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The current work aims to explore the effect of the transition metal doping on the structural, magnetic, and shielding properties of nano Er2O3. Nano Er1.95TM0.05O3 (TM = Mn, Co, Ni) samples were synthesized using the sol-gel technique. An analysis of the crystal structure and microstructure of all specimens was carried out utilizing Rietveld full pattern fitting of XRD measurements. Upon doping, all TM cations were found to be integrated into the Er2O3 lattice substitutionally for Er ions, preferring the 8b crystallographic sites of the cubic bixbyite structure. Also, the lattice parameter expands, the average crystallite size reduced, and the microstrain highly enlarged by TM doping. The application of the Curie–Weiss law aided in establishing the influence of different dopants on the magnetic behavior of the Er1.95TM0.05O3 samples at low temperatures under a magnetic field of 200 Oe. The inclusion of Co or Ni ions in the Er2O3 matrix enhances the super exchange interaction, resulting in stronger antiferromagnetic coupling between the Er ions. The Phy-X/PSD software was used to calculate the radiation shielding parameters for the samples under investigation, covering a broad energy range from 15 KeV to 15 MeV. The effect of transition metal doping of Er2O3 on the different radiation parameters were explored. Er1.95Mn0.05O3 sample has excellent neutron shielding capabilities. [ABSTRACT FROM AUTHOR]

The current work aims to explore the effect of the transition metal doping on the structural, magnetic, and shielding properties of nano Er2O3. Nano Er1.95TM0.05O3 (TM = Mn, Co, Ni) samples were synthesized using the sol-gel technique. An analysis of the crystal structure and microstructure of all specimens was carried out utilizing Rietveld full pattern fitting of XRD measurements. Upon doping, all TM cations were found to be integrated into the Er2O3 lattice substitutionally for Er ions, preferring the 8b crystallographic sites of the cubic bixbyite structure. Also, the lattice parameter expands, the average crystallite size reduced, and the microstrain highly enlarged by TM doping. The application of the Curie–Weiss law aided in establishing the influence of different dopants on the magnetic behavior of the Er1.95TM0.05O3 samples at low temperatures under a magnetic field of 200 Oe. The inclusion of Co or Ni ions in the Er2O3 matrix enhances the super exchange interaction, resulting in stronger antiferromagnetic coupling between the Er ions. The Phy-X/PSD software was used to calculate the radiation shielding parameters for the samples under investigation, covering a broad energy range from 15 KeV to 15 MeV. The effect of transition metal doping of Er2O3 on the different radiation parameters were explored. Er1.95Mn0.05O3 sample has excellent neutron shielding capabilities. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation is the most efficient way to achieve the goal of "Carbon Neutral," and the transition metals (Mn, Co, Ni, Cu)‐embedded faveolate ZnFe2O4 were fabricated and then evaluated with a CO2 hydrogenation test. The systematic investigation of the effect of the introduced transition metals on the catalytic performance revealed that the activity was influenced by the surface structure, especially by the surface Fe−C percentages. The introduction of Zn could increase CO2 adsorption, thus promoting the reverse water gas shift (RWGS) reaction, which is considered the first step during CO2 hydrogenation. The surface Fe−C species played a significant role during the Fischer‐Tropsch (F−T) synthesis, specific to the carbon chain growth process. Among all catalysts, Co‐doped ZnFe2O4 exhibited the highest surface Fe−C percentage; therefore, it exhibited the optimal CO2 conversion, C2+ selectivity, C2‐C4 space‐time yield, and olefin/paraffin ratio, which were 42.12 %, 81.26 %, 34.64 %, and 40.25 %, respectively. Furthermore, the introduced Co species can also act as active sites to enhance the activation and dissociation of CO2, as confirmed by theoretical adsorption calculations. [ABSTRACT FROM AUTHOR]

