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Quantum dot (QD)-decorated semiconductor micro- and nanoparticles are a new class of functional nanomaterials that have attracted considerable interest for their unique structural, optical and electronic properties that result from the large surface-to-volume ratio and the quantum confinement effect. In addition, because of QDs' excellent light-harvesting capacity, unique photoinduced electron transfer, and up-conversion behaviour, semiconductor nanoparticles decorated with quantum dots have been used widely in photocatalytic applications for the degradation of organic pollutants in both the gas and aqueous phases. This review is a comprehensive overview of the recent progress in synthesis methods for quantum dots and quantum dot-decorated semiconductor composites with an emphasis on their composition, morphology and optical behaviour. Furthermore, various approaches used for the preparation of QD-based composites are discussed in detail with respect to visible and UV light-induced photoactivity. Finally, an outlook on future development is proposed with the goal of overcoming challenges and stimulating further research into this promising field.

The TiO2 modified by monometallic (Au-TiO2, Pt-TiO2) and bimetallic (Pt/Au-TiO2) NPs have been synthesized by a simple sol-gel method. The optimal dosage of individual components in Pt/Au composition on photocatalytic activity has been systematically investigated. The obtained photocatalysts were thoroughly characterized by BET surface area measurements, UV–vis diffuse-reflectance spectroscopy (DRS), X-ray diffraction analysis (XRD), scanning transmission microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity under visible light (λ > 420 nm and λ > 455 nm) has been estimated in phenol degradation reaction in an aqueous phase. The best photocatalytic activity has been observed for −mono (0.5)Pt_TiO2 and bimetallic (0.5)Pt/(0.5)Au_TiO2 samples with an optimum platinum content. The Pt/Au_TiO2 radical formation mechanism was systematically investigated with the selected scavenger for the degradation process under vis light irradiation. The formation of O 2− with (0.5)Pt/(0.5)Au_TiO2 was established from the high inhibition of phenol degradation. Based on the XPS analysis it was observed that the greater photoactivity of bimetallic sample (0.5)Pt/(0.5)Au_TiO2 could result from a relatively higher content of platinum compared to gold on the surface layer. It must be noted that only platinum takes a significant part in Pt/Au composites on the photoactivity. Furthermore, in this work we present a linear relationship between the crystal size of TiO2 and the reaction rate of Au-TiO2, Pt-TiO2 and Pt/Au-TiO2.

The precipitation of calcium carbonate was carried out by passing a gaseous mixture of carbon dioxide and air into a calcium chloride solution. The selected compounds enhancing carbon dioxide absorption were used as additives which promote the formation of carbonate ions in the solution. The additives were ammonia, monoethanolamine, triethylamine and triethanolamine. The resulting calcium carbonate particles varied in polymorphic composition and the particle size depending on the used absorption promoter. When absorption occurred quickly in ammonia or monoethanolamine solutions, the obtained calcium carbonate particles were mainly vaterite. Calcium carbonate particles were precipitated as calcite in triethylamine or triethanolamine solutions, while the rate of carbon dioxide mass transfer from gas to liquid phase was much slower. All precipitated calcium carbonate particles had monomodal particle size distributions. Smaller particles of vaterite were produced in the monoethanolamine solution and of calcite in the triethylamine solution.

In search a hydrogen source, we synthesized TiO2-Cu-graphene composite photocatalyst for hydrogen evolution. The catalyst is a new and unique material as it consists of copper-decorated TiO2 particles covered tightly in graphene and obtained in a fluidized bed reactor. Both, reduction of copper from Cu(CH3COO) at the surface of TiO2 particles and covering of TiO2-Cu in graphene thin layer by Chemical Vapour Deposition (CVD) were performed subsequently in the flow reactor by manipulating the gas composition. Obtained photocatalysts were tested in regard to hydrogen generation from photo-induced water conversion with methanol as sacrificial agent. The hydrogen generation rate for the most active sample reached 2296.27 µmol H2 h−1 gcat−1. Combining experimental and computational approaches enabled to define the optimum combination of the synthesis parameters resulting in the highest photocatalytic activity for water splitting for green hydrogen production. The results indicate that the major factor affecting hydrogen production is temperature of the TiO2-Cu-graphene composite synthesis which in turn is inversely correlated to photoactivity.

