Photocatalytic activity of titanium dioxide modified by silver nanoparticles

Performance of TiO2-Based Tubular Membranes in the Photocatalytic Degradation of Organic Compounds

This work presents the photocatalytic degradation of organic pollutants in water with TiO₂ and TiO₂/Ag membranes prepared by immobilising photocatalysts on ceramic porous tubular supports. The permeation capacity of TiO₂ and TiO₂/Ag membranes was checked before the photocatalytic application, showing high water fluxes (≈758 and 690 L m^-2 h^-1 bar^-1, respectively) and <2% rejection against the model pollutants sodium dodecylbenzene sulfonate (DBS) and dichloroacetic acid (DCA). When the membranes were submerged in the aqueous solutions and irradiated with UV-A LEDs, the photocatalytic performance factors for the degradation of DCA were similar to those obtained with suspended TiO₂ particles (1.1-fold and 1.2-fold increase, respectively). However, when the aqueous solution permeated through the pores of the photocatalytic membrane, the performance factors and kinetics were two-fold higher than for the submerged membranes, mostly due to the enhanced contact between the pollutants and the membranes photocatalytic sites where reactive species were generated. These results confirm the advantages of working in a flow-through mode with submerged photocatalytic membranes for the treatment of water polluted with persistent organic molecules, thanks to the reduction in the mass transfer limitations.

Antibacterial properties of photochemically prepared AgTiO2 membranes

Biofouling reduces the membrane performance and has become a problem in many applications. One of the strategies to reduce biofouling is to apply antibacterial materials to the membrane surface, which prevents the attachment and growth of microorganisms. In this study, the surface of flat ceramic supports was covered with TiO₂ powder, and silver was applied by photoreduction using a CH₃COOAg solution at room temperature. After the photoreduction, AgO_x and metallic silver were found on the TiO₂ as analyzed by XPS. While a negligible amount of silver was released from the prepared AgTiO₂ membranes into water, the dissolution of silver was enhanced in a 0.09 M NaCl solution. The AgTiO₂ membranes inhibited the growth of Escherichia coli in dark conditions. The inhibition cannot be explained only by the concentration of silver ions released from the membranes. Microscopic observation showed that direct contact with AgTiO₂ kills E. coli. The results showed the possibility of improving the antibacterial activity of membranes by applying an AgTiO₂ coating.

Preparation of g-C3N4/CQDs/Ag2S Composite Material and Its Antibacterial Properties

The emergence of bacterial resistance to traditional antibiotics and its global spread has brought huge threats to human life and health, and the need for new alternative antibacterial agents has become increasingly urgent. The rapid development of nanoscience provides a potential alternative to antibacterial therapy. In this study, g-C3N4 was synthesized using melamine as the raw material. It was then successfully combined with carbon quantum dots (CQDs) and silver sulfide to synthesize a g-C3N4/CQDs/Ag2S composite material. Such combination narrows the band gap of g-C3N4 from 2.53 eV to 2.21 eV and enhances the photocatalytic efficiency. Consequently, it indicated photocatalytic antimicrobial effects against three strands of bacteria, Shylococcus aureus (Grampositive), Escherichia coli (Gram-negative) and Methicillin-resistant Staphylococcus aureus under the irradiation of visible light. Other than the common pathogens, g-C3N4/CQDs/Ag2S exhibited an appreciable inhibition against the well-known drug-resistant bacteria. With its antimicrobial features and excellent photoelectric properties, the as prepared nanocomposites show its potential in the development of new antimicrobial and photocatalytic materials.

Green, Sustainable Synthesis of γ-Fe2O3/MWCNT/Ag Nano-Composites Using the Viscum album Leaf Extract and Waste Car Tire for Removal of Sulfamethazine and Bacteria from Wastewater Streams

Multi-walled carbon nanotubes (MWCNTs) decorated with Ag nanoparticles (NPs) are bifunctional adsorbent nanomaterials with antibacterial activity. They can be magnetically recovered from wastewater in case of coupling with γ-Fe₂O₃. In this study, for the first time, an environmentally friendly technique was applied to prepare a nanocomposite (NC) material composed of γ-Fe₂O₃/MWCNT/Ag by using Bridgestone disposable tires and Viscum album leaves extract. γ-Fe₂O₃/MWCNTs/Ag NC was employed for the removal of sulfamethazine (SMT) from aqueous solutions. Under the optimized conditions determined via the Taguchi method, the highest SMT adsorption capacity of the γ-Fe₂O₃/MWCNT/Ag NC was measured to be 47.6 mg/g. The experimental data fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm. The thermodynamic parameters implied that the adsorption process was endothermic. In addition to adsorption of the drug pollutant, the NC demonstrated a superior antibacterial activity against Gram-positive bacteria. The reusability test also showed that over 79% SMT can be removed using γ-Fe₂O₃/MWCNTs/Ag NC even after four adsorption cycles. Taken together, γ-Fe₂O₃/MWCNTs/Ag NC was proven to be a promising antibacterial nano-adsorbent for wastewater treatment.