The numerous benefits like smaller size, easy handling, quicker readouts and cost effectiveness render TLDs as prominent radiation dose measuring instruments. Zinc Oxide (ZnO) is well recognized among these TLD materials due to its remarkable post exposure glow properties. Moreover, along with reasonable TL properties it inherently shows good mechanical and chemical stability, non-toxic and non-hygroscopic nature. However, in comparison to its contemporaries it lacks in sensitivity when exposed to low radiation doses and exhibits moderate fading effects. These draw backs stem from ZnO electronic nature i.e. availability of low number of radiation responding electrons along with trapping centers which can retain these electrons and are responsible for thermal assisted glow curve. One of the solutions is doping it with high atomic number metallic ions. Transition metals (TM) and rare earth (RE) elements doped ZnO materials show promising results i.e. doped ZnO shows improved TL response i.e. more linearity, better stability and less fading. As TM and RE doped ZnO appears to be promising TLD materials, this review provides an overview of research on TL characteristics of TM and RE doped ZnO materials. • ZnO TLD sensitivity is tunable in terms of transition and rare earth doping. • Stable TLD performance in high doses is possible employing doped ZnO. • Future passive dosimetry is possible employing cost-effective TM and RE doped ZnO. • The avenue of research for deeper understanding and linearity of response in all dose limits is still open for doped ZnO TLD. [ABSTRACT FROM AUTHOR]

This paper introduces the adsorption of four harmful gases (CH 4 , HCHO, SO 2 , NO 2) on MoTe 2 monolayer and transition metal (V, Cr, Mn) decorated MoTe 2. Based on the density functional calculation (DFT), the adsorption energy, charge transfer, density of state, deformation charge density, and molecular orbitals are analyzed. It was found that transition metal decoration significantly promoted the adsorption ability of MoTe 2. [Display omitted] • Adsorption properties of pristine MoTe 2 decorated with V, Cr, Mn monolayers towards CH 4 , HCHO, SO 2 , NO 2 gases were discussed. • V-MoTe 2 had the highest adsorption energy, making it a better gas removal material. • Sensor response and recovery time were evaluated. For the detection and removal of four hazardous gases (CH 4 , HCHO, SO 2 , NO 2), we used density functional theory to investigate the properties of the pristine MoTe 2 and MoTe 2 decorated with V, Cr, and Mn atoms. By examining the density of state, adsorption energy, and charge transfer of four gases adsorbed on the surface, it was showed that the adsorption capability of MoTe 2 was significantly enhanced after the decorating of transition metals. V-MoTe 2 had the highest adsorption energies (−0.527, −2.574, −1.480, −3.363 eV) of the four gas molecules, making it a better gas removal material. The adsorption energies on Cr-MoTe 2 and Mn-MoTe 2 were lower than that of V-MoTe 2 , and their desorption time were shorter, making them more suitable for the application of gas sensors. This study revealed that V, Cr, and Mn-decorated MoTe 2 were potential materials for the detection or removal of CH 4 , HCHO, SO 2 and NO 2 gases, V-MoTe 2 was more suitable for the removal, while Cr and Mn-MoTe 2 were more suitable for the detection of harmful gases. [ABSTRACT FROM AUTHOR]

The influences of transition metals (Sc, Ti, V, Cr and Mn) doping at different distances on the stability, electronic structure, conductivity and optical properties of CdS are studied by using VASP code. The results show that the Cr-doped CdS is easy to form, followed by V, Ti, Sc and Mn. The next nearest-neighbor doping is the most stable in each transition metal-doped system. The band-gaps gradually decrease with the order of Sc, Ti, V, Cr, Mn-doping, all doped systems become the degenerate semiconductor. Doping not only enhances conductivity, but also improves photocatalytic performance, especially Mn-doped CdS has obvious improvement. The absorption intensity in the visible light range of the single-doping is more than that of two atoms doped system in different distances, of which Mn and Cr single-doping are the most prominent.

The development of low-cost, high-performance electrocatalysts for hydrogen precipitation reactions is the key to solving the energy crisis. Metal organic framework (MOFs) with metal centers and organic ligands are one of the ideal materials for the preparation of non-precious metal carbon-based HER electrocatalysts. In this work, a series of transition metal-doped nano-superstructures carbon-based materials NiMC (M = Fe, Co, Cu) were designed and prepared by introducing different transition metal atoms using Ni-MOF as precursors. And the effect of transition metal doping on the electrocatalytic hydrogen precipitation performance of Ni-MOF has been systematically investigated. Nitrogen adsorption tests have shown that the NiFeC catalyst has the highest specific surface area. The overpotential was only 69 mV at a current density of 10 mA cm−2 in an alkaline electrolyte and exhibited excellent stability. Density functional theory (DFT) calculations show that the electronic interactions between Fe and Ni are tuned after Fe atom doping, which optimizes the hydrogen adsorption energy leading to the excellent HER catalytic performance of NiFeC. [ABSTRACT FROM AUTHOR]