In the present investigation, TiO 2 modified with a different geometry and size of gold particles, such as nanospheres (NSPs), nanostars (NSTs) and nanorods (NRs), were prepared by the immobilization method. The effect of the gold shape, size and TiO 2 matrix type (TiO 2 microspheres or rutile TIO-6_TiO 2 ) were systematically investigated. The obtained photocatalysts were thoroughly characterized by UV–vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning electron microscopy (SEM), scanning transmission microscopy (TEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity under visible light (λ > 420 nm) has been estimated in phenol degradation reaction in an aqueous phase. The significantly high photocatalytic activity under visible light irradiate as demonstrated by the TiO 2 sample modified by spheres of gold. The average rate of phenol decomposition was 1.9 μmol dm −3 min −1 and was three-times higher compared to the pristine TiO 2 amorphous microspheres. On the other hand the photocatalytic activity was relatively lower and was 0.38 and 0.27 μmol dm −3 min −1 for nanorods and nanostars deposited on the amorphous form of TiO 2 microspheres, respectively. The visible light activity decreased in following order: (NSPs)> (NRs)> (NSTs). The obtained photocatalytic efficiency of samples was ascribed to the geometry and the size effect of the enhanced and the possible mechanism for this was discussed in detail. Furthermore, in this work we show the effect of calcination temperature on the structure of gold NPs, NRs and NSs before and after modification on the morphology and photocatalytic activity of Au-TiO 2 .

TiO2 (P25) was modified with small and relatively monodisperse mono- and bimetallic clusters (Ag, Pd, Pt, Ag/Pd, Ag/Pt and Pd/Pt) induced by radiolysis to improve its photocatalytic activity. The as-prepared samples were characterized by X-ray fluorescence spectrometry (XRF), photoluminescence spectrometry (PL), diffuse reflectance spectroscopy (DRS), X-ray powder diffractometry (XRD), scanning transition electron microscopy (STEM) and BET surface area analysis. The effect of metal type (mono- and bimetallic modification) as well as deposition method (simultaneous or subsequent deposition of two metals) on the photocatalytic activity in toluene removal in gas phase under UV–vis irradiation (light-emitting diodes- LEDs) and phenol degradation in liquid phase under visible light irradiation (λ > 420 nm) were investigated. The highest photoactivity under Vis light was observed for TiO2 co-loaded with platinum (0.1%) and palladium (0.1%) clusters. Simultaneous addition of metal precursors results in formation of larger metal nanoparticles (15–30 nm) on TiO2 surface and enhances the Vis-induced activity of Ag/Pd-TiO2 up to four times, while the subsequent metal ions addition results in formation of metal particle size ranging from 4 to 20 nm. Subsequent addition of metal precursors results in formation of BNPs (bimetallic nanoparticle) composites showing higher stability in four cycles of toluene degradation under UV–vis. Obtained results indicated that direct electron transfer from the BNPs to the conduction band of the semiconductor is responsible for visible light photoactivity, whereas superoxide radicals (such as O2 − and OOH) are responsible for pollutants degradation over metal-TiO2 composites.

The problem of nosocomial infections is nothing new. In places, where people, whose immune system is weakened, are gathered and subjected to various kinds of treatments, the risk of infection increases considerably. The use of textiles with biocidal finishing, which contains nanoAg and nanoCu, may give an additional protection against nosocominal infections. This article presents the latest information regarding various methods for synthesis, impregnation and immobilization of antibacterial coatings. It also describes the textile biocidal activity depending on the active agents applied and the type of textile used. The textile biocidal properties obtained by the described methods were systematically lost. Therefore, at the end of the article a method, which enables their constant renewing is presented.

