Single Atom Catalysts (SACs) are a new frontier in catalysis, merging the positive aspects of both homogeneous and heterogenous catalysts. CO2 electrochemical reduction is a key reaction for the ...energy transition. In this work, we investigate the role of the local coordination on the activation of CO2 on SACs, by means of density functional theory (DFT) calculations. We scrutinize 20 transitional metal atoms embedded in a graphene support. The results indicate that the local coordination has a critical role both to the binding energy of the metal to the support and the activation of CO2. The role of the environment around the active site is as important as the nature of the metal atom. At the same time, the stability of reaction intermediates strongly depends on the local coordination. In some cases, the relative stability of the intermediates changes as function of the environment, affecting the selectivity of the reaction. This study provides evidence of the importance of the local coordination in single-atom catalysis, a crucial aspect if one is interested in providing a rationale to the reactivity, or in predicting novel catalysts.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Novel functional materials, namely TPI-TAZ-ISA, NADPI-TAZ-ISA, ADPI-TAZ-ISA, and DMAPDPI-TAZ-ISA, were synthesized utilizing click chemical reactions and subjected to thorough characterization. The ...optical properties of these organic materials, TPI-TAZ-ISA, NADPI-TAZ-ISA, ADPI-TAZ-ISA, and DMAPDPI-TAZ-ISA, were investigated in various solvent environments. Notably, ADPI-TAZ-ISA exhibited a maximum absorption wavelength of 390 nm attributed to π – π* electronic transitions, primarily originating from the fluorophore group, while displaying a blue fluorescence at 465 nm. A comprehensive investigation combining experimental and theoretical approaches was conducted for these compounds, revealing a non-planar molecular structure and theoretical energy band gaps ranging from 4.10 to 4.73 eV. DFT studies demonstrated well-defined spatial separation of the HOMO and LUMO for all compounds in the ground state (S0). NTO studies further elucidated the spatial separation of the HONTO and LUNTO for DMAPDPI-TAZ-ISA at the excited state (S2), corroborated by CDD, hole and electron contributions, and the overlap of hole and electron densities. These findings hold promise for the development of novel luminescent materials. Moreover, on-going research is exploring the integration of ISA to enhance the functionality of these materials further.
•The synthesis and characterization of TPI-TAZ-ISA, NADPI-TAZ-ISA, ADPI-TAZ-ISA, and DMAPDPI-TAZ-ISA compounds are presented.•Absorption and emission properties are determined through experimental and DFT methods.•The optical characteristics of compounds TPI-TAZ-ISA, NADPI-TAZ-ISA, ADPI-TAZ-ISA, and DMAPDPI-TAZ-ISA are primarily attributed to local π–π* transitions.•Comprehensive analyses utilizing DFT and TD-DFT are conducted for the synthesized compounds.•ISA is identified as a potential acceptor, facilitating the creation of desired blue emissive optoelectronic materials.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Electronic and magnetic properties of MoS2/ZnO/VS2 trilayer van der Waals (vdW) heterostructure were investigated for the first time.•Type II Band alignment was observed for the ...trilayer.•Ferromagnetic ground state with Curie temperature 65 K.•Strain engineering of the trilayer.
MoS2/ZnO/VS2 trilayer van der Waals (vdW) heterostructure is reported for its electronic and magnetic properties for the first time. Heyd-Scuseria-Ernzerhof (HSE) hybrid functional is used to compute the electronic band structure and it is observed that the heterojunction exhibits an indirect transition. The trilayer showed type II band alignment. This along with the Charge Density Difference (CDD) isosurface and plot showed the charge transfer in both the spin channels from ZnO to both MoS2 and VS2 monolayer. Monte Carlo (MC) simulation revealed a low Curie temperature (TC) value of 65 K. Effect of compressive and tensile biaxial strain on the trilayer was studied where all the strained system turned metallic. Under both biaxial tensile and compressive strain, the TC at first increased and then gradually decreased which hints at tuning the TC with strain engineering. Thus, the metallic strained MoS2/ZnO/VS2 trilayer has potential application in the spintronics devices.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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•Ag-based core-shell nanoclusters with 3d-5d transition metal cores are investigated by DFT.•The most stable mixing is found in the noble metal-encapsulated structures.•The reaction ...barrier for OH formation is found to be the limiting step.•Ru@Ag, Rh@Ag and Os@Ag mixings are the most suitable for the ORR.•The activity of the nanoclusters is confirmed by the shell strain parameter.