Graphene-based toxic HCl gas sensors and adsorption materials are seldom reported. Utilizing density functional theory (DFT), the adsorption energy, charge density, and density of states, the sensitivity and recovery time of HCl gas adsorbed on graphene and six different transition metal-doped graphenes (TMDGs: TM = Ti, V, Cr, Mn, Fe, Co) were investigated. It indicates that TMDG has larger adsorption energy and chemical adsorption capacity than graphene. The Fe-doped graphene (FeDG) demonstrated better adsorption capacity and higher stability even at high temperature. The Mn- and Co-doped graphenes (MnDG & CoDG), exhibited magnetic changes after the adsorption of HCl molecules. Moreover, MnDG has both fast responsiveness and fast recovery time at a certain temperature. Thus, comparative speaking, among the six TMDGs, MnDG is the most suitable material for the detection of HCl gas, its magnetic property implied a novel application in HCl gas sensor. [Display omitted] • Graphene doped with transition metals show prospective applications in the detection and adsorption of HCl gas. • Fe-doped graphene has higher adsorption energy and better adsorption effect. • Mn-doped graphene has lower desorption temperature and better sensitivity. • Magnetic properties of Mn, Co-doped graphene changed after the HCl adsorption. [ABSTRACT FROM AUTHOR]

[Display omitted] • The potentials of 10 TM atoms doped in the Pt (1 0 0) surface as efficient and sustainable NOER catalysts are systematically studied by DFT. • The results showed that Ti/Co/Ni-Pt has the excellent NOER catalytic activity and better selectivity than HER. • The mechanisms of NO conversion to N 2 O and N 2 on Ti/Cr/Co/Ni-Pt systems were studied under high NO coverage. NO electrocatalytic reduction (NOER) is an efficient and sustainable way to eliminate NO harmful gas and synthesis NH 3. However, finding suitable catalysts for the catalytic reduction of NO to NH 3 and improving the catalytic activity of NOER is one of the challenges to be overcome at present. Hence, the potentials of 10 transition-metal (TM) atoms doped in the Pt (1 0 0) surface as efficient and sustainable NOER catalysts are systematically studied by using first-principles calculation. The mechanisms of NOER were explored by calculating the Gibbs free energy. The results showed that Ti/Cr/Co/Ni-Pt has the excellent NOER catalytic activity, and there is better selectivity than hydrogen evolution reaction (HER) for Ti/Co/Ni-Pt systems. According to results of limiting potential, Ni-Pt exhibits high activity and selectivity for NOER towards NH 3 synthesis. Furthermore, we also studied the mechanisms of NO conversion to N 2 O and N 2 on Ti/Cr/Co/Ni-Pt systems under high NO coverage. It provides an idea to realize controllable multi-product on Pt - based catalyst. [ABSTRACT FROM AUTHOR]

Recently, 2D materials have attracted great interest in the gas-sensing field, in which TMMC GeS, GeSe, SnS, and SnSe monolayers have been reported as promising SO 2 sensing materials [ Chem. Phys. Lett. 686 (2017) 83–87; Appl. Surf. Sci. 484 (2019) 33–38 ]. However, the transport properties, sensitivity, and recovery times of such structures related to the adsorption of SO 2 molecule have not been published to date. In this work, we found that the recovery times of the pristine GeS, GeSe, SnS, and SnSe monolayers after SO 2 adsorption are too short, indicating their low application possibility for SO 2 sensing materials. Interestingly, the transition metals doping (Cr, Mn, or Fe) improves the recovery time of the SnSe monolayer in respect of SO 2 molecules. Especially the calculated recovery time of the Fe-doped SnSe monolayer in respect of SO 2 molecules at 373 K is 27 s, which is suitable for reusable gas sensors. Moreover, we first designed an SO 2 gas sensor based on the Fe-doped SnSe monolayer with two Au electrodes. The NEGF formalism-based calculations show its high sensitivity to an SO 2 molecule. Our results suggest that the Fe-doped SnSe monolayer is a promising 2D material for reusable SO 2 gas sensors with high sensitivity. (Left panel) A schematic of a gas sensor device designed in relation to SO 2 molecules where the proposed device is structured from a doped Fe-SnSe monolayer that acts as a scattering zone with two Au electrodes at either side. The signal of the sensing device before and after absorbed SO 2 molecules is relatively detected. (Right panel) The sensitivity as a function of the bias voltages applied between the given electrodes of the device is thus detected. [Display omitted] • The adsorption properties of GeS, GeSe, SnS, and SnSe monolayers with respect to SO 2 molecules were systematically elucidated. • A short recovery time of the pristine GeS, GeSe, SnS, and SnSe monolayers is found. • Transition metals (Cr, Mn or Fe) doping improves the recovery time of the SnSe monolayers in respect of SO 2. • The Fe-doped SnSe monolayer is a promising 2D material for reusable SO 2 gas sensors. [ABSTRACT FROM AUTHOR]