Spherical microparticles of TiO2 were synthesized by the ionic liquid-assisted solvothermal method at different reaction times (3, 6, 12, and 24 h). The properties of the prepared photocatalysts were investigated by means of UV-VIS diffuse-reflectance spectroscopy (DRS), Brunauer&ndash, Emmett&ndash, Teller (BET) surface area measurements, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that the efficiency of the phenol degradation was related to the time of the solvothermal synthesis, as determined for the TiO2_EAN(1:1)_24h sample. The microparticles of TiO2_EAN(1:1)_3h that formed during only 3 h of the synthesis time revealed a really high photoactivity under visible irradiation (75%). This value increased to 80% and 82% after 12 h and 24 h, respectively. The photoactivity increase was accompanied by the increase of the specific surface area, thus the poresize as well as the ability to absorb UV-VIS irradiation. The high efficiency of the phenol degradation of the ionic liquid (IL)&ndash, TiO2 photocatalysts was ascribed to the interaction between the surface of the TiO2 and ionic liquid components (carbon and nitrogen).

Spherical microparticles of TiO2 were synthesized by the ionic liquid-assisted solvothermal method at different reaction time (3, 6, 12 and 24h). The properties of the prepared photocatalysts were investigated by means of UV-vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning electron microscopy (SEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). The results indicated that the efficiency of phenol degradation was related with a time of the solvothermal synthesis as determined for TiO2_EAN(1:1)_24h sample. Microparticles of TiO2_EAN(1:1)_3h formed during the only 3h of synthesis time revealed really high photoactivity under visible irradiation – 75%. This value increased to 80% and 82% after 12h and 24h, respectively. The photoactivity increase was accompanied by the increase of the specific surface area thus pores size, as well as ability to absorb UV-vis irradiation. The high efficiency of phenol degradation of IL-TiO2 photocatalysts was ascribed to the interaction between the surface of TiO2 and ionic liquid components (carbon and nitrogen).

In this paper, the experimental studies are concerned with the effect of the synthesis parameters on the formation of monometallic Ag and Cu nanoparticles (NPs). We consider the synthesis strategies verification for the bimetallic core-shell and alloy particles preparation. It was successfully obtained by chemical reduction method. The obtained colloidal solution is characterized by the transmission electron microscopy (TEM) with energy-dispersive X-ray spectroscopy (EDX) data, UV-Vis spectra, particle size distribution, and zeta potential. This work presents a comprehensive overview of experimental studies of the most stable colloidal solutions to impregnate fabrics that will exhibit a bactericidal and fungicidal activity againstCandida albicans,Escherichia coli, andStaphylococcus aureus.

Photocatalysis is the change in the rate of reaction caused by light in the presence of a photocatalyst that absorbs light and is involved in the chemical transformation of the reactants. Heterogeneous photocatalysis is based mainly on semiconductor materials such as chalcogenides and metal oxides. Transition metal oxides and mixed oxides are the largest and most important groups of photocatalytic materials. This chapter discusses the photocatalytic reaction mechanisms of metal oxide semiconductors, the semiconductor bandgap structure, and the kinetics of photocatalysis.

TiO 2 modified with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles have been prepared using a water-in-oil microemulsion system (water/AOT/cyclohexane) followed by calcination step. The effect of metal ratio, reducing agent type (NaBH 4 or N 2 H 4 ), TiO 2 matrix type (P-25, ST-01, TiO-5, TiO 2 nanotubes or TiO 2 obtained by TIP hydrolysis) as well as calcination temperature (from 350 to 650 °C) were systematically investigated. Obtained photocatalysts were characterized by UV–vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning transmission microscopy (STEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity under visible light ( λ > 420 nm) has been estimated in phenol degradation reaction in aqueous phase. The results showed that phenol degradation rate under visible light in the presence of TiO 2 loaded with Au/Pt nanoparticles differed from 0.7 to 2.2 μmol dm −3 min −1 for samples prepared using different reducing agent. Sodium borohydride (NaBH 4 ) favors formation of smaller Au/Pt nanoparticles and higher amount gold in Au/Pt is in the form of electronegative species (Au δ − ) resulted in higher photoactivity. TiO 2 obtained by TIP hydrolysis in microemulsion system seems to be the best support for Au/Pt nanoparticles from all among investigated matrix. It was also observed that enhancement of calcination temperature from 450 to 650 °C resulted in rapid drop of Au/Pt-TiO 2 photoactivity under visible light due to surface area shrinkage, crystal structure change and probably change in Au/Pt nanoparticles morphology.

