Photocatalytic paper using zinc oxide nanorods

Polymers

Zinc oxide (ZnO) in various nano forms (nanoparticles, nanorods, nanosheets, nanowires and nanoflowers) has received remarkable attention worldwide for its functional diversity in different fields i.e., paints, cosmetics, coatings, rubber and composites. The purpose of this article is to investigate the role of photocatalytic activity (role of photogenerated radical scavengers) of nano ZnO (nZnO) for the surface activation of polymeric natural fibres especially cotton and their combined effect in photocatalytic applications. Photocatalytic behaviour is a crucial property that enables nZnO as a potential and competitive candidate for commercial applications. The confirmed features of nZnO were characterised by different analytical tools, i.e., scanning electron microscopy (SEM), field emission SEM (FESEM) and elemental detection spectroscopy (EDX). These techniques confirm the size, morphology, structure, crystallinity, shape and dimensions of nZnO. The morphology and size play a cru...

Chemical Communications, 2013

In this report, hierarchical ZnO nano and microstructures were directly grown for the first time in bacterial cellulose substrate and in other two different papers by hydrothermal synthesis without any surface modification layer. Compactness and smoothness of the substrates are two important parameters that allow the growth of oriented structures. Zinc oxide (ZnO) is an optoelectronic material with a plethora of applications in electronic and optoelectronic devices. ZnO is a distinguished material with some special properties owing to its wide direct bandgap (3.37 eV) and large excitation binding energy (60 meV) 1,2 , besides its excellent chemical and mechanical stability. ZnO nanostructures can be found in nanodevices, such as field-effect transistors 3 , lasers 4 , chemical and biological sensors 5 and dye-sensitized solar cells (DSSC) 6 . The interest in growing nanostructures on paper or paper-like substrates is mainly because of their low cost, environmentally friendly properties, biodegradability, recyclability, mechanical flexibility and compatibility with most printing processes 4 . These features are important for novel technologies such as smart cards, flexible displays 7 , solar cells 8 , especially organic photovoltaic solar cells 9,10 , electronic paper 11 , batteries 12 , capacitors and supercapacitors 13 . Bacterial cellulose (BC) has been utilized for developing bio-sensors 14 and organic light-emitting diodes (OLEDs) 15 . Bacterial cellulose can be produced from cultures of Gram-negative bacteria Gluconacetobacter xylinus, which produce highly hydrated membranes (up to 99% water), free of lignin and hemicellulose, as well as other biogenic products . Membranes produced in this way usually have a higher molecular weight and high crystallinity compared to the cellulose from plants. Bacterial cellulose membranes are characterized by a 3D structure consisting of an ultrafine network of cellulose nanofibers ("nanocellulose") . One of the pioneering contributions on the use of paper in electronic devices was reported by Fortunato and cols 20 who developed a transistor based on paper substrates with high performance 20 . Although papers based on cellulose are dielectric materials, in some cases, e. g. composites, it is possible to achieve electrical conducting characteristics.

Journal of Materials Chemistry B, 2014

Small, carboxymethyl-starch-stabilised zinc oxide nanoparticles with a defined shape, size and morphology were prepared in situ in water at relatively low reaction temperatures using soluble carboxymethyl starch (CMS) as a combined crystallising, stabilising and solubilising agent and triethanolamine as the reducing agent. Aqueous colloidal solutions of these CMS-stabilised ZnO nanoparticles were used to deposit a coating of ZnO nanoparticles on cellulose paper by a wet-chemistry, polyelectrolyte, layer-by-layer approach using water as the only solvent. Such cellulose paper samples, coated with these CMSstabilised ZnO nanoparticles, show higher brightness and whiteness than that of blank reference paper and are more stable to UV-radiation than the paper reference as well as demonstrating good antibacterial activity against MRSA and A. baumannii.

