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Photovoltaic technology is a prominent source of renewable energy, but maintenance costs and efficiency attenuation of large photovoltaic devices are significant issues due to their vast energy conversion area. To reduce costs and facilitate maintenance, superhydrophobic surfaces with self‐cleaning properties have been developed for photovoltaic glass. In this study, transparent ZnO nanoarrays (NAs) are synthesized on photovoltaic glass, with Eu3+ doping enhancing the ultraviolet radiation resistance of photovoltaic devices and slightly increasing visible transmittance. A TiO2 passivation layer is introduced on the ZnO NAs surface to enhance acid resistance and mitigate corrosion caused by acidic rainwater. Fluoroalkylsilane (POTS) modification achieves superhydrophobicity with a water contact angle of 160.25°, as demonstrated by droplet rolling experiments. Micro‐interaction of superhydrophobic properties is further investigated by force curve measurement using atomic force microscope, showing almost no nanometer water moisture on the superhydrophobic surface, but conspicuous water moisture on the control glass surface. Finally, simulated models and practical silicon crystal solar cells fabricated using the self‐cleaning glass show excellent acid rain resistance, self‐cleaning, and long service life properties, with no power conversion efficiency degeneration during a 40‐day outdoor application test. [ABSTRACT FROM AUTHOR]

A superhydrophobic and photocatalytic composite fiber material is developed using polystyrene polydimethylsiloxane and graphitic nitride and then thoroughly characterized. SEM is used to determine the nanostructure of the fiber material, and the contact and sliding angles are measured to test the obtained fibers for their hydrophobicity. The degradation of methylene blue is used to monitor the photocatalytic activity of the created materials. This serves to create a self‐cleaning surface where hydrophilic pollutants are repelled from the surface due to the low sliding angle; the lower‐surface‐tension pollutants resist wetting the surface and can be thoroughly washed off; and photocatalytical oxidation can degrade pollutants that fully wet the fabric, allowing the surface to recover. [ABSTRACT FROM AUTHOR]

Abstract A superhydrophobic and photocatalytic composite fiber material is developed using polystyrene polydimethylsiloxane and graphitic nitride and then thoroughly characterized. SEM is used to determine the nanostructure of the fiber material, and the contact and sliding angles are measured to test the obtained fibers for their hydrophobicity. The degradation of methylene blue is used to monitor the photocatalytic activity of the created materials. This serves to create a self‐cleaning surface where hydrophilic pollutants are repelled from the surface due to the low sliding angle; the lower‐surface‐tension pollutants resist wetting the surface and can be thoroughly washed off; and photocatalytical oxidation can degrade pollutants that fully wet the fabric, allowing the surface to recover.

The applications of self‐cleaning coatings on large scale are limited due to their poor durability, remnants of hazardous by‐products and lack of biocompatibility. We propose to solve this problem by developing TiO2‐ZrO2 composite‐based self cleaning coatings. In order to achieve this task another important aspect was to select biocompatible polymers poly (methyl methacrylate) and pluronic F‐127 (PF‐127) as they can enhance the self‐cleaning capability of TiO2‐ZrO2 which itself is biocompatible and endowed with anti‐bacterial capability. The selection of a preparation technique that could produce coatings mimicking the nature has also been important and hence Electrospraying technique was selected as the processing method. The samples were then characterized using various techniques like field emission scanning electron microscopy, X‐ray diffraction, high resolution transmission electron microscopy, Brunauer–Emmett–Teller analysis, and so forth to fathom the interlink between observed properties and morphology. High quality superhydrophobic and superhydrophilic films have been generated and the surfaces were modulated by the addition of tri‐block co‐polymer which was found to provide swapping of superhydrophobic nature to superhydrophilic nature. The integration of superhydrophobic, superhydrophilic, photocatalytic and antibacterial properties in the prepared microsphere coatings is a unique achievement and may interest those in the quest for self‐cleaning materials for antibacterial coatings in mitigating surgical site infections, medical implants, coronary stent surfaces, and so forth. [ABSTRACT FROM AUTHOR]