Ionic liquids (ILs) could serve as a structuring agent, a solvent, or a source of dopant during solvothermal synthesis of semiconductors particles. To understand the role of IL during formation of TiO2 particles, it is necessary to study the stability of this IL in solvothermal synthesis conditions, as well as studying the surface properties of formed TiO2 particles. In view of this, the effect of the 2,3,5-triphenyltetrazolium chloride IL ([TPTZ][Cl]) thermal decomposition during the solvothermal reaction and IL content in the reaction system on photoactivity of TiO2 microparticles has been systematically investigated. The samples obtained by using [TPTZ][Cl] exhibited remarkable photocatalytic properties in phenol degradation reaction under visible light. HPLC analysis of the solvothermal reaction medium and X-ray photoelectron spectroscopy (XPS) analysis of TiO2 particles revealed that [TPTZ][Cl] was decomposed completely and was incorporated into the TiO2 lattice. Generally, increasing the reaction time (1, 4, 12, and 24 h) promoted the TiO2 microspheres formation, as well as raising the visible light-induced photocatalytic activity of the photocatalysts. Longer reaction time was also accompanied by an increase in the efficiency of 2,3,5-triphenyltetrazolium chloride decomposition. The properties of the photocatalysts were investigated by means of UV-VIS diffuse reflectance spectroscopy (DRS), BET surface area measurements, scanning electron microscopy (SEM), X-ray powder diffraction (XRD) analysis, and XPS.

We reported a preparation and characterization of five kinds of impregnation solutions, containing Ag/Cu in the form of bimetallic nanoparticles (alloy and core-shell) as well as ionic species. The cotton-polyester textiles were successfully impregnated during the washing and ironing process by as-prepared solutions to have antibacterial and antifungal properties against toEscherichia coli,Staphylococcus aureus,andCandida albicans. Moreover, we have reported the effect of type of the fabric used and number of washing/impregnation cycles (in a laboratory scale) on the bactericidal and fungicidal activity of obtained textiles. The results indicated that all tested samples after 5, 10, 15, and 20 washing/impregnated cycles exhibited an antimicrobial activity. The antifungal tests showed that only textile impregnated with solutions containing Ag+/Cu2+and Ag NPs/Cu2+exhibited a strong inhibition of fungi growth of the after 5 (99.99%) and 15 (100%) washing/impregnation cycles, respectively.

Titanium dioxide modified with silver-gold bimetallic nanoparticles were prepared by simultaneously formationof Ag/Au and TiO 2 nanoparticles in water-in-oil microemulsion system (water/AOT/cyclohexane). Silver nitrate(AgNO 3 ) and tetrachloroauric(III) acid (HAuCl 4 ) were taken as the precursors and sodium borohydride (NaBH 4 )was used as a reducing agent. The photocatalysts samples were characterized by X-ray powder diffraction (XRD),BET surface area measurements, scanning electron microscopy (SEM) and energy dispersive spectroscopyanalysis (EDS). The photocatalytic activity of bimetallic nanoparticles deposited at the TIP-TiO 2 surface undervisible light irradiation was estimated by measuring the decomposition rate of phenol in aqueous solution. Thehighest photocatalytic activity was obtained for the photocatalyst containing 1.5 mol % of silver and 0.5 mol %of gold. Introduction Bimetallic nanoparticles with core-shell, hetero-structure or intermetallic and alloy structures (1) inwhich two kinds of metals are contained in one particleare of greater interest than monometallic nanoparticles.They are expected to display not only the combinationof the properties associated with two distinct metals,but also new properties due to a synergy between twometals. Bimetallic nanoparticles reveal unique catalytic,magnetic, electronic, optical and structural propertiesas well as posses subsequent technological applicationas catalysts, sensors, nanoelectronic devices, bio-medical tools and biosensors (2). Compared withmonometallic nanoparticles, preparation of bimetallicnanocomposites is much more complicated anddifficult to achieve. Bimetallic colloids can be preparedby simultaneous co-reduction of two kinds of metalions with or without the protective agent (usually apolymer or a surfactant) or by successive reduction ofone metal over the nuclei of another. Mizukoshi et al.(3) prepared bimetallic Au/Pd nanoparticles depositedon TiO