Aminated Multiwalled Carbon Nanotube-Doped Magnetic Flower-like WSe2 Nanosheets for Efficient Adsorption in Acidic Wastewater

The water body environment is related to ecological and human health. Adsorption is an effective means to remove pollutants from water bodies. Currently, the common adsorbents suffer from disadvantages such as structural instability and poor adsorption performance under acidic conditions, which not only affect the adsorption efficiency but also cause secondary pollution of water bodies. In this study, a novel aminated multiwalled carbon nanotube-doped flower-like nanocomposite was designed, where the anionic or neutral groups were protonated under acidic conditions, and it displayed a higher adsorption capacity for dyes by ion exchange, represented by methylene blue (MB) and rhodamine B (RB). WSe₂ in the composite increases its adsorption sites. The adsorption efficiency of pollutants in acidic wastewater was enhanced while avoiding secondary contamination. The synthesized composites showed maximum adsorptions of 27.55 and 27.47 mg/g for MB and RB, respectively. The current work offers a novel approach to treating acidic wastewater.

Synthesis of sodium titanates and their use in the photocatalytic degradation of NO

The synthesis and characterization of sodium titanates (ST), and their evaluation in the photocatalytic reduction of nitric oxide (NO) are described herein. The materials were synthesized by a hydrothermal route using 5 M NaOH as the mineralizer agent and a TiO₂ content of 0.06 mg/mL (expressed as the mass ratio of TiO₂/mL of NaOH), at 170 °C for 48 h, resulting in sodium tri- and hexa-titanates. A nanotubular morphology was observed for the ST, as proved by scanning electron microscopy (SEM); a subsequent heat-treatment at 400 °C allowed a complete transformation of sodium tri- to hexa-titanates and an increase in bandgap. The obtained ST were impregnated with Ag⁺ and Zn⁺ cations, ST-Ag and ST-Zn, respectively, to tune the materials' bandgap. XPS analysis of the ST-Ag materials showed evidence of metallic Ag, pointing to the formation of silver nanoparticles, whereas for ST-Zn oxide phases were mainly spotted. The materials were evaluated for the photocatalytic reduction of NO using a reactor fed with a continuous flow rate of NO, generated in situ at a flow of 280 mL/min using nitrogen and a 253-nm UV irradiation source. The photocatalytic tests showed that pristine ST (tri- and hexa-titanates) displayed better performance in the reduction of NO with respect to the impregnated samples (ST-Ag, ST-Zn). Maximum degradation efficiencies of 80% were achieved when 1 g of photocatalyst was used with a flow of 280 mL/min and a 253 nm UV lamp.

Decoration of titanium dioxide nanotubes with silver nanoparticles using the photochemical deposition method and their application as an electrocatalyst to determine tinidazole

In this study, titanium nanotube electrodes were decorated with silver nanoparticles (AgNPs/TiO₂NTs) and used as an electrocatalyst for the reduction of tinidazole. AgNPs/TiO₂NTs are constructed by anodization of titanium sheet metal and photochemical deposition of AgNPs on TiO₂NTs. The structural and elemental analysis characteristics of the AgNPs/TiO₂NT electrode have been studied by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) methods. Based on the cyclic voltammetric data, it has been confirmed that the AgNPs/TiO₂NT electrode has good electrocatalytic activity to reduce tinidazole. Two liner concentration ranges of 0.2-55.0 μM and 55.0-111.2 μM were obtained by amperometric method. A detection limit of 60.9 nM was obtained for measuring tinidazole at the AgNPs/TiO₂NT electrode surface. In addition, the designed sensor has been successfully used for quantitative measurement of tinidazole in pharmaceutical and human urine samples.