The surface of inorganic materials such as concrete was vulnerable to various pollutants, caused its surface gloss to reduce, the spot increased,the surface powdered and so on, seriously affected its beautiful appearance and the durability. The hydrophobic principle of lotus leaf effect was analyzed, hydrophobicity and self-cleaning effects of bionic self-cleaning materials was studied, effects that different shelling-out ways of self-cleaning materials on waterproofing, self-cleaning and appearance of facing fair-faced concrete was explored. The results show that applying three layers of concrete hydrophobic self-cleaning material can significantly improve the surface compactness and durability of fair-faced concrete, and the problems of dirty and poor durability of facing fair-faced concrete was solved. [ABSTRACT FROM AUTHOR]

The aim of this work was to use electrospray to create photocatalytic TiO 2 coatings and to study their antibacterial and antibiofilm capacity. The electrospray used a sol of TiO 2 anatase nanoparticles prepared by a sol–gel method, which formed stable suspensions of positively charged particles (ζ-potential + 22.3 ± 3.7 mV). The electrospray deposited TiO 2 on non-porous glass surfaces at two loading densities originating homogeneous coatings (3.2–4.3 µm) of particles the top layer of which displayed aggregates ranging from the micron scale to a few hundreds of nanometers, with lower size as TiO 2 loading increased. TiO 2 -functionalized surfaces were tested for the inactivation of the Gram-positive bacterium Staphylococcus aureus . The electrosprayed surface was moderately hydrophilic turning highly hydrophilic upon irradiation (water contact angle 9.6° after 15 h under Xe-arc lamp). photocatalytic surfaces were put in contact with exponentially growing bacterial cultures in a flow system in which solar simulated irradiation followed two different 24 h dark-light arrangements with 9 or 18 h dark exposure followed by 15 or 6 h irradiation. The electrosprayed surfaces experienced extensive colonization by viable bacteria and clear biofilm formation revealed by exopolysaccharide matrix visualization. Using both dark-light cycles all cells became non-viable with extensive membrane damage. Biofilm matrix measurements showed that the irradiated surfaces were essentially free of bacterial exopolysaccharide matrix for specimens with the higher TiO 2 loading density. The biofilm removal reached 99% and no regrowth of viable cells was observed in any case. The results showed that TiO 2 -electrospray can avoid biofilm accumulation under stringent environmental conditions. [ABSTRACT FROM AUTHOR]

New self-cleaning materials of polymer fibers decorated with a hybrid between nanosized zinc oxide and expanded graphite (EG) or fullerene (C 60 ) were obtained. The new materials were prepared by applying electrospinning in conjunction with electrospraying. Poly( l -lactide) (PLA) was selected as a biocompatible and (bio)degradable polymer carrier. PLA solution was electrospun in combination with electrospraying of a suspension that contained the ZnO/EG or ZnO/C 60 hybrid. Mats with different content of EG or C 60 were obtained. The new materials were characterized by scanning and transmission electron microscopy (SEM and TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and X-ray diffraction analysis (XRD). The photocatalytic activity of the materials was evaluated by using model dyes. The formation of a hybrid between ZnO and EG led to enhancement of the photocatalytic activity of the mats at ZnO/EG weight ratios of 90/10 and 85/15. Increase in the photocatalytic activity of the ZnO-containing mats was also achieved by the formation of a hybrid between ZnO and C 60 at a fullerene content of 0.5 and 1.0 wt.% in respect to ZnO weight. The new materials exhibited antibacterial activity as evidenced by the performed studies against Staphylococcus aureus . [ABSTRACT FROM AUTHOR]

Although the discovery of light-activated antimicrobial agents had been reported in the 1900s, only more recently research work has been developed toward the use of photodynamic process as an alternative to more conventional methods of inactivation of micro(organisms). The photoprocess causes cell death through irreversible oxidative damage by reactive oxygen species produced by the interaction between a photosensitizing compound and a light source. With great emphasis on the environmental area, photodynamic inactivation (PDI) has been tested in insect eradication and in water disinfection. Lately, other studies have been carried out concerning its possible use in aquaculture waters or to the control of food-borne pathogens. Other potential applications of PDI in household, industrial and hospital settings have been considered. In the last decade, scientific research in this area has gained importance not only due to great developments in the field of materials chemistry but also because of the serious problem of the increasing number of bacterial species resistant to common antibiotics. In fact, the design of antimicrobial surfaces or self-cleaning materials is a very appealing idea from the economic, social and public health standpoints. Thus, PDI of micro(organisms) represents a promising alternative. In this review, the efforts made in the last decade in the investigation of PDI of (micro)organisms with potential applications beyond the medical field will be discussed, focusing on porphyrins, free or immobilized on solid supports, as photosensitizing agents. [ABSTRACT FROM AUTHOR]

