scholarly journals Efficient Cr(vi) photoreduction under natural solar irradiation using a novel step-scheme ZnS/SnIn4S8 nanoheterostructured photocatalysts

RSC Advances ◽  
2021 ◽  
Vol 11 (47) ◽  
pp. 29433-29440
Author(s):  
Metwally Madkour ◽  
Yasser Abdelmonem ◽  
Umair Yaqub Qazi ◽  
Rahat Javaid ◽  
S. Vadivel

The Cr(vi) photoreduction tests demonstrated an improved photocatalytic activity of SIS and 2Z-SIS to be 61.0% and 92.3% respectively after 120 min. The results indicated the photocatalyst's capability under sun light, allowing for its industrial use.

Catalysts ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 589
Author(s):  
Sivagowri Shanmugaratnam ◽  
Balaranjan Selvaratnam ◽  
Aravind Baride ◽  
Ranjit Koodali ◽  
Punniamoorthy Ravirajan ◽  
...  

Earth–abundant transition metal chalcogenide materials are of great research interest for energy production and environmental remediation, as they exhibit better photocatalytic activity due to their suitable electronic and optical properties. This study focuses on the photocatalytic activity of flower-like SnS2 nanoparticles (composed of nanosheet subunits) embedded in TiO2 synthesized by a facile hydrothermal method. The materials were characterized using different techniques, and their photocatalytic activity was assessed for hydrogen evolution reaction and the degradation of methylene blue. Among the catalysts studied, 10 wt. % of SnS2 loaded TiO2 nanocomposite shows an optimum hydrogen evolution rate of 195.55 µmolg−1, whereas 15 wt. % loading of SnS2 on TiO2 exhibits better performance against the degradation of methylene blue (MB) with the rate constant of 4.415 × 10−4 s−1 under solar simulated irradiation. The improved performance of these materials can be attributed to the effective photo-induced charge transfer and reduced recombination, which make these nanocomposite materials promising candidates for the development of high-performance next-generation photocatalyst materials. Further, scavenging experiments were carried out to confirm the reactive oxygen species (ROS) involved in the photocatalytic degradation. It can be observed that there was a 78% reduction in the rate of degradation when IPA was used as the scavenger, whereas around 95% reduction was attained while N2 was used as the scavenger. Notably, very low degradation (<5%) was attained when the dye alone was directly under solar irradiation. These results further validate that the •OH radical and the superoxide radicals can be acknowledged for the degradation mechanism of MB, and the enhancement of degradation efficiency may be due to the combined effect of in situ dye sensitization during the catalysis and the impregnation of low bandgap materials on TiO2.


2016 ◽  
Vol 19 (1) ◽  
Author(s):  
Xinlu Liu ◽  
Junbo Zhong ◽  
Jianzhang Li ◽  
Wei Hu ◽  
Qizhao Wang ◽  
...  

AbstractIn this paper, α-Fe


2021 ◽  
Vol 13 (4) ◽  
pp. 2004
Author(s):  
Udari Wijesinghe ◽  
Gobika Thiripuranathar ◽  
Haroon Iqbal ◽  
Farid Menaa

Owing to the development of nanotechnology, biosynthesis of nanoparticles (NPs) is gaining considerable attention as a cost-effective and eco-friendly approach that minimizes the effects of toxic chemicals used in NP fabrication. The present work reports low-cost phytofabrication of zinc oxide (ZnO) NPs employing aqueous extracts of various parts (leaves, stems, and inflorescences) of Tephrosia purpurea (T. purpurea). The formation, structure, morphology, and other physicochemical properties of ZnO NPs were characterized by ultraviolet–visible (UV–Vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy, and dynamic light scattering (DLS). UV–Vis spectral analysis revealed sharp surface plasmon resonance (SPR) at around 250–280 nm, while the XRD patterns confirmed distinctive peaks indices to the crystalline planes of hexagonal wurtzite ZnO NPs. TEM analysis confirmed the presence of spherical-shaped ZnO NPs with average particle sizes (PS) between 25–35 nm, which was in agreement with the XRD results. FTIR analysis revealed that phenolics, flavonoids, amides, alkaloids, and amines present in the plant extract are responsible for the stabilization of the ZnO NPs. Further, the hydrodynamic diameter in the range of 85–150 nm was measured using the DLS technique. The fluorescence resonance energy transfer (FRET) ability of biogenic ZnO NPs was evaluated, and the highest efficiency was found in ZnO NPs synthesized via T. purpurea inflorescences extract. Photoluminescence (PL) spectra of biogenic ZnO NPs showed three emission peaks consisting of a UV–Vis region with high-intensity compared to that of chemically synthesized ZnO NPs. The biosynthesized ZnO NPs showed photocatalytic activity under solar irradiation by enhancing the degradation rate of methylene blue (MB). Among the prepared biogenic ZnO NPs, T. purpurea leaves mediated with NPs acted as the most effective photocatalyst, with a maximum degradation efficiency of 98.86% and a half-life of 84.7 min. This is the first report related to the synthesis of multifunctional ZnO NPs using T. purpurea, with interesting characteristics for various potential applications in the future.


2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
C. R. García ◽  
L. A. Diaz-Torres ◽  
J. Oliva ◽  
M. T. Romero ◽  
P. Salas

Blue phosphorescent strontium aluminosilicate powders were prepared by combustion synthesis route and a postannealing treatments at different temperatures. X-ray diffraction analysis showed that phosphors are composed of two main hexagonal phases: SrAl2O4and Sr3Al32O51. The morphology of the phosphors changed from micrograins (1000°C) to a mixture of bars and hexagons (1200°C) and finally to only hexagons (1300°C) as the annealing temperature is increased. Photoluminescence spectra showed a strong blue-green phosphorescent emission centered atλem=455 nm, which is associated with4f65d1→4f6  (8S7/2)transition of the Eu2+. The sample annealed at 1200°C presents the highest luminance value (40 Cd/m2) with CIE coordinates (0.1589, 0.1972). Also, the photocatalytic degradation of methylene blue (MB) under UV light (at 365 nm) was monitored. Samples annealed at 1000°C and 1300°C presented the highest percentage of degradation (32% and 38.5%, resp.) after 360 min. In the case of photocatalytic activity under solar irradiation, the samples annealed at 1000°C, 1150°C, and 1200°C produced total degradation of MB after only 300 min. Hence, the results obtained with solar photocatalysis suggest that our powders could be useful for water cleaning in water treatment plants.


2015 ◽  
Vol 39 (8) ◽  
pp. 6040-6051 ◽  
Author(s):  
Neerugatti KrishnaRao Eswar ◽  
Praveen Chandrashekarapura Ramamurthy ◽  
Giridhar Madras

A novel system of partially etched TiO2nanobelts was developed that exhibits superior photocatalytic activity to purify waste water.


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