RETRACTED ARTICLE: Surface morphology, optical properties and Urbach tail of spray deposited Co3O4 thin films

Zahan, Muslima; Podder, Jiban

doi:10.1007/s10854-019-00717-2

Cited by 20 publications

(9 citation statements)

References 22 publications

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“…Figure 5 ; where R is the reflectance; F(R) is propotional to the absorption coefficient. The obtained curves reveal parabolic band edges that depend on the photon energy and obey Urbachs rule that has been discussed in our previous work [25].…”

Section: Optical Propertiessupporting

confidence: 72%

Structural, optical and electrical properties of Cu:MnO2 nanostructured thin films for glucose sensitivity measurements

Zahan

Podder

2020

SN Appl. Sci.

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In the present investigation, pure MnO 2 and Cu doped MnO 2 (Cu:MnO 2 ) thin films were successfully prepared by the spray pyrolysis deposition technique. Different Cu concentrations were used to analyze the morphological, structural, optical, electrical properties and as well glucose sensitivity measurement has been performed. MnO 2 doped with Cu induces microstructure and is set in the lattice by keeping Mn +2 leading to the micro spherical shape of the samples highlighted from a scanning electron microscope. X-ray diffraction analysis has confirmed the tetragonal MnO 2 crystal structure with α-phase. The crystallite size, crystal structure, texture, and nanoparticle formation in MnO 2 films have been influenced by Cu dopant. The maximum optical transmittance is found to be about 83%. The energy band gap associated with the allowed direct transition is found to increase from 3.82 to 3.96 eV with increasing Cu doping concentration up to 4 at%. Glucose sensitivity was measured by the four-probe technique. Notably, 4 at% Cu:MnO 2 films have demonstrated the superior sensing ability of glucose of 29%.

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Section: Optical Propertiessupporting

confidence: 72%

Structural, optical and electrical properties of Cu:MnO2 nanostructured thin films for glucose sensitivity measurements

Zahan

Podder

2020

SN Appl. Sci.

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“…Urbach energy is calculated by taking the inverse slope of the linear portion of alpha versus photon energy. Urbach energy increases with an increase in the dopant concentration which manifests that the defects of density and structural disorders in the synthesized samples elevates with the Zn content [57][58]. It is distant that the Urbach energy of 0.3 % Zn doped NiO nanoparticles showcase higher quantity in comparison with other less dopant concentrations, inferring that it has generated a significantly higher number of defects.…”

Section: Determination Of Urbach Energy and Electronegativitymentioning

confidence: 82%

Revealing the Substitution of Zn2+ on Nano-Structural, Magneto-Electrical, Antibacterial and Antifungal Attributes of Nickel Oxide Nanoparticles via Sol-Gel Strategy

Aslinjensipriya¹,

R²,

Ragu³

et al. 2022

Preprint

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Transition metal oxides have gathered momentum among the scientific community on account of their peculiar procession in physico-chemical, opto-electronic, magnetic, electrochemical, and biological attributes resulting from anisotropic charge distribution of partly filled d-orbitals, non-stoichiometric behaviour, and diverse oxidation states of the cations. The current work emphasize on the systematic synthesis and characterization of pure and zinc (Zn) incorporated nickel oxide (NiO) nanoparticles in varying concentrations ZnxNi1−xO (x = 0, 0.1, 0.2, and 0.3) via a scalable sol-gel approach assisting citric acid (C6H8O7) as a congealing factor. A series of extensive analyses were executed to investigate the structural, opto-electrical, and magnetic characteristics of prepared nanoparticles. X-Ray Diffraction (XRD) studies confirmed the face-centered cubic structure of as-synthesized samples and the corresponding crystallite size is found to decrease with an increasing dopant concentration as estimated from the Scherrer method. Scanning electron microscopy studies portrayed the spherical structure and porous nature of NiO nanoparticles. Particle size calculated from SEM shows the decreasing trend with dopant discrepancy which is in accordance with crystallite size measured from XRD results. Energy Dispersive X-ray (EDX) spectra revealed the presence of estimated molecular assembly in synthesized samples. The cubic configuration and the presence of functional groups existing in synthesized nanoparticles were endorsed from Fourier Transform Infra-Red (FTIR) spectra. The optical absorption spectrum examined from UltraViolet-visible (UV-vis) spectroscopy evaluates the energy bandgap and it is noticed to increase from 2.48 to 2.87 eV affirming the Burstein Moss shift. The energy dispersion of optical parameters plays a crucial contribution in optical materials pursuant to its prominence in optical communications and in fabricating novel devices for spectral dispersion. Optical and energy dispersion parameters evaluated from Wemple-DiDomenico (WDD) model and non-linear optical parameters were deliberated from optical studies. Urbach energy and another pivotal optical criterion highly correlated with the bandgap energy anchored in the fabrication of optoelectronic devices were assessed. The electrical characteristics such as dielectric constant, loss, and conductivity exhibited by pure and Zn doped nickel oxide nanoparticles were reported. Molecular electronic polarizability assessed through elementary solid-state parameters is in better concurrence with diverse relations like Clausius-Mossotti, Lorentz-Lorent, bulk modulus, optical electronegativity, energy band gap. The pore size distribution of substance matrix and the associated surface area were elucidated from Brunauer-Emmett-Teller (BET) analysis. Dispersive magnetic properties and two pivotal parameters were derived from the Law of Approach to Saturation (LAS) operandi. Further, microbial cell mechanism was illustrated through nano-architecture design, and the antibacterial and antifungal activity encountered by undoped and zinc doped NiO nanoparticles against different microbial strains were deeply discussed for pilot production of antimicrobial agents.