RSC Advances, 2019

We report a facile one-pot green synthesis of zinc oxide (ZnO) nanostructures using aqueous leaf extract of Dolichos Lablab L. as the reducing and capping agent. The optical properties, structure and morphology of the as-synthesized ZnO nanostructures have been characterized by UV-Visible spectroscopy (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) supported with energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM). TEM analysis revealed that the as-synthesized ZnO nanostructures have an average particle diameter of 29 nm. XRD patterns confirmed the formation of phase-pure ZnO nanostructures with a hexagonal wurtzite structure. The synthesized ZnO nanostructures were used as a catalyst in the photodegradation of methylene blue (MB), rhodamine B (RhB) and orange II (OII) under visible and near-UV irradiation. The results showed the highest efficiency of photodegradation of ZnO nanostructures for MB (80%), RhB (95%) and OII (66%) at pH values of 11, 9 and 5, respectively, in a 210 min time interval. In addition, the antimicrobial activity of the ZnO nanostructures using the agar well diffusion method against Bacillus pumilus and Sphingomonas paucimobilis showed the highest zones of inhibition of 18 mm and 20 mm, respectively. Hence, ZnO nanostructures have the potential to be used as a photocatalyst and bactericidal component.

2010

The growth of ZnO nanorods on a flat substrate was studied as a function of the main parameters used in their preparation and their ability to photocatalytically eliminate bacteria in water. The seed layer was obtained, by a spray pyrolysis technique, from a zinc acetate solution. Subsequently, to grow the rods, the seeds were immersed in a basic solution of zinc nitrate maintained at 90°C. The growth parameters, thickness of the seed layer, acidity of the precursor solution used to obtain the seed layer, and the rate of crystal growth on the seed layer during the thermal bath treatment, were studied. The resulting materials were characterized morphologically by scanning electron microscopy and transmission electron microscopy (TEM); X-ray diffraction and TEM were used to study their structure and ultraviolet-visible spectroscopy to determine their absorbance. Most of the obtained materials were textured in the (002) direction perpendicular to the substrate. The rods have a hexagonal cross section between 60 and 150 nm. Using these rods, the photocatalytic degradation of Escherichia coli bacteria in water was studied; a positive influence of the surface area and crystalline growth on the degradation rate was observed.

— To reduce the pollutants from the effluent heterogeneous photocatalysis process is the environment friendly process. In degrading bio-recalcitrant compounds the photocatalytic process has proved to be superior to various conventional treatment processes. During the photocatalytic degradation, the transfer of hazardous contaminants from one form to another do not takes place and complete degradation of contaminants takes place. Due to the use of Artificial UV light and Semiconductor as a catalyst, this process is quite. The application of Photocatalytic process at industrial scale is possible in India. So Photocatalysis is attractive and cost-effective option in our country. With varying parameters like pH, irradiation time, catalyst dose and UV light intensity the degradation process is studied. Under the optimum pH of the solution (7.0 pH), catalyst dose of 1.2 g/500ml after 6 hr conditions 97%, 90% and 83% degradation in BOD, COD & Colour was observed.

2015

This paper reviews the recent advances on the photocatalytic and antibacterial activities of ZnO, metal-doped ZnO, non metal-doped ZnO and nano-composite of ZnO synthesized using different methods. Materials with different morphologies and structures have been investigated, by different groups, under UV, visible light and sunlight irradiations. The majority of data reveal superior performance of modified ZnO nanomaterials compared to unmodified ZnO nanomaterials. The nanocomposite of ZnO exhibits highest photocatalytic and antibacterial activity among all nanomaterial. The degradation of the dyes depends on both its concentration as well as the amount of photocatalyst.

Acta Metallurgica Sinica (English Letters), 2017

This research article explains the removal of methylene blue (MB) and malachite green (MG) from aqueous solution using adsorption/photodegradation activity of ZnO:Ag/bamboo charcoal (BC) nanocomposite. In addition, the antibacterial studies of the prepared samples were tested against Staphylococcus aureus (S. aureus) Gram-positive and Escherichia coli (E. coli) Gram-negative bacteria by the well diffusion method. The ZnO:Ag/BC nanocomposite exhibits superior photocatalytic activity compared with ZnO:Ag. Remarkable degradation efficiencies of 93.95% (MB) and 95.75% (MG) were recorded for ZnO:Ag/BC nanocomposite after 45 min. The degradation process follows a pseudo-first-order kinetics. The rate constant of ZnO:Ag/BC nanocomposite is two times greater than that of pristine ZnO nanopowder for the degradation of MB dye, while for MG dye degradation, it is three times. It is found that the ZnO:Ag/BC nanocomposite shows a higher rate of dye removal due to excellent adsorbing properties of bamboo charcoal (BC). The ZnO:Ag/BC nanocomposite showed better antibacterial properties compared to ZnO:Ag. In this study, the samples were prepared using a simple and low-cost soft chemical route and they were characterized by optical, structural, surface morphological, antibacterial and photocatalytic properties. These characterization studies substantiate the discussions on the photocatalytic and antibacterial activities of the synthesized samples.

