Keywords : photo

Ecofriendly-developed Polyacrylic Acid-coated Magnetic Nanoparticles as Catalysts in Photo-fenton Processes

Laura M. Sanchez; Pablo A. Ochoa Rodríguez; Daniel G. Actis; Verónica R. Elías; Griselda A. Eimer; Verónica Lassalle; Vera A. Alvarez

Advanced Materials Letters, 2020, Volume 11, Issue 3, Pages 1-5
DOI: 10.5185/amlett.2020.031486

In this work, iron oxide-based magnetic nanoparticles (MNPs) stabilized by polyacrylic acid (PAA) polymer were prepared and characterized as a continuation of a previous research already reported. MNPs composed by pure magnetite cores having good magnetic properties were developed, thus achieving an improvement in the modified coprecipitation method used. The photocatalytic activity of the nanoparticles towards acid orange 7 (AO7), under both radiation types, UV-Vis and LED-Vis, was tested. Pollutant degradation percentages of 64 and 37 % were obtained by using UV-Vis and LED-Vis radiation, respectively.

Ag2CO3 / Magnetic reduced graphene oxide nanocomposite as advanced visible light photocatalytic hybrid materials for efficient degradation of azo dye

Mohamed A. Elsayed; Hesham R. Tantawy; Amr A. Nada; Mohamed E. Elmowafy

Advanced Materials Letters, 2019, Volume 10, Issue 7, Pages 491-498
DOI: 10.5185/amlett.2019.2189

Due to intrinsic properties of graphene-like high electrical conductivity and large surface area, these properties make it an attractive matrix for composites. In this work, reduced graphene oxide (RG)/Fe3O4 (M)/Ag2CO3 (S) hybrid nano-composite (MRGS) has been effectively produced by coprecipitation techniques. The prepared composites were investigated by powder X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (UV-vis/DRS), Raman and vibrating sample magnetometer (VSM). The prepared MRGS nano-composite shows significant enhancement in the degradation rate of Tartrazine dye (TZ) compared to commercial photo-catalyst such as TiO2. Meanwhile, the visible light absorption of the MRGS nano-composite is progressively refining with the increase of the percentage of Ag2CO3 on the surface of (RG). The obtained MRGS 75 photo-catalyst shows the best photo-catalytic activity for TZ under visible light irradiation. The close contact between Ag2CO3 and RG in the composite leads to accelerating the charge transfer on Ag2CO3 to RG and thus enhancing the photocatalytic activity. Additionally, the prepared composite displays superb separability and significant stability. Copyright © VBRI Press.

Phase selective growth of Ge nanocrystalline films by ionized cluster beam deposition technique and photo-oxidation study                           

S. Mukherjee; A. Pradhan; T. Maitra; A. Nayak; S. Bhunia

Advanced Materials Letters, 2017, Volume 8, Issue 9, Pages 891-896
DOI: 10.5185/amlett.2017.1462

In this paper, we report the possibility of phase-selective growth of Ge nanocrystals by changing the kinetic energy of the clusters in an ionised cluster beam deposition system. Typically, the films are of mixed phase of normal cubic and high energy tetragonal structures, the relative proportion of which could be controlled by controlling the ionisation and applied accelerating potential as has been confirmed from Raman spectroscopic study. The films deposited using neutral clusters showed higher yield of the tetragonal phase with nanocrystallites of diameter ~7 nm as evidenced from HRTEM data. The optical bandgap of the nanocrystals were observed to be blue shifted upto 1.75 eV compared to the bulk Ge attributing to the presence of Ge tetragonal ST-12 phase and the resulted quantum confinement effect inside the nanocrystals. The tetragonal-rich films were further studied by controlled photo-oxidation to tune their optical band gap. A visible photoluminescence due to excitonic transitions have been observed from the as-grown Ge film enriched in tetragonal phase with average crystallite size ~7 nm. The photoluminescence peak was further blue shifted after the course of photo-oxidation due to reduced nanocrystallite size. 

Low viscosity, stable TiO2 nano-fluid for oxidative photo-degradation of methylene blue

Ujjwal K Bhagat; Anuraj S. Kshirsagar; Ashish Gautam; Pawan K Khanna

Advanced Materials Letters, 2017, Volume 8, Issue 4, Pages 506-517
DOI: 10.5185/amlett.2017.6960

The present article highlights a simple and effective method for preparation of nano-fluid (NF) by employing long carbon chain fatty acid, PVP and ethylene glycol stabilized anatase phase TiO2. The so-prepared nano-fluid (0.5 wt. %) was employed for advanced oxidative photo-degradation of MB with different concentrations (1-5 mL) under short (254 nm) and long UV (365 nm) irradiation against various concentrations (5, 15, 25 ppm).  The maximum degradation efficiency observed was 88% and 71% under short and long UV irradiation respectively. The photocatalytic degradation of the MB was also studied by reaction kinetics.  Initially, titania nanoparticles (NPs) were synthesized and characterized using various advanced tools such as UV-Visible, FTIR, Raman spectroscopy, BET, XRD, SEM/EDAX, TEM etc. for its size, surface area and morphological understanding.

Microstructure And Photo-catalytic Dye Degradation Of Silver- Silica Nano Composites Synthesised By Sol-gel Method

Surender Duhan; B.S. Dehiya;Vijay Tomer

Advanced Materials Letters, 2013, Volume 4, Issue 4, Pages 317-322
DOI: 10.5185/amlett.2012.8414

Sol–gel chemistry has recently attracted a large attention with a view of preparation of silver-silica nano-composites for photo-catalytic applications. This method of synthesis allows glassy materials to be prepared at a much lower temperature than the traditional melt-glass techniques. Moreover, it enables higher doping concentrations and a more uniform distribution of silver in the glass host matrix to be achieved. This method produces large quantities of amorphous gels that are thermal treated in air at the temperature of 500°C for one hour. The silver-silica samples were investigated through X-ray diffraction (XRD for the determination of their microstructure, phase and compositions. It is found that the microstructure depends closely on the solution pH and the extent of silver-doping. MB dye degradation by undoped and Ag doped SiO2 was studied under UV and Visible light irradiation. The results are intriguing as the doping by Ag produces opposite effects on photocatalytic degradation rates under the two conditions.