Rouhollah Azimirad

Bio: Rouhollah Azimirad is an academic researcher from Malek-Ashtar University of Technology. The author has contributed to research in topics: X-ray photoelectron spectroscopy & Thin film. The author has an hindex of 24, co-authored 66 publications receiving 2226 citations. Previous affiliations of Rouhollah Azimirad include Academic Center for Education, Culture and Research & Sharif University of Technology.

CuO/Cu(OH) 2 hierarchical nanostructures as bactericidal photocatalysts

Abstract: Various morphologies of CuO/Cu(OH)2 nanostructures with different adsorbed –OH contents were synthesized on an acid-treated Cu foil through variation of NaOH concentration from 0 to 50 mM with an in situoxidation method. X-ray diffractometry and X-ray photoelectron spectroscopy (XPS) indicated formation of CuO on the Cu(OH)2 crystalline phase at a growth temperature of 60 °C for 20 h. Antibacterial activity of the nanostructures against Escherichia coli bacteria was studied in the dark and under light irradiation. The nanostructures grown at a NaOH concentration of 30 mM showed the highest surface area and the strongest antibacterial activity among the samples. After elimination of the contribution of the effective surface area of the nanostructures to the antibacterial activity, it was found that the surface morphology and chemical composition of the nanostructures were the other most important parameters in the antibacterial activity of the nanostructures. Using XPS analysis, the better photocatalytic activity per surface area of the nanostructures prepared at higher NaOH concentrations was substantially attributed to the amount of adsorbed OH bonds on the surface of the nanostructures.

Visible light photo-induced antibacterial activity of CNT–doped TiO2 thin films with various CNT contents

Abstract: Carbon nanotube (CNT)-doped TiO2 thin films with various CNT contents were synthesized by sol–gel method for visible light photoinactivation of Escherichia coli bacteria. Post annealing of the CNT–doped TiO2 thin films at 450 °C resulted in anatase TiO2 and formation of Ti–C and Ti–O–C carbonaceous bonds in the film. By increasing the CNT content, the thin films could further inactivate the bacteria in the dark. Meanwhile, as the CNT content increased from zero to 40 wt% the effective optical band gap energy of the CNT–doped TiO2 thin films annealed at 450 °C decreased from 3.2–3.3 to less than ∼2.8 eV providing light absorption in the visible region. Concerning this, visible light photoinactivation of the bacteria on the surface of the films was found to be optimum for 20 wt% CNT content. The CNT–doped TiO2 thin films annealed at 450 °C showed a further improved photoinactivation of bacteria than the films annealed at 100 °C. The improvement in the visible light photocatalytic performance was assigned to the charge transfer through the carbonaceous bonds formed between the TiO2 and the CNT content of the films annealed at 450 °C, in contrast to the thin films annealed at 100 °C which contained no such effective bonds.

Hydrothermal synthesis of ZnO nanorod arrays for photocatalytic inactivation of bacteria

Abstract: Arrays of ZnO nanorods were synthesized on ZnO seed layer/glass substrates by a hydrothermal method at a low temperature of 70 °C. The effect of pH > 7 of the hydrated zinc nitrate–NaOH precursor on the morphology and topography (e.g. size, surface area and roughness), the optical characteristics (e.g. optical transmission and band-gap energy), hydrophilicity and antibacterial activity of the grown ZnO nanostructure and nanorod coatings were investigated. For pH = 11.33 of the precursor (NaOH concentration of 0.10M), a fast growth of ZnO nanorods on the seed layer (length of ~1 µm in 1.5 h) was observed. The fast growth of the ZnO nanorods resulted in a significant reduction in the optical band-gap energy of the nanorod coating, which was attributed to the formation of more defects in the nanorods during their fast growth. The surface of the ZnO nanorod arrays was relatively hydrophilic (with a water contact angle of 16°) even after the subtraction of their surface roughness effect (with a contact angle of ca 27°). This hydrophilicity of the ZnO nanorods was assigned to the observed surface OH bonds. These characteristics caused the ZnO nanorod arrays to show an excellent UV-induced photocatalytic degradation of Escherichia coli bacteria. Furthermore, the synthesized ZnO nanorods were found to be strong photo-induced antibacterial material, even without considering their high surface area ratio.

