Metal oxide thin films and nanostructures for self-cleaning applications: current status and future prospects

Krishna, M. Ghanashyam; Madhurima, V.; Purkayastha, Debarun Dhar

doi:10.1051/epjap/2013130048

Cited by 48 publications

(14 citation statements)

References 123 publications

(130 reference statements)

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“…The wettability of a solid surface is characterized by the contact angle “ θ ”. The contact angle “ θ ” can be related to the three interfacial tensions via Young's equation

\cos θ = \frac{Y_{S V} - Y_{S L}}{Y_{L V}}

where Y SV = solid‐vapor interfacial tension, Y SL = solid‐liquid interfacial tension, and Y LV = liquid‐vapor interfacial tension. The water contact angles (WCA) of the un‐annealed and annealed Ag films at different iodization times are presented in Table .…”

Section: Resultsmentioning

confidence: 99%

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Iodization‐Induced Reversible Wettability in Nanostructured Ag Films

Praveena

Vanjarana

Purkayastha

et al. 2017

Physica Status Solidi (a)

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Ag films of 5 nm thickness were iodized for durations up to 3 h leading to the formation of b-AgI structure. The water contact angle (WCA) for the uniodized and as-deposited Ag film was 107.2 which is decreased to 70.7 on iodization for 3 h. In contrast, the Ag films annealed at 300 C for 2 h prior to iodization showed a water contact angle of 40.3 . The WCA decreased further to 14.9 after iodization for 3 h. This hydrophobic-hydrophilic transition can be related to the chemical modification of the surface change in crystal structure and variation in surface roughness. Significantly, the films also exhibited reversible wettabilty under UV irradiation.

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“…The wettability of a solid surface is characterized by the contact angle “ θ ”. The contact angle “ θ ” can be related to the three interfacial tensions via Young's equation

\cos θ = \frac{Y_{S V} - Y_{S L}}{Y_{L V}}

Section: Resultsmentioning

confidence: 99%

“…As iodization can be carried out at room temperature, the process is also scalable to large surfaces. There is significant interest in the fabrication of surfaces with controllable water contact angles . In this paper, an investigation on the wettability of iodized Ag thin films of 5 nm thickness is carried out.…”

Section: Introductionmentioning

confidence: 99%

Iodization‐Induced Reversible Wettability in Nanostructured Ag Films

Praveena

Vanjarana

Purkayastha

et al. 2017

Physica Status Solidi (a)

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“…The incorporation of nano-TiO 2 into textiles increases their UV-protection properties [13] and has also been proposed as a promoter of antimicrobial activity [14]. It should be emphasised that both TiO 2 and ZnO photocatalytic NPs have a similar wide band gap that confines their activity in the UV region of light, [15][16][17]. On the other hand, metal/nonmetal doping extends their spectral response to visible light [9,[16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Long-Lasting Photocatalytic and Antimicrobial Activity of Cotton Towels Modified with TiO2 and ZnO Nanoparticles

et al. 2021

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This study aimed to evaluate the durability of the photocatalytic and antimicrobial activities of ZnO and TiO2 nanoparticles (NPs)-modified 100% cotton terry textiles. SEM-EDX confirmed the long-lasting durability of the washing materials, and TGA analysis revealed that ZnO and TiO2 NPs can be found on the terry fabric surface; however, the amount of NPs decreased 10 times after 15 washes and 1.6 times after the subsequent 15 washes. The efficiency of self-cleaning properties and antimicrobial activity against five microorganisms (Staphylococcus aureus ATCC 6538, Escherichia coli ATCC 10536, Candida albicans ATCC 10231, Aspergillus niger ATCC 16404, and Bacillus subtilis NCAIM 01644) depended on UVA/B radiation intensity. The increase in UVA/B radiation intensity from 400 to 1400 µW/cm2 significantly increases the effectiveness of photocatalysis. Long-lasting self-cleaning properties characterised the tested fabric; however, stronger photocatalytic efficiency was observed in light with a greater intensity of UVA/B radiation. At the UVA/B radiation intensity of 1400 µW/cm2, a biocidal effect (R = 100%) against all tested microorganisms (E. coli, S. aureus. B. subtilis, C. albicans, and A. niger) was observed on the surface of materials. The lower UVA/B radiation intensity (400 µW/cm2) and 30 wash cycles reduce the antimicrobial activity of the material (R = 65.4–99.4%) for B. subtilis, C. albicans, and A. niger. The antimicrobial activity of washed materials modified with TiO2/ZnO nanoparticles can be increased by irradiation with a light bulb (1400 µW/cm2).

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“…Oxide nanoscale structures play a central role in optical, electrical, and biomedical nanotechnological devices and sensors due to their tunable optoelectronic properties, high surface-to-volume ratio, and good stability [ 1 , 2 ]. In particular, surface texturing with high-aspect-ratio oxide nanostructures significantly enhances surface-based properties in sensors [ 3 , 4 ], antibacterial surfaces [ 5 , 6 ], hydrophobic surfaces [ 7 ], and optical lenses [ 8 , 9 ]. Oxide surface texturing has been demonstrated by several nanostructure formations and patterning techniques, including photolithography [ 10 ], nanoimprint lithography [ 11 , 12 ], colloid assembly [ 13 , 14 ], and mesoporous silica layers [ 15 ].…”

Section: Introductionmentioning

confidence: 99%

Fabrication of Nanoscale Oxide Textured Surfaces on Polymers

Barick

Shomrat

Green³

et al. 2021

Polymers

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Nanoscale textured surfaces play an important role in creating antibacterial surfaces, broadband anti-reflective properties, and super-hydrophobicity in many technological systems. Creating nanoscale oxide textures on polymer substrates for applications such as ophthalmic lenses and flexible electronics imposes additional challenges over conventional nanofabrication processes since polymer substrates are typically temperature-sensitive and chemically reactive. In this study, we investigated and developed nanofabrication methodologies to create highly ordered oxide nanostructures on top of polymer substrates without any lithography process. We developed suitable block copolymer self-assembly, sequential infiltration synthesis (SIS), and reactive ion etching (RIE) for processes on polymer substrates. Importantly, to prevent damage to the temperature-sensitive polymer and polymer/oxide interface, we developed the process to be entirely performed at low temperatures, that is, below 80 °C, using a combination of UV crosslinking, solvent annealing, and modified SIS and RIE processes. In addition, we developed a substrate passivation process to overcome reactivity between the polymer substrate and the SIS precursors as well as a high precision RIE process to enable deep etching into the thermally insulated substrate. These methodologies widen the possibilities of nanofabrication on polymers.

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Metal oxide thin films and nanostructures for self-cleaning applications: current status and future prospects

Cited by 48 publications

References 123 publications

Iodization‐Induced Reversible Wettability in Nanostructured Ag Films

Iodization‐Induced Reversible Wettability in Nanostructured Ag Films

Long-Lasting Photocatalytic and Antimicrobial Activity of Cotton Towels Modified with TiO2 and ZnO Nanoparticles

Fabrication of Nanoscale Oxide Textured Surfaces on Polymers

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