TiO2–Zeolite Metal Composites for Photocatalytic Degradation of Organic Pollutants in Water

Immobilization of photocatalysts in porous materials is an approach to significantly minimize the hazards of manipulation and recovery of nanoparticles. Inorganic materials, such as zeolites, are proposed as promising materials for photocatalyst immobilization mainly due to their photochemical stability. In this work, a green synthesis method is proposed to combine TiO2-based photocatalysts with commercial ZY zeolite. Moreover, a preliminary analysis of their performance as photocatalysts for the abatement of organic pollutants in waters was performed. Our results show that the physical mixture of TiO2 and zeolite maintains photocatalytic activity. Meanwhile, composites fabricated by doping TiO2–zeolite Y materials with silver and palladium nanoparticles do not contribute to improving the photocatalytic activity beyond that of TiO2.

Fly ash-, foundry sand-, clay-, and pumice-based metal oxide nanocomposites as green photocatalysts

Metal oxides possess exceptional physicochemical properties which make them ideal materials for critical photocatalytic applications. However, of major interest, their photocatalytic applications are hampered by several drawbacks, consisting of prompt charge recombination of charge carriers, low surface area, inactive under visible light, and inefficient as well as expensive post-treatment recovery. The immobilization of metal oxide semiconductors on materials possessing high binding strength eliminates the impractical and costly recovery of spent catalysts in large-scale operations. Notably, the synthesis of green material (ash, clay, foundry sand, and pumice)-based metal oxides could provide a synergistic effect of the superior adsorption capacity of supporting materials and the photocatalytic activity of metal oxides. This phenomenon significantly improves the overall degradation efficiency of emerging pollutants. Inspired by the novel concept of "treating waste with waste", this contribution highlights recent advances in the utilization of natural material (clay mineral and pumice)- and waste material (ash and foundry sand)-based metal oxide nanocomposites for photodegradation of various pollutants. First, principles, mechanism, challenges towards using metal oxide as photocatalysts, and immobilization techniques are systematically summarized. Then, sources, classifications, properties, and chemical composition of green materials are briefly described. Recent advances in the utilization of green materials-based metal oxide composites for the photodegradation of various pollutants are highlighted. Finally, in the further development of green materials-derived photocatalysts, we underlined the current gaps that are worthy of deeper research in the future.

Applications of Green Synthesized Nanomaterials in Water Remediation

Water is the most important component on the earth for living organisms. With industrial development, population increase and climate change, water pollution becomes a critical issue around the world. Its contamination with different types of pollutants created naturally or due to anthropogenic activities has become the most concerned global environmental issue. These contaminations destroy the quality of water and become harmful to living organisms. A number of physical, chemical and biological techniques have been used for the purification of water, but they suffer in one or the other respect. The development of nanomaterials and nanotechnology has provided a better path for the purification of water. Compared to conventional methods using activated carbon, nanomaterials offer a better and economical approach for water remediation. Different types of nanomaterials acting as nanocatalysts, nanosorbents, nanostructured catalytic membranes, bioactive nanoparticles, nanomembranes and nanoparticles provide an alternative and efficient methodology in solving water pollution problems. However, the major issue with nanomaterials synthesized in a conventional way is their toxicity. In recent days, a considerable amount of research is being carried out on the synthesis of nanomaterials using green routes. Nanomaterials synthesized by using the green method are now being used in different technologies, including water remediation. The remediation of water by using nanomaterials synthesized by the green method has been reviewed and discussed in this paper.

Rational design of magnetically separable core/shell Fe3O4/ZnO heterostructures for enhanced visible-light photodegradation performance

Magnetically separable core/shell Fe₃O₄/ZnO heteronanostructures (MSCSFZ) were synthesized by a facile approach, and their application for enhanced solar photodegradation of RhB was studied. The formation mechanism of MSCSFZ was proposed, in which Fe₃O₄ nanoparticles served as a template for supporting and anchoring the ZnO crystal layer as the shells. The morphology of MSCSFZ can be varied from spherical to rice seed-like structures, and the bandgap was able to be narrowed down to 2.78 eV by controlling the core–shell ratios. As a result, the MSCSFZ exhibited excellent visible-light photocatalytic activity for degradation of rhodamine B (RhB) in aqueous solution as compared to the controlled ZnO nanoparticles. Moreover, MSCSFZ could be easily detached from RhB solution and maintained its performance after 4 cycles of usage. This work provides new insights for the design of high-efficient core/shell recyclable photocatalysts with visible light photocatalytic performance.