We have synthesized Ti-doped (Tl $$_{1-x}$$ Ti $$_{x})$$ Ba $$_{2}$$ Ca $$_{2}$$ Cu $$_{3}$$ O $$_{y}$$ ( x = 0, 0.2, 0.4, 0.6, 0.8) superconductors at normal pressure. The samples have shown $$T_\mathrm{c}$$ onset at 117, 118, 113, 110, and 115 K and the $$T_\mathrm{c}$$ $$(R=0)$$ at 103, 96, 94, 97, and 106 K and the onset of diamagnetism around 109, 100, 98, 111, 100 K, respectively. The apical oxygen-related phonon modes are observed around 485 and 540 cm $$^{-1 }$$ , and the planar oxygen modes at 600 cm $$^{-1}$$ . These phonon modes are softened with the increase concentration of Ti in the final compound showing that Ti is incorporated into the (Tl $$_{1-x}$$ Ti $$_{x})$$ Ba $$_{2}$$ Ca $$_{2}$$ Cu $$_{3}$$ O $$_{y}$$ ( x = 0, 0.2, 0.4, 0.6, 0.8) samples. The excess conductivity analysis of these samples has shown an enhancement in the values of the parameters such as $$\xi _{\mathrm{c}(0)}$$ , J, and $$V_\mathrm{F}$$ with the doping of Ti. We proposed that the doping of Ti in the $$( {\mathrm{Tl}_{1-{\textit{x}}} \mathrm {Ti}_{{x}} })\mathrm{Ba}_2 \mathrm{O}_{4-\delta } $$ charge reservoir layer facilitates the charge transfer mechanism for conducting CuO $$_{2}$$ planes which in turn enhance the values of aforementioned superconductivity parameters. The values of superconductivity parameters such as $$B_\mathrm{c(0), }$$ $$B_\mathrm{c1(0), }$$ $$B_\mathrm{c2(0)}$$ , and $$J_\mathrm{c}$$ (0) are, however, suppressed with Ti doping. We suggested this to be arising from the weakening of flux pinning character in the final compound. These results have shown that the oxygen defect density in (Tl $$_{1-x}$$ Ti $$_{x})$$ Ba $$_{2}$$ Ca $$_{2}$$ Cu $$_{3}$$ O $$_{y}$$ samples is significantly suppressed with Ti doping. [ABSTRACT FROM AUTHOR]

A facile transition metals (TM = Mn, Co, Cu) doping has been employed as an effective approach to alter the electrical and optical properties of LaFeO 3 with substantially improved photoelectrochemical (PEC) water oxidation performance under visible light. It is found that the highest photocurrent density is obtained with 10% doping concentration, and the promoted photoconversion efficiency follows the order of LaFe 0.9 Cu 0.1 O 3 > LaFe 0.9 Co 0.1 O 3 > LaFe 0.9 Mn 0.1 O 3 > LaFeO 3 . The 10% Cu dopant yields the highest photocurrent density of 0.99 mA/cm 2 at 1 V vs. Ag/AgCl, which is three times higher than that of pure LaFeO 3 under visible light illumination (>420 nm). The Fe 3+ discharge is observed in the doped samples by cyclic voltammetry study, wherein the discharge capacity exhibits the same trend with the PEC enhancement. The electrochemical impedance spectroscopy shows the enhanced charge transfer on the surface of the TM doped LaFeO 3 , which is responsible for the improved PEC performance. Furthermore, the increased carrier densities upon TM doping revealed by Mott–Schottky plots also contribute to the PEC enhancement. Our results demonstrate that TM doping is a viable way to promote the photoconversion efficiency of LaFeO 3 -based PEC cells under visible light. [ABSTRACT FROM AUTHOR]