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“…Photoexcitation into the 400 nm LMCT transition of Co 3 O 4 produces a localized exciton with a Bohr radius of 3.3 Å . The absorption extending from 500 to 900 nm in Co 3 O 4 has been discussed to include contributions from a variety of metal-centered d–d and MMCT transitions. ,, For CoPi, further broadening and weakening of optical absorption from metal-centered transitions in this spectral region have been anticipated due to confinement effects arising from the small domain sizes and contributions from the relatively high proportion of edge and defect sites with coordination geometries that are distorted compared to those in interior lattice sites. ,,, Further, we note that photoconductive activity in wide-band-gap semiconductors can be produced from excitation of localized d – d transitions for impurities that have d -shell states in the mid-gap region . Mechanisms analogous to these might be relevant to consider in CoPi, upon the transition from insulator to semiconductor states that involve edge, defect, or catalytic sites with ligand field distortions.…”

Section: Optical and Electronic Properties Of Copi Under In Situ Elec...mentioning

confidence: 99%

Photo-electrochemical Effect in the Amorphous Cobalt Oxide Water Oxidation Catalyst Cobalt–Phosphate (CoPi)

Sprague-Klein

Mara

et al. 2022

ACS Energy Lett.

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The cobalt–phosphate amorphous oxyhydroxide water-splitting catalyst, CoPi, is widely investigated because of its reactivity and self-repair analogous to the oxygen-evolving catalyst in Photosystem II. CoPi films show optical absorption features analogous to those seen more generally in transition metal oxides and oxygen-evolving catalysts. Possible photocatalytic properties of CoPi have, up until now, not been considered. Herein, we report on the finding of wavelength-dependent photo-electrochemical responses in CoPi. Red light excitation (623 nm) into a manifold of charge transfer and d–d electronic transitions was seen to produce photoanodic current responses that enhance OER, while blue light excitation (415 nm) within the ligand-to-metal charge-transfer transition was found to produce photocathodic responses that inhibit OER and oxidative repair. These results demonstrate intrinsic wavelength-dependent photo-electrochemistry in CoPi and opportunities to use light-excited states in CoPi, and potentially other transition metal oxides, to enhance OER and to track reaction mechanisms using light-triggered, pump–probe techniques.

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RETRACTED ARTICLE: Surface morphology, optical properties and Urbach tail of spray deposited Co3O4 thin films

Cited by 20 publications

References 22 publications

Structural, optical and electrical properties of Cu:MnO2 nanostructured thin films for glucose sensitivity measurements

Structural, optical and electrical properties of Cu:MnO2 nanostructured thin films for glucose sensitivity measurements

Revealing the Substitution of Zn2+ on Nano-Structural, Magneto-Electrical, Antibacterial and Antifungal Attributes of Nickel Oxide Nanoparticles via Sol-Gel Strategy

Photo-electrochemical Effect in the Amorphous Cobalt Oxide Water Oxidation Catalyst Cobalt–Phosphate (CoPi)

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