ACS Omega

A high-performance semiconductor zinc oxide (ZnO) on melamine formaldehyde-coated cellulose nanocrystals (MFCNCs) was synthesized and evaluated for its application in smart cosmetics. These ZnO@MFCNC hybrid nanostructures were evaluated for their in vitro sun protection factor performance and photocatalytic activity under simulated UV and solar radiation. The photodegradation kinetics of a model pigment (methylene blue) was fitted to the Langmuir− Hinshelwood model. A 4-fold increase in the photocatalytic activity of ZnO@MFCNCs was observed when compared to pure ZnO. This is associated with (i) increased specific surface area provided by the MFCNC template, (ii) confined surface energy and controlled growth of ZnO nanoparticles, and (iii) entrapment of photoinduced charge carriers in the pores of the core−shell MFCNC rod, followed by fast promotion of interfacial e-charge transfer to the surface of the catalyst. The present study demonstrates how an increase in photocatalytic activity can be engineered without the introduction of structural defects or band gap tailoring of the semiconductor. The aqueous-based ZnO@MFCNC hybrid system displayed attractive UVabsorption and photocatalytic characteristics, offering the conversion of this renewable and sustainable technology into intelligent cosmetic formulations. ■ INTRODUCTION Recent advances in the epitaxy of semiconductor materials have made it possible to fabricate metal oxide structures, where the confined electrons (e −) and holes (h +) could potentially be used to fine-tune the redox functionalities. 1,2 For solid-state systems, ZnO semiconductors with a wide band gap energy of 3.37 eV and with inherent UV-absorbing characteristics are promising materials because of their high quantum efficiency. They have found applications in optical devices, sensors, transparent electrodes, solar cells, photocatalysis, antibacterial activity, and cosmetics. 3−5 For these principal applications, the structural defects, morphology, size, surface area, and crystallinity are prime factors that determine the efficacy of the metal oxide. Research on these systems has focused on strategies to enhance the properties mainly through the introduction of oxygen vacancies, structural defects on the surface of the crystal, and widening the band gap of the metal oxide to limit the fast recombination of photogenerated charge carriers. 4 Doping with a variety of materials including both metal ions 6−8 and metal oxides 4,9−11 has shown that the band gap can be tailored and the range is promising for functional optoelectronic devices. However, in applications that require formulation in solution, the use of colloidal ZnO nanocrystals has encountered various challenges because of their tendency to aggregate through Ostwald ripening associated with their high surface energy. 3 As a result, these nanoparticles (NPs) are unstable during storage and their surface reactivity is reduced, which hinders their application in waste water treatment, photocatalysis, personal care, and biological systems. The possibility of using hybrid nanocomposites to fabricate functional systems in a simple aqueous solution process could overcome this issue and allow broader engineering application. One such hybrid that has the flexibility to meet these demands is a cellulose-based nanorod derived from wood pulp known as cellulose nanocrystal (CNC). The biocompatible 150 × 5 nm dimensional crystalline domains, extracted from wood fiber, are excellent substrates for the growth of semiconductor ZnO NPs. Large scale production of CNCs has been demonstrated by CelluForce Inc. in Montreal, Canada. The naturally uniform nanocrystal offers high specific surface area, long term stability in water, consistent dimensions, and high mechanical strength. 12 A comparison on the preparation methods, size, morphology, and application of reported CNC−ZnO nanocomposites is summarized in Table 1.

Thin Solid Films, 2011

Nano-sized zinc oxide was synthesized and deposited onto cellulosic fibers using the sol–gel process at ambient temperature. The prepared materials were characterized using several techniques including scanning electron microscopy, transmission electron microscopy, diffuse ...