[Display omitted] • The TM (Ti, Mn, Fe, Co, Ni, Cu) doping can induce magnetism in monolayer WSe 2. • The spin-resolved anti-bonding states filling influence the HER activity of TM-WSe 2. • The Ni/Cu-WSe 2 possesses optimal HER property with lower Δ G H* (-0.20 and 0.06 eV). Transition metal dichalcogenide monolayers are an emerging family of electrocatalysts, in which Tungsten diselenide (WSe 2) has attracted attention for Hydrogen evolution reaction (HER). Here, the magnetism and HER performance of 3 d transition metal atoms doping WSe 2 (TM-WSe 2) are comprehensively studied using density functional theory. The hybridization between the localized TM-3 d and the delocalized Se-4 p or W-5 d states leads to the ferromagnetic/antiferromagnetic coupling between the TM spins and Se or W spins, which induces magnetism in WSe 2. With the analysis of the integrated-crystal orbital Hamilton population (ICOHP), the ICOHP spin up values of TM-WSe 2 are decreased compared to the pure WSe 2 , which improves the interaction of Se-H, thereby the H atom is easier to be adsorbed on the Se1 site. While all the ICOHP spin down values of TM-WSe 2 are increased, this indicates the weak interaction of Se-H, which promotes the desorption of H 2 molecule. Thus, the synergistic effect of spin up and spin down anti-bonding states filling makes TM-WSe 2 possess an enhanced HER performance. Moreover, the Ni/Cu-WSe 2 possesses optimal HER performance with lower Δ G H* (-0.20 and 0.06 eV). Therefore, our results provide a primary understanding for the relationship between the spin up/down anti-bonding states filling and HER electrocatalytic performance. [ABSTRACT FROM AUTHOR]

Abstract: Ti-doped (Cu0.5Tl0.5)Ba2Ca2 (Cu3− x Ti x )O10− δ (x =0, 0.25, 0.50, 0.75) samples have been synthesized at 860°C by following two step solid state reaction methods and studied their superconducting properties by X-ray diffraction, resistivity, ac-susceptibility, FTIR absorption measurements. Ti-doped samples have shown orthorhombic crystal structure and the cell parameters increase with the increase of Ti-contents. The T c(R =0) and onset of diamagnetism increases with increase Ti-doping in the final compound. The magnitude of superconductivity, however, increases for Ti-doping of y =0.25,0.75. The numbers of carriers in the conducting planes have been optimized by carrying out post-annealing of the samples in oxygen atmosphere. After the post-annealing the T c(R =0) is improved in un-doped samples whereas it is suppressed in all Ti-doped samples. After post annealing in oxygen atmosphere, the magnitude of superconductivity (measured in emu/gm.Os) remains unchanged in un-doped samples whereas it is suppressed in all Ti-doped samples. In FTIR absorption measurements, the CuO2/TiO2 planar oxygen modes are slightly hardened in Ti-doped samples. The most likely reason for the hardening of the planar oxygen modes is decrease in the mass of Ti (47.90amu) in comparison with Cu (63.54amu) atoms; the atoms with lighter-mass vibrate at higher frequency. It is most likely that the existence of atoms of different masses in CuO2/TiO2 planes may suppress the density of phonon population due to setting-in of an-harmonic oscillations. The phonons of harmonic oscillation with wave vector q interact with q′ of an-harmonic oscillation and produce a new phonon with wave vector Q. The phonons with wave vector Q do not contribute in the Cooper-pair formation. It is most likely that a decrease in the population of desired phonons required for higher T c occurs that in turn suppress the density of the Cooper-pair which in turn promote a decrease in the magnitude of superconductivity. These studies indicate the essential role of electron–phonons-interactions in the mechanism of high T c superconductivity. [Copyright &y& Elsevier]