Magnetically separable core/shell Fe₃O₄/ZnO heteronanostructures (MSCSFZ) were synthesized by a facile approach, and their application for enhanced solar photodegradation of RhB was studied.

A comprehensive systematic review of photocatalytic degradation of pesticides using nano TiO2

This study has systematically reviewed all of the research articles about the photocatalytic degradation of pesticides using titanium dioxide (TiO₂) nanoparticles (NPs) and ultraviolet (UV) irradiation. Online databases were searched for peer-reviewed research articles and conference proceedings published during 2009-2019, and ultimately 112 eligible articles were included in the review. Fifty-three active ingredients of pesticides and one mixture had been investigated, most of them were organophosphorus (22%), followed by triazine derivatives (11%), chloropyridines (9%), and organochlorines (9%). Sixteen types of TiO₂ with an average photodegradation efficiency of 71% were determined. Based on the type of pesticide and experimental conditions such as irradiation time, the complete photodegradation had been observed. The removal of each group of pesticides has been sufficiently discussed in the article. Effect of experimental conditions on photocatalytic activity has been investigated using linear and polynomial regressions. The strategies to reduce the required energy for this process, doping TiO₂ with metal and non-metal agents, innovative reactor designs, etc., were also discussed. In conclusion, TiO₂ NPs have been successful for degradation of pesticides. Future direction for research incorporates developing and application of heterogeneous doped and immobilized titania having optimized characteristics such as surface area, reactive centers, recombination rate, and phase, and capable to photo-degrade low levels of pesticides residues under solar light in an efficient full-scale size.

The Photocatalytic Degradation of 2,3,7,8-Tetrachlorodibenzo-p-Dioxin in the Presence of Silver–Titanium Based Catalysts

Polychlorinated dibenzo-p-dioxins (PCDD) are persistent toxic compounds that are ubiquitous in the environment. The photodegradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the presence of silver titanium oxide (AgTi) and silver titanium doped into the Y-zeolite (AgTiY) was tested using high (254 nm) and mid (302 nm) energy UV irradiation sources. AgTi and AgTiY, both showed success in the photodegradation of 2,3,7,8-TCDD dissolved in methanol/tetrahydrofuran solution. Both catalysts were found to effectively decompose TCDD at 302 nm (lower energy) reaching in between 98–99% degradation after five hours, but AgTiY showed better performance than AgTi at 60 min reaching 91% removal. Byproducts of degradation were evaluated using Gas chromatography/mass spectrometry (GC–MS), resulting in 2,3,7-trichlorodibenzo-p-dioxin, a lower chlorinated congener and less toxic, as the main degradation product. Enzyme Linked Immunosorbent Assay (ELISA) was used to evaluate the relative toxicity of the degradation byproducts were a decrease in optical density indicated that some products of degradation could be potentially more toxic than the parent TCDD. On the other hand, a decrease in toxicity was observed for the samples with the highest 2,3,7,8-TCDD degradation, confirming that AgTiY irradiated at 302 nm is an excellent choice for degrading TCDD. This is the first study to report on the efficiency of silver titanium doped zeolites for the removal of toxic organic contaminants such as dioxins and furans from aquatic ecosystems.

Antioxidant Functionalized Nanoparticles: A Combat against Oxidative Stress

Numerous abiotic stresses trigger the overproduction of reactive oxygen species (ROS) that are highly toxic and reactive. These ROS are known to cause damage to carbohydrates, DNA, lipids and proteins, and build the oxidative stress and results in the induction of various diseases. To resolve this issue, antioxidants molecules have gained significant attention to scavenge these free radicals and ROS. However, poor absorption ability, difficulty in crossing the cell membranes and degradation of these antioxidants during delivery are the few challenges associated with both natural and synthetic antioxidants that limit their bioavailability. Moreover, the use of nanoparticles as an antioxidant is overlooked, and is limited to a few nanomaterials. To address these issues, antioxidant functionalized nanoparticles derived from various biological origin have emerged as an important alternative, because of properties like biocompatibility, high stability and targeted delivery. Algae, bacteria, fungi, lichens and plants are known as the producers of diverse secondary metabolites and phenolic compounds with extraordinary antioxidant properties. Hence, these compounds could be used in amalgamation with biogenic derived nanoparticles (NPs) for better antioxidant potential. This review intends to increase our knowledge about the antioxidant functionalized nanoparticles and the mechanism by which antioxidants empower nanoparticles to combat oxidative stress.

