α-Fe₂O₃ Nanocolumns and Nanorods Fabricated by Electron Beam Evaporation for Visible Light Photocatalytic and Antimicrobial Applications

Abstract

Both Fe2O3 thin films and nanorod arrays are deposited using electron beam evaporation through normal thin film deposition and oblique angle deposition (OAD) and are characterized structurally, optically, and photocatalytically. The morphologies of the thin films are found to be arrays of very thin and closely packed columnar structures, while the OAD films are well-aligned nanorod arrays. All films were determined to be in the hematite phase (α-Fe2O3), as confirmed by both structural and optical characterization. Texture measurements indicate that films have similar growth modes where the [110] direction aligns with the direction of material growth. Under visible light illumination, the thin film samples were more efficient at photocatalytically degrading methylene blue, while the nanorod arrays were more efficient at inactivating E. coli O157:H7. The size of the targeted agent and the different film morphologies result in different reactant/surface interactions, which is the main factor that determines photoactivity. Furthermore, an analytic mathematical model of bacterial inactivation based on chemotactic bacterial diffusion and surface deactivation is developed to quantify and compare the inactivation rate of the samples. These results indicate that α-Fe2O3 nanorods are promising candidates for antimicrobial applications and are expected to provide insight into the development of better visible-light antimicrobial materials for food products and processing environments, as well as other related applications.

Response difference of transgenic and conventional rice (Oryza sativa) to nanoparticles (γFe2O3)

“…For example, iron oxide nanoparticles (Fe 2 O 3 NPs) have been used extensively in many fields including microelectronics, biomedical imaging, and the detection and visualization of various phases and interfaces in oil reservoirs (Basnet et al 2013;Laurent et al 2008;Mahmoudi et al 2011). The increased prevalence of engineered nanoparticles (ENPs) has led to their release into the environment, which is potentially having an impact in living organisms (Shah et al 2014;Zhao et al 2014), especially plants Liao et al 2014;Martinez-Ballesta and Carvajal 2014).…”

Nanocolumnar growth of thin films deposited at oblique angles: Beyond the tangent rule

“…[1][2][3] This anisotropy combined with their high open porosity [4][5][6][7] are essential for other applications such as Bragg reflectors with tunable optical response, 8 templates for nanocomposite films, [9][10][11][12] broad band antireflection coatings, 13,14 optical microresonators, 15 light emitting diodes, 16 photovoltaic cells, 17 advanced plasmon photocatalysis, 18,19 microfluidic sensors, 20 transparent conductive electrodes 21 and many others. In this technique, a given material is sublimated in a vacuum reactor, either thermally or assisted by an electron beam, yielding vapor species that follow straight trajectories in a "line of sight" configuration with respect to the substrate, and giving rise to thin films with well-defined tilted nanocolumnar structures.…”

Fabrication of magnetic nanorods and their applications in medicine

“…Some of the most important of these methods are electrospinning [34], plasmon-enhanced spectroscopy [35], Ultraviolet fluorescence [36], adhesion [37], novel flame-gradient [38], and direct growth on Titanium foil [39], adsorption [40], layer by layer [41] and electron beam [42].…”