The depletion of traditional fossil fuels, as well as the increase in global energy demand, is currently driving the need for sustainable energy solutions. The primary challenge in the practical application of hydrogen fuel cells is to reduce or replace the use of platinum material in the electrode catalysts. In this work, by using density functional theory (DFT) we investigate the oxygen reduction reaction of Ag-based core-shell nanoclusters with 12 different 3d-5d transition metal (TM) cores (groups 8–11). The stability is assessed by calculating the binding, excess and segregation energies, indicating that the most stable mixing is found in the noble metal-encapsulated structures, such as Pd@Ag, Pt@Ag, Rh@Ag and Ir@Ag particles. The reaction barrier for OH formation is found to be the limiting step with values ranging from 0.59 to 1.36 eV among the core-shell Ag-based nanoclusters, which are comparable with the energy barrier of the Pt(111) surface (0.97 eV). However, the correlation of the d-band center and activation barriers indicate that Ru@Ag, Rh@Ag, and Os@Ag mixings are the most suitable for the oxygen reduction reaction. These results indicate that small Ag-based core-shell nanoclusters with transition metal cores are active for the ORR application in alkaline media.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The adsorption and sensing capabilities of CO and NO on pristine and metal-decorated (8,0) SWCNT were analyzed by DFT. Both gases cause a slight deformation of the nanotube curvature in the direction ...of molecular adsorption. The molecule's adsorption and sensing performance are enhanced with the transition metal (Sc, Cr, Fe, and Ni) decoration on SWCNT. Decorated nanotubes are suitable for high-temperature sensors. According to relative energies for NO, the operational range is 900–1200 K. For CO/Cr- and Sc-SWCNT between 100 and 200 K and close to 550 K in the cases of decoration with Fe and Ni. From the recovery time analysis, the metal-decorated materials exhibit better performance at high temperatures and low pressures for NO compared to CO. Changes in magnetic moment suggest that Cr-decorated SWCNT could serve as a magnetic sensor for both molecules.
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•The pristine CNT is more reactive to NO than CO.•The transition metal (TM) doping enhances the adsorption energy and sensing performance for NO and CO.•TM-doped SWCNTs are better for sensing NO at high temperature and low pressure.•Recovery time shows that the best sensors for NO are Cr and Ni decorated CNT.•At room temperature, TM-SWCNTs could be effective for absorbing material to clean both gases.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Hydrogen and hydrogen-containing gases are commonly used as reductants in chemical vapor deposition growth of MoS2. Here, we consider the defects resulting from the presence of hydrogen during growth ...and the resulting electronically active defects. In particular, we find that the interstitial hydrogen defect is a negative-U center with amphoteric donor and acceptor properties. Additionally, we consider the effects of interaction with water and oxygen. The defects are analysed using density functional theory calculations.
Different concentrations of zirconium with a fixed quantity (4 wt%) of chitosan (CS) doped nickel cobaltite (NiCo2O4) nanorods were synthesized using a co-precipitation approach. This cutting-edge ...research explores the cooperative effect of Zr-doped CS-NiCo2O4 to degrade the Eriochrome black T (EBT) and investigates potent antibacterial activity against Staphylococcus aureus (S. aureus). Advanced characterization techniques were conducted to analyze structural textures, morphological analysis, and optical characteristics of synthesized materials. XRD pattern unveiled the spinal cubic structure of NiCo2O4, incorporating Zr and CS peak shifted to a lower 2θ value. UV–Vis spectroscopy revealed the absorption range increased with CS and the same trend was observed upon Zr, showing a decrease in bandgap energy (Eg) from 2.55 to 2.4 eV. The optimal photocatalytic efficacy of doped NiCo2O4 within the basic medium was around 96.26 %, and bactericidal efficacy was examined against S. aureus, revealing a remarkable inhibition zone (5.95 mm).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
In this study, we have investigated the electronic , structural, elastic, optical and thermodynamic properties of the copper-based ternary semiconductors, that is, KCuZ (Z= Te, Se). The properties of ...these materials have been precisely determined based on first-principle calculations. The lattice constants, bulk modulus and equilibrium total energies were obtained from Murnaghan equation of state and have a good agreement with other theoretical and experimental methods. The absorption spectra was analyzed to determine the active window of electromagnetic spectrum of the compounds. The elastic constants of these materials were elucidated and hence provided vital information about the material’s ability to withstand external stress. The results indicate that the materials conform to the stability criteria with brittle behavior and anisotropic nature in the HCP structure. The electronic band structures and density of states were computed and the results obtained suggests that the these materials have a band gap of 1.25 eV and 1.1 eV for KCuTe and KCuSe respectively and therefore they are suitable for photovoltaic applications. The materials are also found to posses desirable optical properties i.e. the materials have a good optical absorption since highest absorption peaks occur within the UV region, small reflectivity and high dielectric constant indicating that the materials is suitable for use as solar absorbers.
•KCuTe and KCuSe are both hexagonal in nature and belong to space group P63/mmc.•KCuTe and KCuSe structures are mechanically and thermodynamically stable.•All the two compounds are brittle.•Band gaps of 1.1 eV for KCuSe and 1.25 eV fo KCuTe.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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