Visible-light-absorbing graphitic carbon nitride–TiO 2 nanorod nanomaterials (g-C 3 N 4 @TiO 2 NR) were successfully immobilized using a one-step UVA-induced photocatalytic procedure on commercially obtained flexible low-density polyethylene (LDPE) films. Self-cleaning properties were evaluated in solid–liquid and solid–gas phases using malachite green as a model molecule under UV-A and visible light irradiation. For comparison purpose, LDPE films containing P25 TiO 2 nanoparticles was prepared using the same synthetic strategy (P25/LDPE). Among the fabricated films, the g-C 3 N 4 @TiO 2 NR/LDPE films exhibited the highest photocatalytic activity both in solid–liquid and solid–gas phases after 120 min of visible light irradiation (λ > 455 nm) removing efficiently malachite green stains probably due to the attack of photoinduced reactive oxygen species (ROS) such as singlet oxygen (1O 2), hydroxyl radical (•OH) and superoxide anion radical (O 2 −•). Furthermore, the g-C 3 N 4 @TiO 2 NR/LDPE films retained their visible-light-photoinduced photocatalytic properties after four reuse cycles. The g-C 3 N 4 @TiO 2 NR/LDPE films also exhibited significant visible-light-photoinduced hydrophilicity. The high visible-light-photoinduced photocatalytic capacity of g-C 3 N 4 @TiO 2 NR/LDPE films was found to be related to the textural and electronic properties, superior visible-light absorption, and surface roughness of the films. [Display omitted] • Visible-light active g-C 3 N 4 @TiO 2 nanorod were photocatalytically immobilized on LDPE. • g-C 3 N 4 @TiO 2 NR/LDPE films exhibited enhanced visible-light photocatalytic activity. • Visible-light-photoinduced wettability was observed in g-C 3 N 4 @TiO 2 NR/LDPE films. • Films exhibited high visible-light photocatalytic activity after four reuse cycles. [ABSTRACT FROM AUTHOR]

Looking back to less than three centuries of industrialization, responsible for alarming levels of pollution and consumption of non-renewable resources that has led to the exhaustion of the earth's capacity, the humankind only now begins to grasp the overwhelming potential of natural systems. During almost 40 million centuries, Nature has developed materials and processes with optimal performance which are totally biodegradable. Analysis of bioinspired materials requires the knowledge of both biological and engineering principles which are being a part of a large research area termed biotechnology. This hot area is one of the six strategic Key Enabling Technologies that will be funded under the EU Framework Programme Horizon 2020. This paper reviews the current knowledge on the potential of this emerging field, particularly in the development of materials and technologies for the construction industry. It covers the use of bacteria for enhancing concrete durability and for soil stabilization. It also covers bioinspired tough composite materials, bioinspired adhesives and coatings, and self-cleaning materials. Incorporation of biology basics in the civil engineering curriculum would ease the communication between biologists and civil engineers, helping to foster research on biotechnologies and bioinspired materials for the construction industry. [ABSTRACT FROM PUBLISHER]

Superhydrophobic materials with surface drying, self-cleaning, and antibiological pollution characters are broadly used in biotechnology, medicine, and shipbuilding sectors. In this paper, micro-nano silica is modified using a silane-based coupling agent. An organosilicon compound is grafted to the silica surface to obtain a superhydrophobic material with low surface energy. The results show that the superhydrophobic material with a 20 nm particle size silica modified with vinyltriethoxysilane (VTES-SiO 2) offers the best properties with a contact angle of 163.32° and a rolling angle of smaller than 3°. Compared with the raw material, the treated silica reveals superhydrophobicity under nano conditions with a rolling angle smaller than 3°. The wettability of the prepared material does not decrease after being placed in the air for 3 months. Moreover, it still maintains self-cleaning performance after being placed in water for one month, showing the potential of long-term use of the material. The prepared materials provide excellent superhydrophobic properties while is environmentally friendly. Thus, this study delivers potential value for the preparation of environmentally friendly superhydrophobic materials with broad application prospects of superhydrophobicity and self-cleaning characters. [Display omitted] • Developed treated SiO 2 superhydrophobic materials without fluorine compounds. • Treatment with vinyltriethoxysilane (VTES) significantly decreased SiO 2 surface energy. • Superhydrophobic product remained with stable performance in water for a month. • Superhydrophobic product revealed high durability in air with stable performance. • Product can be applied by brushing and spraying on various substrates surfaces. [ABSTRACT FROM AUTHOR]