Photocatalytic property of Fe2O3 nanograin chains coated by TiO2 nanolayer in visible light irradiation

Abstract: The visible light photocatalytic activity of α-Fe 2 O 3 nanograin chains coated by anatase TiO 2 nanolayer, as a photocatalyst thin film for inactivation of Escherichia coli bacteria, was investigated for the solutions containing 10 6 colony forming units per milliliter of the bacteria, without and with H 2 O 2 (60 μM) Thin films of the α-Fe 2 O 3 nanograins with the grain size of 40–280 nm were grown on glass substrates by post-annealing of the thermal evaporated Fe 3 O 4 thin films at 400 °C in air The TiO 2 layer with thickness of about 20 nm was coated on the nanograins by dipping the Fe 2 O 3 thin films in a prepared TiO 2 sol and re-annealing them at 400 °C in air The antibacterial activity of the α-Fe 2 O 3 nanograins with the optical band-gap of 21 eV (so better activity than the TiO 2 in the visible light) was doubled in presence of the low-concentration H 2 O 2 Deposition of the TiO 2 nanolayer on the α-Fe 2 O 3 nanograins resulted in 24 and 54% (59 and 276%) improvement in the photocatalytic activity of the TiO 2 /α-Fe 2 O 3 thin film than the bare α-Fe 2 O 3 nanograin (TiO 2 ) thin film, for the solution without and with H 2 O 2 , respectively In addition, for the TiO 2 /α-Fe 2 O 3 thin film, the bactericidal activity was improved by a factor of 25 in presence of the low-concentration H 2 O 2 as compared to the case without H 2 O 2 A mechanism was proposed based on which the electrons excited in the photocatalytic process were directly or indirectly absorbed by H 2 O 2 to produce active OH − radicals for promoting inactivation of the bacteria

Advanced Nanoarchitectures for Solar Photocatalytic Applications

Abstract: UV-Visible ار راد ن .د TiO2 ( تیفرظ راون مان هب نورتکلا یاراد یژرنا زارت لماش VB و ) رگید زارت ی یژرنا اب ( ییاناسر راون مان هب نورتکلا زا یلاخ و رتلااب VB یم ) .دشاب ت ود نیا نیب یژرنا توافت یژرنا فاکش زار ، پگ دناب هدیمان یم .دوش هک ینامز زا نورتکلا لاقتنا VB هب VB یم ماجنا دریگ ، TiO2 اب ودح یژرنا بذج د ev 2 / 3 ، نورتکلا تفج کی دیلوت یم هرفح .دیامن و نورتکلا هرفح ی نا اب هدش دیلوت یم کرتشم حطس هب لاقت ثعاب دناوت شنکاو ماجنا اه یی ددرگ . TiO2 دربراک ،دراد یدایز یاه هلمج زا یم ناوت اوه یگدولآ هیفصت یارب (CO2) و بآ و ... نآ زا هدافتسا درک .

Size-Dependent Bacterial Growth Inhibition and Mechanism of Antibacterial Activity of Zinc Oxide Nanoparticles

Abstract: The antibacterial properties of zinc oxide nanoparticles were investigated using both Gram-positive and Gram-negative microorganisms. These studies demonstrate that ZnO nanoparticles have a wide range of antibacterial activities toward various microorganisms that are commonly found in environmental settings. The antibacterial activity of the ZnO nanoparticles was inversely proportional to the size of the nanoparticles in S. aureus. Surprisingly, the antibacterial activity did not require specific UV activation using artificial lamps, rather activation was achieved under ambient lighting conditions. Northern analyses of various reactive oxygen species (ROS) specific genes and confocal microscopy suggest that the antibacterial activity of ZnO nanoparticles might involve both the production of reactive oxygen species and the accumulation of nanoparticles in the cytoplasm or on the outer membranes. Overall, the experimental results suggest that ZnO nanoparticles could be developed as antibacterial agents agai...