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.
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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•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.
VO2 is promising sensing material for gas selection, and it has appealed to great attention. The structures of VO2 (M) and VO2 (R) crystal have been studied through the first principles. We ...investigated band structure, the density of states (DOS) and charge density difference of phases of VO2, the results show that when VO2 (M) is transformed into VO2 (R), the structure changes from semiconductor to conductor. The special property is expected to be used in gas sensors, lithium batteries, catalysis, supercapacitors and other fields. The basic findings of this calculation will be conducive to better comprehending of the characteristics and performance of VO2 crystal as a gas sensor material.
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.
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).
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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•CoM/TNTs showed high ACE degradation efficiency after PMS activation.•Efficient PMS activation was due to the synergic effect of Co(OH)2 and TNTs.•TNTs with abundant surface –OH ...facilitated formation of CoOH+.•PES analysis well explained the higher feasibility of Co(OH)+ on PMS activation.•ACE atoms with high Fukui index are active sites for electrophilic attack.
Pharmaceuticals and personal care products (PPCPs) are of great concern due to their increasing health effects, so advanced treatment technologies for PPCPs removal are urgently needed. In this study, titanate nanotubes decorated Co(OH)2 hollow microsphere (CoM/TNTs) composites were synthesized by a two-step solvothermal method, and used to activate peroxymonosulfate (PMS) through heterogenous catalysis for acetaminophen (ACE) degradation in water. The optimum material (CoM/TNTs0.5) activated PMS system exhibited high ACE removal efficiency and quick kinetic, as 93.0% ACE was degraded even within 10 min. The two components in CoM/TNTs showed a synergetic effect on PMS activation for radicals production: Co(OH)+ from CoM was the primary active species to active PMS, while TNTs could offer abundant –OH groups for Co(OH)+ formation. Density functional theory (DFT) calculation further interpreted the mechanism of Co(OH)+ for PMS activation by means of reaction potential energy surface (PES) analysis. Both the scavenger quenching tests and electron paramagnetic resonance analysis revealed that the sulfate radical (SO4-·) played a dominant role in ACE degradation. Moreover, DFT calculation also suggested that the ACE atoms with high Fukui index (f-) represented the active sites for electrophilic attack by SO4-·. The toxicity analysis based on quantitative structure-activity relationship (QSAR) verified the reduced toxicity of transformation products. Furthermore, CoM/TNTs also had good reusability and stability over five cycles. This work provides deep insights into the reaction mechanisms of radical production and organics attack in cobalt-based PMS activation system.
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