Light-Activated Heterostructured Nanomaterials for Antibacterial Applications

An outbreak of a bacterial contagion is a critical threat for human health worldwide. Recently, light-activated heterostructured nanomaterials (LAHNs) have shown potential as antibacterial agents, owing to their unique structural and optical properties. Many investigations have revealed that heterostructured nanomaterials are potential antibacterial agents under light irradiation. In this review, we summarize recent developments of light-activated antibacterial agents using heterostructured nanomaterials and specifically categorized those agents based on their various light harvesters. The detailed antibacterial mechanisms are also addressed. With the achievements of LAHNs as antibacterial agents, we further discuss the challenges and opportunities for their future clinical applications.

Metal-based engineered nanoparticles in the drinking water treatment systems: A critical review

The emergence of nanotechnologically-enabled materials, compounds or products inevitably leads to engineered nanoparticles (ENPs) released into surface waters. ENPs have already been detected in wastewater streams, drinking water sources and even in tap water at concentrations in the ng/L and μg/L range, making the latter a potential route for humans. The presence of ENPs in raw waters raises concerns over the possibility that ENPs might pose a hazard to the quality and security of drinking water and whether drinking water treatment plants (DWTPs) are prepared to handle this problem. Therefore, it is essential to critically evaluate if ENPs can be effectively removed through water treatment processes to control environmental and human health risks associated with their release. This review includes a summary of the available information on production, presence, potential hazards to human health and environment, and release and behaviour of metal-based ENPs in surface waters and drinking water. In addition, the most extensively studied water treatment processes to remove metal-based ENPs, specifically conventional and advanced processes, are discussed and highlighted in detail. Furthermore, this work identifies the research gaps regarding ENPs removal in DWTPs and discusses future aspects of ENPs in water treatment.

Preparation of a Ti0.7W0.3O2/TiO2 nanocomposite interfacial photocatalyst and its photocatalytic degradation of phenol pollutants in wastewater

A Ti_0.7W_0.3O₂/TiO₂ nanocomposite interfacial photocatalyst was designed and prepared for the photocatalytic degradation of phenol pollutants in wastewater. The detailed properties of the Ti_0.7W_0.3O₂/TiO₂ nanocomposite interface (NCI) were analyzed by XRD, SEM, EDX, DRS, UPS and XPS technologies, showing that anatase TiO₂ nanospheres (NSs) were uniformly dispersed on the surface of rutile Ti_0.7W_0.3O₂ nanoparticles (NPs) and formed the nanocomposite interface. The DRS and UPS results of 5 wt% Ti_0.7W_0.3O₂/TiO₂ NCI indicated a greatly broadened light response range with a wavelength shorter than 527 nm and a shorter band gap energy of 2.37 eV. The conduction band of TiO₂ NSs, Ti_0.7W_0.3O₂ NPs and 5 wt% Ti_0.7W_0.3O₂/TiO₂ NCI were measured based on the results of the valence band and band gap energy obtained via XPS and DRS, and then the energy level diagram of Ti_0.7W_0.3O₂/TiO₂ NCI was proposed. The photocatalytic degradation of phenol at Ti_0.7W_0.3O₂/TiO₂ NCI with different loading ratios of Ti_0.7W_0.3O₂ NPs was investigated under optimum conditions (i.e., pH of 4.5, catalyst dosage of 0.45 g L^-1 and phenol initial concentration of 95 ppm) under the illumination of ultraviolet visible light. Also, 5 wt% Ti_0.7W_0.3O₂/TiO₂ NCI exhibited the highest photocatalytic activity, with the initial rate constant (k) calculated as 0.09111 min^-1. After recycling six times, Ti_0.7W_0.3O₂/TiO₂ NCI showed good stability and recyclability. The involvement of superoxide radicals in the initial reaction at Ti_0.7W_0.3O₂/TiO₂ NCI was evidenced by the use of a terephthalic acid (TA) fluorescent probe. Besides, UV-Vis spectroscopy, UHPLC-MS and GC-MS technologies were used to analyze the main intermediates in the photocatalytic degradation of phenol. The probable photocatalytic degradation mechanism of phenol at Ti_0.7W_0.3O₂/TiO₂ NCI was also proposed.