A comparative study of the functional properties of transition metals (M = Fe, Co, Mn and Ni) doped ZnO nanostructured films has been performed for applications in optoelectronics and optical devices. Pristine and M-doped ZnO (M = Fe, Co, Mn, Ni) nanostructured films were prepared by spray pyrolysis procedure. The surfaces' morphology, elemental analysis, bonds' vibrations, structural and optical properties of the samples are studied by a scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), FT-IR spectrophotometry, X-ray diffraction and UV–visible–NIR spectrophotometry, respectively. The structural analysis shows that all samples possess hexagonal wurtzite structures. The Rietveld refinement results reveal noticeable variations in the lattice parameters of the M-doped ZnO nanostructures as compared with those of the pristine one. Due to M-doping, clear deviations in the crystallite size, micro-strain and dislocation density as well as the crystallinity nature are noticed in the host ZnO nanostructures. The UV–visible–NIR spectra analysis reveals that the optical bandgap of the pristine ZnO films varies from 3.36 eV to 3.13 eV, 3.20 eV, 3.30 eV and 3.58 eV due to doping with Fe, Co, Mn and Ni respectively. The effect of M-doping on the Urbach energy and refractive index of the ZnO nanostructures has been explored. To the best of our knowledge, this is the first time that a comparative study on the functional properties of four sprayed transition metals doped in ZnO nanostructures has been reported. These unique findings introduce the sprayed M-doped ZnO nanostructures for new applications in optoelectronics and optical devices. • Nanosstructured ZnO doped with metals (M = Fe, Co, Mn, Ni) films were prepared by spray pyrolysis procedure. • Structural analysis shows that all samples possess hexagonal wurtzite structures. • Optical bandgap of the plain ZnO films varies from 3.36 eV to 3.13 eV, 3.20 eV, 3.30 eV and 3.58 eV due to M-doping. • Clear deviations in the crystallite size, micro-strain, dislocation density and the crystallinity nature are noticed. • Our findings introduce the sprayed M-doped ZnO nanostructures for new applications in optoelectronics and optical devices. [ABSTRACT FROM AUTHOR]

• The reaction path of low temperature RWGS on M/C 2 N (M=Cu, Co, Fe) was studied by DFT. • After doping, electrons transfer from m to C 2 N and gather directionally on the surface of C 2 N. • Low-temperature RWGS on Cu/C 2 N and Co/C 2 N proceed to redox mechanism, while Fe/C 2 N tend to carboxyl mechanism. • The energy barrier of rate-determining step in redox mechanism for Cu/C 2 N is the lowest. The reaction path of low temperature reverse water gas reaction (RWGS) on M/C 2 N (M=Cu, Co, Fe) was studied by density functional theory (DFT). The results show that after doping, electrons transfer from M to C 2 N and gather directionally on the surface of C 2 N, which significantly changes the catalytic behavior of C 2 N. Because the increase of electronic activity reduces the reaction activation energy, it effectively promotes the RWGS on C 2 N at low temperature. We also found that the low-temperature RWGS on Cu/C 2 N and Co/C 2 N proceed according to the redox mechanism, while Fe/C 2 N tend to the carboxyl mechanism. Moreover, the energy barrier of rate-determining step in redox mechanism for Cu/C 2 N is the lowest, indicating that the low-temperature RWGS reaction is more likely to occur on this structure. [Display omitted] [ABSTRACT FROM AUTHOR]

• The structural characteristics and optical characteristics of Sc, Ti, V, Cr and Mn-doped CdS are systematically studied. • The effective mass-related characteristics are studied. • The influence of doped distance between transition metals on the structure and optical properties of CdS. The influences of transition metals (Sc, Ti, V, Cr and Mn) doping at different distances on the stability, electronic structure, conductivity and optical properties of CdS are studied by using VASP code. The results show that the Cr-doped CdS is easy to form, followed by V, Ti, Sc and Mn. The next nearest-neighbor doping is the most stable in each transition metal-doped system. The band-gaps gradually decrease with the order of Sc, Ti, V, Cr, Mn-doping, all doped systems become the degenerate semiconductor. Doping not only enhances conductivity, but also improves photocatalytic performance, especially Mn-doped CdS has obvious improvement. The absorption intensity in the visible light range of the single-doping is more than that of two atoms doped system in different distances, of which Mn and Cr single-doping are the most prominent. [ABSTRACT FROM AUTHOR]