Self-cleaning polymeric fibers have been successfully prepared by depositing ZnO nanoparticle onto wool and polyacrylonitrile (PAN) fibers with good compatibility and significant photocatalytic self-cleaning activity using the sol-gel process at ambient temperature. scanning electron microscopy, energy dispersive spectroscopy, transmission electron microscopy, diffuse reflectance spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area analysis, and thermogravimetric analysis have been adopted as the characterization techniques. Transmission electron microscopy studies revealed presence of zinc oxide nanoparticles with 10-15 nm in size. Brunauer-Emmett-Teller measurement showed surface area of 48 m/g for the ZnO nanoparticles. Photocatalytic activity of the self-cleaning materials were tested by measuring the photo-assisted degradation of methylene blue (MB) and eosin yellowish (EY) under ultraviolet-visible illumination. The results indicate that both of the ZnO-coated polyacrylonitrile and ZnO-coated wool fibers acquire photocatalytic activity toward dyes degradation. The photocatalytic activity of the treated fibers is maintained upon several numbers of photodegradation cycles. This facile and cheap preparation technique can be also applied to new polymeric fabrics to produce self-cleaning materials for industrial application. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 [ABSTRACT FROM AUTHOR]

Abstract: This study concentrated on the direct immobilization of anatase nano titanium dioxide particles (TiO2, 10nm particle size) into or onto a biodegradable polymer, polycaprolactone, by solvent-cast processes. The self-cleaning, namely photocatalytic properties of the produced materials were tested by photocatalytic removal of methylene blue as model compound and antimicrobial properties were investigated using Candida albicans as model microorganism. Produced TiO2 immobilized polymer successfully removed methylene blue (MB, 1×10−5 M) from aqueous solution without additional pH arrangement employing a UV-A light (365nm) source. Almost 83.2% of dye was removed or decomposed by 5wt% TiO2 immobilized into PCL (0.08g) and removal percentage reached to 94.2% with 5wt% TiO2 immobilized onto PCL after a 150min exposure period. Although removal percentage decrease with increased ionic strength and usage of a visible light source, produced materials were still effective. TiO2 immobilized onto PCL (5wt%) was quite effective killing almost 54% of C. albicans (2×106 CFU/mL) after only 60min exposure with a near visible light source. Control experiments employing PCL alone in the presence and absence of light were ineffective under the same condition. [Copyright &y& Elsevier]

Abstract: Self-cleaning materials are widely applied, but the available methods for determining their photocatalytic activity are time consuming. A simple analysis method was proposed to evaluate rapidly the photocatalytic activity of self-cleaning materials. This method is based on monitoring of a highly fluorescent product generated by the self-cleaning materials after illumination. Under UV irradiation, holes photo-induced on the surface of self-cleaning materials can oxidize water molecules (or hydroxide ions) adsorbed on the surface to produce hydroxyl radicals, which then quantitatively oxidize coumarin to highly fluorescent 7-hydroxycoumarin. It was observed that the fluorescence intensity of photo-generated 7-hydroxycoumarin at 456nm (excited at 346nm) linearly increased with irradiation time, and the fluorescence intensity at a given irradiation time was linearly proportional to the photocatalytic activity of self-cleaning materials. Consequently, the photocatalytic activity of self-cleaning materials was able to be probed simply by using this new method, which requires an analysis time of 40min, being much less than 250min required for a dye method. [Copyright &y& Elsevier]