Pathways to Tailor Photocatalytic Performance of TiO2 Thin Films Deposited by Reactive Magnetron Sputtering

TiO₂ thin films are used extensively for a broad range of applications including environmental remediation, self-cleaning technologies (windows, building exteriors, and textiles), water splitting, antibacterial, and biomedical surfaces. While a broad range of methods such as wet-chemical synthesis techniques, chemical vapor deposition (CVD), and physical vapor deposition (PVD) have been developed for preparation of TiO₂ thin films, PVD techniques allow a good control of the homogeneity and thickness as well as provide a good film adhesion. On the other hand, the choice of the PVD technique enormously influences the photocatalytic performance of the TiO₂ layer to be deposited. Three important parameters play an important role on the photocatalytic performance of TiO₂ thin films: first, the different pathways in crystallization (nucleation and growth); second, anatase/rutile formation; and third, surface area at the interface to the reactants. This study aims to provide a review regarding some strategies developed by our research group in recent years to improve the photocatalytic performance of TiO₂ thin films. An innovative approach, which uses thermally induced nanocrack networks as an effective tool to enhance the photocatalytic performance of sputter deposited TiO₂ thin films, is presented. Plasmonic and non-plasmonic enhancement of photocatalytic performance by decorating TiO₂ thin films with metallic nanostructures are also briefly discussed by case studies. In addition to remediation applications, a new approach, which utilizes highly active photocatalytic TiO₂ thin film for micro- and nanostructuring, is also presented.

Ag Nanoparticles/α-Ag2WO4 Composite Formed by Electron Beam and Femtosecond Irradiation as Potent Antifungal and Antitumor Agents

The ability to manipulate the structure and function of promising systems via external stimuli is emerging with the development of reconfigurable and programmable multifunctional materials. Increasing antifungal and antitumor activity requires novel, effective treatments to be diligently sought. In this work, the synthesis, characterization, and in vitro biological screening of pure α-Ag₂WO₄, irradiated with electrons and with non-focused and focused femtosecond laser beams are reported. We demonstrate, for the first time, that Ag nanoparticles/α-Ag₂WO₄ composite displays potent antifungal and antitumor activity. This composite had an extreme low inhibition concentration against Candida albicans, cause the modulation of α-Ag₂WO₄ perform the fungicidal activity more efficient. For tumor activity, it was found that the composite showed a high selectivity against the cancer cells (MB49), thus depleting the populations of cancer cells by necrosis and apoptosis, without the healthy cells (BALB/3T3) being affected.

Photocatalytic and Antimicrobial Properties of Ag2O/TiO2 Heterojunction

Ag2O/TiO2 heterojunctions were prepared by a simple method, i.e., the grinding of argentous oxide with six different titania photocatalysts. The physicochemical properties of the obtained photocatalysts were characterized by diffuse-reflectance spectroscopy (DRS), X-ray powder diffraction (XRD) and scanning transmission electron microscopy (STEM) with an energy dispersive X-ray spectroscopy (EDS). The photocatalytic activity was investigated for the oxidative decomposition of acetic acid and methanol dehydrogenation under UV/vis irradiation and for the oxidative decomposition of phenol and 2-propanol under vis irradiation. Antimicrobial properties were tested for bacteria (Escherichia coli) and fungi (Candida albicans and Penicillium chrysogenum) under UV and vis irradiation and in the dark. Enhanced activity was observed under UV/vis (with synergism for fine anatase-containing samples) and vis irradiation for almost all samples. This suggests a hindered recombination of charge carriers by p-n heterojunction or Z-scheme mechanisms under UV irradiation and photo-excited electron transfer from Ag2O to TiO2 under vis irradiation. Improved antimicrobial properties were achieved, especially under vis irradiation, probably due to electrostatic attractions between the negative surface of microorganisms and the positively charged Ag2O.

Engineering nanomaterials for water and wastewater treatment: review of classifications, properties and applications

Based on their characteristics and applicability, a new category of NMs is proposed for water and wastewater treatment.

TiO2 nanotubes/Ti plates modified by silver–benzene with enhanced photocatalytic antibacterial properties

A novel Ag/Benzene-Mod/TiO₂ nanotubes/Ti plate was fabricated via photo-modification by benzene, followed by electrodeposition of Ag on the TiO₂ nanotubes/Ti plate.

Electrospun CuAl2O4 hollow nanofibers as visible light photocatalyst with enhanced activity and excellent stability under acid and alkali conditions

Electrospun CuAl₂O₄ hollow nanofibers are reported with enhanced visible light photocatalytic activity and excellent stability under acid and alkali conditions.

