Solar-light-driven photocatalytic performance of Cr and Co doped Sr1-xCoxFe12-yCryO19 and effect of doping on optical, structural and dielectric properties

2022 ◽  
Vol 124 ◽  
pp. 111961
Ismat Bibi ◽  
Shahid Iqbal ◽  
Farzana Majid ◽  
Noor Fatima ◽  
Norah Alwadai ◽  
Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3230
Theeranuch Nachaithong ◽  
Narong Chanlek ◽  
Pairot Moontragoon ◽  
Prasit Thongbai

(Co, Nb) co-doped rutile TiO2 (CoNTO) nanoparticles with low dopant concentrations were prepared using a wet chemistry method. A pure rutile TiO2 phase with a dense microstructure and homogeneous dispersion of the dopants was obtained. By co-doping rutile TiO2 with 0.5 at.% (Co, Nb), a very high dielectric permittivity of ε′ » 36,105 and a low loss tangent of tanδ » 0.04 were achieved. The sample–electrode contact and resistive outer-surface layer (surface barrier layer capacitor) have a significant impact on the dielectric response in the CoNTO ceramics. The density functional theory calculation shows that the 2Co atoms are located near the oxygen vacancy, creating a triangle-shaped 2CoVoTi complex defect. On the other hand, the substitution of TiO2 with Nb atoms can form a diamond-shaped 2Nb2Ti complex defect. These two types of complex defects are far away from each other. Therefore, the electron-pinned defect dipoles cannot be considered the primary origins of the dielectric response in the CoNTO ceramics. Impedance spectroscopy shows that the CoNTO ceramics are electrically heterogeneous, comprised of insulating and semiconducting regions. Thus, the dielectric properties of the CoNTO ceramics are attributed to the interfacial polarization at the internal insulating layers with very high resistivity, giving rise to a low loss tangent.

CrystEngComm ◽  
2021 ◽  
Sumana Paul ◽  
Dulal Barman ◽  
Chandra Chowdhury ◽  
Pravat Kumar Giri ◽  
Subodh Kumar De

In promoting the application of green and sustainable solution towards the photodegradation of organic dyes and toxic ions, it is urgent to fabricate semiconductor based effective and stable photocatalysts. Constructing...

2018 ◽  
Vol 5 (6) ◽  
pp. 172005 ◽  
Chentao Hou ◽  
Wenli Liu

TiO 2 /TiOF 2 nanohybrids were quickly synthesized through a hydrothermal process using titanium n-butoxide (TBOT), ethanol (C 2 H 5 OH) and hydrofluoric acid as precursors. The prepared nanohybrids underwent additional NaOH treatment (OH-TiO 2 /TiOF 2 ) to enhance their photocatalytic performance. In this paper, the mechanism of NaOH affecting the pathway of transformation from TBOT (Ti precursor) to TiO 2 nanosheets was discussed. The synthesized TiO 2 /TiOF 2 and OH-TiO 2 /TiOF 2 were characterized by field emission scanning electron microscopy (FE-SEM), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction pattern (XRD), Fourier infrared spectroscopic analysis (FT-IR), Photoluminescence (PL) emission spectra and UV–visible diffuse reflection spectra (UV–vis DRS). The photocatalytic activity and stability of synthesized samples were evaluated by degradation of methylene blue (MB) under the simulated solar light. The results showed that a larger ratio of TiO 2 to TiOF 2 in TiO 2 /TiOF 2 and OH-TiO 2 /TiOF 2 nanohybrids could allow for even higher MB conversion compared with only TiO 2 nanosheets. NaOH treatment can wash off the F ions from TiOF 2 and induce this larger ratio. The highest efficiency of MB removal was just above 90% in 1 h. Lower electron–hole pairs recombination rate is the dominant factor that induces the photocatalytic performance enhancement of TiO 2 /TiOF 2 nanohybrids. The synthesized OH-TiO 2 /TiOF 2 nanohybrids exhibit great potential in the abatement of organic pollutants.

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