multiple metal oxides, synthesized CoCu 2 O 3 exhibits favourable properties towards applications in solar, thermal and catalytic processes. This progressive contribution applies DFT + U and atomistic thermodynamic approaches to examine the structure and relative stability of CoCu 2 O 3 surfaces. Twenty-five surfaces along the [001], [010], [100], [011], [101], [110] and [111] low-Miller-indices, with varying surface-termination configurations were selected in this study. The results portray satisfactory geometrical parameters for bulk CoCu 2 O 3, and a band gap of 1.25 e V. Furthermore, we clarified the stoichiometrically balanced inverted (010)CoCuO, and the non-stoichiometric (001)CuOCu, (001)CoOCo, (110)OCoO and (110)CoOCu surface terminations as the most stable configurations, out of which, the (001)CuOCu shows the optimum stability in ambient conditions. The systematic approach applied in this study should prove instrumental for the analysis of other 3-element multicomponent systems. To the best of our knowledge, the present study is the first to report DFT + U analysis to any 3-multicompnent systems with two of them requires inclusion of U treatment (i.e., f - and d - orbitals) in the electronic structure calculations. [ABSTRACT FROM AUTHOR]

• Very-few-layer graphene (VFLG) can be produced using facile and green process. • VFLG consists of 1–3 layers which is dominated by single layer graphene. • VFLG has edge chirality of armchairs and zigzag with mean lateral size of ~375.4 nm. • DFT calculations provided pertinent optical/electronic properties of graphene. A defect-free graphene with 1–3 layers (very-few-layer graphene, VFLG) has been successfully produced using a facile and environmentally friendly two-step shear exfoliation method in rotating-blade mixer (kitchen blender) and in high shear rotor–stator mixer. An aqueous solution containing an inexpensive and safe anionic surfactant of sodium lauryl sulphate (SLS) was deployed as the working fluid. Raman spectroscopy (RS) and Raman imaging (RI), density functional theory (DFT) simulation, transmission electron microscopy and high-resolution transmission electron microscopy (TEM-HRTEM), as well as Fourier-transform infrared spectroscopy (FTIR) analyses were used to characterize the samples. Some configurations of mixer setting were applied, and the exfoliation mechanisms were discussed. RS analysis revealed that the exfoliation process in rotating-blade mixer continued by high shear in rotor–stator mixer for 3 h had produced VFLG dominated by a single layer of graphene. The Lorentzian peak fitting of 2D band was well-fitted by a single Lorentzian component at Raman shift of 2651.317 cm−1. The produced VFLG endured the lowest peak intensity ratio of D and G bands (I D /I G) of 0.146 which corresponded with the highest lateral size. RI analysis showed that produced VFLG had edge chirality of armchairs and zigzag terminations. TEM-HRTEM confirmed the presence of VFLG with the highest mean lateral size of ~375.4 nm. DFT calculations provided pertinent optical/electronic properties of graphene in terms of Raman Spectra, density of states (DOS) curve and nuclear magnetic resonance (NMR) shielding tensor. FTIR analysis showed that the exfoliation process did not cause any oxidation, sulphonation, or functional defects on the VFLG. The turbulence and hydrodynamic force in liquid were the critical factors in the exfoliation processes. High-quality VFLG, with a facile, inexpensive, and environmentally friendly synthesis process, rendered this process to be a promising route for large-scale high-quality graphene production. [ABSTRACT FROM AUTHOR]

The elevated metaldehyde (a toxic molluscicide) concentrations in UK and EU water bodies are a major concern among water treatment professionals and related stakeholders. The difficulty of removing metaldehyde using conventional water treatment methods has motivated researchers to develop more effective treatment solutions. In this contribution, we have utilized density functional theory (DFT) to fundamentally investigate the adsorptive interactions (e.g. binding energy) between metaldehyde and sulfonic functional group in an ion exchange resin. Adsorption of the cationic metaldehyde on deprotonated sulfonic group is substantial with a binding energy amounting to 130.9 kcal/mol. Preliminary results on an experimental study involving adsorption of metaldehyde on ion exchange resin are also reported. Our findings would complement the existing body of knowledge on metaldehyde removal. Unlabelled Image • We study adsorptive interactions between metaldehyde and sulfonic functional group. • This occurs in an ion exchange resin. • Adsorption (binding) energies are calculated using density functional theory. • Binding energy of cationic metaldehyde-deprotonated sulfonic group = 130.9 kcal/mol. [ABSTRACT FROM AUTHOR]

Co-pyrolysis of brominated flame retardants (BFRs) with polymeric materials prevails in scenarios pertinent to thermal recycling of bromine-laden objects; most notably the non-metallic fraction in e-waste. Hydro-dehalogenation of aromatic compounds in a hydrogen-donating medium constitutes a key step in refining pyrolysis oil of BFRs. Chemical reactions underpinning this process are poorly understood. Herein, we utilize accurate density functional theory (DFT) calculations to report thermo-kinetic parameters for the reaction of solid polyethylene, PE, (as a surrogate model for aliphatic polymers) with prime products sourced from thermal decomposition of BFRs, namely, HBr, bromophenols; benzene, and phenyl radical. Facile abstraction of an ethylenic H by Br atoms is expected to contribute to the formation of abundant HBr concentrations in practical systems. Likewise, a relatively low energy barrier for aromatic Br atom abstraction from a 2-bromophenol molecule by an alkyl radical site, concurs with the reported noticeable hydro-debromination capacity of PE. Pathways entailing a PE-induced bromination of a phenoxy radical should be hindered in view of high energy barrier for a Br transfer into the para position of the phenoxy radical. Adsorption of a phenoxy radical onto a Cu(Br) site substituted at the PE chain affords the commonly discussed PBDD/Fs precursor of a surface-bounded bromophenolate adduct. Such scenario arises due to the heterogeneous integration of metals into the bromine-rich carbon matrix in primitive recycling of e-waste and their open burning. Image 1 • Hydro-dehalogenation of aromatic compounds constitutes a key step in refining pyrolysis oil of BFRs. • We describe the interaction of a bromphenoxy radical with a PE-Cu(Br) configuration. • Such a scenario arises in primitive recycling of e-waste and their open burning. • Computed parameters are useful for understanding the combustion chemistry of BFRs-polymers blends. [ABSTRACT FROM AUTHOR]