Wet-Chemical Preparation of TiO₂-Based Composites with Different Morphologies and Photocatalytic Properties

TiO₂-based composites have been paid significant attention in the photocatalysis field. The size, crystallinity and nanomorphology of TiO₂ materials have an important effect on the photocatalytic efficiency. The synthesis and photocatalytic activity of TiO₂-based materials have been widely investigated in past decades. Based on our group’s research works on TiO₂ materials, this review introduces several methods for the fabrication of TiO₂, rare-earth-doped TiO₂ and noble-metal-decorated TiO₂ particles with different morphologies. We focused on the preparation and the formation mechanism of TiO₂-based materials with unique structures including spheres, hollow spheres, porous spheres, hollow porous spheres and urchin-like spheres. The photocatalytical activity of urchin-like TiO₂, noble metal nanoparticle-decorated 3D (three-dimensional) urchin-like TiO₂ and bimetallic core/shell nanoparticle-decorated urchin-like hierarchical TiO₂ are briefly discussed.

Highly-repeatable generation of very small nanoparticles by pulsed-laser ablation in liquids of a high-speed rotating target

Very small and pure Ag nanoparticles are generated by pulsed-laser ablation in water of a silver target rotated at a high-speed.

Single-Step Synthesis of SnS₂ Nanosheet-Decorated TiO₂ Anatase Nanofibers as Efficient Photocatalysts for the Degradation of Gas-Phase Diethylsulfide

We report on a facile one-step soft hydrothermal process for synthesizing 1D anatase TiO2 nanofibers decorated with ultrathin SnS2 nanosheets. H-titanate nanofibers were used as preshaped Ti precursor. Under controlled conditions, the H-titanate structure was transformed into anatase maintaining the fibril morphology, while at the same time SnS2 nanosheets were grown in situ on the surface of the nanofibers. The successful formation of SnS2 nanosheets on the TiO2 nanofibers was confirmed by high-resolution TEM, and together with XPS spectroscopy, the tight interface formed between the SnS2 and the anatase TiO2 nanofibers was verified. The 1D SnS2/TiO2 hierarchical nanostructures with semiconductor heterojunction were proven to be very efficient under artificial solar irradiation in the photocatalytic degradation of gaseous diethylsulfide as simulant for live yperite chemical warfare agent as well as model substrate for malodorous organosulfide volatile organic compounds. SnS2 did not operate as a visible light sensitizer for TiO2 but rather as an oxidizing agent and charge-carrier separator. The semiconductor ratio in the heterostructure controlled the photoactivity. Samples with no or high content of SnS2 were less active than those with moderate SnS2 content. Enhanced reactivity was ascribed to an efficient separation of the photogenerated charge carriers driven by the differences in band edge positions and favored by the tight interface within the coupled heterostructure.

Bimodal sintered silver nanoparticle paste with ultrahigh thermal conductivity and shear strength for high temperature thermal interface material applications

A bimodal silver nanoparticle (AgNP) paste has been synthesized via the simple ultrasonic mixing of two types of unimodal AgNPs (10 and 50 nm in diameter). By sintering this paste at 250 °C for 30 min, we obtained an ultrahigh thermal conductivity of 278.5 W m(-1) K(-1), approximately 65% of the theoretical value for bulk Ag. The shear strength before and after thermal cycling at 50-200 °C for 1000 cycles was approximately 41.80 and 28.75 MPa, respectively. The results show that this excellent performance is attributable to the unique sintered structures inside the bimodal AgNP paste, including its low but stable porosity and the high density coherent twins. In addition, we systematically discuss the sintering behavior of this paste, including the decomposition of the organic layers and the formation of the coherent twins. On the basis of these results, we confirm that our bimodal AgNP paste has excellent potential as a thermal interface material for high temperature power device applications.

Nanosilver as a new generation of silver catalysts in organic transformations for efficient synthesis of fine chemicals

Silver nanoparticles catalysis has been of great interest in organic synthesis and has expanded rapidly in the past ten years because of nanosilver catalysts' unique reactivity and selectivity, stability, as well as recyclability in catalytic reactions.

Template-induced synthesis and superior antibacterial activity of hierarchical Ag/TiO2composites

Hierarchical Ag/TiO₂composites were successfully synthesizedviahydrated magnesium carbonate hydroxide template-induced route, which exhibit superior and long-term antimicrobial activity.