Colloidal silver has been known to have unique antimicrobial activity that may be useful in the construction of antibacterial materials (self-cleaning materials) to aid in the fight against bacteria-related infections. In this study, silver-coated TiO2 (Ag/TiO2) particles prepared through the photo-reduction of Ag+ were investigated as an antibacterial agent against Escherichia coli and Staphylococcus aureus. The deposition of Ag onto the surface was confirmed with SEM and EDS analysis of the post-reaction particles. It was also determined that the initial concentration of Ag+ in solution played a significant role in the effective size of the post-irradiation particles. The antibacterial effectiveness of the Ag/TiO2 was evaluated through the determination of the minimum inhibitory concentration (MIC) of AgTiO2 for each species of bacteria. The MIC values for the Ag/TiO2, on both E. coli and S. aureus, were much lower than the MIC values for Ag metal, and quite comparable to the MIC values for AgNO3. A disc diffusion/antibiotic sensitivity test was also performed using the Ag/TiO2 particles and the results compared with the results obtained for Ag metal, AgNO3 and common antibacterial agents; tetracycline, chloramphenicol, erythromycin, and neomycin. The zone of inhibition diameters for the Ag/TiO2 particles were found to be comparable with those of the other antimicrobial agents. [ABSTRACT FROM AUTHOR]

The use of superhydrophobic surfaces in a broad range of applications is receiving a great deal of attention due to their numerous functionalities. However, fabricating these surfaces using low-cost raw materials through green and fluorine-free routes has been a bottleneck in their industrial deployment. This work presents a facile and environmentally friendly strategy to prepare mechanically robust superhydrophobic surfaces with engineered lotus leaf mimetic multiscale hierarchical structures via a hybrid route combining soft imprinting and spin-coating. Direct soft-imprinting lithography onto starch/polyhydroxyurethane/cellulose nanocrystal (SPC) films formed micro-scaled features resembling the pillar architecture of lotus leaf. Spin-coating was then used to assemble a thin layer of low-surface-energy poly(dimethylsiloxane) (PDMS) over these microstructures. Silica nanoparticles (SNPs) were grafted with vinyltriethoxysilane (VTES) to form functional silica nanoparticles (V-SNPs) and subsequently used for the fabrication of superhydrophobic coatings. A further modification of PDMS@SPC film with V-SNPs enabled the interlocking of V-SNPs microparticles within the cross-linked PDMS network. The simultaneous introduction of hierarchical microscale surface topography, the low surface tension of the PDMS layer, and the nanoscale roughness induced by V-SNPs contributed to the fabrication of a superhydrophobic interface with a water contact angle (WCA) of ∼150° and a sliding angle (SA) of <10°. The PDMS/V-SNP@SPC films showed an ∼52% reduction in water vapor transmission rate compared to that of uncoated films. These results indicated that the coating served as an excellent moisture barrier and imparted good hydrophobicity to the film substrate. The coated film surfaces were able to withstand extensive knife scratches, finger-rubbing, jet-water impact, a sandpaper-abrasion test for 20 cycles, and a tape-peeling test for ∼10 repetitions without losing superhydrophobicity, suggesting superior mechanical durability. Self-cleaning behavior was also demonstrated when the surfaces were cleared of artificial dust and various food liquids. The green and innovative approach presented in the current study can potentially serve as an attractive new tool for the development of robust superhydrophobic surfaces without adverse environmental consequences.

The aim of the study was to assess the photocatalytic (decompose staining particles, K/S values, the color differences, CIE L*a*b* color) and antimicrobial properties of textiles modified with TiO2 and ZnO nanoparticles (NPs) confirmed by X-ray diffraction, dynamic light scattering, SEM-EDX) in visible light conditions. The antimicrobial effectiveness of modified textiles under model conditions has been reported against 5 microorganisms: Staphylococcus aureus, Escherichia coli, Bacillus subtilis, Candida albicans, Aspergillus niger (AATCC Test Method 100-2004). In real conditions in bathrooms, significant biostatic activity was shown on the surface of the modified towels. The number of microorganisms decreased by 1–5 log to the level of 0–5 CFU/cm2 in the case of bacteria: Enterobacteriaceae, Enterococcus, the coli group and E. coli, Pseudomonas. Statistically significant reduction of the total number of bacteria and fungi (by 1 log), and the concentration of gases (NO2, CO2, CO) in the air of bathrooms was determined. The removal or reduction of volatile organic compounds (VOCs) concentration (SPME-GC-MS analysis) in the air above the modified towels has also been determined. It was found that the lighting type (natural, artificial), time (1.5 and 7 h/day), air humidity (RH = 36–67%) and light intensity (81–167 lux) are important for the efficiency of photocatalysis. Textile materials modified with TiO2 and ZnO NPs can be used as self-cleaning towels. They can also help purify air from microorganisms, VOCs and undesirable gases. [ABSTRACT FROM AUTHOR]